12 October 2021

Carbon Drawdown

Christina Giudici

Making biochar is one of the ways that we can combat climate change. How?


In order to take carbon out of the atmosphere, we need to:

– capture it,

– stabilise in, and

– store it long term.


Nature does the capture part, through the miraculous process of photosynthesis. This uses the energy of the sun, plus water and a few minerals from the soil, to transform atmospheric carbon dioxide into sugars which are used to build the bodies of plants.

The bodies of plants are eaten by insects, animals, humans, and the teeming soil life when plants die and are broken down. Eventually the carbon compounds in plants are mostly broken down and find their way back into the atmosphere again. This is part of the carbon cycle. Some carbon is diverted into soil organic carbon, and can last as humus for some years in that form.

Biochar can take the parts of the plants that are not used, eg straw after a grain harvest, waste wood after timber milling, even food scraps and organic waste, and stabilise the carbon in them through pyrolysis.

During pyrolysis, all the ‘volatile’ organic compounds get driven off, together with water vapour, methanol, and eventually flammable vapours such as methane, hydrogen and carbon monoxide. In our particular technology these gases are captured and either fed back into the pyrolysis chamber, or condensed to make fuel for electric plant.

What’s left is a stable carbon matrix that is very porous. The many beneficial uses of biochar in agriculture usually mean that the biochar ends up in soil. Even when fed to animals, the biochar passes through the animal via their manure, and can continue to provide positive outcomes in manure handling, composting or incorporation into soil by dung beetles and other soil dwelling life.

Once in the soil, its stored there for good. Or at least for hundreds of years.

If biochar is used in building and industrial materials, eg as a cement replacement, or additive to bitumen, it is also stored at least for the life of the infrastructure.

This chain of capture-stabilise-store in which biochar plays a huge role is recognised by the Intergovernmental Panel on Climate Change (IPCC). The IPCC has recognised 6 technologies as Negative Emissions Technologies. ie they have the capacity to take atmospheric carbon out of circulation and store it safely. The biochar technology is known as PyCCS – Pyrolytic Carbon Capture and Storage.

The beauty of the biochar value chain is that we can be sequestering carbon long term, at the same time as generating heat energy for positive use, and creating a product that can enhance regenerative agricultural efforts and reduce the carbon footprint of building and industry. So many wins!