Holzvergasung

Holzvergasung is a thermochemical process that converts solid biomass, primarily wood, into a combustible gas mixture known as syngas or wood gas. This process involves heating the wood in a controlled environment with a limited supply of oxygen, air, or steam. Instead of complete combustion, which would produce mainly carbon dioxide and water, the partial oxidation and pyrolysis reactions break down the wood's complex organic molecules into simpler gaseous components.

The primary products of Holzvergasung are hydrogen (H2), carbon monoxide (CO), methane (CH4), and nitrogen (N2) if air is used as the gasifying agent. In addition, small amounts of carbon dioxide (CO2), water vapor, and various trace impurities like tars and ash are also produced. The exact composition of the syngas depends on the type of wood used, the gasifier design, and the operating parameters such as temperature and pressure.

Wood gas is a versatile fuel. It can be burned directly in modified internal combustion engines to generate electricity and heat simultaneously, a process known as combined heat and power (CHP). Alternatively, the syngas can be further processed. The carbon monoxide and hydrogen can be used in chemical synthesis to produce liquid fuels like methanol or Fischer-Tropsch diesel, or they can be used to produce hydrogen gas itself.

The efficiency and effectiveness of Holzvergasung are influenced by factors such as feedstock moisture content and particle size. Lower moisture content generally leads to higher gas quality and efficiency. Various gasifier designs exist, including updraft, downdraft, and crossdraft gasifiers, each with its own advantages and disadvantages regarding tar production and gas cleaning requirements. Holzvergasung is considered a renewable energy technology because wood is a renewable resource.