Energy from cherry stones in CHP system

Plant combining biomass and fossil fuel

Following a successful district heating project using biomass, we were the consultants of choice for the town council of Sasbachwalden, Germany, in an ambitious follow-on project: a district heating network supplying the local swimming pool, spa and 31 private dwellings. Our design was awarded government support to the tune of 100,000 Euro for our innovative concept of deriving energy from a plentiful local resource: the stones of cherries, a waste product of the local kirsch distilleries!!

Three sub-systems produce a total output of around 1MW:

• A 400kW biomass boiler is used for space heating in winter; this is fired with cherry stones mixed with wood chips
• A 600kW fossil-fuel boiler provides redundancy and tops up heat output from the biomass boiler during peak periods (this boiler runs for around 5% of the time)
• A 40kW diesel generator produces electricity all-year-round; its waste heat is sufficient for heating the swimming pool and all other LTHW during the summer; using waste heat throughout the year provides an overall efficiency of around 80%

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