Making Biochar

Instructions for using the various biochar stoves are given on the biochar stoves page. These stoves enable people to make biochar whilst using the heat produced during the process. It is better to keep a constant stream of biochar going into your soil and to effectively capture the heat than it is to make a big batch of biochar in a day, waste the heat produced and then cook and heat your home with fossil fuel energy for the rest of the year.

Biochar is charcoal which is made with the intention of adding it to the soil. It differs from charcoal as it should meet certain ethical and environmental criteria.

In order to prevent charcoal which has been made in an environmentally detremental way or made from feedstock other than biomass from being sold as biochar, the IBI (international biochar initiative) has proposed a set of standards which should be met for biochar production.

Even if the IBI standards are met, much biochar sold will not offset the fossil fuels used in producing, packaging and transporting the biochar.

Given that biochar may stabilise carbon for a few thousand years at the most, whereas  fossil fuels if unburnt are stable for many millions of years, biochar production should not be considered a justification for offsetting the carbon released from burning fossil fuels.

Producing your own biochar, on the other hand, can be truly carbon negative. Local production of the feedstock, local use of the biochar and no packaging are only half of the story. Producing biochar also generates a lot of heat which can be used for domestic heating purposes.

Around 70% of the heat produced by burning a piece of wood is from the wood gases and the remaining 30% is in the charcoal. Traditional charcoal production usually releases the wood gases as smoke pollution. More recently, many retorts burn the gases to provide heat for char production. A more efficient approach is to use the heat from burning the gases both to feed back into the production and to produce domestic heat.

Paul Anderson and other pioneers have developed various ‘tlud‘ (top-light upward draught) cook stoves which produce biochar. As well as developing the cook stoves, intended for use in majority world countries, these stoves are designed to meet many cultural and environmental requirements:

1, They are smokeless thereby reducing inhalation of emissions and associated diseases. This also equates to a very efficient, hot burn.

2, They allow the user to maintain and improve soil fertility.

3, They allow the user to sequester carbon.

Biochar can also be made in other ways, such as in traditional kilns or retorts. These methods waste the heat produced from pyrolisis and can even create pollution (unburnt smoke) and will not be discussed here.

Whilst there are several commercial heat or CHP (combined heat and power) units which produce biochar whilst using the heat generated from the pyrolisis process, these will not be discussed as this site is concerned with garden and permaculture scale biochar production.

Sourcing the Feedstock.

This should not involve cutting down trees unnecessarily. Here at Swansea biochar we allow gardeners and tree surgeons to drop off logs or chipped wood if they want rid of them. We then sun dry the chipped wood, weather permitting. logs are cut, split, seasoned and either used in wood burners or, if split further, in tlud stoves.

In order to become a fully sustainable closed system, growing your own biomass is an option. The biochar carbon capture page discusses various suitable crops for doing this.