Energy fromWaste: Reuse of Compost Heat as a Source of Renewable Energy

An in-vessel tunnel composting facility in Scotland was used to investigate the potential for collection and reuse of compost heat as a source of renewable energy. The amount of energy offered by the compost was calculated and seasonal variations analysed. A heat exchanger was designed in order to collect and transfer the heat. This allowed heated water of 47.3 degrees C to be obtained. The temperature could be further increased to above 60 degrees C by passing it throughmultiple tunnels in series. Estimated costs for installing and running the system were calculated. In order to analyse these costs alternative solar thermal and ground source heat pump systems were also designed. The levels of supply and economic performance were then compared. A capital cost of 11,662 pound and operating cost of 1,039 pound per year were estimated, resulting in a cost of 0.50 pound per kWh for domestic water and 0.10 pound per kWh for spatial heat. Using the heat of the compost was found to provide the most reliable level of supply at a similar price to its rivals.