The form of the combined heat and power plant(CHP), the materials used, the detailing and the siting in the landscapegive Eco Zathe an integrated appearance. The Eco Zathe combined heat and power plant supplies some 9,988 homes in theneighbourhoods of Techum and Jabikswoude in De Zuidlanden district with electricity and heat. It is a classic exampleof “neighbourhoodenergy”: utilising sources in the immediate surroundingsto generate energy for local use. The cattleon a Frisianexperimental farmprovidethe fuelfor theheat and power plant. The energy is actuallyproduced from cow dungand hot biogas.
Eco Zathe started as a unique collaboration between the Municipality of Leeuwarden, GEM De Zuidlanden, Nij Bosma Zathe and Essent. The pursuit of sustainability prompted the construction of the heat and power plant. The municipality of Leeuwarden’s long-term objective is to be no longer dependent on fossil fuels. Using biogas at theplant saves natural gas. For De Zuidlanden district the municipality stipulateda reduction of 8%emission of CO2. Essent, in conjunctionwith the partners, developed aninnovative,renewable energy system, one that makes a significant contribution to the energy objective specified. The project can function as a springboard for Leeuwarden to realise a heat conduction circuit that would link up heat sources andconsumers.
The cow dung undergoes anaerobic digestion at Nij Bosma Zathe, an experimental farm. This process also digests grass and waste residue – from the food industry, for example – at the same time. The anaerobic digestion takes approximately eight days. During this processbiogas is released in the anaerobic digester and this is used as fuelfor the gas engineat the Eco Zathe combined heat and power plant. The gas produced at the experimental farm is delivered to the plant 5½ kilometres awayvia a special biogas pipe. The gas flows to Eco Zathe at the same speed as a steadycyclist. The heat generated there is used for heating and hot-water supplies in the homes and institutions in the De Zuidlanden district. It is delivered via Essent’s heating grid. When there is no demand for heating the gas engine cannot deliver heat directly to the homes so the heat generated is stored in two large storage tanks. The tanks have a 65 m3 and 75m3 capacity respectively. If the gas engine and the storage tanks cannot meet the heating demand, then two auxiliary boilers provide extra heat.