Study of geothermal direct use for coffee drying at Wayang Windu geothermal field

Indonesia has the largest geothermal potential in the world. However, the utilization has not optimal yet. Wayang Windu Power Plant is two phase geothermal system, where 100% of the separated brine is reinjected through an injection well 14 km away from the plant. The energy from the brine can be utilized before reinjection, such as for direct use, i.e. coffee drying. The area surrounding the plant is known as coffee producing area. Coffee production in Pangalengan reaches 6499.05 tons in 2014. The coffee drying method used is semi-washed. Geothermal drying system scheme uses heat exchanger and hot water, as working fluid. Hot water with a temperature of 80 °C flows in a closed loop system to heat the air inside the drying apparatus. The coffee drying is done at 50 °C from water content of 60% to 12% remaining in total time of 12.5 hours. The total energy used for drying is 32.65 kW. Drying coffee using geothermal fluid is aptly applied at the research site, because the potential of commodities and the resources is available. The utilization of geothermal brine is an alternative to diesel oil to power the drying apparatus.