Decarbonising energy systems is a crucial step towards mitigating the effects of global warming. The European Union and a growing list of countries around the world have identified biogas and biomethane as critical sources of carbon-neutral, renewable power.
In 2023, the EU is projected to produce 18.4 billion cubic metres (bcm) of biomethane and biogas. Calculations show that production quantities of these fuels will increase nearly five times by 2050 to 167 bcm; together, they have the potential to reduce worldwide greenhouse gas emissions by 10 to 13 per cent.
Biomethane and biogas have a clear role to play in reducing global warming. But what’s the difference between these two renewable fuels?
Both biogas and biomethane are sourced from organic waste and produced through a fermentation process called anaerobic digestion (AD). They’re both sources of renewable energy. But when it comes to their end usage, their similarities stop there. Let’s take a closer look at what makes biomethane different—and more versatile—than biogas.
Biogas, an unrefined product for localised applications
Biogas is the raw, unrefined product of the AD process. Producing it involves taking organic materials like agricultural byproducts, sewage sludge and food waste and using bacteria to break them down in controlled environments that are free from oxygen. The breakdown of the organic material produces gases like methane and carbon dioxide, as well as small amounts of hydrogen sulfide and water vapour.
This raw gas can be used for localised combined heat and power (CHP) applications such as energy generation and heating. In 2021, the EU produced 14.9 bcm of energy from biogas.
While biogas presents a valuable source of carbon-neutral energy, the impurities and low methane content, between 45 to 75 per cent by volume, decreases its energy efficiency. Biogas has a lower heating value (LHV) ranging from 16 megajoules per cubic metre (MJ/m3) to 28 MJ/m3.
This inefficiency, combined with the restriction that biogas can only be used near where it’s produced, makes it generally unsuitable for broader applications. Instead, biogas can be upgraded to produce biomethane.
Biomethane, a versatile fuel for the clean energy transition
Biomethane is produced by filtering biogas to remove impurities like carbon dioxide, hydrogen sulfide and water. This upgrading process results in gas that has at least 95 per cent methane content, which is known as biomethane, renewable natural gas (RNG), or green gas. In other words, biomethane is purified biogas.
RNG is an extremely versatile carbon-neutral fuel source because it can be used as a direct replacement for fossil-based natural gas. It can be injected directly into the gas grid, or used to decarbonise the transport industry.
Greater energy efficiency
Due to its higher methane content, RNG has greater energy density, which makes it more efficient than biogas. Biomethane has an LHV of around 36 MJ/m3, which makes it suitable for providing consistent energy output for applications like industrial power supply and heavy transport.
Long-term storage and transport
Biomethane can be converted to a liquid form (Bio-LNG) or compressed into tube trailers (Bio-CNG). In these formats, it can be stored and transported easily to any location, where it can be used as fuel for LNG- or CNG-powered vehicles. CNG can also be injected directly into the existing gas grid and used interchangeably with fossil natural gas.
Energy security and independence
Because biomethane is produced domestically, it reduces reliance on imported fuels. Biomethane can be liquefied, stored and used to provide a consistent source of energy that’s not weather-dependent such as wind or solar power.
Fuelling the clean energy transition
Biogas and biomethane will play a critical role in helping the world to decarbonise energy systems, achieve net-zero goals and mitigate climate change.
In 2021, the EU produced just 3.5 bcm of biomethane. But the European Biogas Association estimates biomethane production could reach 41 bcm by 2030 and 151 bcm by 2050. As of 2020, the EU’s natural gas consumption was ~400 bcm, and ~155 bcm of that total was imported from Russia. Accordingly, biomethane has the potential to replace nearly 40 per cent of the EU’s fossil-based fuel sources with carbon-neutral, renewable natural gas.
It’s important to note that both of these biofuels reduce the amount of methane being emitted into the atmosphere. Methane is a greenhouse gas that has 80 times the warming potential of carbon dioxide. Reducing these emissions is a vital step towards slowing climate change.
Biogas presents an opportunity to continue to provide a clean source of localised heating fuel and generation of electricity to supply power grids. As such, it’s an important piece of the clean energy puzzle.
Because of its versatility, efficiency and storage potential, biomethane is a readily-available technology that represents one of the biggest opportunities for decarbonising energy systems now.
Learn more about the benefits of biomethane here!