Bioenergy and Greenhouse Gas Emissions
Careful use of sustainable bioenergy can play an important role in our efforts to stall climate change.
Many international bodies, including the European Union, recognise bioenergy as a low carbon renewable energy source. This is because, when burned, plants release the same amount of Carbon Dioxide (CO2) as they have collected while growing. By comparison, fossil fuels release carbon that has been locked away in the ground for millions of years.
What are the risks?
Despite the benefits of this carbon cycle, careless use of biomass fuels is associated with potential threats to climate change. The main risks are:
Supply chain emissions
Biomass needs fertiliser and energy so that we can grow, transport and refine it before use. These activities can cause additional greenhouse gases.
Mature trees, which can take decades to grow, absorb more carbon than younger trees. When we use large amounts of forest biomass inefficiently, it can cause short-term increases in CO2. This carbon debt can take years to pay back with new forest growth.
How to manage biomass emission risks
Plant more trees
The amount of forest harvested each year should be at least equal to new growth. Laws in Ireland require all harvested forests to be replanted. The Government of Ireland also runs a grant scheme to increase forestry.
Source the right wood fuel
In Ireland, we grow commercial forests to provide wood for high-value material items. Only low-value timber is suitable for bioenergy. Collecting wood residue helps prevent forest fires and limits emissions from rotting wood.
Use suitable land
We should not grow energy crops on land with high carbon stocks. Regulations in the EU limit the amount of available grass land and prevent the use of peatland for the growing of energy crops.
Use efficient technology
The processes used to grow, refine and convert biomass fuels should be as efficient as possible. The Support Scheme for Renewable Heat (SSRH) expects technologies to meet set efficiency levels. SEAI does not provide support for low-efficiency electricity generation.
Count greenhouse gas emissions
We need to verify that biomass fuels are not causing a climate problem. Measuring supply chain emissions and imposing strict limits will help reduce bioenergy greenhouse gas emissions. The SSRH requires a reduction of at least 70%, compared to fossil fuels.
EU biomass fuel sustainability criteria
The EU’s 2021 renewable energy directive requires proof of a significant reduction in greenhouse gas emissions compared with fossil fuels. It also requires proof of suitable land and forest management to reduce the risk of harmful land-use change and carbon debt.
- Biomass fuels from energy crops must not come from protected and highly biodiverse land.
- Biomass fuels from forests must not come from areas of conservation.
- Biomass fuels must not reduce the long-term production capacity of the forest.
- The sourcing of biomass fuels from forests must minimise the impact of soil quality and biodiversity.
- You must be able to prove that biomass wood was legally harvested.