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Biochar: Breakthrough Zero-Carbon Fertilizer

Wouldn't it be good news if every time you threw out your garden waste, you were helping fight global warming? That’s the capacity a new technology hopes to unleash across the world.

A handful of biochar, a zero carbon fertilizer
Kari Kohvakka/Stockholm Batten och Avfall/Stockholm Biochar Project/Nordregio

This potentially-revolutionary method of making fertilizer that almost completely removes greenhouse gas emissions has received a grant from Bloomberg Philanthropies to be incorporated into 7 major cities’ landscaping programs.

Making “biochar” as it’s called, has been modernized recently in Sweden, and is done by putting grass trimmings, hedge clippings, tree branches, or any other kind of garden waste, into an enclosed space and “pyrolyzing it” in such a way as to avoid the rapid oxidation of CO2.

Turned into a charcoal-like substance, it’s not only carbon negative, meaning it removes more CO2 than it produces, but also more effective soil nutrition than other traditional soil amendments like nitrogen-phosphorus fertilizer.

This revolution started in Stockholm, where, after opening its first five biochar plants in 2017, the city began distributing this new fertilizer/soil amendment to citizens for free, if they merely bring whatever yard waste they might have.

Now Bloomberg Philanthropies is awarding grants of $400,000 to four major cities in Europe and three in the U.S. to implement the biochar technology.

Each city will receive implementation and technical support from Bloomberg to develop city-wide biochar projects and engage residents in the fight against climate change. It’s expected to produce 3,750 tons of biochar, all from lawn and garden waste from city parks and other green spaces, which would sequester almost 10,000 tons of CO2 per year - the equivalent of taking 6,250 cars off the roads.

Normally, municipal lawn and garden waste is trucked to landfills where it will decompose and release all the carbon it absorbed through its life back into the atmosphere, as well as other gasses from the bacteria feeding on it. With a biochar plant however, every branch and twig thrown into the sophisticated-yet-straight-forward furnace is having its carbon captured almost forever.


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