The role of biogas and biomethane in pathways to net zero
Biogas is produced as the main product of anaerobic digestion (AD) of wet biomass. Biogas can be used locally for heating purposes or for power and heat production (CHP); Alternatively, biogas can be upgraded to biomethane to replace natural gas. As such, it is one of the means to reduce fossil fuel consumption and contribute to the transition to a net zero energy system.
This position paper – developed by members of IEA Bioenergy Task 37 (“Energy from Biogas”) – provides central knowledge and characteristics of biogas and biomethane. The most important conclusion is that biogas and biomethane have plenty of potential to be used on the road to net zero. They offer sustainable flexible systems that play an essential role in circular economy, energy and environmental systems.
Highlights:
Energy transition
- The path to net zero requires much more than the supply of renewable electricity; renewable gases and liquids are just as important.
- Biomethane can be introduced into existing gas infrastructure and offers the path of least resistance to decarbonize natural gas applications. With biomethane, the total cost of ownership of the energy system is minimized as the infrastructure for distribution and use is in place.
- Biogas systems are one of many solutions in a net zero future. To achieve a net zero future, a diversity of solutions is in demand. Biogas and biomethane can make an important contribution with tailor-made sustainable and technically highly adaptable solutions. For example, biogas systems can provide controllable electricity and, even better, biogas production can be increased to provide more electricity when demand on the electricity grid is high.
Multifunctionality
- In the production of biogas based on anaerobic digestion, a wide variety of organic raw materials can be used, such as: municipal or industrial organic waste and waste water; industrial residues (such as stillage); agricultural residual flows (such as manure and straw); or plant material.
- Biogas plants contribute to energy security because the entire production chain can be set up and operated decentrally and locally. Moreover, biogas is not the only product of anaerobic digestion; digestate, can be used locally as a renewable biofertilizer (directly or after upgrading). CO 2 , which must be separated from biogas to obtain biomethane, can also be valorized as a by-product.
- Biogas solutions reduce fugitive methane emissions, protect water quality, reduce pathogen levels in slurry, produce biofertilizers, reduce odors and improve air quality. Often the driver for a biogas solution is the reduction of fugitive emissions from wet organic waste.
Circular economy
- Anaerobic digestion can be an essential part of any multi-stage use of organic matter and as such, biogas solutions are strategic components in biorefineries.
- Biogas installations as part of the circular economy in agriculture. For example, digestate from biogas systems can be returned to the land where the crops were grown and produced crops can provide feed to animals whose slurry is digested in a circular economy farming system, reducing fugitive emissions, reducing the use of fossil fertilizers and the soil is improved organic content.
Region-specific solutions
- All biogas solutions are geographically and politically customized. The best solution in one region is not always optimal in another region, depending on the climate and policies of the region in question.
- A detailed, region-specific analysis of availability, costs and impact of specific feedstock uses is recommended to ensure an effective and sustainable biogas sector.
Use of CO 2
- Modern facilities that produce biomethane include carbon capture and reuse. CO 2 in biogas is one of the cheapest sources of biogenic CO 2 for further use.
- Power to methane applications using hydrogen to react with CO 2 in biogas to upgrade to biomethane (and synthetic methane) typically result in a 60% increase in energy output in the form of renewable methane.
Economy
- Compare like with like: biomethane must be compared with other renewable gases, such as hydrogen or synthetic methane.
- Biomethane is cheaper than green hydrogen and is expected to remain so for some time in the future. Moreover, unlike with biomethane, the infrastructure for broad distribution and use of hydrogen is not yet in place.
- Both hydrogen and biomethane are part of larger markets and external factors can determine their optimal use and value to society.
- In addition to replacing fossil fuels and thus reducing greenhouse gas emissions, it must be taken into account that biogas systems are multifunctional and integrated into larger systems. Externalities can be given an economic value or at least should be taken into account in the multi-criteria assessment of decarbonization pathways.
How to stimulate the use of biogas systems
- Incentives should reflect the real investment costs and long-term operation of the renewable gas industry to ensure the developer's bankability and to ensure a price-effective market environment for the renewable gas user.
- Unnecessary barriers and restrictive regulations on both technical and regulatory levels must be removed.
- A stable and predictable framework is recommended to create favorable conditions for the growth of the renewable gas sector.
- A carbon tax on fossil fuels should stimulate development and encourage the transition to renewable energy, while at the same time providing a common basis for competition between renewable technologies.
Roll in the path to net zero
- Renewable hydrocarbons such as biogas and biomethane are required in our future net-zero world and they have many potential uses.
- Biogas and biomethane are sustainable flexible systems that play an essential role in circular economy, energy and environmental systems.
Source IEA Bioenergy
