Solar Bud's Wild Ramblings - Wonderfuel Charcoal

Well, apparently it's the most depressing time of the year, and that crazy old nonagenarian genius James Lovelock, author of ‘The Gaia Hypothesis', foresees a grim future.

In amongst all the doom and gloom about the inevitable consequences of climate change are a couple of glimmers of hope - one is that in the future the UK will be one of the few habitable places on a warming planet Earth; the other is the potential of something called 'biochar' for taking carbon dioxide out of the atmosphere and beginning the process of bringing climate change under control.

The story of biochar began thousands of years ago in Peru, where the civilisation of the time discovered - by accident or by design - that the process of burying charcoal in the soil, over time, actually multiplied the fertility and productivity of that soil many times. Even today, these 'Terra Preta' (black earth) soils are sold as rich potting compost.

Although charcoal doesn't actually contain any nutrients, it turns out that charcoal in the soil acts as a reservoir for nutrients, preventing them from leaching away into neighbouring watercourses, thus keeping the soil nutrient rich and also preventing algal blooms in lakes which consume the oxygen fish and other water creatures need to survive.

The charcoal also acts as a home to beneficial bacteria and fungal mycelia. All of these services which the charcoal provides result in the hugely improved fertility of 'Terra Preta' soils.

But one consequence of burying charcoal, which most likely never crossed the minds of the ancient Peruvians, is that it actually takes carbon dioxide out of the atmosphere - permanently. The non-biodegradeable charcoal which is ploughed into the soil is basically the carbon which was fixed by the tree from the atmosphere whilst it was growing. Normally, this carbon dioxide is returned to the atmosphere when the charcoal or wood is burned, but the act of burying it returns it to the Earth, just as digging up and burning fossil fuels takes carbon from the Earth and puts it into the atmosphere.

But it gets better - if wood is heated in the absence of oxygen in a process known as pyrolysis, it is possible to extract a combustible gas from it, known as wood gas. This wood gas can be used as a fuel directly, or by a further process turned into a biodiesel. The process of pyrolysis that produces the wood gas leaves charcoal as its by-product - which can then be ploughed into agricultural land to improve its fertility.

No wonder James Lovelock, one of the foremost uber-doomers when it comes to climate change, mentions it almost as humanity's one hope.

This amazing product, known as ‘biochar', not only takes carbon out of the atmosphere, limiting the effects of climate change, but in the process can produce a biofuel and also improve the fertility of agricultural land. I think most people would agree there is no 'silver bullet' which can 'solve' climate change - but ‘biochar' comes pretty close.

The idea of ploughing charcoal into your soil seems a bit odd at first, but I've tried it in my small terraced house back garden. I bought a few bags of locally produced, sustainable charcoal, and walked on them and beat them with a rolling pin (you may like to enlist the assistance of your spouse with this one) until the charcoal was well crushed and powdered. Then I spread it onto my raised beds, and dug it in a bit. That was a year or two ago - it's difficult to tell if it has made any difference yet to be honest, but it can do no harm, and has taken a small amount of carbon out of 'circulation'. If everyone dug it into their garden, it could all add up.

I've found it useful to use a few larger pieces of charcoal for drainage in the bottom of plant pots - the advantage here is that when you finally come to 'plant out', the charcoal stays around the roots of the plant a little way below the soil surface, in exactly the right place to carry out its beneficial role, and it stays there from that point onwards. I've even heard of people mixing charcoal in with manure before spreading, to increase the longevity of the benefit of the manure.

So the next time you buy a couple of bags of charcoal for a barbeque this summer (fingers crossed we actually have one, we've had a winter for a change!!), why not buy two or three more, and engage in a bit of 'Terra Preta'. You might be the planet's last hope!!

Buying your charcoal from local and sustainable sources is even more environmentally friendly. The lovely people at The Wood Education Programme Trust and Coppice Association North West not only kindly provided us with the photos for this article but are an amazing resource for anyone inerested in sustainable woodland management. They also provide a list of UK outlets that sell charcoal from sustainable, local charcoal producers. Click on the links below for more information:

www.woodeducation.org.uk
www.coppicenorthwest.org.uk

Our Affiliate Merchant AMAZON has lots of books for sale around this subject. The Big Green Idea is paid a commission if you choose to buy via our links. These are not recommendations by the author and are chosen purely to give a representation.