A biofuel is a fuel that is produced through contemporary biological
processes, such as agriculture and anaerobic digestion, rather than a
fuel produced by geological processes such as those involved in the
formation of fossil fuels, such as coal and petroleum, from
prehistoric biological matter.
Biofuels can be derived directly from plants, or indirectly from
agricultural, commercial, domestic, and/or industrial wastes.
Renewable biofuels generally involve contemporary carbon fixation,
such as those that occur in plants or microalgae through the process
of photosynthesis. Other renewable biofuels are made through the use
or conversion of biomass (referring to recently living organisms, most
often referring to plants or plant-derived materials). This biomass
can be converted to convenient energy-containing substances in three
different ways: thermal conversion, chemical conversion, and
biochemical conversion. This biomass conversion can result in fuel in
solid, liquid, or gas form. This new biomass can also be used directly
Bioethanol is an alcohol made by fermentation, mostly from
carbohydrates produced in sugar or starch crops such as corn,
sugarcane, or sweet sorghum. Cellulosic biomass, derived from non-food
sources, such as trees and grasses, is also being developed as a
feedstock for ethanol production.
Ethanol can be used as a fuel for
vehicles in its pure form, but it is usually used as a gasoline
additive to increase octane and improve vehicle emissions. Bioethanol
is widely used in the
United States and in Brazil. Current plant
design does not provide for converting the lignin portion of plant raw
materials to fuel components by fermentation.
Biodiesel can be used as a fuel for vehicles in its pure form, but it
is usually used as a diesel additive to reduce levels of particulates,
carbon monoxide, and hydrocarbons from diesel-powered vehicles.
Biodiesel is produced from oils or fats using transesterification and
is the most common biofuel in Europe.
In 2010, worldwide biofuel production reached 105 billion liters (28
billion gallons US), up 17% from 2009, and biofuels provided 2.7%
of the world's fuels for road transport. Global ethanol fuel
production reached 86 billion liters (23 billion gallons US) in 2010,
United States and
Brazil as the world's top producers,
accounting together for about 90% of global production. The world's
largest biodiesel producer is the European Union, accounting for 53%
of all biodiesel production in 2010. As of 2011, mandates for
blending biofuels exist in 31 countries at the national level and in
29 states or provinces. The
International Energy Agency
International Energy Agency has a goal
for biofuels to meet more than a quarter of world demand for
transportation fuels by 2050 to reduce dependence on petroleum and
coal. The production of biofuels also led into a flourishing
automotive industry, where by 2010, 79% of all cars produced in Brazil
were made with a hybrid fuel system of bioethanol and gasoline.
There are various social, economic, environmental and technical issues
relating to biofuels production and use, which have been debated in
the popular media and scientific journals.
1.1 First-generation biofuels
1.2 Second-generation biofuels
1.3 Third-generation biofuels
1.4 Fourth-generation biofuels
2.3 Other bioalcohols
2.4 Green diesel
2.6 Vegetable oil
Solid biomass fuels
3 By region
4 Air pollution
5 Debates regarding the production and use of biofuel
5.1 Banning of first-generation biofuels
Greenhouse gas emissions
5.4 Water Use
6 Current research
Ethanol biofuels (bioethanol)
6.4 Animal gut bacteria
7 See also
9 Further reading
10 External links
"First-generation" or conventional biofuels are biofuels made from
food crops grown on arable land. With this biofuel production
generation, food crops are thus explicitly grown for fuel production,
and not anything else. The sugar, starch, or vegetable oil obtained
from the crops is converted into biodiesel or ethanol, using
transesterification, or yeast fermentation.
Main article: Second-generation biofuels
Second generation biofuels are fuels manufactured from various types
Biomass is a wide-ranging term meaning any source of
organic carbon that is renewed rapidly as part of the carbon cycle.
Biomass is derived from plant materials, but can also include animal
Whereas first generation biofuels are made from the sugars and
vegetable oils found in arable crops, second generation biofuels are
made from lignocellulosic biomass or woody crops, agricultural
residues or waste plant material (from food crops but they have
already fulfilled their food purpose). The feedstock used to
generate second-generation biofuels should grow on lands which cannot
be used to effectively grow food and their growing should not consume
lots of water or fertilizer. The feedstock sources include grasses,
jatropha and other seed crops, waste vegetable oil, municipal solid
waste and so forth.
This has both advantages and disadvantages. The advantage is that,
unlike with regular food crops, no arable land is used solely for the
production of fuel. The disadvantage is that unlike with regular food
crops, it may be rather difficult to extract the fuel. For instance, a
series of physical and chemical treatments might be required to
convert lignocellulosic biomass to liquid fuels suitable for
Algaculture and Algae fuel
From 1978 to 1996, the US NREL experimented with using algae as a
biofuels source in the "Aquatic Species Program". A self-published
article by Michael Briggs, at the UNH
Biofuels Group, offers estimates
for the realistic replacement of all vehicular fuel with biofuels by
using algae that have a natural oil content greater than 50%, which
Briggs suggests can be grown on algae ponds at wastewater treatment
plants. This oil-rich algae can then be extracted from the system
and processed into biofuels, with the dried remainder further
reprocessed to create ethanol. The production of algae to harvest oil
for biofuels has not yet been undertaken on a commercial scale, but
feasibility studies have been conducted to arrive at the above yield
estimate. In addition to its projected high yield,
algaculture – unlike crop-based biofuels – does not
entail a decrease in food production, since it requires neither
farmland nor fresh water. Many companies are pursuing algae
bioreactors for various purposes, including scaling up biofuels
production to commercial levels. Prof. Rodrigo E. Teixeira
University of Alabama in Huntsville
University of Alabama in Huntsville demonstrated the
extraction of biofuels lipids from wet algae using a simple and
economical reaction in ionic liquids.
Similarly to third-generation biofuels, fourth-generation biofuels are
made using non-arable land. However, unlike third-generation biofuels,
they do not require the destruction of biomass. This class of biofuels
includes electrofuels and photobiological solar fuels. Some of
these fuels are carbon-neutral. The conversion of crude oil from the
plant seeds into useful fuels is called transesterification.
The following fuels can be produced using first, second, third or
fourth-generation biofuel production procedures. Most of these can
even be produced using two or three of the different biofuel
Neat ethanol on the left (A), gasoline on the right (G) at a
filling station in Brazil
Biologically produced alcohols, most commonly ethanol, and less
commonly propanol and butanol, are produced by the action of
microorganisms and enzymes through the fermentation of sugars or
starches (easiest), or cellulose (which is more difficult). Biobutanol
(also called biogasoline) is often claimed to provide a direct
replacement for gasoline, because it can be used directly in a
George W. Bush
George W. Bush looks at sugar cane, a source of
biofuel, with Brazilian President
Luiz Inácio Lula da Silva
Luiz Inácio Lula da Silva during a
tour on biofuel technology at
Petrobras in São Paulo, Brazil, 9 March
Ethanol fuel is the most common biofuel worldwide, particularly in
Alcohol fuels are produced by fermentation of sugars derived
from wheat, corn, sugar beets, sugar cane, molasses and any sugar or
starch from which alcoholic beverages such as whiskey, can be made
(such as potato and fruit waste, etc.). The ethanol production methods
used are enzyme digestion (to release sugars from stored starches),
fermentation of the sugars, distillation and drying. The distillation
process requires significant energy input for heat (sometimes
unsustainable natural gas fossil fuel, but cellulosic biomass such as
bagasse, the waste left after sugar cane is pressed to extract its
juice, is the most common fuel in Brazil, while pellets, wood chips
and also waste heat are more common in Europe) Waste steam fuels
ethanol factory – where waste heat from the factories also is
used in the district heating grid.
Ethanol can be used in petrol engines as a replacement for gasoline;
it can be mixed with gasoline to any percentage. Most existing car
petrol engines can run on blends of up to 15% bioethanol with
Ethanol has a smaller energy density than that of
gasoline; this means it takes more fuel (volume and mass) to produce
the same amount of work. An advantage of ethanol (CH
2OH) is that it has a higher octane rating than ethanol-free gasoline
available at roadside gas stations, which allows an increase of an
engine's compression ratio for increased thermal efficiency. In
high-altitude (thin air) locations, some states mandate a mix of
gasoline and ethanol as a winter oxidizer to reduce atmospheric
Ethanol is also used to fuel bioethanol fireplaces. As they do not
require a chimney and are "flueless", bioethanol fires are
extremely useful for newly built homes and apartments without a flue.
The downsides to these fireplaces is that their heat output is
slightly less than electric heat or gas fires, and precautions must be
taken to avoid carbon monoxide poisoning.
Corn-to-ethanol and other food stocks has led to the development of
cellulosic ethanol. According to a joint research agenda conducted
through the US Department of Energy, the fossil energy ratios
(FER) for cellulosic ethanol, corn ethanol, and gasoline are 10.3,
1.36, and 0.81, respectively.
Ethanol has roughly one-third lower energy content per unit of volume
compared to gasoline. This is partly counteracted by the better
efficiency when using ethanol (in a long-term test of more than 2.1
million km, the BEST project found FFV vehicles to be 1–26% more
energy efficient than petrol cars, but the volumetric consumption
increases by approximately 30%, so more fuel stops are required).
With current subsidies, ethanol fuel is slightly cheaper per distance
traveled in the United States.
Main article: Biodiesel
Biodiesel around the world
Biodiesel is the most common biofuel in Europe. It is produced from
oils or fats using transesterification and is a liquid similar in
composition to fossil/mineral diesel. Chemically, it consists mostly
of fatty acid methyl (or ethyl) esters (FAMEs). Feedstocks for
biodiesel include animal fats, vegetable oils, soy, rapeseed,
jatropha, mahua, mustard, flax, sunflower, palm oil, hemp, field
Pongamia pinnata and algae. Pure biodiesel (B100, also
known as "neat" biodiesel) currently reduces emissions with up to 60%
compared to diesel Second generation B100.
Biofuels Division railcar transporting Biodiesel.
Biodiesel can be used in any diesel engine when mixed with mineral
diesel. In some countries, manufacturers cover their diesel engines
under warranty for B100 use, although
Volkswagen of Germany, for
example, asks drivers to check by telephone with the VW environmental
services department before switching to B100. B100 may become more
viscous at lower temperatures, depending on the feedstock used. In
most cases, biodiesel is compatible with diesel engines from 1994
onwards, which use 'Viton' (by DuPont) synthetic rubber in their
mechanical fuel injection systems. Note however, that no vehicles are
certified for using pure biodiesel before 2014, as there was no
emission control protocol available for biodiesel before this date.
Electronically controlled 'common rail' and 'unit injector' type
systems from the late 1990s onwards may only use biodiesel blended
with conventional diesel fuel. These engines have finely metered and
atomized multiple-stage injection systems that are very sensitive to
the viscosity of the fuel. Many current-generation diesel engines are
made so that they can run on B100 without altering the engine itself,
although this depends on the fuel rail design. Since biodiesel is an
effective solvent and cleans residues deposited by mineral diesel,
engine filters may need to be replaced more often, as the biofuel
dissolves old deposits in the fuel tank and pipes. It also effectively
cleans the engine combustion chamber of carbon deposits, helping to
maintain efficiency. In many European countries, a 5% biodiesel blend
is widely used and is available at thousands of gas stations.
Biodiesel is also an oxygenated fuel, meaning it contains a reduced
amount of carbon and higher hydrogen and oxygen content than fossil
diesel. This improves the combustion of biodiesel and reduces the
particulate emissions from unburnt carbon. However, using pure
biodiesel may increase NOx-emissions
Biodiesel is also safe to handle and transport because it is non-toxic
and biodegradable, and has a high flash point of about 300 °F
(148 °C) compared to petroleum diesel fuel, which has a flash
point of 125 °F (52 °C).
In the USA, more than 80% of commercial trucks and city buses run on
diesel. The emerging US biodiesel market is estimated to have grown
200% from 2004 to 2005. "By the end of 2006 biodiesel production was
estimated to increase fourfold [from 2004] to more than"
1 billion US gallons (3,800,000 m3).
In France, biodiesel is incorporated at a rate of 8% in the fuel used
by all French diesel vehicles.
Avril Group produces under the
brand Diester, a fifth of 11 million tons of biodiesel consumed
annually by the European Union. It is the leading European
producer of biodiesel.
Methanol is currently produced from natural gas, a non-renewable
fossil fuel. In the future it is hoped to be produced from biomass as
biomethanol. This is technically feasible, but the production is
currently being postponed for concerns of Jacob S. Gibbs and Brinsley
Coleberd that the economic viability is still pending. The
methanol economy is an alternative to the hydrogen economy, compared
to today's hydrogen production from natural gas.
9OH) is formed by ABE fermentation (acetone, butanol, ethanol) and
experimental modifications of the process show potentially high net
energy gains with butanol as the only liquid product. Butanol will
produce more energy and allegedly can be burned "straight" in existing
gasoline engines (without modification to the engine or car), and
is less corrosive and less water-soluble than ethanol, and could be
distributed via existing infrastructures.
DuPont and BP are working
together to help develop butanol.
Escherichia coli strains have also
been successfully engineered to produce butanol by modifying their
amino acid metabolism.
Vegetable oil refining
Green diesel is produced through hydrocracking biological oil
feedstocks, such as vegetable oils and animal fats.
Hydrocracking is a refinery method that uses elevated temperatures and
pressure in the presence of a catalyst to break down larger molecules,
such as those found in vegetable oils, into shorter hydrocarbon chains
used in diesel engines. It may also be called renewable diesel,
hydrotreated vegetable oil or hydrogen-derived renewable
diesel. Green diesel has the same chemical properties as
petroleum-based diesel. It does not require new engines, pipelines
or infrastructure to distribute and use, but has not been produced at
a cost that is competitive with petroleum.
Gasoline versions are
also being developed. Green diesel is being developed in Louisiana
Singapore by ConocoPhillips, Neste Oil, Valero, Dynamic Fuels, and
Honeywell UOP as well as Preem in Gothenburg, Sweden, creating
what is known as Evolution Diesel.
In 2013 UK researchers developed a genetically modified strain of E.
coli, which could transform glucose into biofuel gasoline that does
not need to be blended. Later in 2013
UCLA researchers engineered
a new metabolic pathway to bypass glycolysis and increase the rate of
conversion of sugars into biofuel, while
developed a strain capable of producing short-chain alkanes, free
fatty acids, fatty esters and fatty alcohols through the fatty acyl
(acyl carrier protein (ACP)) to fatty acid to fatty acyl-CoA pathway
in vivo. It is believed that in the future it will be possible to
"tweak" the genes to make gasoline from straw or animal manure.
Filtered waste vegetable oil
This truck is one of 15 based at Walmart's Buckeye, Arizona
distribution center that was converted to run on a biofuel made from
reclaimed cooking grease produced during food preparation at Walmart
Vegetable oil fuel
Straight unmodified edible vegetable oil is generally not used as
fuel, but lower-quality oil has been used for this purpose. Used
vegetable oil is increasingly being processed into biodiesel, or (more
rarely) cleaned of water and particulates and then used as a fuel.
As with 100% biodiesel (B100), to ensure the fuel injectors atomize
the vegetable oil in the correct pattern for efficient combustion,
vegetable oil fuel must be heated to reduce its viscosity to that of
diesel, either by electric coils or heat exchangers. This is easier in
warm or temperate climates. MAN B&W Diesel, Wärtsilä, and Deutz
AG, as well as a number of smaller companies, such as Elsbett, offer
engines that are compatible with straight vegetable oil, without the
need for after-market modifications.
Vegetable oil can also be used in many older diesel engines that do
not use common rail or unit injection electronic diesel injection
systems. Due to the design of the combustion chambers in indirect
injection engines, these are the best engines for use with vegetable
oil. This system allows the relatively larger oil molecules more time
to burn. Some older engines, especially Mercedes, are driven
experimentally by enthusiasts without any conversion, a handful of
drivers have experienced limited success with earlier pre-"Pumpe Duse"
VW TDI engines and other similar engines with direct injection.
Several companies, such as
Elsbett or Wolf, have developed
professional conversion kits and successfully installed hundreds of
them over the last decades.
Oils and fats can be hydrogenated to give a diesel substitute. The
resulting product is a straight-chain hydrocarbon with a high cetane
number, low in aromatics and sulfur and does not contain oxygen.
Hydrogenated oils can be blended with diesel in all proportions. They
have several advantages over biodiesel, including good performance at
low temperatures, no storage stability problems and no susceptibility
to microbial attack.
Bioethers (also referred to as fuel ethers or oxygenated fuels) are
cost-effective compounds that act as octane rating
enhancers."Bioethers are produced by the reaction of reactive
iso-olefins, such as iso-butylene, with bioethanol." Bioethers are
created by wheat or sugar beet. They also enhance engine
performance, whilst significantly reducing engine wear and toxic
exhaust emissions. Though bioethers are likely to replace petroethers
in the UK, it is highly unlikely they will become a fuel in and of
itself due to the low energy density. Greatly reducing the amount
of ground-level ozone emissions, they contribute to air
When it comes to transportation fuel there are six ether additives:
dimethyl ether (DME), diethyl ether (DEE), methyl teritiary-butyl
ether (MTBE), ethyl ter-butyl ether (ETBE), ter-amyl methyl ether
(TAME), and ter-amyl ethyl ether (TAEE).
Fuel Oxygenates Association (EFOA) credits methyl
Ttertiary-butyl ether (MTBE) and ethyl ter-butyl ether (ETBE) as the
most commonly used ethers in fuel to replace lead.
introduced in Europe in the 1970s to replace the highly toxic
compound. Although Europeans still use bio-ether additives, the US
no longer has an oxygenate requirement therefore bio-ethers are no
longer used as the main fuel additive.
Pipes carrying biogas
Main article: Biogas
Biogas is methane produced by the process of anaerobic digestion of
organic material by anaerobes. It can be produced either from
biodegradable waste materials or by the use of energy crops fed into
anaerobic digesters to supplement gas yields. The solid byproduct,
digestate, can be used as a biofuel or a fertilizer.
Biogas can be recovered from mechanical biological treatment waste
Landfill gas, a less clean form of biogas, is
produced in landfills through naturally occurring anaerobic digestion.
If it escapes into the atmosphere, it is a potential greenhouse gas.
Farmers can produce biogas from manure from their cattle by using
Main article: Gasification
Syngas, a mixture of carbon monoxide, hydrogen and other hydrocarbons,
is produced by partial combustion of biomass, that is, combustion with
an amount of oxygen that is not sufficient to convert the biomass
completely to carbon dioxide and water. Before partial combustion,
the biomass is dried, and sometimes pyrolysed. The resulting gas
mixture, syngas, is more efficient than direct combustion of the
original biofuel; more of the energy contained in the fuel is
Syngas may be burned directly in internal combustion engines, turbines
or high-temperature fuel cells. The wood gas generator, a
wood-fueled gasification reactor, can be connected to an internal
Syngas can be used to produce methanol, DME and hydrogen, or converted
Fischer-Tropsch process to produce a diesel substitute, or a
mixture of alcohols that can be blended into gasoline. Gasification
normally relies on temperatures greater than 700 °C.
Lower-temperature gasification is desirable when co-producing biochar,
but results in syngas polluted with tar.
Solid biomass fuels
Examples include wood, sawdust, grass trimmings, domestic refuse,
charcoal, agricultural waste, nonfood energy crops, and dried manure.
When solid biomass is already in a suitable form (such as firewood),
it can burn directly in a stove or furnace to provide heat or raise
steam. When solid biomass is in an inconvenient form (such as sawdust,
wood chips, grass, urban waste wood, agricultural residues), the
typical process is to densify the biomass. This process includes
grinding the raw biomass to an appropriate particulate size (known as
hogfuel), which, depending on the densification type, can be from 1 to
3 cm (0.4 to 1.2 in), which is then concentrated into a fuel
product. The current processes produce wood pellets, cubes, or pucks.
The pellet process is most common in Europe, and is typically a pure
wood product. The other types of densification are larger in size
compared to a pellet and are compatible with a broad range of input
feedstocks. The resulting densified fuel is easier to transport and
feed into thermal generation systems, such as boilers.
Sawdust, bark and chips are already used for decades for fuel in
industrial processes; examples include the pulp and paper industry and
the sugar cane industry. Boilers in the range of 500,000 lb/hr of
steam, and larger, are in routine operation, using grate, spreader
stoker, suspension burning and fluid bed combustion. Utilities
generate power, typically in the range of 5 to 50 MW, using locally
available fuel. Other industries have also installed wood waste fueled
boilers and dryers in areas with low-cost fuel.
One of the advantages of solid biomass fuel is that it is often a
byproduct, residue or waste-product of other processes, such as
farming, animal husbandry and forestry. In theory, this means fuel
and food production do not compete for resources, although this is not
always the case.
A problem with the combustion of solid biomass fuels is that it emits
considerable amounts of pollutants, such as particulates and
polycyclic aromatic hydrocarbons. Even modern pellet boilers generate
much more pollutants than oil or natural gas boilers. Pellets made
from agricultural residues are usually worse than wood pellets,
producing much larger emissions of dioxins and chlorophenols.
A derived fuel is biochar, which is produced by biomass pyrolysis.
Biochar made from agricultural waste can substitute for wood charcoal.
As wood stock becomes scarce, this alternative is gaining ground. In
eastern Democratic Republic of Congo, for example, biomass briquettes
are being marketed as an alternative to charcoal to protect Virunga
National Park from deforestation associated with charcoal
Biofuels by region
Biodiesel around the world
Bio Diesel Powered Fast Attack Craft Of
Indian Navy patrolling during
IFR 2016.The green bands on the vessels are indicative of the fact
that the vessels are powered by bio-diesel
There are international organizations such as IEA Bioenergy,
established in 1978 by the
International Energy Agency
International Energy Agency (IEA),
with the aim of improving cooperation and information exchange between
countries that have national programs in bioenergy research,
development and deployment. The UN International
Biofuels Forum is
formed by Brazil, China, India, Pakistan, South Africa, the United
States and the European Commission. The world leaders in biofuel
development and use are Brazil, the United States, France, Sweden and
Germany. Russia also has 22% of world's forest, and is a big
biomass (solid biofuels) supplier. In 2010, Russian pulp and paper
maker, Vyborgskaya Cellulose, said they would be producing pellets
that can be used in heat and electricity generation from its plant in
Vyborg by the end of the year. The plant will eventually produce
about 900,000 tons of pellets per year, making it the largest in the
world once operational.
Biofuels currently make up 3.1% of the total road transport fuel
in the UK or 1,440 million litres. By 2020, 10% of the energy used in
UK road and rail transport must come from renewable sources – this
is the equivalent of replacing 4.3 million tonnes of fossil oil each
year. Conventional biofuels are likely to produce between 3.7 and 6.6%
of the energy needed in road and rail transport, while advanced
biofuels could meet up to 4.3% of the UK's renewable transport fuel
target by 2020.
Biomass § Environmental damage, and Ethanol_fuel
Biofuels are similar to fossil fuels in that biofuels contribute to
air pollution. Burning produces carbon dioxide, airborne carbon
particulates, carbon monoxide and nitrous oxides. The WHO
estimates 3.7 million premature deaths worldwide in 2012 due to air
Brazil burns significant amounts of ethanol biofuel.
Gas chromatograph studies were performed of ambient air in São Paulo,
Brazil, and compared to Osaka, Japan, which does not burn ethanol
fuel. Atmospheric Formaldehyde was 160% higher in Brazil, and
Acetaldehyde was 260% higher.
The Environmental Protection Agency has acknowledged in April 2007
that the increased use of bio-ethanol will lead to worse air quality.
The total emissions of air pollutants such as nitrogen oxides will
rise due the growing use of bio-ethanol. There is an increase in
carbon dioxide from the burning of fossil fuels to produce the
biofuels as well as nitrous oxide from the soil, which has most likely
been treated with nitrogen fertilizer.
Nitrous oxide is known to have
a greater impact on the atmosphere in relation to global warming, as
it is also an ozone destroyer.
Debates regarding the production and use of biofuel
Main article: Issues relating to biofuels
There are various social, economic, environmental and technical issues
with biofuel production and use, which have been discussed in the
popular media and scientific journals. These include: the effect of
moderating oil prices, the "food vs fuel" debate, food prices, poverty
reduction potential, energy ratio, energy requirements, carbon
emissions levels, sustainable biofuel production, deforestation and
soil erosion, loss of biodiversity, impact on water resources, the
possible modifications necessary to run the engine on biofuel, as well
as energy balance and efficiency. The International Resource
Panel, which provides independent scientific assessments and expert
advice on a variety of resource-related themes, assessed the issues
relating to biofuel use in its first report Towards sustainable
production and use of resources: Assessing Biofuels. "Assessing
Biofuels" outlined the wider and interrelated factors that need to be
considered when deciding on the relative merits of pursuing one
biofuel over another. It concluded that not all biofuels perform
equally in terms of their impact on climate, energy security and
ecosystems, and suggested that environmental and social impacts need
to be assessed throughout the entire life-cycle.
Another issue with biofuel use and production is the US has changed
mandates many times because the production has been taking longer than
expected. The Renewable
Fuel Standard (RFS) set by congress for 2010
was pushed back to at best 2012 to produce 100 million gallons of pure
ethanol (not blended with a fossil fuel).
Banning of first-generation biofuels
In the EU, the revised renewable energy directive calls for a complete
ban on first-generation biofuels. Particularly fuels made from such
oils such as palm oil and soy oil are being targeted.
Many of the biofuels that were being supplied in 2008 (using the
first-generation biofuel production procedure) have been criticised
for their adverse impacts on the natural environment, food security,
and land use. In 2008, the Nobel-prize winning chemist Paul J.
Crutzen published findings that the release of nitrous oxide (N2O)
emissions in the production of biofuels means that overall they
contribute more to global warming than the fossil fuels they
replace. In 2008, the challenge was to support biofuel
development, including the development of new cellulosic technologies,
with responsible policies and economic instruments to help ensure that
biofuel commercialization is sustainable. Responsible
commercialization of biofuels represented an opportunity to enhance
sustainable economic prospects in Africa, Latin America and
Asia. Now, biofuels in the form of liquid fuels derived
from plant materials are entering the market, driven by the perception
that they reduce climate gas emissions, and also by factors such as
oil price spikes and the need for increased energy security.
According to the Rocky Mountain Institute, sound biofuel production
practices would not hamper food and fibre production, nor cause water
or environmental problems, and would enhance soil fertility. The
selection of land on which to grow the feedstocks is a critical
component of the ability of biofuels to deliver sustainable solutions.
A key consideration is the minimisation of biofuel competition for
Greenhouse gas emissions
Some scientists have expressed concerns about land-use change in
response to greater demand for crops to use for biofuel and the
subsequent carbon emissions. The payback period, that is, the time
it will take biofuels to pay back the carbon debt they acquire due to
land-use change, has been estimated to be between 100 and 1000 years,
depending on the specific instance and location of land-use change.
However, no-till practices combined with cover-crop practices can
reduce the payback period to three years for grassland conversion and
14 years for forest conversion.
A study conducted in the Tocantis State, in northern Brazil, found
that many families were cutting down forests in order to produce two
conglomerates of oilseed plants, the J. curcas (JC group) and the R.
communis (RC group). This region is composed of 15% Amazonian
rainforest with high biodiversity, and 80% Cerrado forest with lower
biodiversity. During the study, the farmers that planted the JC group
released over 2193 Mg CO2, while losing 53-105 Mg CO2 sequestration
from deforestation; and the RC group farmers released 562 Mg CO2,
while losing 48-90 Mg CO2 to be sequestered from forest depletion.
The production of these types of biofuels not only led into an
increased emission of carbon dioxide, but also to lower efficiency of
forests to absorb the gases that these farms were emitting. This has
to do with the amount of fossil fuel the production of fuel crops
involves. In addition, the intensive use of monocropping agriculture
requires large amounts of water irrigation, as well as of fertilizers,
herbicides and pesticides. This does not only lead to poisonous
chemicals to disperse on water runoff, but also to the emission of
nitrous oxide (NO2) as a fertilizer byproduct, which is three hundred
times more efficient in producing a greenhouse effect than carbon
Converting rainforests, peatlands, savannas, or grasslands to produce
food crop–based biofuels in Brazil, Southeast Asia, and the United
States creates a “biofuel carbon debt” by releasing 17 to 420
times more CO2 than the annual greenhouse gas (GHG) reductions that
these biofuels would provide by displacing fossil fuels.
from waste biomass or from biomass grown on abandoned agricultural
lands incur little to no carbon debt.
In addition to crop growth requiring water, biofuel facilities require
significant process water.
Research is ongoing into finding more suitable biofuel crops and
improving the oil yields of these crops. Using the current yields,
vast amounts of land and fresh water would be needed to produce enough
oil to completely replace fossil fuel usage. It would require twice
the land area of the US to be devoted to soybean production, or
two-thirds to be devoted to rapeseed production, to meet current US
heating and transportation needs.
Specially bred mustard varieties can produce reasonably high oil
yields and are very useful in crop rotation with cereals, and have the
added benefit that the meal left over after the oil has been pressed
out can act as an effective and biodegradable pesticide.
The NFESC, with Santa Barbara-based
Biodiesel Industries, is working
to develop biofuels technologies for the US navy and military, one of
the largest diesel fuel users in the world. A group of Spanish
developers working for a company called Ecofasa announced a new
biofuel made from trash. The fuel is created from general urban waste
which is treated by bacteria to produce fatty acids, which can be used
to make biofuels. Before its shutdown,
Joule Unlimited was
attempting to make cheap ethanol and biodiesel from a genetically
modified photosynthetic bacterium.
Ethanol biofuels (bioethanol)
Ethanol fuel and
Cellulosic ethanol commercialization
As the primary source of biofuels in North America, many organizations
are conducting research in the area of ethanol production. The
Ethanol Research Center (NCERC) is a research
Southern Illinois University Edwardsville
Southern Illinois University Edwardsville dedicated solely
to ethanol-based biofuel research projects. On the federal level,
USDA conducts a large amount of research regarding ethanol
production in the United States. Much of this research is targeted
toward the effect of ethanol production on domestic food markets.
A division of the U.S. Department of Energy, the National Renewable
Energy Laboratory (NREL), has also conducted various ethanol research
projects, mainly in the area of cellulosic ethanol.
Cellulosic ethanol commercialization is the process of building an
industry out of methods of turning cellulose-containing organic matter
into fuel. Companies, such as Iogen, POET, and Abengoa, are building
refineries that can process biomass and turn it into bioethanol.
Companies, such as Diversa, Novozymes, and Dyadic, are producing
enzymes that could enable a cellulosic ethanol future. The shift from
food crop feedstocks to waste residues and native grasses offers
significant opportunities for a range of players, from farmers to
biotechnology firms, and from project developers to investors.
As of 2013, the first commercial-scale plants to produce cellulosic
biofuels have begun operating. Multiple pathways for the conversion of
different biofuel feedstocks are being used. In the next few years,
the cost data of these technologies operating at commercial scale, and
their relative performance, will become available. Lessons learnt will
lower the costs of the industrial processes involved.
In parts of Asia and Africa where drylands prevail, sweet sorghum is
being investigated as a potential source of food, feed and fuel
combined. The crop is particularly suitable for growing in arid
conditions, as it only extracts one seventh of the water used by
sugarcane. In India, and other places, sweet sorghum stalks are used
to produce biofuel by squeezing the juice and then fermenting into
A study by researchers at the International Crops Research Institute
for the Semi-Arid Tropics (ICRISAT) found that growing sweet sorghum
instead of grain sorghum could increase farmers incomes by US$40 per
hectare per crop because it can provide fuel in addition to food and
animal feed. With grain sorghum currently grown on over 11 million
hectares (ha) in Asia and on 23.4 million ha in Africa, a switch to
sweet sorghum could have a considerable economic impact.
Main article: Jatropha biofuel
Several groups in various sectors are conducting research on Jatropha
curcas, a poisonous shrub-like tree that produces seeds considered by
many to be a viable source of biofuels feedstock oil. Much of
this research focuses on improving the overall per acre oil yield of
Jatropha through advancements in genetics, soil science, and
SG Biofuels, a San Diego-based jatropha developer, has used molecular
breeding and biotechnology to produce elite hybrid seeds that show
significant yield improvements over first-generation varieties.
SG Biofuels also claims additional benefits have arisen from such
strains, including improved flowering synchronicity, higher resistance
to pests and diseases, and increased cold-weather tolerance.
Plant Research International, a department of the Wageningen
University and Research Centre in the Netherlands, maintains an
ongoing Jatropha Evaluation Project that examines the feasibility of
large-scale jatropha cultivation through field and laboratory
experiments. The Center for
Sustainable Energy Farming (CfSEF) is
a Los Angeles-based nonprofit research organization dedicated to
jatropha research in the areas of plant science, agronomy, and
horticulture. Successful exploration of these disciplines is projected
to increase jatropha farm production yields by 200-300% in the next 10
A group at the
Russian Academy of Sciences
Russian Academy of Sciences in Moscow, in a 2008 paper,
stated they had isolated large amounts of lipids from single-celled
fungi and turned it into biofuels in an economically efficient manner.
More research on this fungal species,
Cunninghamella japonica, and
others, is likely to appear in the near future. The recent
discovery of a variant of the fungus
Gliocladium roseum (later renamed
Ascocoryne sarcoides) points toward the production of so-called
myco-diesel from cellulose. This organism was recently discovered in
the rainforests of northern Patagonia, and has the unique capability
of converting cellulose into medium-length hydrocarbons typically
found in diesel fuel. Many other fungi that can degrade cellulose
and other polymers have been observed to produce molecules that are
currently being engineered using organisms from other kingdoms,
suggesting that fungi may play a large role in the bio-production of
fuels in the future (reviewed in ).
Animal gut bacteria
Microbial gastrointestinal flora in a variety of animals have shown
potential for the production of biofuels. Recent research has shown
that TU-103, a strain of
Clostridium bacteria found in Zebra feces,
can convert nearly any form of cellulose into butanol fuel.
Microbes in panda waste are being investigated for their use in
creating biofuels from bamboo and other plant materials. There
has also been substantial research into the technology of using the
gut microbiomes of wood-feeding insects for the conversion of
lignocellulotic material into biofuel.
Biofuels Center of North Carolina
Bioheat, a biofuel blended with heating oil.
Food vs. fuel
Biomass to liquid bio-oil
Renewable energy by country
List of biofuel companies and researchers
List of emerging technologies
List of vegetable oils used for biofuel
Sustainable aviation fuel
Table of biofuel crop yields
Access related topics
Renewable energy portal
Sustainable development portal
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Look up biofuel in Wiktionary, the free dictionary.
Alternative Fueling Station Locator (EERE)
Sustainable Production and Use of Resources: Assessing
Biofuels by the
United Nations Environment Programme, October 2009.
Biofuels guidance for businesses, including permits and licences
required on NetRegs.gov.uk
How Much Water Does It Take to Make Electricity?—Natural gas
requires the least water to produce energy, some biofuels the most,
according to a new study.
International Conference on
Biofuels Standards – European Union
Biofuels from Biomass: Technology and Policy Considerations Thorough
overview from MIT
The Guardian news on biofuels
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Clean Cities Program – links to all of the Clean
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Biofuels Factsheet by the University of Michigan's Center for
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