There is a certain irony to the fact that an ancient technology is providing the basis of one potential solution to the modern problem of climate change.
Biochar, produced when organic substances are heated at high temperatures in the absence of oxygen, has a history dating back thousands of years. Today, it is emerging as a viable long-term, high-quality form of carbon removal.
Alongside measures to drastically reduce carbon emissions, carbon removal is crucial to the world reaching its climate targets and building a sustainable future.
Biochar is gathering increasing attention because it doesn’t suffer from some of the drawbacks affecting some other carbon removal solutions – in areas including cost, scalability, and longevity.
But what exactly is it and how does it work?
What is biochar?
Every living organism is made from carbon. Biochar is produced when once-living things are heated at high temperatures without oxygen – through a process known as pyrolysis or thermolysis – to create a black, charcoal-like substance.
This product isn’t designed for your barbecue though: typically produced at a higher temperature than charcoal, biochar is not created with heat generation in mind. Instead, it converts carbon stored for the short term in living things into mineralized carbon that can be stored long term in a product that has uses in a range of industries including agriculture, technology, and manufacturing.
According to Carbofex, a biochar project Microsoft is working with for a second consecutive year as part of its carbon removal portfolio, every kilogram of biochar produced permanently binds about 3.5 kg of carbon dioxide. This makes the process net negative – it captures and stores more carbon from the atmosphere than it emits during its production.
What is biochar used for?
Because of its high surface area and porosity, uses for biochar are plentiful. As well as improving soil, it can be used for filtration of harmful chemicals, binding toxins such as mercury and phosphorus. Studies suggest that as an animal feed additive it helps with animal health and growth, assists with removing toxins and can reduce methane production. Biochar also has the potential to be used as an electrode material in batteries.
Carbofex co-founder and ex-CEO Sampo Tukiainen is clear that biochar’s benefits extend far beyond carbon removal. He sees huge potential to develop further uses. “In the future, I think we are going to see carbon like steel, so that we can build just about anything out of it.”
This combination of factors makes biochar an in-demand product – Carbofex’s production is sold out over a year in advance.
How is biochar produced?
Carbofex’s plant in Finland has been running since 2017. It carbonizes biomass from sources including waste wood chips, olive pits, and coconut shells at 600°C to create biochar.
Biochar production is a precisely controlled process. Pyrolysis of biomass creates gases including carbon monoxide and dioxide, as well as methane, which have to be captured to ensure biochar production doesn’t generate more greenhouse gas emissions.
However, these gases don’t go to waste; they can be combusted and fed back to enable pyrolysis or, if they exceed the needs of the biochar plant, they can be used for heating or electricity generation. Carbofex uses the excess gases to provide carbon-negative heating to the city of Tampere, Finland, on a commercial scale.
Another by-product of biochar production is bio-oil, which has potential as an alternative to fuel oil or diesel in engines, boilers and turbines for electricity generation. It is also a source of several useful chemical products including acetic acid, resins, adhesives and fertilizers.
Because of the potential contained in this oil and gas, Carbofex’s process produces more energy than it consumes. From an input of 3,500 tons of biomass it creates 1,000 tons of biochar, 5,000 megawatt-hours of clean energy and removes 3,000 tons of carbon dioxide.
Biochar’s role in carbon removal
Biochar has immediate advantages over some other carbon capture technologies. It is highly scalable and all the technology already exists.
Tukiainen estimates that converting even 50% of the residues from the world’s five most important crops would put a significant dent in the (up to) 10 gigatons (GT) of carbon scientists estimate needs to be removed from the atmosphere each year by 2050. Once ocean biomass and forest residues are added in, biochar’s capacity expands significantly, possibly covering the whole 10 GT on its own.
“I really see that biochar is going to be the leading carbon dioxide removal technology for the next 10 years or so, at least until direct air capture (DAC) is able to address the energy challenges and investment cost and so on,” he says.
Tukiainen is clear we are going to need all the capacity that the crucial DAC technology will bring. “But the point is that DAC is still 5 to 10 years away from deployment, but biochar – at least talking about us – we can deploy today. And we’re in a hurry, so we should do it.”
How do we scale biochar production?
The process may be highly scalable, but that doesn’t mean it comes without challenges and a lot of work. One important step is the mass production of pyrolysis machines to convert biomass to biochar.
Another is making the mindset changes to get this plan into action. People need to be incentivized into thinking about carbon dioxide removal, believes Tukiainen. And the creation of a carbon removal market is one way to do this.
Microsoft procured a number of biochar projects over the past two years as part of its commitment to being carbon negative by 2030, and to ultimately remove all of the company’s historic emissions since 1975.
To help meet these targets, Microsoft is working with Puro.earth, which has created the first business-to-business market for carbon removals, backed up by a registry and verifiable standards.
Every carbon removal project on the Puro.earth marketplace is independently verified to a set of standards the platform has established. These criteria are vital to differentiate between the quality and duration of the carbon removal available.
Carbofex is one of the projects Puro.earth has certified, with companies able to buy carbon removal credits based on the volume and quality of biochar it produces.
German sustainable agriculture company Carbon Cycle is another Puro.earth-certified project Microsoft has bought into. It produces biochar from wood chips sourced from local forests, using it as both an animal feed and a soil additive.
Puro.earth CEO Antti Vihavainen explains: “Our mission is to transform the world’s economy in a way that it starts to reward for negative emissions. Our role is to establish a standards registry and a marketplace where transactions can happen between the suppliers of negative emissions and the buyers.”
Biochar in Europe
The EU is aiming to become carbon neutral by 2050, and has committed to investing in technological solutions to enable the transition. The bloc is also leading the way on the establishment of policies to help measure and mature the carbon market.
But there is still a lot of progress to be made.
An additional step to dramatically accelerate the carbon removal market would be including carbon dioxide removal in the EU’s Emission Trading System (ETS), Vihavainen argues. This could start from the more permanent solutions that are easiest to measure and quantify (as well as verify) in the long term.
He would also like to see a minimum level of carbon removal purchases established for everybody as part of the ETS, as well as a maximum level so that emission reductions would still be the first priority.
Biochar has an important role to play as countries work together to scale up carbon removal. The technology exists; we now need to support the market and policies that will enable it to scale.