Farmed Carbon Co-Founder and Chief Engineer, Stuart Grover, laying what could be Australia's first piece of carbon negative asphalt.

The key ingredients for this little patch of road started life a few months ago as rice straw waste that was destined to burnt.

​Biochar, aka Black Gold, is a charcoal-like substance that is made from organic materials such as agricultural waste.  

​It is produced by heating this waste in the absence of oxygen by a process called pyrolysis.  Instead of the carbon contained within the agricultural waste combining with oxygen to form CO2, it is transformed into biochar – an incredibly stable solid form of carbon. ​

Biochar can be added to concrete in a number of ways. It can be mixed with the concrete ingredients before mixing, or it can be added to the concrete after mixing. Biochar can also be used to make concrete blocks and other precast concrete products.
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The amount of biochar that is added to concrete depends on the desired properties. For example, to improve the compressive strength of concrete, typically 1-5% biochar is added by weight of cement. To increase the fire resistance of concrete, typically 5-10% biochar is added by weight of cement.

Carbon Dioxide Removal (“CDR”) and emissions avoidance are both important strategies for combating climate change. However, there is a key difference between the two: CDR removes carbon dioxide that has already been emitted into the atmosphere, while emissions avoidance prevents carbon dioxide from being emitted in the first place.

Asphalt is used to make >95% of the world’s roads.  Bitumen is a key ingredient in asphalt, it is the binder that holds together the various aggregates.

Bitumen is traditionally derived from crude oil.  It is made by distilling crude oil to remove lighter fractions, such as gasoline and diesel. The remaining heavier fraction is bitumen.  Bitumen is a globally traded commodity with its price inherently linked to the cost of a barrel of oil. 

The cost of a ton of bitumen has risen from approx. US$160 in 2002 to US$900 in 2023.  It has a carbon footprint of approx. 0.5 tonnes per ton of bitumen.
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Bio-bitumen is a sustainable alternative to traditional fossil-fuel based bitumen.  It produced during the pyrolysis of agricultural waste.  Bio-bitumen can be used to make asphalt that is just as durable and long-lasting as asphalt made with traditional bitumen. In some cases, bio-bitumen asphalt can even be more durable and resistant to cracking and potholes.  It is also far more environmentally friendly with one ton of Bio-bitumen sequestering approx. 1.5 tonnes of CO2 that would have otherwise been released into the atmosphere.      

Wood Vinegar, also known as pyroligneous acid, is a liquid by-product of the pyrolysis process. It’s obtained by the slow burning of agricultural waste in an oxygen-limited environment, producing a dark liquid that consists of over 200 different organic compounds. 

The mission of Farmed Carbon is to remove 1 billion tons of CO2 from the atmosphere.

Stuart and David previously worked together building and scaling one of Australia’s leading FinTech companies.  They sold this business to a FTSE100 company in late 2021 so they could focus their attention on their passion of trying to build a company that can make a meaningful difference to climate change.