Substitute

natural gas Natural gas (also fossil gas, methane gas, and gas) is a naturally occurring compound of gaseous hydrocarbons, primarily methane (95%), small amounts of higher alkanes, and traces of carbon dioxide and nitrogen, hydrogen sulfide and helium ...

(SNG), or synthetic natural gas, is a fuel gas (predominantly

methane Methane ( , ) is a chemical compound with the chemical formula (one carbon atom bonded to four hydrogen atoms). It is a group-14 hydride, the simplest alkane, and the main constituent of natural gas. The abundance of methane on Earth makes ...

, CH₄) that can be produced from

fossil fuels A fossil fuel is a flammable carbon compound- or hydrocarbon-containing material formed naturally in the Earth's crust from the buried remains of prehistoric organisms (animals, plants or microplanktons), a process that occurs within geologica ...

such as

lignite coal Lignite (derived from Latin ''lignum'' meaning 'wood'), often referred to as brown coal, is a soft, brown, combustible sedimentary rock formed from naturally compressed peat. It has a carbon content around 25–35% and is considered the lowest ...

oil shale Oil shale is an organic-rich Granularity, fine-grained sedimentary rock containing kerogen (a solid mixture of Organic compound, organic chemical compounds) from which liquid hydrocarbons can be produced. In addition to kerogen, general compos ...

, or from

biofuel Biofuel is a fuel that is produced over a short time span from Biomass (energy), biomass, rather than by the very slow natural processes involved in the formation of fossil fuels such as oil. Biofuel can be produced from plants or from agricu ...

s (when it is named bio-SNG) or using electricity with power-to-gas systems. SNG in the form of

LNG Liquefied natural gas (LNG) is natural gas (predominantly methane, CH4, with some mixture of ethane, C2H6) that has been cooled to liquid form for ease and safety of non-pressurized storage or transport. It takes up about 1/600th the volume o ...

or CNG can be used in road, rail, air and marine transport vehicles as a substitute for costly diesel, petrol, etc. The

carbon footprint A carbon footprint (or greenhouse gas footprint) is a calculated value or index that makes it possible to compare the total amount of greenhouse gases that an activity, product, company or country Greenhouse gas emissions, adds to the atmospher ...

of SNG derived from coal is comparable to petroleum products. Bio-SNG has a much smaller carbon footprint when compared to petroleum products. LPG can also be produced by synthesising SNG with partial reverse

hydrogenation Hydrogenation is a chemical reaction between molecular hydrogen (H2) and another compound or element, usually in the presence of a catalyst such as nickel, palladium or platinum. The process is commonly employed to redox, reduce or Saturated ...

at high pressure and low temperature. LPG is more easily transportable than SNG, more suitable as fuel in two-wheeler or smaller HP vehicles/engines, and also fetches higher price in international market due to short supply. Renewable electrical energy can also be used to create SNG (methane) via for example electrolysis of water or via a PEM fuel cell in reverse to create hydrogen which is then reacted with from for example, CSS/U Utilisation in the

Sabatier reaction The Sabatier reaction or Sabatier process produces methane and water from a reaction of hydrogen with carbon dioxide at elevated temperatures (optimally 300–400 °C) and pressures (perhaps ) in the presence of a nickel catalyst. It was di ...

. : + 4H₂ → CH₄ + 2H₂O

Distribution

It is advantageous to distribute SNG and bio-SNG together with natural gas in a gas grid. In this way, the production of renewable gas can be phased in at the same rate as the production capacity is increased. The gas market and infrastructure the natural gas has contributed with is a condition for large scale introduction of renewable biomethane produced through anaerobic digestion (

biogas Biogas is a gaseous renewable energy source produced from raw materials such as agricultural waste, manure, municipal waste, plant material, sewage, green waste, Wastewater treatment, wastewater, and food waste. Biogas is produced by anaerobic ...

) or gasification and methanation bio-SNG.

Projects

The Great Plains Synfuels Plant injects approximately 4.1 million m³/day of SNG from lignite coal into the

United States The United States of America (USA), also known as the United States (U.S.) or America, is a country primarily located in North America. It is a federal republic of 50 U.S. state, states and a federal capital district, Washington, D.C. The 48 ...

national gas grid. The production process of SNG at the Great Plains plant involves

gasification Gasification is a process that converts biomass- or fossil fuel-based carbonaceous materials into gases, including as the largest fractions: nitrogen (N2), carbon monoxide (CO), hydrogen (H2), and carbon dioxide (). This is achieved by reacting ...

, gas cleaning, shift, and

methanation Methanation is the conversion of carbon monoxide and carbon dioxide (COx) to methane (CH4) through hydrogenation. The methanation reactions of COx were first discovered by Sabatier and Senderens in 1902. CO''x'' methanation has many practical ap ...

. China is constructing nearly 30 nos massive SNG production plants from coal / lignite with aggregate annual capacity of 120 billion standard cubic meters of SNG. SNG can be produced from low rank coal/lignite using hydrogen. When hydrogen is used in place of oxygen/air, the

process is called hydrogasification.

References

External links

SGC Rapport 187 Substitute natural gas from biomass gasification

SGC-rapport on gasification and methanation
{{fuel gas Natural gas Synthetic fuel technologies

Distribution

Projects

See also

References

External links