The Azimuth Project
Biochar (Rev #1)

Biochar is charcoal created by pyrolysis of biomass, and differs from charcoal only in the sense that its primary use is not for fuel, but for biosequestration or atmospheric carbon capture and storage. Charcoal is a stable solid rich in carbon content, and thus, can be used to lock carbon in the soil for hundreds to thousands of years. Biochar is of increasing interest because of concerns about climate change caused by emissions of carbon dioxide. Biochar is a low-tech way to draw carbon dioxide from the atmosphere and reduce the carbon footprint of agricultural waste.

For more information, see:

Biochar can be used to create Terra preta.

To set the stage: in the Amazon Basin, there’s a lot of nice rich soil. This is man-made! The soil there is naturally infertile, but between 450 BC and 950 AD, the natives enriched it using bone, manure and charcoal… producing a layer of soil full of organic material as much as 2 meters thick. This is called "terra preta", which means "black earth" in Portuguese.

Below at left we see nutrient-poor soil in the Amazon basin. At right, terra preta.


But besides improving the soil, there’s another wonderful thing about turning plant matter into charcoal and burying it this way. It keeps the carbon underground for hundreds of thousands of years. Thus, it significantly slows the rate at which carbon returns to the atmosphere in the form of carbon dioxide!

In fact, the people believe the only real chance to fight global warming on the massive scale needed is via massive "biochar" projects. It’s low tech: anyone can do it.

In the Guardian, James Lovelock wrote:

I said in my recent book that perhaps the only tool we had to bring carbon dioxide back to pre-industrial levels was to let the biosphere pump it from the air for us. It currently removes 550bn tons a year, about 18 times more than we emit, but 99.9% of the carbon captured this way goes back to the air as CO2 when things are eaten.

What we have to do is turn a portion of all the waste of agriculture into charcoal and bury it. Consider grain like wheat or rice; most of the plant mass is in the stems, stalks and roots and we only eat the seeds. So instead of just ploughing in the stalks or turning them into cardboard, make it into charcoal and bury it or sink it in the ocean. We don’t need plantations or crops planted for biochar, what we need is a charcoal maker on every farm so the farmer can turn his waste into carbon. Charcoal making might even work instead of landfill for waste paper and plastic.

Incidentally, in making charcoal this way, there is a by-product of biofuel that the farmer can sell. If we are to make this idea work it is vital that it pays for itself and requires no subsidy. Subsidies almost always breed scams and this is true of most forms of renewable energy now proposed and used. No one would invest in plantations to make charcoal without a subsidy, but if we can show the farmers they can turn their waste to profit they will

do it freely and help us and Gaia too.

There is no chance that carbon capture and storage from industry or power stations will make a dent in CO2 accumulation, even if we had the will and money to do it. But we have to grow food, so why not help Gaia do the job of CO2 removal for us?

In the humid and hot tropics terra preta is easy to produce: Add charcoal dust to soil and get amazing soil productivity boosts. In other climate zones two things need to be taken care of:

  1. Pure charcoal eats up surrounding soil.

  2. Charcoal is water repellant at first. You need to cook it, e.g. by flushing the fireplace with water.