| Abstract |
Low temperature, micro-geothermal power generation offers significant power generation potential worldwide. In the past, low temperature geothermal and co-produced fluids were considered a nuisance and un-economical for power generation. However, technology is available to tap this prevalent resource to produce fuel-free, emission-free power and increase power output and site efficiency. But a lack of focus on sustainability in the industry has left this green energy opportunity on the side-lines, with hot water from micro-geothermal being overlooked almost completely. This presentation will discuss various case studies, beginning with a grant with the US Department of Energy to demonstrate waste heat to power generation for low temperature geothermal applications at a gold mine in Nevada. The mine utilizes geothermal water for its gold processing, and through the grant, Organic Rankine Cycle (ORC) technology was used to tap the previously wasted heat for electricity generation. The presentation will discuss the challenges and lessons learned, and how the site is easily repeatable at low temperature micro-geothermal sites worldwide. With a clearer picture of the reality of micro-geothermal, small scale waste heat to power technologies are more focused on economics and where units can be deployed with an acceptable payback. New technology using optimized equipment and new low global warming potential (GWP) refrigerants are driving additional acceptance across the industry. Another case study example will detail a geothermal unit in Romania. The unit was a commercial unit and ran successfully for several years. However, feed-in-tariff changes in the country have ultimately ceased operations. Finally, the presentation will focus on Japan with its geothermal feed-in-tariffs of ~30+ cents/kw. Small scale heat to power technology was recently commissioned on micro-geothermal in Japan and ORC companies continue to focus there today. This presentation will focus not only on the technical successes but economic challenges when making decisions on which projects move forward and which do not. |