The UK’s first high-profile biochar carbon credit deal was completed in June when sustainable architecture firm Bennetts Associates purchase 8.6 tons of carbon removal credits from Restord, a biochar producer based in Cornwall.
Bennetts Associates paid £200 ($271; €237) per ton – the firm has a 50-tonne pre-purchase agreement in place with Restord.
The credits were generated using on-farm biochar production technology developed by British company CapChar and certified under its Biochar Carbon Code.
The deal marks a key moment in the evolution of the UK’s carbon removal marketplace, which is being stimulated by growing demand for locally produced, verified carbon removals.
Agri Investor spoke to CapChar co-founder Adam Samuel to understand how this nascent market works.
How biochar is produced and used
Biochar is a charcoal-like substance produced by heating biomass – such as wood chips or agricultural residues – in the absence of oxygen, a process known as pyrolysis.
The result is a highly stable form of carbon that, once applied to soils, can remain locked away for hundreds of years.
CapChar’s system involves farmers and landowners installing pyrolysis units on site, allowing them to turn local biomass into biochar, which can then be applied to farmland or used in other applications such as animal bedding, water filtration or construction materials.
The process delivers multiple benefits:
- Carbon sequestration: The inert carbon in biochar is recognized by the IPCC as a valid carbon removal method;
- Soil health: Biochar improves water retention, nutrient availability and microbial activity;
- Air quality: When mixed with manures, biochar can reduce ammonia emissions.
Who generates and owns the carbon credits
In CapChar’s model, the owner of the pyrolysis machine – often the farmer or landowner – is the party eligible to generate carbon credits.
“The person who owns the machine is the person that applies for carbon credits,” Samuel explained. “They have to show us where it’s been sequestered so we understand where the biochar’s final resting place is, which becomes part of our chain of custody of data.”
In the Restored deal, Restored purchased a CapChar system and used it to produce biochar on its Cornwall farm, making Restored the generator and seller of the credits.
The Biochar Carbon Code
One of the distinctive features of CapChar’s approach is the use of its in-house Biochar Carbon Code, which was developed in response to the lack of suitable international methodologies for batch-based pyrolysis systems, and the variability of UK biomass feedstocks.
CapChar’s code sets standards for:
- Measurement: Monthly lab testing of biochar to determine carbon content;
- Permanence: the code adopts an 80 percent performance assumption over 100 years, striking a balance between more conservative (74 percent) and more optimistic (98 percent) models in the sector;
- Emissions accounting: the code factors in transport, operational and embodied emissions, including site setup.
“Our code is in the public domain. We are happy for it to be adopted by universities or the government. We built it because there was no code that was going to work for the kind of operations that we were looking to provide our customers,” Samuel said.
How the carbon value is monetized
The carbon value in this market comes from the biochar itself – not from broader soil carbon improvements. CapChar’s focus is on the stable carbon content in the biochar, measured by mass and carbon percentage.
The £200 per ton price paid in the Restored deal is significantly above typical voluntary carbon market averages. According to Samuel, this was driven by:
- Bennetts Associates’ interest in local, high-integrity removals;
- The firm’s willingness to pay for quality and to help stimulate the UK market;
- The internal high carbon price the company has set itself, which is used to drive behavioral change across its operations.
Permanence and monitoring challenges
Ensuring the long-term permanence of carbon removals is one of the biggest challenges for carbon markets and biochar is no exception.
CapChar’s methodology focuses on the biochar’s chemical stability – the inert carbon fraction – as the basis for crediting.
Laboratory analysis determines the proportion of stable carbon and the system’s lifecycle analysis boundary ends at the point of sequestration, meaning when the biochar is applied to land.
“It’s a whole other discipline to look at its longevity over time in the soil,” Samuel said. “The global industry has come up with the science to try and predict how permanent carbon is in the soil.
“Biochar is straightforward. We know the weight of the material that’s gone in, we know the weight of the material that’s come out. Typically, the biochar that will come out of a kiln will be somewhere between 70 percent and 90 percent carbon.”
Current scientific estimates suggest 74 percent to 98 percent of the carbon in biochar remains after 100 years, depending on factors such as feedstock, pyrolysis temperature, soil type and land management.
CapChar adopts an 80 percent permanence figure, based on peer-reviewed studies, as a conservative defensible position.
As for ongoing monitoring of biochar in situ, Samuel acknowledged this is still an emerging field:
- Soil cores and satellite imaging (such as LiDAR) are being explored to track changes in soil carbon over time;
- Carbon isotope tracing (such as carbon-14 dating) may eventually offer more precise verification;
- Few commercial tools currently exist to directly measure biochar content in soil.
“Measuring how much of the biochar is still in the soil is a technology that doesn’t really exist at the moment. That’s another challenge that an industry will have to solve over time,” Samuel said.
Until more advanced in-soil monitoring becomes mainstream, robust chain of custody, conservative permanence assumptions and transparent reporting will remain key to market integrity.
Business model and market growth
CapChar’s model offers multiple pathways to market:
- Farmers and landowners can buy a CapChar system and generate credits themselves;
- Aggregators like Restored can operate systems and sell credits on behalf of tenant farmers or partners.
The company is now rolling out an upgraded version of its technology, with the aim of having 5-10 systems in place across the UK this year.
“We’re trying to get a modular system that anyone can buy and then if you’ve got more biomass or you’ve got a larger site, you would just buy the second set and the third set. We’re trying to market our kits at sub £100,000 [per unit].”
Outlook
The UK’s biochar carbon market is still in its early stages and holds significant promise.
It offers:
- A new income stream for farmers and landowners;
- A domestic carbon removal option for corporates looking for verified, local solutions;
- Potential environmental benefits in terms of soil health and pollution mitigation.
With growing demand for “made in the UK” carbon credits and a maturing regulatory and verification framework, CapChar and its partners are positioning themselves to grow alongside this nascent market.
