35 kWe electric output ~ 210 MWh/year
140 kWth thermal output ~ 840 MWh/year
200 kW char ~ 1,200 MWh/year

The leading Danish ecologic farmer Aarstiderne A/S located in Barrit, Denmark, wished to become self-sufficient with regards to their energy consumption. Aarstiderne A/S offers, to the public, door-to-door delivery of ecologic fruit and vegetable. These are delivered in wooden boxes which are re-used several times.

Aarstiderne wanted to utilize such broken wooden boxes, as well as other by-products from the farm Barritskov, as fue for heat and electricity productionl. Since they were also interested in char, which has soil improving effects for specifically ecologic farmes, a solution based on a pyrolysis unit coupled with a Stirling engine was chosen.

The world's first small scale, CO2 neutural pyrolysis plant was lauched in December 2008. Based on the Stirling engine, the plant is fueled by wood chips which are heated to 600 C without any oxygen being allowed. This process creates pyrolysis gases which are direction to a combustion chamber where they are mixed with pre-heated air and ignited. The heat from the combustion process is used to heat the Stirling engine whereby power is generated.

The main components of the plant consist of a 400 kW pyrolysator unit, a combustion chamber, and one (1) 35 kWe Stirling engine. The pyralisor and combustion chamber, designed by Stirling DK, were manufactured by the Danish boiler manufacturer Danstoker. The control system, based on Siemens components, was supplied by the Austrian company Larsys.

The plant is fully automized and designed to operate up to 7,000 hours per year.