| Title | The Repowering of Lightning Dock Plant in New Mexico |
|---|---|
| Authors | Joseph BONAFIN, Nick GOODMAN, Halley K. DICKEY |
| Year | 2020 |
| Conference | World Geothermal Congress |
| Keywords | geothermal, power plant, revamping, orc, binary, Usa, distributed generation, renewable energy |
| Abstract | The paper presents the repowering of the Lightning Dock plant in New Mexico, USA. The Lightning Dock geothermal resource area is located on the east side of Animas Valley in Hidalgo County, New Mexico. The area was identified as a Known Geothermal Resource Area in 1974. Lightning Dock area was previously home to one of the biggest greenhouse complexes in the U.S. In 2013, a 4 MW plant was realized by Cyrq, with plans to further enhance it to 10 MW. However, the second phase of the development with the original equipment supplier was never realized. The site is at 4236 ft above mean sea level, with an average ambient temperature of 60 °F. Turboden was selected together with Industrial Builders to perform a complete revamp of the power plant at Lightning Dock. The contractor offered to provide a brand new power plant producing 11.2 MW net (14 MW gross) electric power with a single ORC turbine. Cyrq ordered the new plant in 2017, which is currently in commercial operation since December 2018. The client secured a PPA for a period of 25 years. The plant is designed to exploit geothermal brine from existing geothermal wells. Isobutane is the design working fluid selected in its approach to efficiently harness the geothermal fluid readily available in the area. The choice of the working fluid was made after other alternatives were carefully studied. Other fluids such as pentane have been put onto test but they have failed to deliver results as efficient as isobutane. The power plant is composed by heat exchangers, a single turbine directly coupled with a generator, a recuperator, a condenser, and feed pumps. The plant will be fed by 5000 gal/min of geothermal brine at 310 °F. After cooling in the plant heat exchangers, the brine will be returned to the reinjection wells at about 170 °F. The project is an interesting example on how an improved design and technologies can be utilized for revamping older plants and create a positive business case, due to the expected higher plant availability and increased efficiency. |