Waste pyrolysis chars offer carbon removal route

25 May 2021
Posted in News
25 May 2021 sg-admin

Regulatory changes based on wider end-product research are key to boosting carbon capture and storage from pyrolysis processing of mixed waste streams, says Standard Gas’ Richard Jackson

Waste processing via pyrolysis – generating energy and biochar and char – offers a more productive and decarbonising alternative to landfill and incineration. Furthermore, sequestration of biochar and char residues from respectively biogenic and mixed wastes offers an important pathway for carbon removal. But realising this will require regulatory regimes to recognise the carbon sink potential of these chars, in alignment with science-based efforts such as BiCRS (biomass carbon removal and storage), which will facilitate the development of valuable carbon-removing end-uses for these products. 

In a short online presentation for the UK Biochar Research Centre’s Green Carbon Webinar series (https://www.youtube.com/watch?v=fwwtSGK0x6U), Standard Gas director and the company’s co-Carbon Lead, Richard Jackson, outlined the potential for carbon sequestration of biochar and char in the broader contexts of regulation, waste processing waste economics, and changes driven by scientific advances.

For nascent biochar/char producers such as Standard Gas, an immediate challenge is the distinct classification of these as ‘wastes’ rather than products with a value, Jackson said. In the regulatory environment, “biochar” is the term applied to the high carbon-content residue from pyrolysis or gasification of 100% plant-based material. “Char” is the term applied to mixed waste residues, despite these wastes also having high biogenic content, often well above 50%.  

Significant academic work has been undertaken to ensure biochar sequestration pathways are well regulated and safe. Currently, these pathways are mostly agricultural – primarily as a soil stabiliser and conditioner – and economically limited. But with increasing emphasis on carbon removal as a key element of climate change mitigation, the focus on biochar is now shifting towards its permanent carbon sink potential, Jackson noted. 

To date, the carbon sequestering pathways for char remain relatively unexplored in economic terms, and also under researched in terms of safety and environmental outcomes which result in a lack of regulatory frameworks. Standard Gas is working with the scientific community and partners in several sectors to explore potential routes to use and sequester char safely in a range of valuable end-products, the company’s director said. 

However, Jackson underlined the need for much wider research into sequestration pathways for mixed waste char given its considerable potential as a decarbonizing commodity alongside biochar. Finding new ways to use biochar and char will transform non-recyclable wastes into valuable products that can replace fossil-derived materials, support the UK’s efforts to meet its Net-Zero targets, and help reverse climate change. 

But Jackson highlighted another factor likely to drive these developments: a significant increase in the price of carbon to increase the viability and range of both carbon removal pathways and technologies. 

Low disposal gate-fees, primarily for landfill and incineration, make these the preferred outlet for biogenic waste generators. However, much higher gate-fees for disposal of mixed wastes – on account of their higher fossil content – mean waste processors prefer these feedstocks over biogenic wastes. Furthermore, neither landfill nor incineration remove carbon, and both waste management options have significant related emissions.

To fix this market imperfection, end-product uses need to be developed to provide an economic route for the sequestration of char from mixed waste that contains significant levels of biogenic carbon.   

For more information contact: 

Richard Jackson [email protected] and Peter Coombes [email protected]