2.1.3.5. Gasification
Gasification is the process by which any carbonaceous material (coal and petroleum as well
as biomass) is substantially converted into a stream of carbon monoxide and hydrogen in a
high temperature reaction and controlled-oxygen environment, sometimes at high pressures
of 15–50 bars (Bridgewater, 2006). The gas mixture is the key energy output and the
gasification process has an application as a clean waste disposal technique (Bapat et al.,
1998). In slow pyrolysis facilities, gasification is often used to generate further syngas from
biochar ‘waste’.
Syngas may be used for electricity generation via gas or steam turbines (or both), used to
manufacture chemicals and fertilisers, or further cleaned for use as liquid fuel. Since
conversion of feedstock to syngas is often the main objective, the process is maximised for
gas production and so the biochar yield from gasification tends to be very low (Table 1).
However, this also carries the risk of higher levels of metals and minerals that may be