Biochar Production by Controlled Biomass Pyrolysis

Biochar Production

Klean produces biochar by pyrolysis — controlled thermal conversion of biomass in the absence of oxygen.

Combustion destroys the carbon in biomass. Pyrolysis preserves it. By heating biomass indirectly, with no oxygen present to support burning, the volatile fraction is driven off as gas and condensable vapour while the fixed carbon remains behind as a porous, stable solid. That solid is biochar, and the conditions under which it is made — temperature, residence time, heating rate, feedstock — determine its surface area, pore structure, carbon content and, ultimately, what it is good for.

The reactor decides the product

Klean's reference configuration is an indirectly heated rotary kiln. Heat is applied through the shell rather than by burning part of the feedstock inside the vessel, which keeps combustion products out of the char and keeps the gas stream concentrated enough to be worth recovering. The kiln yields three streams: biochar, syngas and bio-oil. Each one has a market, and the production case for any plant is built on all three together.

Operating history, not a prototype

The 1 MW biochar power plant Klean operates in Japan has been running since 2012, developed with Chubu Electric Power, Seiko Epson and the Toyama Research Institute. It produces about 1,000 tonnes of biochar a year while exporting base-load green electricity sufficient for roughly 1,000 homes and offsetting over 6,500 tonnes of CO2 equivalent annually. Fourteen years of continuous operation is what separates a production technology from a demonstration.

Mobile production where feedstock cannot travel

Not every residue stream justifies a fixed plant. A 40 tonne-per-day mobile biomass pyrolysis retort — MORPPS — has started operations in Vancouver for exactly that case: forestry and agricultural residue that is cheap at the pile and expensive on a truck. The unit goes to the biomass, converts it on site, and leaves with a dense, stable, high-value product instead of a load of wet chips.

Specifying a production line

Feedstock characterisation comes first, because moisture, ash and particle size set throughput, yield and the heat balance of the whole plant. From there the work is conventional process engineering: kiln sizing, gas cleaning, energy recovery, char handling and product conditioning. Klean runs that sequence as a feasibility study and can deliver the outcome on a turn-key basis. Yield tables and plant economics are released under NDA.