There is a French firm using pyrolysis to achieve 500c temperature to slow burn biomass to charcoal.
A pilot plant Pyro 7 in Mali funded through a foundation Altran uses agricultural residues or renewable biomass and transforms them into biochar and then, where needed, into briquettes of "green charcoal', a sustainable and alternative cooking fuel. Savannah weeds, reeds, straw of wheat or rice, cotton and corn stems, rice or coffee husk, bamboo and even sawdust can be used, and yield around 3 times more than using classical batch processes. Each Pyro-7 machine allows the economical and ecological production of between 4 and 5 tons of biochar per day. Cost per machine 80,000 euros.