To slow climate change, humanity has two main options: reduce greenhouse gas emissions directly or find ways to remove them from the atmosphere. On the latter, storing carbon in soil – or carbon farming – is often touted as a promising way to offset emissions from other sources such as energy generation, industry and transport.
The Morrison Government’s Technology Investment Roadmap, now open for public comment, identifies soil carbon as a potential way to reduce emissions from agriculture and to offset other emissions.
In particular, it points to so-called “biochar” – plant material transformed into carbon-rich charcoal then applied to soil.
But the government’s plan contains misconceptions about both biochar, and the general effectiveness of soil carbon as an emissions reduction strategy.
- Storing carbon in soil is often touted as a way to remove greenhouse gas from the atmosphere to slow climate change.
- Biochar, material transformed to carbon-rich charcoal, is seen as one way of sequestering stable carbon in the soil but there is a catch.
- When all energy inputs and outputs of producing biochar are considered, the net energy balance can be negative – the process can create more greenhouse gas emissions than it saves.
- The Government Carbon Farming Initiative has largely failed.
- To be effective, future emissions technology in Australia should focus on improving energy efficiency in industry, the residential sector and transport, where big gains are to be made.