Jessica Murray: This dark material: the black alchemy that can arrest carbon emissions
It traps carbon in the ground for centuries, boosts plant growth, provides a
sustainable heat source and could even reduce methane emissions from cows.
Biochar may not be a silver bullet to combating the climate emergency, but it
certainly ticks a lot of boxes. A form of charcoal
created via a special chemical process, biochar is not much to look at,
resembling the aftermath of a particularly good barbecue. But it is already
heating homes in Stockholm, feeding cows in Lincolnshire, and nourishing trees
near Loch Ness.
“When you look at the
range of benefits it has, it is quite phenomenal,” says Marc Redmile-Gordon,
senior scientist for soil and climate change at the Royal Horticultural Society
(RHS). While stressing that biochar is only part of the solution, he adds: “If
we stop burning fossil fuels tomorrow, we’ll still have a lot of carbon dioxide
removal to be doing, and this is one of the most effective ways we can achieve
that.” Following biochar’s
recognition in the IPCC
2018 report, earlier this year Redmile-Gordon launched the society’s first
trials to see how the material could improve plant growth. He estimates
planting 10-20kg of biochar in your garden could offset the carbon from a
five-mile return commute in a car for a month.
Biochar is a form of
charcoal produced when organic matter – for example wood, leaves or dead plants
– is heated at high temperatures with little or no oxygen in a process called
pyrolysis. The normal burning or decomposition of these materials would release
large amounts of methane and carbon dioxide into the atmosphere. Instead,
creating biochar traps this carbon in solid form for centuries; it becomes a
carbon sink that can be buried underground....
