What is Biochar?

Biochar is a carbon-rich substance produced from biomass (plant matter) which can be used to store carbon dioxide taken up from the air by plants. Biochar is created by a process called pyrolysis, where the biomass is heated to very high temperatures under low oxygen conditions.

Biochar can be produced from a wide range of feedstock materials, including some waste materials that have no other use, such as domestic green waste, agricultural and forestry residues. If biochar is to be applied to land it should not be made from waste construction wood, as this type of wood contains potentially harmful contaminants.

Biochar can potentially be applied to soils to sequester (lock up) carbon for thousands of years, removing carbon dioxide from the atmosphere. It can also improve the soil by increasing pH of acidic soils, improving water and nutrient retention, and improving soil structure. These can be beneficial to plant health, crop yield and can minimise fertiliser losses.

Climate change is happening as a result of greenhouse gas emissions caused by human activity, these gases include carbon dioxide. To limit the impacts of climate change we need to take action to reduce greenhouse gas emissions. Unfortunately not all industries can reduce their emissions to zero, so technologies which take carbon dioxide and other greenhouse gases out of the air, known as Greenhouse Gas Removal (GGR), are needed to achieve net zero.

Biochar is just one of several GGR technologies that will need to be explored in tandem to achieve net zero.

Biochar made from agricultural and forestry residues can be applied to soils and is potentially a means of sequestering (locking up) carbon for thousands of years, thereby removing carbon dioxide from the atmosphere. It can also act as a soil conditioner by increasing pH of acidic soils, improving water holding capacity, modifying nutrient exchange between plant and soil, and improving soil aeration and structure, especially in heavy soils. These are beneficial to plant health, yield and can minimise fertiliser losses.

Biochar is a material that can be produced from a range of organic sources including organic waste that has no other use. It can be produced from virgin and non-contaminated wood, domestic green waste, agricultural waste (including crop residues and livestock manure) and forestry waste. Biochar should not be produced from waste construction wood due to contaminants. If contaminated biochar was applied to soil, this would negatively affect plant growth, and could potentially contaminate groundwater and the food chain.

The biochar demonstrator is designed to address the uncertainties and barriers to the deployment of biochar at a large scale. It is investigating the extent and scope to which biochar can be deployed, its stability as a carbon sequestration method, and the effects of biochar on ecosystems. This will help to develop business models and inform policy on biochar and its use as a carbon sequestration method.

Field trials will deploy over 200 tonnes of biochar produced from virgin and recycled wood over the course of the project. These trials will be undertaken at a range of different sites including arable and grassland sites in the Midlands and Wales, an open cast coal mine site in Cumbria, denuded railway embankments, and forestry sites in England and Wales. These trials are expected to last up to 7 years, for the duration of the demonstrator (4 years) and then monitored by students at the University of Nottingham for an additional 3 years.
These trials are designed to assess the long-term stability of carbon dioxide storage in the soils, study soil health and the ecosystems soils amended with biochar and assess the co-benefits of biochar application such as preventing agricultural run-off. The demonstrator is also conducting social research and life cycle assessments to understand the perspectives of different stakeholders from manufacturing, farming, civil society, and finance, and engage with each of these stakeholders to encourage robust business models and policy to emerge.