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Wood chips in the front, energy out the back to the households

In the district of Lohen in the Upper Bavarian municipality of Schechen, district of Rosenheim, 10 households look forward to their constant energy supply from their own village every day. The local wood-fired power plant is part of the Weber Sepp's operations and supplies 9 surrounding households as well as its own residential building and the Theaterstadl with CO2-neutral thermal energy based on wood gasification technology from wood chips as fuel.


A local heating network for Lohen

Weber Sepp originally went into operation with an HKA 30 in September 2012. In October 2017, the system was expanded from 30 to 55 kWel by replacing the CHP. In 2018, a new hall was built specifically for the wood gasification plant. A second wood gasifier was added in October 2018. The system was thus expanded again to a total of 110 kWel. The third extension was made in December 2021. A third wood gasifier was set up and the two small CHP units, each with 55 kWel, were replaced by a large CHP unit from Hochreiter with 210 kWel. With a thermal output of approx. 260 kW, the three wood gasifiers and the combined heat and power plant supply 10 households and the company's own theater barn with heat via a pipe network with a length of almost 700 m. In addition, the wood chips required for plant operation are dried themselves. In addition, Weber Sepp also operates a contract drying facility in which wood chips, square bales (hay / straw), grain maize, soybeans, etc. are dried for customers. The generated electricity of around 200 kW is fed into the public grid and paid for by the energy supplier.

The "just in time" wood chip economy

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The wood chip management of the Weber company is truly a logistical peak performance, especially when you consider that Sepp, as a civil engineer and trained bricklayer, was completely "self-directed" from the planning to the implementation of the system concept. The entire system can no longer be surpassed in terms of compactness and was housed entirely in a three-storey hall.

There are two drying systems:
On the one hand, a drive-in bunker open to the front for contract drying of hay, maize and wood chips with an area of ​​60 m². Usually 50 to 100 cm of material to be dried is placed on it and delivered immediately after drying or picked up by the customer. When drying the square bales, the bales are usually placed in one layer. If there is an increased need, the bales can also be placed in two layers thanks to the powerful blower. On the other hand, there is a moving floor dryer in the basement near the three wood gasifiers. The drying capacity of around 25m³ per day is geared towards the fuel consumption of the three HKA70 systems. The moving floor dryer dries and continuously conveys the wood chips into an intermediate bunker. The wood chips are simultaneously screened out on the conveying path. The fine parts are used by local farmers as bedding, and Weber uses the long parts for firewood in their own kitchen oven. From the intermediate bunker, the wood gasifiers use the dry and screened wood chips as required.

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 The storage container for the moist wood chips is charged at ground level. It reaches into the basement (where the moving floor dryer is) and has a capacity of approx. 75 m³. The bunker is filled about twice a week. The concrete forecourt in front of the hall serves as a delivery area and, if necessary, as an interim storage area.

The screening of fine and long parts takes place on the upper floor of the plant and the dried wood chips are conveyed vertically approx. 9 m upwards with an ascending screw. After screening, the wood chips automatically fall into the intermediate bunker. The moving floor dryer constantly requests the necessary delivery volume itself and is controlled via the fill level in the intermediate bunker and the automatically recorded wood chip moisture content. The wood chips are only transported further when they have reached the desired degree of drying.

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The Josef Weber wood-power-plant

In Germany we actually speak more of multiple systems. At Weber Sepp, however, this term no longer does justice to the system concept. The three HKA70 wood gasifiers from Spanner Re² GmbH supply the Hochreiter CHP HODEUTZ V8 VK 200 with sufficient wood gas at a capacity utilization of over 95% per year. The self-developed, permanent supply of the wood gasifier with wood chips from the moving floor dryer is very interesting. According to the operator, the service effort for the system is around one hour per day for the three wood gasifiers and the CHP. Added to this is the effort involved in the production of the dried wood chips and their procurement. Even the waste heat from the plant room is used to dry the wood chips by the moving floor dryer. The warm air from the dryer is extracted from the system room through a generously dimensioned metal duct. The installed fire damper in the metal duct is automatically closed in the event of a fire.

Anmerkung: Sepp has given a lot of thought to his local heating network, which is supplied with wood gas technology, which has allowed a functioning operation to emerge in just a few years. Most of the time the simplest means were used, but the "simplicity" is not very noticeable. If you then consider that here is a Re² triple system and a Hochreiter large-scale CHP almost the entire district of Lohen in the municipality of Schechen fully automated and CO2-neutral with energy, you can only do that "pull hat".

Photos of the facility: (please click to enlarge)