Biochar & Biofuel production in Botriver

Visit to the biochar and biofuel factory in Botriver, Overberg.

The factory was initially set up to produce biofuel from used waste tyres, by Jerome Kennedy.  A major problem exists with what to do with used tyres. They accumulate in massive tyre dump sites. Supply to the factory is cheap.

Tyres are loaded into one of three steel containers which accommodate about 6 tons at a time. These are able to rotate in order to mix the contents. They then get heated, from a fire box below, to about 500 degrees Celsius, using diesel or the fuel produced from the factory. A vacuum system withdraws the fumes from the melting rubber through condensers, which is then piped into storage tanks. There is some exhaust of the water vapour and some of the initial fumes given off. What remains in the boiler is the wire from the tyres which is clean and can be recycled as scrap metal. There is also fine coke left over which can be pelleted to provide a fuel that can be burnt. About 1000l of fuel is produced from each batch.

There are obviously huge potential fire hazards because of the high temperatures. An intricate fire system is in place with a foam system. The whole initial set up is fairly costly. The system is recycling a complete waste product, the tyres. Unfortunately, the product is then burnt which releases carbon into the atmosphere. However, the carbon is at least being used twice.

The system can be loaded with wood products, which would be mainly to produce charcoal, some flammable fuel is also a product produced from wood. The input can be pieces of wood, chips or even the saw dust from timber production. Any woody source can be used and this would be an ideal way to use alien species from clearing operations. The biggest cost is the transport cost involved in getting the alien species onto site and the chipping of the material reduces this cost considerably.

The charcoal produced is inert and needs to be added to compost manufacturing or inoculated with nutrients such as chicken manure to convert it to biochar. The carbon is then added to soils, which increases their water holding capacity, soil structure and increases nutrient availability to plants. The biochar locks up carbon in the soil for decades rather than a few years. If the wood chips are composted or used directly the carbon is mostly released in the composting process or within 3 to 4 years.

Michael Austin Environmentalist. May 2021.

This article on biochar & biofuel was initially published in a Botfriends newsletter.