In order to combust the feed that is supplied to the gasifier, there must be a continuous addition of heat in the gasifier. To determine the energy added an energy-balance must be made.

Two losses can be pointed out. The synthesis gas will leave the gasifier with a certain temperature and there will be losses through the walls of the gasifier. The loss through the wall depends on the insulation. This loss depends only on the thickness of the insulation-layer and the choice of insulation-material. Because of the high-temperature at the gasifier-wall, the insulation-layer must be built with two components. Directly at the gasifier-wall, a small layer of ceramic wool (~25 mm) must be positioned. The layer around the ceramic wool, consisting of rock wool will be placed to reduce heat-loss through the wall further. The second energy loss consists of the energy taken out by the synthesis gas. Both losses have to be compensated for by the energy generated in the gasifier, usually by the heat of reaction (combustion of the feed). This means for every ton of feed put into the gasifier, between 32.6% and 39.4% is needed to compensate the losses (Van Kasteren et al., 2005).