Position Paper – The role of biogas and biomethane in pathways to net zero
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 heat purposes or for power and heat production (CHP); as an alternative, biogas can be upgraded to bio-methane to replace natural gas. As such, it is one of the means to reduce the consumption of fossil fuels and contribute to the transition towards a net zero energy system.
This position paper – developed by members of IEA Bioenergy Task 37 (“Energy from Biogas”) – provides central knowledge and features of biogas and biomethane. The main conclusion is that biogas and biomethane have plenty of options to be used in a pathway to net zero. They provide sustainable flexible systems that play essential roles in circular economy, energy, and environmental systems.
- The pathway to net zero requires far more than provision of renewable electricity; renewable gases and liquids are as important.
- Biomethane can be fed into the existing gas infrastructure and provides the path of least resistance to decarbonise natural gas applications. With biomethane the total cost of ownership of the energy system is minimised as the infrastructure for distribution and use is in place.
- Biogas systems are one of a range of solutions in a net zero future. To achieve a net zero future there is a demand for a diversity of solutions. Biogas and biomethane can contribute significantly with bespoke sustainable and technically highly customizable solutions. For example, biogas systems can provide dispatchable electricity and even better, production of biogas may be ramped up to provide increased volumes of electricity when demand on the electricity grid is high.
- Biogas production based on anaerobic digestion can utilize a wide variety of organic feedstocks such as: municipal or industrial organic waste and wastewater; industry residues (such as stillage); agricultural residues (such as manures and straw); or plant materials.
- Biogas systems contribute to energy security since the whole 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 biofertiliser (directly, or after upgrading). CO2, which needs to be separated from biogas to obtain biomethane, may also be valorised as a co-product.
- Biogas solutions reduce fugitive methane emissions, protect water quality, reduce pathogen content of slurries, produce biofertilisers, reduce smells, and improve air quality. Often the driver for a biogas solution is the reduction in fugitive emissions from wet organic wastes.
- Anaerobic digestion can be an essential element of any cascaded utilization of organic material and as such biogas solutions are strategic components in biorefineries.
- Biogas systems as part of circular economy in agriculture. For example, digestate from biogas systems may be applied back to the land where the crops were grown and crops produced can provide feed to animals whose slurry is digested in a circular economy agriculture system, reducing fugitive emissions, reducing use of fossil fertiliser and improving soil organic content.
- All biogas solutions are geographically and politically bespoke. The best solution in one region is not always optimal in another region depending on climate and policy of the particular region.
- A detailed, region-specific analysis of availability, costs and impact of specific feedstock utilization is recommended in order to ensure an effective and sustainable biogas sector.
Use of CO2
- Modern facilities that produce biomethane include for carbon capture and reuse. CO2 in biogas is one of the cheapest sources of biogenic CO2 for further utilization.
- Power to methane applications whereby hydrogen is used to react with CO2 in biogas to upgrade to biomethane (and synthetic methane) results in typically, a 60% increase in energy output in the form of renewable methane.
- Compare like with like: biomethane should 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. In addition, unlike the case for biomethane, the infrastructure for wide distribution and use of hydrogen is not yet in place.
- Both hydrogen and biomethane are part of larger markets and externalities may decide their optimum use and value to society.
- Other than replacing fossil fuels and in so doing, reducing GHG emissions, it has to be considered that biogas systems are multi-functional and integrated in larger systems. Externalities could be assigned an economic value or should anyway be considered in multi criteria assessment of decarbonisation pathways.
How to incentivise deployment of biogas systems
- Incentives should reflect the actual costs of investment and long-term operation of the renewable gas industry to ensure bankability for the developer and to ensure a price effective market environment for the user of renewable gas.
- Unnecessary barriers and inhibitory regulations on both technical and regulatory level should be removed.
- A stable and predictable framework is recommended to provide favourable conditions for the renewable gas sector to grow.
- A carbon tax on fossil fuels should stimulate development and drive the transformation towards renewables whilst simultaneously providing a common base for competition between renewable technologies.
Role in the pathway to net zero
- Renewable hydrocarbons such as biogas and biomethane are required in our future net zero world and they have plenty of options to be used.
- Biogas and biomethane are sustainable flexible systems that play essential roles in circular economy, energy, and environmental systems.