I attended a Charcoal talk last night by David Hutchinson of the Yorkshire Charcoal Company at the University of Hull (Scarborough Campus)
on 4th December 2007
Apparently Charcoal has enormous historic significance.
- Until it was discovered how to make coke, it was the only fuel suitable for smelting metals from their ores.
- It’s long been used in medicine as a way of soaking up toxins.
- Because it absorbs water, was used by the ancient Chinese as a hygrometer.
- It’s role in agriculture helped solve the riddle of El Dorado.
Charcoal can be made from any organic material. Just heat it up in a restricted supply of oxygen and just about everything will be driven off except the material’s basic carbon skeleton. What you’re left with is almost pure carbon arranged in an open lattice work with an enormous surface area.
Because carbon atoms like to stick together, it’s really good at absorbing organic compounds (which by definition contain carbon). So, it’s a really good filter and is used in numerous applications from water treatment to the NBC suits worn by our troops in Iraq.
Tropical rain forest soils are very thin and the high rainfall tends to flush out any nutrients. The lost city of El Dorado, in the Amazonian rainforest, was a huge puzzle for archaeologists who, once they’d accepted that a major civilization had existed (with the one time residents killed off by diseases unwittingly introduced by European explorers) remained puzzled by how large populations could be supported on such poor soils. The clue lay in the so called dark earth “terra praeta”.
This soil was dark because it contained large quantities of charcoal. Simple experiments, by the archaeologist Bruno Glazer, showed that this dramatically improved the soil’s fertility.
It turns out that 8000 years ago charcoal was also being used as a soil improver in East Anglia.
In the present day we are faced with the challenge of climate change. Leave a bit of wood on the ground and it will slowly decay releasing all it’s carbon as carbon dioxide or methane. Turn the piece of wood into charcoal and the carbon that remains is fixed forever. The only way you can release it as carbon dioxide is to set fire to it. So, charcoal could play an important role in sequestering carbon from the atmosphere.
For example, an essential part of woodland management is to thin the trees so that those that remain don’t grow too leggy. Some of these thinning’s are used, e.g. to make chipboard, but about half the world’s timber harvest ends up as waste. If this waste were converted to charcoal and used as a soil improver it would reduce dependency on fertilizers, improve water retention and provide a permanent carbon sink.
There are a number of current technological developments that are aimed at making charcoal production cleaner as well as more efficient. Kilns now exist that have very low emissions of pollutants and recover the energy from the gases that are given off. Further development, and widespread adoption, of these technologies could play an important role in
- Improving soil fertility and quality without artificial fertilizers
- Sequestering carbon out of the atmosphere, permanently
- Cleaning up pollution from organic compounds (e.g. oil spills)
- Providing rural employment as part of sustainable woodland management.
Surprisingly perhaps, these simple facts about charcoal are not well known; either among the general population or among decision makers in Government and elsewhere.
David proposes the establishment of a Charcoal Foundation that would help bring charcoal’s virtues to wider public attention, would bring together existing research and would help practitioners find markets for their products.