The invention relates to a biochar production plant, a combustion chamber, and a method of operating same. The plant comprises a fuel hopper, a fuel delivery system, a combustion stage, and a post combustion stage. The post combustion stage includes a generator; a biochar removal stage and a flue gas scrubber. The combustion stage comprises a combustion chamber having an active fluid biochar bed comprising a pair of oscillating plates, one on top of the other; an air injection ring positioned above and spaced apart from the pair of oscillating plates; a biochar shelf, below and surrounding the active fluid biochar bed, positioned to receive biochar falling from the pair of oscillating plates, and means to transfer the biochar from the biochar shelf to a biochar outlet. There is provided at least one sensor operable to measure the depth of the active fluid biochar bed on the oscillating plates and a controller responsive to the sensor. The controller is operable to control the depth of the active fluid biochar bed and the temperature of combustion by controlling the oscillating plates and the air delivered into the combustion chamber. In this way, the construction is very simple, cost effective and has accurate combustion control leading to a quality biochar end product.