A Spanner in the works that pays
In 2011, Engelsberg, a village that is part of the German market town of Lauterhofen, invested in a wood gasifier from compatriot Spanner Re² GmbH. After more than six years of operation, the Spanner Re² Biomass CHP “HKA 30“ has provided the village with renewable energy self-sufficiency and a sizeable income from producing more than 1.5GWh of electricity and 3.6 GWh of heat – all from regionally sourced woodchips.
There has been a woodchip heating plant operating in Engelsberg since 2006. With approximately 5 000 voluntary working hours, a 1.5 km long local heating network that connects 27 of the 30 houses in the Engelsberg village district was built by the community itself.
Our wish was to generate not only heat but also electricity from wood, explained Mayor Ludwig Lang and Willi Locker Baumamt, Director of the market town of Lauterhofen.
In 2011 Engelsberg went one step further towards renewable energy self-sufficiency and installed a wood gasifier from the Lower Bavarian plant manufacturer Spanner Re² GmbH. At the beginning of the project, Michael Gottschalk, then Mayor of Lauterhofen, said that the wood gasifier fitted exactly in terms of its output of around 30 kW electrical and 70 kW heat.
The combined heat and power (CHP) plant is designed to cover the baseload heat requirements of the households and, together with a 320 kW woodchip heating system, continuously supplies the local heating network with heat generated from renewable sources. The old reserve oil heating system has not been used since the implementation of the wood gasifier and woodchip boiler combination.
In the wood-fired gasification plant, energy is generated from woodchips according to the principle of CHP generation. With a moisture content of around ten percent, the dry woodchips are transported from the storage bunker to the plant via a screw conveyor. An integrated metal separator removes possible metallic impurities to protect the gasifier before the fuel reaches the heart of the plant, called the reformer, via another feed unit.
The actual wood gasification takes place in the reformer. At temperatures of around 1 200 degrees C, a thermochemical process produces clean wood gas. This is cooled via heat exchangers, which recovers around 10 kW of thermal energy. The cooled wood gas then passes through two filter systems before it is fed to a gas engine in the downstream genset.
Heat is also generated during the process and the waste heat in the boiler room is also used in Engelsberg to dry the woodchips in the fuel bunker to the correct moisture from below via perforated plates.
Spanner in the works pays
With operating times of 8 200 hours annually, around 1 200 m³ of woodchips are required and these are sourced exclusively from the Engelsberg catchment area. The heat price for customers in Engelsberg is 6.3 ct/kWh – a price that is more than competitive with fossil-generated energy.
The annual consumption of electricity in Engelsberg is around 100 MWh. With the Spanner Re² gasifier CHP plant, more than twice as much electrical energy is generated annually and is fed into the public power grid. The excess provides a 5-digit EUR annual feed-in tariff (FIT) income for the village under the Renewable Energy Sources Act (EEG).