Geothermal Plant Supplies ~20% of Hawaii’s Electricity

Living on active volcanic islands has its downsides and its upsides. When it comes to the plus side, there’s the potential to use geothermal energy to produce significant amounts of cheap, clean, renewable electrical power. And that’s what’s happening on the ‘Big Island’ of Hawaii, where Ormat Technologies‘ Puna Geothermal Venture is producing about 20% of the electricity consumed on the island, eliminating the need to buy and burn some 144,000 barrels of oil a year.

Puna Geothermal Venture has a contract with Hawaii Electric & Light (HELCO) to supply the utility with 30 megawatts (MW) of electricity through 2030 sourced from the company’s geothermal plant located within Mt. Kilauea’s East Rift zone. Geothermal fluids about 650 degrees Fahrenheit are brought up to the plant through through five production wells where steam is then separated from brine. The steam is used to drive the plant’s generators.

A secondary power generation circuit captures waste heat from the primary circuit using the fluid pentane, which increases the plant’s power output and its energy conversion efficiency, as well as significantly reducing the amount of steam vented into the atmosphere. The geothermal fluids are injected back into the reservoir through injection wells, which lie far below the production zone and the water table.

Puna and Ormat aim to build on the plant’s success. It’s working to increase the plant’s output by 8MW in the near future. The company is also exploring for geothermal reservoirs off the coast of Maui, and it’s discussing building a plant on Hualalai to help meet electricity demand in West Hawaii.

“Modular geothermal power units can contribute a large portion of an island’s electricity demand,” Puna Geothermal plant manager Michael Kaleikini was quoted as saying in this report from West Hawaii Today. “Geothermal energy is environmentally friendly and is cost-effective for islands.”