Natural gas, LNG, biomethane and hydrogen: how do they differ?

Gas is an energy source that comes in many shapes and sizes. Here's our overview of the various forms it can take...

Natural gas: an abundant, naturally occurring source of energy

Natural gas is a source of energy created by the decomposition over millions of years of organic matter, such as plankton and algae. It is 95 % methane. The world has abundant reserves of natural gas, with underground and subsea reserves being widely distributed around the earth.

It is transported to the point of consumption in two ways:

• Either in its gaseous form, via steel gas pipelines laid underground, and then via utilities networks: this is what we call natural gas.
• Or in its liquid form, at a temperature below 160°C to reduce its volume: this is what we call liquefied natural gas (LNG). It is transported in ships called LNG carriers, and regasified in specialist LNG terminals for injection into the gas transportation or supply networks.

When burned, natural gas gives off mainly water vapor, and is soot-free, dust-free and smoke-free. . It emits 30 % less carbon dioxide (CO) than fuel oil et 45 % less than coal, it also omits only half the nitrogen oxides (NO) and very little sulfur dioxide (SO).

Biogas, the heart of the circular economy

The local-level conversion of fermentable organic matter from a broad diversity of sources (agricultural, industrial and catering waste, local authority waste, etc.) produces biogas. This type of renewable gas can be used directly as a fuel for industrial heating plants or district heating networks.

It can also be purified to the same level of quality as natural gas, in which case it is referred to as 'biomethane' or 'green gas'. Once odorized, controlled, metered and pressure-regulated, it can be injected into the supply network, since it is perfectly suited to all the same uses as natural gas: space heating, cooking, water heating, etc. It can also be used as a biofuel for vehicles.

Biomethane, an alternative and renewable source of energy

Biomethane makes it possible to recover energy from waste as part of the circular economy, and to reduce greenhouse gas emissions. In practical terms, when waste decomposes, it releases methane. Waste collection and treatment avoids the release of these emissions into the atmosphere, and converts them to clean energy. The greenhouse gas emissions resulting from the use of this energy source are therefore virtually zero, because the CO produced by recovering the biomethane has previously been captured by the decomposed organic matter.

New technologies also make it possible to produce so-called 'second-generation' biomethane from lignocellulosic biomass (wood and straw). This process is currently at the research and development stage. ENGIE is focusing its R&D effort on this issue through its construction of the Gaya platform.

Looking further into the future, we will be able to cultivate microalgae, which produce the 100 % renewable gas known as 'third-generation' biomethane.

Biomethane in Europe

In Europe, the largest producer of biogas is Germany, which injects 10,000 GWh of this energy source into its supply networks from 190 production units. Then comes the UK, with 2,000 GWh of energy produced by 51 production units. Both countries benefit from attractive feed-in tariffs, and produce cultures dedicated to biogas production, which enable them to obtain the more consistent quality of raw material required to industrialize the recovery processes used for biogas and the methanation residues known as digestates.

In France, biomethane production is part of the national renewable energy development strategy. The French law of August 17, 2015 - the energy transition for green growth (LTE) law - requires that 10 % of all gas consumed in France by 2030 must be from renewable sources. In 2017, there are 31 sites injecting biomethane into the natural gas supply network operated by GSDF. ADEME (the French Environment and Energy Management Agency) forecasts that between 500 and 1,400 production units could be injecting between 12 and 30 TWh of biomethane energy per year into supply networks by 2030. This quantity of energy is sufficient to heat 2,500,000 homes and fuel 55,000 buses or trucks.

Source : GRTGAZ

ADEME : the French Environment and Energy Management Agency