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District heating (also known as heat networks or teleheating) is a system for distributing heat generated in a centralized location through a system of
insulated pipe Insulated pipes (called also preinsulated pipes or bonded pipe ) are widely used for district heating and hot water supply. They consist of a steel pipe called "service pipe", a thermal insulation layer and an outer casing. The main purpose of suc ...
s for residential and commercial heating requirements such as
space heating Heating, ventilation, and air conditioning (HVAC) is the use of various technologies to control the temperature, humidity, and purity of the air in an enclosed space. Its goal is to provide thermal comfort and acceptable indoor air quality. HV ...
and
water heating Water heating is a heat transfer process that uses an energy source to heat water above its initial temperature. Typical domestic uses of hot water include cooking, cleaning, bathing, and space heating. In industry, hot water and water heated t ...
. The heat is often obtained from a
cogeneration Cogeneration or combined heat and power (CHP) is the use of a heat engine or power station to generate electricity and useful heat at the same time. Cogeneration is a more efficient use of fuel or heat, because otherwise- wasted heat from elect ...
plant burning fossil fuels or
biomass Biomass is plant-based material used as a fuel for heat or electricity production. It can be in the form of wood, wood residues, energy crops, agricultural residues, and waste from industry, farms, and households. Some people use the terms bi ...
, but
heat-only boiler station A heating plant, also called a physical plant, or steam plant, generates thermal energy in the form of steam for use in district heating applications. Unlike combined heat and power installations which produce thermal energy as a by-product ...
s,
geothermal heating Geothermal heating is the direct use of geothermal energy for some heating applications. Humans have taken advantage of geothermal heat this way since the Paleolithic era. Approximately seventy countries made direct use of a total of 270 PJ o ...
,
heat pump A heat pump is a device that can heat a building (or part of a building) by transferring thermal energy from the outside using a refrigeration cycle. Many heat pumps can also operate in the opposite direction, cooling the building by removing h ...
s and
central solar heating Central solar heating is the provision of central heating and hot water from solar energy by a system in which the water is heated centrally by arrays of solar thermal collectors (central solar heating plants - CSHPs) and distributed through distr ...
are also used, as well as heat waste from factories and
nuclear power Nuclear power is the use of nuclear reactions to produce electricity. Nuclear power can be obtained from nuclear fission, nuclear decay and nuclear fusion reactions. Presently, the vast majority of electricity from nuclear power is produced b ...
electricity generation. District heating plants can provide higher efficiencies and better pollution control than localized boilers. According to some research, district heating with combined heat and power (CHPDH) is the cheapest method of cutting carbon emissions, and has one of the lowest carbon footprints of all fossil generation plants. Fifth-generation district heat networks do not use combustion on-site and have zero emissions of CO and NO on-site; they employ heat transfer using electricity, which may be generated from renewable energy or from remote fossil-fuelled power stations. A combination of CHP and centralized heat pumps is used in the Stockholm multi-energy system. This allows the production of heat through electricity when there is an abundance of intermittent power production, and cogeneration of electric power and district heating when the availability of intermittent power production is low. District heating is ranked number 27 in
Project Drawdown Climate drawdown refers to the future point in time when levels of greenhouse gas concentrations in the atmosphere stop climbing and start to steadily decline. Drawdown is a milestone in reversing climate change and eventually reducing global ave ...
's 100 solutions to
global warming In common usage, climate change describes global warming—the ongoing increase in global average temperature—and its effects on Earth's climate system. Climate change in a broader sense also includes previous long-term changes to E ...
.


History

District heating traces its roots to the hot water-heated baths and greenhouses of the ancient
Roman Empire The Roman Empire ( la, Imperium Romanum ; grc-gre, Βασιλεία τῶν Ῥωμαίων, Basileía tôn Rhōmaíōn) was the post-Republican period of ancient Rome. As a polity, it included large territorial holdings around the Mediterr ...
. A hot water distribution system in
Chaudes-Aigues Chaudes-Aigues (; oc, Chaudas Aigas, ) is a commune in the Cantal department in south-central France. It is a spa town, famous for its hot spring waters. Geography The commune is situated in the Massif Central in Aubrac. Its inhabitants are ca ...
in France is generally regarded as the first real district heating system. It used geothermal energy to provide heat for about 30 houses and started operation in the 14th century. The
U.S. Naval Academy The United States Naval Academy (US Naval Academy, USNA, or Navy) is a United States Service academies, federal service academy in Annapolis, Maryland. It was established on 10 October 1845 during the tenure of George Bancroft as Secretary of ...
in
Annapolis Annapolis ( ) is the capital city of the U.S. state of Maryland and the county seat of, and only incorporated city in, Anne Arundel County. Situated on the Chesapeake Bay at the mouth of the Severn River, south of Baltimore and about east o ...
began
steam Steam is a substance containing water in the gas phase, and sometimes also an aerosol of liquid water droplets, or air. This may occur due to evaporation or due to boiling, where heat is applied until water reaches the enthalpy of vaporization ...
district heating service in 1853. Although these and numerous other systems have operated over the centuries, the first commercially successful district heating system was launched in Lockport,
New York New York most commonly refers to: * New York City, the most populous city in the United States, located in the state of New York * New York (state), a state in the northeastern United States New York may also refer to: Film and television * '' ...
, in 1877 by American hydraulic engineer
Birdsill Holly Birdsill Holly Jr. (November 8, 1820 – April 27, 1894) was an American mechanical engineer and inventor of water hydraulics devices. He is known for inventing mechanical devices that improved city water systems and patented an improved fire hy ...
, considered the founder of modern district heating.


Generations of district heating

Generally, all modern district heating system are demand driven, meaning that the heat supplier reacts to the demand from the consumers and ensures that there is sufficient temperature and water pressure to deliver the demanded heat to the users. The five generations have defining features that sets them apart from the prior generations. The feature of each generation can be used to give an indication of the development status of an existing district heating system.


First generation

The first generation was a steam-based system fueled by
coal Coal is a combustible black or brownish-black sedimentary rock, formed as rock strata called coal seams. Coal is mostly carbon with variable amounts of other elements, chiefly hydrogen, sulfur, oxygen, and nitrogen. Coal is formed when dea ...
and was first introduced in the US in the 1880s and became popular in some European countries, too. It was state of the art until the 1930s and used concrete ducts, operated with very high temperatures and was therefore not very efficient. There were also problems with reliability and safety due to the hot pressurized steam tubes. Nowadays, this generation is technologically outdated. However, some of these systems are still in use, for example in New York or Paris. Other systems originally built have subsequently been converted to later generations.


Second generation

The second generation was developed in the 1930s and was built until the 1970s. It burned coal and oil, and the energy was transmitted through pressurized hot water as the heat carrier. The systems usually had supply temperatures above 100 °C, and used water pipes in concrete ducts, mostly assembled on site, and heavy equipment. A main reason for these systems was the primary energy savings, which arose from using combined heat and power plants. While also used in other countries, typical systems of this generation were the Soviet-style district heating systems that were built after WW2 in several countries in Eastern Europe.


Third generation

In the 1970s the third generation was developed and was subsequently used in most of the following systems all over the world. This generation is also called the "Scandinavian district heating technology", because many of the district heating component manufacturers are based in Scandinavia. The third generation uses prefabricated, pre-insulated pipes, which are directly buried into the ground and operates with lower temperatures, usually below 100 °C. A primary motivation for building these systems was security of supply by improving the
energy efficiency Energy efficiency may refer to: * Energy efficiency (physics), the ratio between the useful output and input of an energy conversion process ** Electrical efficiency, useful power output per electrical power consumed ** Mechanical efficiency, a ra ...
after the two oil crises led to disruption of the oil supply. Therefore, those systems usually used coal, biomass and waste as energy sources, in preference to oil. In some systems,
geothermal energy Geothermal energy is the thermal energy in the Earth's crust which originates from the formation of the planet and from radioactive decay of materials in currently uncertain but possibly roughly equal proportions. The high temperature and pres ...
and
solar energy Solar energy is radiant light and heat from the Sun that is harnessed using a range of technologies such as solar power to generate electricity, solar thermal energy (including solar water heating), and solar architecture. It is an essenti ...
are also used in the energy mix. For example, Paris has been using
geothermal heating Geothermal heating is the direct use of geothermal energy for some heating applications. Humans have taken advantage of geothermal heat this way since the Paleolithic era. Approximately seventy countries made direct use of a total of 270 PJ o ...
from a 55–70 °C source 1–2 km below the surface since the 1970s for domestic heating.


Fourth generation

Currently, the fourth generation is being developed, with the transition to 4th generation already in process in
Denmark ) , song = ( en, "King Christian stood by the lofty mast") , song_type = National and royal anthem , image_map = EU-Denmark.svg , map_caption = , subdivision_type = Sovereign state , subdivision_name = Danish Realm, Kingdom of Denmark ...
. The fourth generation is designed to combat climate change and integrate high shares of variable renewable energy into the district heating by providing high flexibility to the electricity system. According to the review by Lund et al. those systems have to have the following abilities: * "1. Ability to supply low-temperature district heating for space heating and domestic hot water (DHW) to existing buildings, energy-renovated existing buildings and new low-energy buildings." * "2. Ability to distribute heat in networks with low grid losses." * "3. Ability to recycle heat from low-temperature sources and integrate renewable heat sources such as solar and geothermal heat." * "4. Ability to be an integrated part of smart energy systems (i.e. integrated smart electricity, gas, fluid and thermal grids) including being an integrated part of 4th Generation District Cooling systems." * "5. Ability to ensure suitable planning, cost and motivation structures in relation to the operation as well as to strategic investments related to the transformation into future sustainable energy systems". Compared to the previous generations the temperature levels have been reduced to increase the energy efficiency of the system, with supply side temperatures of 70 °C and lower. Potential heat sources are waste heat from industry, CHP plants burning waste, biomass power plants, geothermal and solar thermal energy (
central solar heating Central solar heating is the provision of central heating and hot water from solar energy by a system in which the water is heated centrally by arrays of solar thermal collectors (central solar heating plants - CSHPs) and distributed through distr ...
), large scale
heat pump A heat pump is a device that can heat a building (or part of a building) by transferring thermal energy from the outside using a refrigeration cycle. Many heat pumps can also operate in the opposite direction, cooling the building by removing h ...
s, waste heat from cooling purposes and
data center A data center (American English) or data centre (British English)See spelling differences. is a building, a dedicated space within a building, or a group of buildings used to house computer systems and associated components, such as telecommunic ...
s and other sustainable energy sources. With those energy sources and large scale
thermal energy storage Thermal energy storage (TES) is achieved with widely different technologies. Depending on the specific technology, it allows excess thermal energy to be stored and used hours, days, months later, at scales ranging from the individual process, ...
, including
seasonal thermal energy storage Seasonal thermal energy storage (STES), also known as inter-seasonal thermal energy storage, is the storage of heat or cold for periods of up to several months. The thermal energy can be collected whenever it is available and be used whenever nee ...
, fourth generation district heating systems are expected to provide flexibility for balancing
wind Wind is the natural movement of air or other gases relative to a planet's surface. Winds occur on a range of scales, from thunderstorm flows lasting tens of minutes, to local breezes generated by heating of land surfaces and lasting a few hou ...
and
solar power Solar power is the conversion of energy from sunlight into electricity, either directly using photovoltaics (PV) or indirectly using concentrated solar power. Photovoltaic cells convert light into an electric current using the photovoltaic e ...
generation, for example by using heat pumps to integrate surplus electric power as heat when there is much wind energy or providing electricity from biomass plants when back-up power is needed. Therefore, large scale heat pumps are regarded as a key technology for smart energy systems with high shares of
renewable energy Renewable energy is energy that is collected from renewable resources that are naturally replenished on a human timescale. It includes sources such as sunlight, wind, the movement of water, and geothermal heat. Although most renewable energy ...
up to 100% and advanced fourth generation district heating systems.


Fifth generation/cold district heating

A fifth generation district heating and cooling network (5GDHC), also called ''cold district heating'', distributes heat at near ambient ground temperature: this in principle minimizes heat losses to the ground and reduces the need for extensive insulation. Each building on the network uses a heat pump in its own plant room to extract heat from the ambient circuit when it needs heat, and uses the same heat pump in reverse to reject heat when it needs cooling. In periods of simultaneous cooling and heating demands this allows waste heat from cooling to be used in heat pumps at those buildings which need heating. The overall temperature within the ambient circuit is preferably controlled by heat exchange with an aquifer or another low temperature water source to remain within a temperature range from 10 °C to 25 °C. While network piping for ambient ground temperature networks is less expensive to install per pipe diameter than in earlier generations, as it does not need the same degree of insulation for the piping circuits, it has to be kept in mind that the lower temperature difference of the pipe network leads to significantly larger pipe diameters than in prior generations. Due to the requirement of each connected building in the fifth generation district heating and cooling systems to have their own heat pump the system can be used both as a heat source or a heat sink for the heat pump, depending on if it is operated in a heating and cooling mode. As with prior generations the pipe network is an infrastructure that in principle provides an open access for various low temperature heat sources, such as ambient heat, ambient water from rivers, lakes, sea, or lagoons, and waste heat from industrial or commercial sources. Based on the above description it is clear that there is a fundamental difference between the 5GDHC and the prior generations of district heating, particularly in the individualization of the heat generation. This critical system has a significant impact when comparing the efficiencies between the different generations, as the individualization of the heat generation moves the comparison from being a simple distribution system efficiency comparison to a supply system efficiency comparison, where both the heat generation efficiency as well as the distribution system efficiency needs to be included. A modern building with a low-temperature internal heat distribution system can install an efficient heat pump delivering heat output at 45 °C. An older building with a higher-temperature internal distribution system e.g. using radiators will require a high-temperature heat pump to deliver heat output. A larger example of a fifth generation heating and cooling grid is Mijnwater in Heerlen, the Netherlands. In this case the distinguishing feature is a unique access to an abandoned water-filled coal mine within the city boundary that provides a stable heat source for the system. A fifth generation network ("Balanced Energy Network", BEN) was installed in 2016 at two large buildings of the London South Bank University as a research and development project.


Heat sources

District heating networks exploit various energy sources, sometimes indirectly through multipurpose infrastructure such as
combined heat and power Cogeneration or combined heat and power (CHP) is the use of a heat engine or power station to generate electricity and useful heat at the same time. Cogeneration is a more efficient use of fuel or heat, because otherwise- wasted heat from elect ...
plants (CHP, also called co-generation).


Combustion of fossil or renewable fuels

The most used energy source for district heating is the burning of
hydrocarbons In organic chemistry, a hydrocarbon is an organic compound consisting entirely of hydrogen and carbon. Hydrocarbons are examples of group 14 hydrides. Hydrocarbons are generally colourless and hydrophobic, and their odors are usually weak or ex ...
. As the supply of renewable fuels is insufficient, the fossil fuels
coal Coal is a combustible black or brownish-black sedimentary rock, formed as rock strata called coal seams. Coal is mostly carbon with variable amounts of other elements, chiefly hydrogen, sulfur, oxygen, and nitrogen. Coal is formed when dea ...
and
gas Gas is one of the four fundamental states of matter (the others being solid, liquid, and plasma). A pure gas may be made up of individual atoms (e.g. a noble gas like neon), elemental molecules made from one type of atom (e.g. oxygen), or ...
are massively used for district heating. This burning of fossil hydrocarbons usually contributes to
climate change In common usage, climate change describes global warming—the ongoing increase in global average temperature—and its effects on Earth's climate system. Climate change in a broader sense also includes previous long-term changes to E ...
, as the use of systems to capture and store the CO2 instead of releasing it into the atmosphere is rare. In the case of a cogeneration plant, the heat output is typically sized to meet half of the peak winter heat load, but over the year will provide 90% of the heat supplied. Much of the heat produced in summer will generally be wasted. The boiler capacity will be able to meet the entire heat demand unaided and can cover for breakdowns in the cogeneration plant. It is not economic to size the cogeneration plant alone to be able to meet the full heat load. In the
New York City steam system The New York City steam systems include Con Edison, Con Edison's Steam Operations, and other smaller systems that provide steam to New York University and Columbia University. Many individual buildings in New York City, New York have their ow ...
, that is around 2.5 GW. Germany has the largest amount of CHP in Europe. A simple
thermal power station A thermal power station is a type of power station in which heat energy is converted to electrical energy. In a steam-generating cycle heat is used to boil water in a large pressure vessel to produce high-pressure steam, which drives a stea ...
can be 20–35% efficient, whereas a more advanced facility with the ability to recover waste heat can reach total energy efficiency of nearly 80%. Some may approach 100% based on the
lower heating value The heating value (or energy value or calorific value) of a substance, usually a fuel or food (see food energy), is the amount of heat released during the combustion of a specified amount of it. The ''calorific value'' is the total energy relea ...
by condensing the flue gas as well.


Nuclear fission

The heat produced by
nuclear chain reaction In nuclear physics, a nuclear chain reaction occurs when one single nuclear reaction causes an average of one or more subsequent nuclear reactions, thus leading to the possibility of a self-propagating series of these reactions. The specific nu ...
s can be injected into district heating networks. This does not contaminate the district pipes with radioactive elements, as the heat is transferred to the network through
heat exchanger A heat exchanger is a system used to transfer heat between a source and a working fluid. Heat exchangers are used in both cooling and heating processes. The fluids may be separated by a solid wall to prevent mixing or they may be in direct contac ...
s. It is not technically necessary for the nuclear reactor to be very close to the district heating network, as heat can be transported over significant distances (exceeding 200 km) with affordable losses, using
insulated pipe Insulated pipes (called also preinsulated pipes or bonded pipe ) are widely used for district heating and hot water supply. They consist of a steel pipe called "service pipe", a thermal insulation layer and an outer casing. The main purpose of suc ...
s. Since nuclear reactors do not significantly contribute to either
air pollution Air pollution is the contamination of air due to the presence of substances in the atmosphere that are harmful to the health of humans and other living beings, or cause damage to the climate or to materials. There are many different types ...
or
global warming In common usage, climate change describes global warming—the ongoing increase in global average temperature—and its effects on Earth's climate system. Climate change in a broader sense also includes previous long-term changes to E ...
, they can be an advantageous alternative to the combustion of fossil hydrocarbons. However, only a small minority of the nuclear reactors currently in operation around the world are connected to a district heating network. These reactors are in Bulgaria, China, Hungary, Romania, Russia, Slovakia, Slovenia, Switzerland and Ukraine. The Ågesta Nuclear Power Plant in Sweden was an early example of nuclear cogeneration, providing small quantities of both heat and electricity to a suburb of the country's capital between 1964 and 1974. The
Beznau Nuclear Power Plant The Beznau nuclear power plant (german: Kernkraftwerk Beznau ''KKB is a nuclear power plant of the Swiss energy utility Axpo, located in the municipality Döttingen, Canton of Aargau, Switzerland, on an artificial island in the Aar river. The ...
in Switzerland has been generating electricity since 1969 and supplying district heating since 1984. The
Haiyang Nuclear Power Plant Haiyang Nuclear Power Plant is a nuclear power plant in Haiyang, Shandong province, China. It is the second site to house AP1000 units, after the Sanmen Nuclear Power Station. History Groundbreaking happened one month ahead of schedule on July& ...
in China started operating in 2018 and started supplying small scale heat to the Haiyang city area in 2020. By November 2022, the plant used 345 MW-thermal effect to heat 200,000 homes, replacing 12 coal heating plants. Recent years have seen renewed interest in
small modular reactors Small modular reactors (SMRs) are a proposed class of nuclear fission reactors, smaller than conventional nuclear reactors, which can be built in one location (such as a factory), then shipped, commissioned, and operated at a separate site. The ...
(SMRs) and their potential to supply district heating. Speaking on the
Energy Impact Center The Energy Impact Center is an American research institute based in Washington, D.C. It primarily advocates for the expansion of nuclear power as a clean energy solution to climate change. The organization's research into nuclear power has led it ...
's (EIC) podcast, ''
Titans of Nuclear ''Titans of Nuclear'' is an interview podcast developed by the Energy Impact Center. Each episode features interviews led by Bret Kugelmass. Other hosts include Jadwiga Najder, Olubunmi Olajide, and Naomi Senehi. Guests generally include nuclear ...
'', principal engineer at
GE Hitachi Nuclear Energy GE Hitachi Nuclear Energy (GEH) is a provider of advanced reactors and nuclear services. It is headquartered in Wilmington, North Carolina, United States. Established in June 2007, GEH is a nuclear alliance created by General Electric and Hitac ...
Christer Dahlgren noted that district heating could be the impetus for the construction of new nuclear power plants in the future. EIC's own open-source SMR blueprint design,
OPEN100 OPEN100 is a project that publishes open-source blueprints to build nuclear power plants. Its stated goal is to reduce the cost and duration of nuclear reactor construction and increase the nuclear power supply 100-fold by 2040 to aid in the decar ...
, could be incorporated into a district heating system.


Natural underground heat

History Geothermal district heating was used in
Pompeii Pompeii (, ) was an ancient city located in what is now the ''comune'' of Pompei near Naples in the Campania region of Italy. Pompeii, along with Herculaneum and many villas in the surrounding area (e.g. at Boscoreale, Stabiae), was buried ...
, and in
Chaudes-Aigues Chaudes-Aigues (; oc, Chaudas Aigas, ) is a commune in the Cantal department in south-central France. It is a spa town, famous for its hot spring waters. Geography The commune is situated in the Massif Central in Aubrac. Its inhabitants are ca ...
since the 14th Century. United States Direct use geothermal district heating systems, which tap geothermal reservoirs and distribute the hot water to multiple buildings for a variety of uses, are uncommon in the United States, but have existed in America for over a century. In 1890, the first wells were drilled to access a hot water resource outside of Boise, Idaho. In 1892, after routing the water to homes and businesses in the area via a wooden pipeline, the first geothermal district heating system was created. As of a 2007 study, there were 22 geothermal district heating systems (GDHS) in the United States. As of 2010, two of those systems have shut down. The table below describes the 20 GDHS currently operational in America.


Solar heat

Use of solar heat for district heating has been increasing in Denmark and Germany in recent years. The systems usually include inter
seasonal thermal energy storage Seasonal thermal energy storage (STES), also known as inter-seasonal thermal energy storage, is the storage of heat or cold for periods of up to several months. The thermal energy can be collected whenever it is available and be used whenever nee ...
for a consistent heat output day to day and between summer and winter. Good examples are in
Vojens Vojens (german: Woyens) is a railway town in Denmark with a population of 7,475 (1 January 2022).Dronninglund Dronninglund is a town with a population of 3,487 (1 January 2022)Drake Landing Solar Community The Drake Landing Solar Community (DLSC) is a planned community in Okotoks, Alberta, Canada, equipped with a central solar heating system and other energy efficient technologies. This heating system is the first of its kind in North America, altho ...
has achieved a world record 97% annual solar fraction for heating needs, using solar-thermal panels on the garage roofs and thermal storage in a borehole cluster.


Low temperature natural or waste heat

In Stockholm, the first heat pump was installed in 1977 to deliver district heating sourced from IBM servers. Today the installed capacity is about 660 MW heat, utilizing treated sewage water, sea water, district cooling, data centers and grocery stores as heat sources. Another example is the Drammen Fjernvarme District Heating project in Norway which produces 14 MW from water at just 8 °C, industrial heat pumps are demonstrated heat sources for district heating networks. Among the ways that industrial heat pumps can be utilized are: # As the primary base load source where water from a low grade source of heat, e.g. a river, fjord,
data center A data center (American English) or data centre (British English)See spelling differences. is a building, a dedicated space within a building, or a group of buildings used to house computer systems and associated components, such as telecommunic ...
, power station outfall, sewage treatment works outfall (all typically between 0 ˚C and 25 ˚C), is boosted up to the network temperature of typically 60 ˚C to 90 ˚C using
heat pump A heat pump is a device that can heat a building (or part of a building) by transferring thermal energy from the outside using a refrigeration cycle. Many heat pumps can also operate in the opposite direction, cooling the building by removing h ...
s. These devices, although consuming electricity, will transfer a heat output three to six times larger than the amount of electricity consumed. An example of a district system using a heat pump to source heat from raw sewage is in Oslo, Norway that has a heat output of 18 MW(thermal). # As a means of recovering heat from the cooling loop of a power plant to increase either the level of flue gas heat recovery (as the district heating plant return pipe is now cooled by the heat pump) or by cooling the closed steam loop and artificially lowering the condensing pressure and thereby increasing the electricity generation efficiency. # As a means of cooling flue gas scrubbing working fluid (typically water) from 60 ˚C post-injection to 20 ˚C pre-injection temperatures. Heat is recovered using a heat pump and can be sold and injected into the network side of the facility at a much higher temperature (e.g. about 80 ˚C). # Where the network has reached capacity, large individual load users can be decoupled from the hot feed pipe, say 80 ˚C and coupled to the return pipe, at e.g. 40 ˚C. By adding a heat pump locally to this user, the 40 ˚C pipe is cooled further (the heat being delivered into the heat pump evaporator). The output from the heat pump is then a dedicated loop for the user at 40 ˚C to 70 ˚C. Therefore, the overall network capacity has changed as the total temperature difference of the loop has varied from 80 to 40 ˚C to 80 ˚C–x (x being a value lower than 40 ˚C). Concerns have existed about the use of hydrofluorocarbons as the working fluid (refrigerant) for large heat pumps. Whilst leakage is not usually measured, it is generally reported to be relatively low, such as 1% (compared to 25% for supermarket cooling systems). A 30-megawatt heatpump could therefore leak (annually) around 75 kg of R134a or other working fluid. Given the high
global warming potential Global warming potential (GWP) is the heat absorbed by any greenhouse gas in the atmosphere, as a multiple of the heat that would be absorbed by the same mass of carbon dioxide (). GWP is 1 for . For other gases it depends on the gas and the time f ...
of some HFCs, this could equate to over of car travel per year. However, recent technical advances allow the use of natural heat pump refrigerants that have very low global warming potential (GWP). CO2 refrigerant (R744, GWP=1) or ammonia (R717, GWP=0) also have the benefit, depending on operating conditions, of resulting in higher heat pump efficiency than conventional refrigerants. An example is a 14 MW(thermal) district heating network in
Drammen Drammen () is a city and municipality in Viken (county), Viken, Norway. The port and river city of Drammen is centrally located in the south-eastern and most populated part of Norway. Drammen municipality also includes smaller towns and village ...
, Norway, which is supplied by seawater-source heatpumps that use R717 refrigerant, and has been operating since 2011. 90 °C water is delivered to the district loop (and returns at 65 °C). Heat is extracted from seawater (from depth) that is 8 to 9 °C all year round, giving an average
coefficient of performance The coefficient of performance or COP (sometimes CP or CoP) of a heat pump, refrigerator or air conditioning system is a ratio of useful heating or cooling provided to work (energy) required. Higher COPs equate to higher efficiency, lower energy ( ...
(COP) of about 3.15. In the process the seawater is chilled to 4 °C; however, this resource is not utilized. In a district system where the chilled water could be utilized for air conditioning, the effective COP would be considerably higher.Hoffman, & Pearson, D. 2011
Ammonia heat pumps for district heating in Norway 7 – a case study
. Presented at Institute of Refrigeration, 7 April, London.
In the future, industrial
heat pump A heat pump is a device that can heat a building (or part of a building) by transferring thermal energy from the outside using a refrigeration cycle. Many heat pumps can also operate in the opposite direction, cooling the building by removing h ...
s will be further de-carbonised by using, on one side, excess renewable electrical energy (otherwise spilled due to meeting of grid demand) from wind, solar, etc. and, on the other side, by making more of renewable heat sources (lake and ocean heat, geothermal, etc.). Furthermore, higher efficiency can be expected through operation on the high voltage network.


Heat accumulators and storage

Increasingly large heat stores are being used with district heating networks to maximise efficiency and financial returns. This allows cogeneration units to be run at times of maximum electrical tariff, the electrical production having much higher rates of return than heat production, whilst storing the excess heat production. It also allows solar heat to be collected in summer and redistributed off season in very large but relatively low-cost in-ground insulated reservoirs or borehole systems. The expected heat loss at the 203,000m³ insulated pond in
Vojens Vojens (german: Woyens) is a railway town in Denmark with a population of 7,475 (1 January 2022).Power-to-X Power-to-X (also P2X and P2Y and P2Z) is a number of electricity conversion, energy storage, and reconversion pathways that use surplus electric power, typically during periods where fluctuating renewable energy generation exceeds load. Pow ...
) is regarded as a key factor for energy systems with high shares of renewable energy.


Heat distribution

After generation, the heat is distributed to the customer via a network of
insulated pipe Insulated pipes (called also preinsulated pipes or bonded pipe ) are widely used for district heating and hot water supply. They consist of a steel pipe called "service pipe", a thermal insulation layer and an outer casing. The main purpose of suc ...
s. District heating systems consist of feed and return lines. Usually the pipes are installed underground but there are also systems with overground pipes. Within the system heat storage units may be installed to even out peak load demands. The common medium used for heat distribution is water or
superheated water Superheated water is liquid water under pressure at temperatures between the usual boiling point, and the critical temperature, . It is also known as "subcritical water" or "pressurized hot water". Superheated water is stable because of overpres ...
, but
steam Steam is a substance containing water in the gas phase, and sometimes also an aerosol of liquid water droplets, or air. This may occur due to evaporation or due to boiling, where heat is applied until water reaches the enthalpy of vaporization ...
is also used. The advantage of steam is that in addition to heating purposes it can be used in
industrial processes Industrial processes are procedures involving chemical, physical, electrical or mechanical steps to aid in the manufacturing of an item or items, usually carried out on a very large scale. Industrial processes are the key components of heavy ind ...
due to its higher temperature. The disadvantage of steam is a higher heat loss due to the high temperature. Also, the
thermal efficiency In thermodynamics, the thermal efficiency (\eta_) is a dimensionless performance measure of a device that uses thermal energy, such as an internal combustion engine, steam turbine, steam engine, boiler, furnace, refrigerator, ACs etc. For a he ...
of cogeneration plants is significantly lower if the cooling medium is high-temperature steam, reducing
electric power Electric power is the rate at which electrical energy is transferred by an electric circuit. The SI unit of power is the watt, one joule per second. Standard prefixes apply to watts as with other SI units: thousands, millions and billions o ...
generation. Heat transfer oils are generally not used for district heating, although they have higher heat capacities than water, as they are expensive and have environmental issues. At customer level the heat network is usually connected to the
central heating A central heating system provides warmth to a number of spaces within a building from one main source of heat. It is a component of heating, ventilation, and air conditioning (short: HVAC) systems, which can both cool and warm interior spaces. ...
system of the dwellings via
heat exchanger A heat exchanger is a system used to transfer heat between a source and a working fluid. Heat exchangers are used in both cooling and heating processes. The fluids may be separated by a solid wall to prevent mixing or they may be in direct contac ...
s ( heat substations): the working fluids of both networks (generally water or steam) do not mix. However, direct connection is used in the
Odense Odense ( , , ) is the third largest city in Denmark (behind Copenhagen and Aarhus) and the largest city on the island of Funen. As of 1 January 2022, the city proper had a population of 180,863 while Odense Municipality had a population of 20 ...
system. Typical annual loss of thermal energy through distribution is around 10%, as seen in Norway's district heating network.


Heat metering

The amount of heat provided to customers is often recorded with a
heat meter A heat meter attached to a heat exchanger in a District heating substation in a residential neighborhood. Right in white-blue: the calculator; in the center in bronze: the ultrasonic flow meter A heat meter or energy meter is a device which mea ...
to encourage conservation and maximize the number of customers which can be served, but such meters are expensive. Due to the expense of heat metering, an alternative approach is simply to meter the water – water meters are much cheaper than heat meters, and have the advantage of encouraging consumers to extract as much heat as possible, leading to a very low return temperature, which increases the efficiency of power generation. Many systems were installed under a
socialist Socialism is a left-wing economic philosophy and movement encompassing a range of economic systems characterized by the dominance of social ownership of the means of production as opposed to private ownership. As a term, it describes the e ...
economy (such as in the former
Eastern Bloc The Eastern Bloc, also known as the Communist Bloc and the Soviet Bloc, was the group of socialist states of Central and Eastern Europe, East Asia, Southeast Asia, Africa, and Latin America under the influence of the Soviet Union that existed du ...
) which lacked heat metering and means to adjust the heat delivery to each apartment. This led to great inefficiencies – users had to simply open windows when too hot – wasting energy and minimising the numbers of connectable customers.


Size of systems

District heating systems can vary in size. Some systems cover entire cities such as
Stockholm Stockholm () is the Capital city, capital and List of urban areas in Sweden by population, largest city of Sweden as well as the List of urban areas in the Nordic countries, largest urban area in Scandinavia. Approximately 980,000 people liv ...
or
Flensburg Flensburg (; Danish, Low Saxon: ''Flensborg''; North Frisian: ''Flansborj''; South Jutlandic: ''Flensborre'') is an independent town (''kreisfreie Stadt'') in the north of the German state of Schleswig-Holstein. Flensburg is the centre of the ...
, using a network of large 1000 mm diameter primary pipes linked to secondary pipes – e.g. 200 mm diameter, which in turn link to tertiary pipes that might be of 25 mm diameter which might connect to 10 to 50 houses. Some district heating schemes might only be sized to meet the needs of a small village or area of a city in which case only the secondary and tertiary pipes will be needed. Some schemes may be designed to serve only a limited number of dwellings, of about 20 to 50 houses, in which case only tertiary sized pipes are needed.


Pros and cons

District heating has various advantages compared to individual heating systems. Usually district heating is more energy efficient, due to simultaneous production of heat and electricity in
combined heat and power Cogeneration or combined heat and power (CHP) is the use of a heat engine or power station to generate electricity and useful heat at the same time. Cogeneration is a more efficient use of fuel or heat, because otherwise- wasted heat from elect ...
generation plants. This has the added benefit of reducing
greenhouse gas emissions Greenhouse gas emissions from human activities strengthen the greenhouse effect, contributing to climate change. Most is carbon dioxide from burning fossil fuels: coal, oil, and natural gas. The largest emitters include coal in China and lar ...
. The larger combustion units also have a more advanced
flue gas Flue gas is the gas exiting to the atmosphere via a flue, which is a pipe or channel for conveying exhaust gases from a fireplace, oven, furnace, boiler or steam generator. Quite often, the flue gas refers to the combustion exhaust gas produced a ...
cleaning than single boiler systems. In the case of surplus heat from industries, district heating systems do not use additional fuel because they recover heat which would otherwise be dispersed to the environment. District heating requires a long-term financial commitment that fits poorly with a focus on short-term returns on investment. Benefits to the community include avoided costs of energy through the use of surplus and wasted heat energy, and reduced investment in individual household or building heating equipment. District heating networks, heat-only boiler stations, and cogeneration plants require high initial capital expenditure and financing. Only if considered as long-term investments will these translate into profitable operations for the owners of district heating systems, or combined heat and power plant operators. District heating is less attractive for areas with low population densities, as the investment per household is considerably higher. Also it is less attractive in areas of many small buildings; e.g. detached houses than in areas with a fewer larger buildings; e.g. blocks of flats, because each connection to a single-family house is quite expensive. Individual heating systems can be completely shutdown intermittently according to local heating demand which is not the case with a district heating system.


Ownership, monopoly issues and charging structures

In many cases large combined heat and power district heating schemes are owned by a single entity. This was typically the case in the old Eastern bloc countries. However, for many schemes, the ownership of the cogeneration plant is separate from the heat using part. Examples are Warsaw which has such split ownership with PGNiG Termika owning the cogeneration unit, the Veolia owning 85% of the heat distribution, the rest of the heat distribution is owned by municipality and workers. Similarly all the large CHP/CH schemes in Denmark are of split ownership. Sweden provides an alternative example where the heating market is deregulated. In Sweden it is most common that the ownership of the district heating network is not separated from the ownership of the cogeneration plants, the district cooling network or the centralized heat pumps. There are also examples where the competition has spawned parallel networks and interconnected networks where multiple utilities cooperate. In the United Kingdom there have been complaints that district heating companies have too much of a monopoly and are insufficiently regulated, an issue the industry is aware of, and has taken steps to improve consumer experience through the use of customer charters as set out by the Heat Trust. Some customers are taking legal action against the supplier for Misrepresentation & Unfair Trading, claiming district Heating is not delivering the savings promised by many heat suppliers.


National variation

Since conditions from city to city differ, every district heating system is unique. In addition, nations have different access to primary energy carriers and so they have a different approach on how to address heating markets within their borders.


Europe

Since 1954, district heating has been promoted in Europe by Euroheat & Power. They have compiled an analysis of district heating and cooling markets in Europe within their Ecoheatcool project supported by the
European Commission The European Commission (EC) is the executive of the European Union (EU). It operates as a cabinet government, with 27 members of the Commission (informally known as "Commissioners") headed by a President. It includes an administrative body o ...
. A separate study, entitled Heat Roadmap Europe, has indicated that district heating can reduce the price of energy in the European Union between now and 2050. The legal framework in the member states of the
European Union The European Union (EU) is a supranational political and economic union of member states that are located primarily in Europe. The union has a total area of and an estimated total population of about 447million. The EU has often been des ...
is currently influenced by the EU's
CHP Directive The Directive on the promotion of cogeneration based on a useful heat demand in the internal energy market and amending Directive 92/42/EEC,
.


Cogeneration in Europe

The EU has actively incorporated cogeneration into its energy policy via the
CHP Directive The Directive on the promotion of cogeneration based on a useful heat demand in the internal energy market and amending Directive 92/42/EEC,
. In September 2008 at a hearing of the European Parliament's Urban Lodgment Intergroup, Energy Commissioner Andris Piebalgs is quoted as saying, "security of supply really starts with energy efficiency." Energy efficiency and cogeneration are recognized in the opening paragraphs of the European Union's Cogeneration Directive 2004/08/EC. This directive intends to support cogeneration and establish a method for calculating cogeneration abilities per country. The development of cogeneration has been very uneven over the years and has been dominated throughout the last decades by national circumstances. As a whole, the European Union currently generates 11% of its electricity using cogeneration, saving Europe an estimated 35 Mtoe per annum. However, there are large differences between the member states, with energy savings ranging from 2% to 60%. Europe has the three countries with the world's most intensive cogeneration economies: Denmark, the Netherlands and Finland. Other European countries are also making great efforts to increase their efficiency. Germany reports that over 50% of the country's total electricity demand could be provided through cogeneration. Germany set a target to double its electricity cogeneration from 12.5% of the country's electricity to 25% by 2020 and has passed supporting legislation accordingly in "Federal Ministry of Economics and Technology", (BMWi), Germany, August 2007. The UK is also actively supporting district heating. In the light of UK's goal to achieve an 80% reduction in carbon dioxide emissions by 2050, the government had set a target to source at least 15% of government electricity from CHP by 2010. Other UK measures to encourage CHP growth are financial incentives, grant support, a greater regulatory framework, and government leadership and partnership. According to the IEA 2008 modelling of cogeneration expansion for the G8 countries, expansion of cogeneration in France, Germany, Italy and the UK alone would effectively double the existing primary fuel savings by 2030. This would increase Europe's savings from today's 155 TWh to 465 TWh in 2030. It would also result in a 16% to 29% increase in each country's total cogenerated electricity by 2030. Governments are being assisted in their CHP endeavors by organizations like
COGEN Europe COGEN Europe is a European advocacy group based in Belgium that promotes the practice of cogeneration in energy production. The group acts as a liaison between its member companies and European Union The European Union (EU) is a supranat ...
who serve as an information hub for the most recent updates within Europe's energy policy. COGEN is Europe's umbrella organization representing the interests of the cogeneration industry, users of the technology and promoting its benefits in the EU and the wider Europe. The association is backed by the key players in the industry including gas and electricity companies, ESCOs, equipment suppliers, consultancies, national promotion organisations, financial and other service companies. A 2016 EU energy strategy suggests increased use of district heating.


Austria

The largest district heating system in Austria is in
Vienna en, Viennese , iso_code = AT-9 , registration_plate = W , postal_code_type = Postal code , postal_code = , timezone = CET , utc_offset = +1 , timezone_DST ...
(Fernwärme Wien) – with many smaller systems distributed over the whole country. District heating in Vienna is run by Wien Energie. In the business year of 2004/2005 a total of 5,163 GWh was sold, 1,602 GWh to 251,224 private apartments and houses and 3,561 GWh to 5211 major customers. The three large municipal waste
incinerators Incineration is a list of solid waste treatment technologies, waste treatment process that involves the combustion of substances contained in waste materials. Industrial plants for waste incineration are commonly referred to as waste-to-ene ...
provide 22% of the total in producing 116 GWh electric power and 1,220 GWh heat. Waste heat from municipal power plants and large industrial plants account for 72% of the total. The remaining 6% is produced by peak heating boilers from fossil fuel. A biomass-fired power plant has produced heat since 2006. In the rest of Austria the newer district heating plants are constructed as biomass plants or as CHP-biomass plants like the biomass district heating of Mödling or the biomass district heating of Baden. Most of the older fossil-fired district heating systems have a district heating accumulator, so that it is possible to produce the thermal district heating power only at that time where the electric power price is high.


Belgium

Belgium has district heating in multiple cities. The largest system is in the Flemish city
Ghent Ghent ( nl, Gent ; french: Gand ; traditional English: Gaunt) is a city and a municipality in the Flemish Region of Belgium. It is the capital and largest city of the East Flanders province, and the third largest in the country, exceeded in ...
, the piping network of this power plant is 22 km long. The system dates back to 1958.


Bulgaria

Bulgaria has district heating in around a dozen towns and cities. The largest system is in the capital
Sofia Sofia ( ; bg, София, Sofiya, ) is the capital and largest city of Bulgaria. It is situated in the Sofia Valley at the foot of the Vitosha mountain in the western parts of the country. The city is built west of the Iskar river, and ha ...
, where there are four power plants (two CHPs and two boiler stations) providing heat to the majority of the city. The system dates back to 1949.


Czech Republic

The largest district heating system in the
Czech Republic The Czech Republic, or simply Czechia, is a landlocked country in Central Europe. Historically known as Bohemia, it is bordered by Austria to the south, Germany to the west, Poland to the northeast, and Slovakia to the southeast. The ...
is in Prague owned and operated by Pražská teplárenská, serving 265,000 households and selling c. 13 PJ of heat annually. Most of the heat is actually produced as
waste heat Waste heat is heat that is produced by a machine, or other process that uses energy, as a byproduct of doing work. All such processes give off some waste heat as a fundamental result of the laws of thermodynamics. Waste heat has lower utility ...
in 30 km distant
thermal power station A thermal power station is a type of power station in which heat energy is converted to electrical energy. In a steam-generating cycle heat is used to boil water in a large pressure vessel to produce high-pressure steam, which drives a stea ...
in
Mělník Mělník (; german: Melnik) is a town in the Central Bohemian Region of the Czech Republic. It has about 19,000 inhabitants. The town centre is well preserved and is protected by law as an urban monument zone. Mělník lies in one of the most im ...
. There are many smaller central heating systems spread around the country including waste heat usage,
municipal solid waste Municipal solid waste (MSW), commonly known as trash or garbage in the United States and rubbish in Britain, is a waste type consisting of everyday items that are discarded by the public. "Garbage" can also refer specifically to food waste, ...
incineration Incineration is a waste treatment process that involves the combustion of substances contained in waste materials. Industrial plants for waste incineration are commonly referred to as waste-to-energy facilities. Incineration and other high ...
and .


Denmark

In Denmark district heating covers more than 64% of
space heating Heating, ventilation, and air conditioning (HVAC) is the use of various technologies to control the temperature, humidity, and purity of the air in an enclosed space. Its goal is to provide thermal comfort and acceptable indoor air quality. HV ...
and
water heating Water heating is a heat transfer process that uses an energy source to heat water above its initial temperature. Typical domestic uses of hot water include cooking, cleaning, bathing, and space heating. In industry, hot water and water heated t ...
. In 2007, 80.5% of this heat was produced by
combined heat and power Cogeneration or combined heat and power (CHP) is the use of a heat engine or power station to generate electricity and useful heat at the same time. Cogeneration is a more efficient use of fuel or heat, because otherwise- wasted heat from elect ...
plants. Heat recovered from
waste incineration Incineration is a waste treatment process that involves the combustion of substances contained in waste materials. Industrial plants for waste incineration are commonly referred to as waste-to-energy facilities. Incineration and other high ...
accounted for 20.4% of the total Danish district heat production. In 2013, Denmark imported 158,000 ton waste for incineration. Most major cities in Denmark have big district heating networks, including transmission networks operating with up to 125 °C and 25 bar pressure and distribution networks operating with up to 95 °C and between 6 and 10 bar pressure. The largest district heating system in Denmark is in the
Copenhagen Copenhagen ( or .; da, København ) is the capital and most populous city of Denmark, with a proper population of around 815.000 in the last quarter of 2022; and some 1.370,000 in the urban area; and the wider Copenhagen metropolitan ar ...
area operated by CTR I/S and VEKS I/S. In central Copenhagen, the CTR network serves 275,000 households (90–95% of the area's population) through a network of 54 km double district heating distribution pipes providing a peak capacity of 663 MW, some of which is combined with
district cooling District cooling is the cooling equivalent of district heating. Working on broadly similar principles to district heating, district cooling delivers chilled water to buildings like offices and factories needing cooling. In winter, the source for t ...
. The consumer price of heat from CTR is approximately €49 per MWh plus taxes (2009). Several towns have
central solar heating Central solar heating is the provision of central heating and hot water from solar energy by a system in which the water is heated centrally by arrays of solar thermal collectors (central solar heating plants - CSHPs) and distributed through distr ...
with various types of
thermal energy storage Thermal energy storage (TES) is achieved with widely different technologies. Depending on the specific technology, it allows excess thermal energy to be stored and used hours, days, months later, at scales ranging from the individual process, ...
. The Danish island of
Samsø Samsø (Anglicized: "Samso" or "Samsoe") is a Denmark, Danish island in the Kattegat off the Jutland Peninsula. Samsø is located in Samsø municipality. The community has 3,724 inhabitants (2017) (January 2010:4,010) called ''Samsings'' and is ...
has three straw-fueled plants producing district heating.


Finland

In Finland district heating accounts for about 50% of the total heating market, 80% of which is produced by combined heat and power plants. Over 90% of apartment blocks, more than half of all terraced houses, and the bulk of public buildings and business premises are connected to a district heating network.
Natural gas Natural gas (also called fossil gas or simply gas) is a naturally occurring mixture of gaseous hydrocarbons consisting primarily of methane in addition to various smaller amounts of other higher alkanes. Low levels of trace gases like carbo ...
is mostly used in the south-east gas pipeline network, imported
coal Coal is a combustible black or brownish-black sedimentary rock, formed as rock strata called coal seams. Coal is mostly carbon with variable amounts of other elements, chiefly hydrogen, sulfur, oxygen, and nitrogen. Coal is formed when dea ...
is used in areas close to ports, and
peat Peat (), also known as turf (), is an accumulation of partially decayed vegetation or organic matter. It is unique to natural areas called peatlands, bogs, mires, moors, or muskegs. The peatland ecosystem covers and is the most efficien ...
is used in northern areas where peat is a local resource. Renewables, such as wood chips and other paper industry combustible by-products, are also used, as is the energy recovered by the
incineration Incineration is a waste treatment process that involves the combustion of substances contained in waste materials. Industrial plants for waste incineration are commonly referred to as waste-to-energy facilities. Incineration and other high ...
of
municipal solid waste Municipal solid waste (MSW), commonly known as trash or garbage in the United States and rubbish in Britain, is a waste type consisting of everyday items that are discarded by the public. "Garbage" can also refer specifically to food waste, ...
. Industrial units which generate heat as an industrial by-product may sell otherwise waste heat to the network rather than release it into the environment. Excess heat and power from
pulp mill A pulp mill is a manufacturing facility that converts wood chips or other plant fiber sources into a thick fiber board which can be shipped to a paper mill for further processing. Pulp can be manufactured using mechanical, semi-chemical, or ful ...
recovery boiler Recovery boiler is the part of kraft process of pulping where chemicals for white liquor are recovered and reformed from black liquor, which contains lignin from previously processed wood. The black liquor is burned, generating heat, which is usual ...
s is a significant source in mill towns. In some towns waste incineration can contribute as much as 8% of the district heating heat requirement.
Availability In reliability engineering, the term availability has the following meanings: * The degree to which a system, subsystem or equipment is in a specified operable and committable state at the start of a mission, when the mission is called for at a ...
is 99.98% and disruptions, when they do occur, usually reduce temperatures by only a few degrees. In Helsinki, an underground
datacenter A data center (American English) or data centre (British English)See spelling differences. is a building, a dedicated space within a building, or a group of buildings used to house computer systems and associated components, such as telecommunic ...
next to the President's palace releases excess heat into neighboring homes, producing enough heat to heat approximately 500 large houses. A quarter of a million households around
Espoo Espoo (, ; sv, Esbo) is a city and municipality in the region of Uusimaa in the Republic of Finland. It is located on the northern shore of the Gulf of Finland, bordering the cities of Helsinki, Vantaa, Kirkkonummi, Vihti and Nurmijärvi ...
are scheduled to receive district heating from datacenters.


Germany

In Germany district heating has a market share of around 14% in the residential buildings sector. The connected heat load is around 52,729 MW. The heat comes mainly from cogeneration plants (83%). Heat-only boilers supply 16% and 1% is surplus heat from industry. The cogeneration plants use natural gas (42%), coal (39%), lignite (12%) and waste/others (7%) as fuel. The largest district heating network is located in Berlin whereas the highest diffusion of district heating occurs in
Flensburg Flensburg (; Danish, Low Saxon: ''Flensborg''; North Frisian: ''Flansborj''; South Jutlandic: ''Flensborre'') is an independent town (''kreisfreie Stadt'') in the north of the German state of Schleswig-Holstein. Flensburg is the centre of the ...
with around 90% market share. In
Munich Munich ( ; german: München ; bar, Minga ) is the capital and most populous city of the States of Germany, German state of Bavaria. With a population of 1,558,395 inhabitants as of 31 July 2020, it is the List of cities in Germany by popu ...
about 70% of the electricity produced comes from district heating plants. District heating has rather little legal framework in Germany. There is no law on it as most elements of district heating are regulated in governmental or regional orders. There is no governmental support for district heating networks but a law to support cogeneration plants. As in the European Union the
CHP Directive The Directive on the promotion of cogeneration based on a useful heat demand in the internal energy market and amending Directive 92/42/EEC,
will come effective, this law probably needs some adjustment.


Greece

Greece has district heating mainly in the Province of
Western Macedonia Western Macedonia ( el, Δυτική Μακεδονία, translit=Ditikí Makedonía, ) is one of the thirteen Modern regions of Greece, regions of Greece, consisting of the western part of Macedonia (Greece), Macedonia. Located in north-western ...
, Central Macedonia and the Peloponnese Province. The largest system is the city of
Ptolemaida Ptolemaida ( el, Πτολεμαΐδα, Ptolemaïda, Katharevousa: Πτολεμαΐς, ''Ptolemaïs'') is a town and a former municipality in Kozani regional unit, Western Macedonia, Greece. Since the 2011 local government reform it is part of th ...
, where there are five power plants (
thermal power station A thermal power station is a type of power station in which heat energy is converted to electrical energy. In a steam-generating cycle heat is used to boil water in a large pressure vessel to produce high-pressure steam, which drives a stea ...
s or TPS in particular) providing heat to the majority of the largest towns and cities of the area and some villages. The first small installation took place in Ptolemaida in 1960, offering heating to Proastio village of
Eordaea Eordaea ( el, Ἐορδαία) was a geographical region of upper Macedonia and later an administrative region of the kingdom of Macedon. Eordaea was located south of Lynkestis, west of Emathia, north of Elimiotis and east of Orestis.Dimitrio ...
using the TPS of Ptolemaida. Today District heating installations are also available in
Kozani Kozani ( el, Κοζάνη, ) is a city in northern Greece, capital of Kozani (regional unit), Kozani regional unit and of Western Macedonia. It is located in the western part of Macedonia (Greece), Macedonia, in the northern part of the Aliakmona ...
, Ptolemaida,
Amyntaio Amyntaio ( el, Αμύνταιο, before 1928: Σόροβιτς - ''Sorovits''; Bulgarian/ Macedonian: Суровичево, Сорович), is a town and municipality in the Florina regional unit of Macedonia, Greece. The population of Amyntaio p ...
,
Philotas Philotas ( el, Φιλώτας; 365 BC – October 330 BC) was the eldest son of Parmenion, one of Alexander the Great's most experienced and talented generals. He rose to command the Companion Cavalry, but was accused of conspiring against Alexa ...
, Serres and
Megalopolis A megalopolis () or a supercity, also called a megaregion, is a group of metropolitan areas which are perceived as a continuous urban area through common systems of transport, economy, resources, ecology, and so on. They are integrated enoug ...
using nearby power plants. In Serres the power plant is a Hi-Efficiency CHP Plant using natural gas, while coal is the primary fuel for all other district heating networks.


Hungary

According to the 2011 census there were 607,578 dwellings (15.5% of all) in Hungary with district heating, mostly panel flats in urban areas. The largest district heating system located in
Budapest Budapest (, ; ) is the capital and most populous city of Hungary. It is the ninth-largest city in the European Union by population within city limits and the second-largest city on the Danube river; the city has an estimated population ...
, the municipality-owned ''Főtáv Zrt.'' ("Metropolitan Teleheating Company") provides heat and piped hot water for 238,000 households and 7,000 companies.


Iceland

93% of all housing in Iceland enjoy district heating services – 89.6% from
geothermal energy Geothermal energy is the thermal energy in the Earth's crust which originates from the formation of the planet and from radioactive decay of materials in currently uncertain but possibly roughly equal proportions. The high temperature and pres ...
, Iceland is the country with the highest penetration of district heating. There are 117 local district heating systems supplying towns as well as rural areas with hot water – reaching almost all of the population. The average price is around US$0.027 per kWh of hot water. Southwest Iceland and Reykjavík's hot water supply for district heating comes from three geothermal power plants, producing over 800 MWth: * Svartsengi Combined heat and power plant (CHP) * Nesjavellir CHP plant * Hellisheiði CHP plant


Ireland

The Dublin Waste-to-Energy Facility will provide district heating for up to 50,000 homes in
Poolbeg Poolbeg () is an artificial peninsula extending from Ringsend, Dublin, into Dublin Bay. History The Poolbeg peninsula was built between the mid 18th century and the present day, starting with the Ballast Office Wall, the first section of the G ...
and surrounding areas. Some existing residential developments in the North Docklands have been constructed for conversion to district heating – currently using on-site gas boilers – and pipes are in place in the
Liffey Service Tunnel The Liffey Service Tunnel is a service tunnel for various pipelines in Dublin, Ireland, owned by Dublin City Council. Project The tunnel was designed by British company Atkins and constructed by a joint venture of the German contractor Zübl ...
to connect these to the incinerator or other waste heat sources in the area. Tralee in Co Kerry has a 1 MW district heating system providing heat to an apartment complex, sheltered housing for the elderly, a library and over 100 individual houses. The system is fuelled by locally produced wood chip. In Glenstal Abbey in Co Limerick there exists a pond-based 150 kW heating system for a school. A scheme to use waste heat from an
Amazon Web Services Amazon Web Services, Inc. (AWS) is a subsidiary of Amazon.com, Amazon that provides Software as a service, on-demand cloud computing computing platform, platforms and Application programming interface, APIs to individuals, companies, and gover ...
datacentre in Tallaght is intended to heat 1200 units and municipal buildings


Italy

In Italy, district heating is used in some cities (
Bergamo Bergamo (; lmo, Bèrghem ; from the proto- Germanic elements *''berg +*heim'', the "mountain home") is a city in the alpine Lombardy region of northern Italy, approximately northeast of Milan, and about from Switzerland, the alpine lakes Como ...
,
Brescia Brescia (, locally ; lmo, link=no, label= Lombard, Brèsa ; lat, Brixia; vec, Bressa) is a city and ''comune'' in the region of Lombardy, Northern Italy. It is situated at the foot of the Alps, a few kilometers from the lakes Garda and Iseo. ...
,
Cremona Cremona (, also ; ; lmo, label= Cremunés, Cremùna; egl, Carmona) is a city and ''comune'' in northern Italy, situated in Lombardy, on the left bank of the Po river in the middle of the ''Pianura Padana'' ( Po Valley). It is the capital of th ...
,
Bolzano Bolzano ( or ; german: Bozen, (formerly ); bar, Bozn; lld, Balsan or ) is the capital city of the province of South Tyrol in northern Italy. With a population of 108,245, Bolzano is also by far the largest city in South Tyrol and the third la ...
,
Verona Verona ( , ; vec, Verona or ) is a city on the Adige River in Veneto, Northern Italy, Italy, with 258,031 inhabitants. It is one of the seven provincial capitals of the region. It is the largest city Comune, municipality in the region and the ...
,
Ferrara Ferrara (, ; egl, Fràra ) is a city and ''comune'' in Emilia-Romagna, northern Italy, capital of the Province of Ferrara. it had 132,009 inhabitants. It is situated northeast of Bologna, on the Po di Volano, a branch channel of the main stream ...
,
Imola Imola (; rgn, Jômla or ) is a city and ''comune'' in the Metropolitan City of Bologna, located on the river Santerno, in the Emilia-Romagna region of northern Italy. The city is traditionally considered the western entrance to the historical re ...
,
Modena Modena (, , ; egl, label=Emilian language#Dialects, Modenese, Mòdna ; ett, Mutna; la, Mutina) is a city and ''comune'' (municipality) on the south side of the Po Valley, in the Province of Modena in the Emilia-Romagna region of northern I ...
,
Reggio Emilia Reggio nell'Emilia ( egl, Rèz; la, Regium Lepidi), usually referred to as Reggio Emilia, or simply Reggio by its inhabitants, and known until 1861 as Reggio di Lombardia, is a city in northern Italy, in the Emilia-Romagna region. It has abou ...
,
Terlan Terlan (; it, Terlano ) is a ''comune'' (municipality) in South Tyrol in northern Italy. Geography The municipal area is situated within the Adige Valley, about northwest of the city of Bolzano. Terlan is famous for its wine and asparagus produ ...
,
Turin Turin ( , Piedmontese language, Piedmontese: ; it, Torino ) is a city and an important business and cultural centre in Northern Italy. It is the capital city of Piedmont and of the Metropolitan City of Turin, and was the first Italian capital ...
,
Parma Parma (; egl, Pärma, ) is a city in the northern Italian region of Emilia-Romagna known for its architecture, Giuseppe Verdi, music, art, prosciutto (ham), Parmigiano-Reggiano, cheese and surrounding countryside. With a population of 198,292 ...
, Lodi, and now
Milan Milan ( , , Lombard: ; it, Milano ) is a city in northern Italy, capital of Lombardy, and the second-most populous city proper in Italy after Rome. The city proper has a population of about 1.4 million, while its metropolitan city h ...
). The district heating of Turin is the biggest of the country and it supplies 550.000 people (62% of the whole city population).


Latvia

In Latvia, district heating is used in major cities such as
Riga Riga (; lv, Rīga , liv, Rīgõ) is the capital and largest city of Latvia and is home to 605,802 inhabitants which is a third of Latvia's population. The city lies on the Gulf of Riga at the mouth of the Daugava river where it meets the Ba ...
,
Daugavpils Daugavpils (; russian: Двинск; ltg, Daugpiļs ; german: Dünaburg, ; pl, Dyneburg; see other names) is a state city in south-eastern Latvia, located on the banks of the Daugava River, from which the city gets its name. The parts of the c ...
,
Liepāja Liepāja (; liv, Līepõ; see #Names and toponymy, other names) is a state city in western Latvia, located on the Baltic Sea. It is the largest-city in the Kurzeme Planning Region, Kurzeme Region and the third-largest city in the country after R ...
,
Jelgava Jelgava (; german: Mitau, ; see also other names) is a state city in central Latvia about southwest of Riga with 55,972 inhabitants (2019). It is the largest town in the region of Zemgale (Semigalia). Jelgava was the capital of the united Duch ...
. The first district heating system was constructed in Riga in 1952. Each major city has a local company responsible for the generation, administration, and maintenance of the district heating system.


Netherlands

District heating is used in
Rotterdam Rotterdam ( , , , lit. ''The Dam on the River Rotte'') is the second largest city and municipality in the Netherlands. It is in the province of South Holland, part of the North Sea mouth of the Rhine–Meuse–Scheldt delta, via the ''"N ...
,
Amsterdam Amsterdam ( , , , lit. ''The Dam on the River Amstel'') is the Capital of the Netherlands, capital and Municipalities of the Netherlands, most populous city of the Netherlands, with The Hague being the seat of government. It has a population ...
,
Utrecht Utrecht ( , , ) is the List of cities in the Netherlands by province, fourth-largest city and a List of municipalities of the Netherlands, municipality of the Netherlands, capital and most populous city of the Provinces of the Netherlands, pro ...
, and
Almere Almere () is a Planned community, planned List of cities in the Netherlands by province, city and List of municipalities of the Netherlands, municipality in the Provinces of the Netherlands, province of Flevoland, Netherlands, located about 20 km ...
with more expected as the government has mandated a transition away from natural gas for all homes in the country by 2050. The town of Heerlen has developed a grid using water in disused coalmines as a source and storage for heat and cold. This is a good example of a 5th generation heating and cooling grid


North Macedonia

District heating is only available in Skopje. Balkan Energy Group (BEG) operates three DH production plants, which cover majority of the network, and supply heat to around 60,000 households in Skopje, more than 80 buildings in the educational sector (schools and kindergartens) and more than 1,000 other consumers (mostly commercial). The three BEG production plants use natural gas as a fuel source. There is also one cogeneration plant TE-TO AD Skopje producing heat delivered to the Skopje district heating system. The share of cogeneration in DH production was 47% in 2017. The distribution and supply of district heating is carried out by companies owned by BEG.


Norway

In Norway district heating only constitutes approximately 2% of energy needs for heating. This is a very low number compared to similar countries. One of the main reasons district heating has a low penetration in Norway is access to cheap hydro-based electricity, and 80% of private electricity consumption goes to heat rooms and water. However, there is district heating in the major cities.


Poland

In 2009, 40% of Polish households used district heating, most of them in urban areas. Heat is provided primarily by combined heat and power plants, most of which burn hard coal. The largest district heating system is in Warsaw, owned and operated by Veolia Warszawa, distributing approx. 34 PJ annually.


Romania

The largest district heating system in
Romania Romania ( ; ro, România ) is a country located at the crossroads of Central Europe, Central, Eastern Europe, Eastern, and Southeast Europe, Southeastern Europe. It borders Bulgaria to the south, Ukraine to the north, Hungary to the west, S ...
is in
Bucharest Bucharest ( , ; ro, București ) is the capital and largest city of Romania, as well as its cultural, industrial, and financial centre. It is located in the southeast of the country, on the banks of the Dâmbovița River, less than north of ...
. Owned and operated by RADET, it distributes approximately 24 PJ annually, serving 570 000 households. This corresponds to 68% of Bucharest's total domestic heat requirements (RADET fulfills another 4% through single-building boiler systems, for a total of 72%).


Russia

In most Russian cities, district-level
combined heat and power Cogeneration or combined heat and power (CHP) is the use of a heat engine or power station to generate electricity and useful heat at the same time. Cogeneration is a more efficient use of fuel or heat, because otherwise- wasted heat from elect ...
plants () produce more than 50% of the nation's electricity and simultaneously provide hot water for neighbouring city blocks. They mostly use
coal Coal is a combustible black or brownish-black sedimentary rock, formed as rock strata called coal seams. Coal is mostly carbon with variable amounts of other elements, chiefly hydrogen, sulfur, oxygen, and nitrogen. Coal is formed when dea ...
- and Fuel gas, gas-powered steam turbines for cogeneration of heat. Now, Combined cycle power plant, combined cycle gas turbines designs are beginning to be widely used as well.


Serbia

In Serbia, district heating is used throughout the main cities, particularly in the capital, Belgrade. The first district heating plant was built in 1961 as a means to provide effective heating to the newly built suburbs of New Belgrade, Novi Beograd. Since then, numerous plants have been built to heat the ever-growing city. They use natural gas as fuel, because it has less of an effect on the environment. The district heating system of Belgrade possesses 112 heat sources of 2,454 MW capacity, over 500 km of pipeline, and 4,365 connection stations, providing district heating to 240,000 apartments and 7,500 office/commercial buildings of total floor area exceeding 17,000,000 square meters.


Slovakia

Slovakia's centralised heating system covers more than 54% of the overall demand for heat. In 2015 approximately 1.8 million citizens, 35% of the total population of Slovakia, were served by district heating. The infrastructure was built mainly during the 1960s and 1980s. In recent years large investments were made to increase the share of renewable energy sources and energy efficiency in district heating systems. The heat production comes mostly from natural gas and biomass sources, and 54% of the heat in district heating is generated through cogeneration. The distribution system consists of 2800 km of pipes. Warm and hot water are the most common heat carriers, but older high-pressure steam transport still accounts for around one-quarter of the primary distribution, which results in more losses in the system. In terms of the market structure, there were 338 heat suppliers licensed to produce and/or distribute heat in 2016, of which 87% were both producers and distributors. Most are small companies that operate in a single municipality, but some large companies such as Veolia are also present in the market. The state owns and operates large co-generation plants that produce district heat and electricity in six cities (Bratislava, Košice, Žilina, Trnava, Zvolen and Martin). Multiple companies can operate in one city, which is the case in larger cities. A large share of DH is produced by small natural gas heat boilers connected to blocks of buildings. In 2014, nearly 40% of the total DH generation was from natural gas boilers, other than co-generation.


Sweden

Sweden has a long tradition for using district heating (fjärrvärme) in urban areas. In 2015, about 60% of Sweden's houses (private and commercial) were heated by district heating, according to the Swedish association of district heating. The city of Växjö reduced its emissions from fossil fuels by 34% from 1993 to 2009. This was to achieved largely by way of biomass fired district heating. Another example is the plant of Enköping, combining the use of short rotation plantations both for fuel as well as for phytoremediation. 47% of the heat generated in Swedish district heating systems are produced with renewable bioenergy sources, as well as 16% in waste-to-energy plants, 7% is provided by
heat pump A heat pump is a device that can heat a building (or part of a building) by transferring thermal energy from the outside using a refrigeration cycle. Many heat pumps can also operate in the opposite direction, cooling the building by removing h ...
s, 10% by flue-gas condensation and 6% by industrial waste heat recovery unit, waste heat recovery. The remaining are mostly fossil fuels: oil (3%), natural gas (3%),
peat Peat (), also known as turf (), is an accumulation of partially decayed vegetation or organic matter. It is unique to natural areas called peatlands, bogs, mires, moors, or muskegs. The peatland ecosystem covers and is the most efficien ...
(2%), and coal (1%). Because of the law banning traditional landfills, waste is commonly used as a fuel.


Ukraine


United Kingdom

In the United Kingdom, district heating became popular after World War II, but on a restricted scale, to heat the large residential estates that replaced areas devastated by the The Blitz, Blitz. In 2013 there were 1,765 district heating schemes with 920 based in London alone. In total around 210,000 homes and 1,700 businesses are supplied by heat networks in the UK. The Pimlico District Heating Undertaking (PDHU) first became operational in 1950 and continues to expand to this day. The PDHU once relied on waste heat from the now-disused Battersea Power Station on the South side of the River Thames. It is still in operation, the water now being heated locally by a new energy centre which incorporates 3.1 MWe / 4.0 MWth of gas fired CHP engines and 3 × 8 MW gas-fired boilers. One of the United Kingdom's largest district heating schemes is EnviroEnergy in Nottingham. The plant initially built by Boots (company), Boots is now used to heat 4,600 homes, and a wide variety of business premises, including the Nottingham Royal Concert Hall, Concert Hall, the Motorpoint Arena Nottingham, Nottingham Arena, the Victoria Baths, the Broadmarsh, Broadmarsh Shopping Centre, the Victoria Centre, and others. The heat source is a waste-to-energy incinerator. Scotland has several district heating systems with the first in the UK being installed at Aviemore and others following at Lochgilphead, Fort William and Forfar. Sheffield's district heating network was established in 1988 and is still expanding today. It saves an equivalent 21,000 plus tonnes of CO2 each year when compared to conventional sources of energy – electricity from the national grid and heat generated by individual boilers. There are currently over 140 buildings connected to the district heating network. These include city landmarks such as the Sheffield City Hall, the Lyceum Theatre, Sheffield, Lyceum Theatre, the University of Sheffield, Sheffield Hallam University, hospitals, shops, offices and leisure facilities plus 2,800 homes. More than 44 km of underground pipes deliver energy which is generated at Sheffield Energy Recovery Facility. This converts 225,000 tonnes of waste into energy, producing up to 60 MWe of thermal energy and up to 19 MWe of electrical energy. The Southampton District Energy Scheme was originally built to use just Geothermal heating, geothermal energy, but now also uses the heat from a gas fired CHP generator. It supplies heating and
district cooling District cooling is the cooling equivalent of district heating. Working on broadly similar principles to district heating, district cooling delivers chilled water to buildings like offices and factories needing cooling. In winter, the source for t ...
to many large premises in the city, including the Westquay shopping centre, the De Vere Grand Harbour hotel, the Royal South Hants Hospital, and several housing schemes. In the 1980s Southampton began utilising combined heat and power district heating, taking advantage of geothermal heat "trapped" in the area. The geothermal heat provided by the well works in conjunction with the Combined Heat and Power scheme. Geothermal energy provides 15–20%, fuel oil 10%, and natural gas 70% of the total heat input for this scheme and the combined heat and power generators use conventional fuels to make electricity. "Waste heat" from this process is recovered for distribution through the 11 km mains network. Lerwick District Heating and Energy Recovery Plant, Lerwick District Heating Scheme is of note because it is one of the few schemes where a completely new system was added to a previously existing small town. ADE has an online map of district heating installations in the UK. ADE estimates that 54 percent of energy used to produce electricity is being wasted via conventional power production, which relates to £9.5 billion ($US12.5 billion) per year.


Spain


North America

In North America, district heating systems fall into two general categories. Those that are owned by and serve the buildings of a single entity are considered institutional systems. All others fall into the commercial category.


Canada

District Heating is becoming a growing industry in Canadian cities, with many new systems being built in the last ten years. Some of the major systems in Canada include: * Calgary: ENMAX currently operates the Calgary Downtown District Energy Centre which provides heating to up to of new and existing residential and commercial buildings. The District Energy Centre began operations in March 2010 providing heat to its first customer, the City of Calgary Municipal building. * Edmonton: The community of Blatchford, Edmonton, Blatchford, which is currently being developed on the grounds of Edmonton's former Edmonton City Centre Airport, City Centre Airport, is launching a District Energy Sharing System (DESS) in phases. A geo-exchange field went online in 2019, and Blatchford's energy utility is in the planning and design phase for a sewage heat exchange system. * Hamilton, Ontario, Hamilton, ON has a district heating and cooling system in the downtown core, operated by HCE Energy Inc. * Montreal has a district heating and cooling system in the downtown core. * Toronto: ** Enwave provides district heating and cooling within the downtown core of Toronto, including deep lake cooling technology, which circulates cold water from Lake Ontario through heat exchangers to provide cooling for many buildings in the city. ** Creative Energy is constructing a combined-heat-and-power district energy system for the Mirvish Village development. * Surrey, British Columbia, Surrey: Surrey City Energy owned by the city, provides district heating to the city's Whalley, Surrey, City Centre district. * Vancouver: ** Creative Energy#Beatty Street, Vancouver, Creative Energy's Beatty Street facility has operated since 1968 and provides a central heating plant for the city's downtown core of Vancouver. In addition to heating 180 buildings, the Central Heat Distribution network also drives a steam clock. Work is currently underway to move the facility from natural gas to electric equipment. ** A large scale district heating system known as the Neighbourhood Energy Utility in the South East False Creek area is in initial operations with natural gas boilers and serves the 2010 Olympic Village. The untreated sewage heat recovery system began operations in January 2010, supplying 70% of annual energy demands, with retrofit work underway to move the facility off its remaining natural gas use. * Windsor, Ontario has a district heating and cooling system in the downtown core. *
Drake Landing Solar Community The Drake Landing Solar Community (DLSC) is a planned community in Okotoks, Alberta, Canada, equipped with a central solar heating system and other energy efficient technologies. This heating system is the first of its kind in North America, altho ...
, AB, is small in size (52 homes) but notable for having the only
central solar heating Central solar heating is the provision of central heating and hot water from solar energy by a system in which the water is heated centrally by arrays of solar thermal collectors (central solar heating plants - CSHPs) and distributed through distr ...
system in North America. * London, Ontario and Charlottetown, PEI have district heating co-generation systems owned and operated by Veresen. * Greater Sudbury, Sudbury, Ontario has a district heating cogeneration system in its downtown core, as well as a standalone cogeneration plant for the Sudbury Regional Hospital. In addition, Naneff Gardens, a new residential subdivision off Donnelly Drive in the city's Garson, Ontario, Garson neighbourhood, features a geothermal district heating system using technology developed by a local company, Renewable Resource Recovery Corporation. * Ottawa, contains a significant district heating and cooling system serving the large number of federal government buildings in the city. The system loop contains nearly of chilled or heated water at any time. * Cornwall, Ontario operates a district heating system which serves a number of city buildings and schools. * Markham, Ontario: Markham District Energy operates several district heating sites: ** Warden Energy Centre (c. 2000), Clegg Energy Centre and Birchmount Energy Centre serving customers in the Markham Centre area ** Bur Oak Energy Centre (c. 2012) serving customers in the Cornell Centre area Many Canadian universities operate central campus heating plants.


United States

The Holly Steam Combination Company was the first steam heating company to commercially distribute district heating from a central steam heating system. As of 2013, approximately 2,500 district heating and cooling systems existed in the United States, in one form or another, with the majority providing heat. * Consolidated Edison of
New York New York most commonly refers to: * New York City, the most populous city in the United States, located in the state of New York * New York (state), a state in the northeastern United States New York may also refer to: Film and television * '' ...
(Con Ed) operates the
New York City steam system The New York City steam systems include Con Edison, Con Edison's Steam Operations, and other smaller systems that provide steam to New York University and Columbia University. Many individual buildings in New York City, New York have their ow ...
, the largest commercial district heating system in the United States. The system has operated continuously since March 3, 1882 and serves Manhattan Island from the Battery through 96th Street. In addition to providing space- and water-heating, steam from the system is used in numerous restaurants for food preparation, for process heat in laundries and dry cleaners, for steam sterilization, and to power Absorption refrigerator, absorption chillers for air conditioning. On July 18, 2007, one person was killed and numerous others injured when a 2007 New York City steam explosion, steam pipe exploded on 41st Street at Lexington. On August 19, 1989, three people were killed in an Gramercy Park asbestos steam explosion, explosion in Gramercy Park. * Milwaukee, Wisconsin has been using district heating for its central business district since the Valley Power Plant commenced operations in 1968. The air quality in the immediate vicinity of the plant, has been measured with significantly reduced ozone levels. The 2012 conversion of the plant, which changed the fuel input from
coal Coal is a combustible black or brownish-black sedimentary rock, formed as rock strata called coal seams. Coal is mostly carbon with variable amounts of other elements, chiefly hydrogen, sulfur, oxygen, and nitrogen. Coal is formed when dea ...
to natural gas, is expected to further improve air quality at both the local César Chavez sensor as well as Antarctic sensors The Wisconsin power plants double as breeding grounds for peregrine falcons. * Denver's district steam system is the oldest continuously operated commercial district heating system in the world. It began service November 5, 1880 and continues to serve 135 customers. The system is partially powered by the Xcel Energy Zuni Cogeneration Station, which was originally built in 1900. * NRG Energy operates district systems in the cities of San Francisco, Harrisburg, Pennsylvania, Harrisburg, Minneapolis, Omaha, Nebraska, Omaha, Pittsburgh, and San Diego. * Seattle Steam Company, a district system operated by Enwave, in Seattle. Enwave also operates district heat system in Chicago, Houston, Las Vegas, Los Angeles, New Orleans, and Portland, Oregon, Portland along with additional Canadian cities. * Detroit Thermal operates a district system in Detroit that started operation at the Willis Avenue Station in 1903, originally operated by Detroit Edison. * Citizens Energy Group in Indianapolis, Indiana, operates the Perry K. Generating Station, a gas-fired power plant that produces and distributes steam to about 160 downtown Indianapolis customers. * Lansing Board of Water & Light, a municipal utility system in Lansing, Michigan operates a heated and chilled water system from their existing coal plant. They have announced their new natural gas cogeneration plant will continue to provide this service. * Cleveland Thermal operates a district steam (since 1894) from the Canal Road plant near The Flats and district cooling system (since 1993) from Hamilton Avenue plant on the bluffs east of downtown. * Veresen operates district heating/co-generation plants in Ripon, California, and San Gabriel, California. * Veolia Energy, a successor of the 1887 Boston Heating Company, operates a district system in Boston and Cambridge, Massachusetts, and also operates systems in Philadelphia PA, Baltimore MD, Kansas City MO, Tulsa OK, Houston TX and other cities. * District Energy St. Paul operates the largest hot water district heating system in North America and generates the majority of its energy from an adjacent biomass-fueled combined heat and power plant. In March 2011, a 1 MWh thermal solar array was integrated into the system, consisting of 144 20' x 8' solar panels installed on the roof of a customer building, RiverCentre. * The California Department of General Services runs a central plant providing district heating to four million square feet in 23 state-owned buildings, including the State Capitol, using high-pressure steam boilers. Historically, district heating was primarily used in urban areas of the US, but by 1985, it was mainly used in institutions. A handful of smaller municipalities in New England maintained municipal steam into the 21st century, in cities like Holyoke, Massachusetts and Concord, New Hampshire, however the former would end service in 2010 and the latter in 2017, attributing aging infrastructure and capital expenses to their closures. In 2019, Concord replaced a number of remaining pipes with more efficient ones for a smaller steam system heating only the New Hampshire State House, State House and New Hampshire State Library, State Library, mainly due to historic preservation reasons rather than a broader energy plan. District heating is also used on many college campuses, often in combination with district cooling and electricity generation. Colleges using district heating include the University of Texas at Austin; Rice University; Brigham Young University; Georgetown University; Cornell University, which also employs deep water source cooling using the waters of nearby Cayuga Lake; Purdue University; University of Massachusetts Amherst; University of Maine at Farmington; University of Notre Dame; Michigan State University; Eastern Michigan University; Case Western Reserve University; Iowa State University; University of Delaware; University of Maryland, College Park , University of Wisconsin–Madison, University of Georgia, University of Cincinnati, North Carolina State University, and several campuses of the University of California. Massachusetts Institute of Technology, MIT installed a cogeneration system in 1995 that provides electricity, heating and cooling to 80% of its campus buildings. The University of New Hampshire has a cogeneration plant run on methane from an adjacent landfill, providing the university with 100% of its heat and power needs without burning oil or natural gas. North Dakota State University (NDSU) in Fargo, North Dakota has used district heating for over a century from their coal-fired heating plant.


Asia


Japan

87 district heating enterprises are operating in Japan, serving 148 districts. Many companies operate district cogeneration facilities that provide steam and/or hot water to many of the office buildings. Also, most operators in the Greater Tokyo serve district cooling.


China

In southern China (south of the Qinling–Huaihe Line), there are nearly no district heating systems. In northern China, district heating systems are common. Most district heating system which are just for heating instead of CHP use Anthracite, hard coal. Since air pollution in China has become quite serious, many cities gradually are now using natural gas rather than coal in district heating system. There is also some amount of
geothermal heating Geothermal heating is the direct use of geothermal energy for some heating applications. Humans have taken advantage of geothermal heat this way since the Paleolithic era. Approximately seventy countries made direct use of a total of 270 PJ o ...
and sea
heat pump A heat pump is a device that can heat a building (or part of a building) by transferring thermal energy from the outside using a refrigeration cycle. Many heat pumps can also operate in the opposite direction, cooling the building by removing h ...
systems. In February 2019, China's State Power Investment Corporation (SPIC) signed a cooperation agreement with the Baishan municipal government in Jilin province for the Baishan Nuclear Energy Heating Demonstration Project, which would use a China National Nuclear Corporation DHR-400 (District Heating Reactor 400 MWt). Building cost is 1.5 billion yuan ($230 million), taking three years to build.


Turkey

Geothermal energy in Turkey provides some district heating, and residential district heating and cooling requirements have been mapped.


Market penetration

Penetration of district heating (DH) into the heat market varies by country. Penetration is influenced by different factors, including environmental conditions, availability of heat sources, economics, and economic and legal framework. The
European Commission The European Commission (EC) is the executive of the European Union (EU). It operates as a cabinet government, with 27 members of the Commission (informally known as "Commissioners") headed by a President. It includes an administrative body o ...
aims to develop sustainable practices through implementation of district heating and cooling technology. In the year 2000 the percentage of houses supplied by district heat in some European countries was as follows: In Iceland the prevailing positive influence on DH is availability of easily captured geothermal heating, geothermal heat. In most Eastern European countries, energy planning included development of
cogeneration Cogeneration or combined heat and power (CHP) is the use of a heat engine or power station to generate electricity and useful heat at the same time. Cogeneration is a more efficient use of fuel or heat, because otherwise- wasted heat from elect ...
and district heating. Negative influence in the Netherlands and UK can be attributed partially to milder climate, along with competition from natural gas. The tax on domestic gas prices in the UK is a third of that in France and a fifth of that in Germany.


See also

* District cooling * Central solar heating * Geothermal heating * List of public utilities *
CHP Directive The Directive on the promotion of cogeneration based on a useful heat demand in the internal energy market and amending Directive 92/42/EEC,
*
New York City steam system The New York City steam systems include Con Edison, Con Edison's Steam Operations, and other smaller systems that provide steam to New York University and Columbia University. Many individual buildings in New York City, New York have their ow ...
* Public utility * Thermal energy storage * Deep water source cooling * Energy policy of the European Union * Cost of electricity by source * Cogeneration * Alchevsk#Winter disaster of 2006, Alchevsk district heating disaster (2006)


Footnotes


External links


UK's Information Portal on Decentralised and District Energy

District Energy Library

Technical description of district heating and district cooling at Munich Airport, Germany

Geothermal District Heating, Iceland


* [http://www.maxfordham.com/news/publications/a-case-against-the-widespread-use-of-district-heating-and-chp-in-the-uk Max Fordham argues against use of CHP District Heating]
Energy Hub – EU funded FP7 Project – District heating, cooling and power aiming for 100% on-site renewable energy at Leuven, Belgium


* [http://www.benuk.net A Balanced Energy Network integrates heat pumps, demand side response and distributed heat storage in a district heat sharing network.]
Heat Interface UnitsThe Celsius Toolbox – Information on district energy solutions and energy transition.
{{DEFAULTSORT:District heating District heating, American inventions Energy conservation Residential heating