Heating systems with wood gasifiers

Wood gasifiers are a not so well-known technology in the field of biomass heating systems, but it certainly has its advantages. How heating systems work with wood gasifiers and where there are advantages over other wood heating systems is explained in detail in this article.

Principle of wood gasification

Seen from the outside, wood gasifiers are similar to ordinary wood burning wood stoves. They are also operated in the same way as ordinary firewood heaters. The principle of wood gasifiers is only visible if you look at the technology in detail. This also opens up the reason for the usually much higher price.

The wood gasifier burns firewood just like the ordinary natural draft boiler. Incineration - or rather smoldering - also produces wood gas that is burned separately in a wood gasifier - or can be used externally.

Efficiency of the plant

While only one fifth of the energy stored in the wood is used to burn wood in the conventional boiler, this efficiency increases to a good third in the wood gasifier boiler. Wood gasification boilers are therefore significantly more efficient than any other type of wood heating that only burns wood.


The wood gasification technology produces significantly lower emissions than other wood heating systems. In conjunction with the higher efficiency of the wood gasifier heating, a clear ecological advantage is created here.

Promotion for wood gasification plants

Wood gasifiers - like all other biomass heating systems - are considerably supported by the BAFA. For wood gasification boilers, however, there is only a subsidy of 1,400 EUR per boiler, regardless of the performance of the wood gasifier.

In addition, in specially insulated buildings, however, there is still a special bonus of EUR 700, but a standard corresponding to the KfW Efficiency House 55 must be proven.

The promotion of wood gasification heating systems can only be claimed for existing buildings which were either already in operation on 1.1.2009 or for which a building application had already been submitted at least on this date.

Despite the sometimes lower purchase price for firewood and pellet boilers, higher subsidies are sometimes possible - but there is no official explanation for this disproportion.

Buffer requirement

The law also requires a buffer tank for all wood gasifiers that produce more than 15 kW of power. This buffer must be permanently integrated in the heating circuit. The required 25 liters of memory content are usually at least doubled in practice.

Wood gasification heaters versus oil and gas

A change to a wood gasifier heating can be well worth it. Alone, the operating costs and the heating costs are much cheaper for wood gasification heaters than for oil or gas, as biomass fundamentally brings as heating a significant cost advantage.

In the long term, wood prices are unlikely to increase, since wood is a raw material that is available almost everywhere and is not tied to specific industries (in the case of wood pellets, on the other hand, this is the case).

In any case, wood gasifiers are more ecological, and in terms of climate damage and the emission of sulfur dioxide (acid rain), wood has clear advantages over fossil fuels.

An interesting option for the household, too, may be a combined heat and power plant based on a wood gasifier.

Video Board: Biomass CHP – wood chips to power and heat - wood gasification at Scotston Farm