Closeup of Ormat Energy Converters at Puna Geothermal Venture
Closeup of Ormat Energy Converters at Puna Geothermal Venture

After years of citing its advantage as a base load resource, geothermal power advocates must take a new tact in promoting the advantages of this form of renewable energy. Like coal and natural gas power plants, geothermal plants can provide stable power for long periods of time without emitting a whole lot of greenhouse gases.

In fact, geothermal power plants in the Philippines even have higher capacity factors than coal and natural gas powered thermal plants owing to shorter maintenance periods. But changes in the electric industry landscape, particularly the incorporation of more intermittent power resources like wind and solar and the increasing popularity of distributed generation, make base load power a less attractive option.

At the 2014 Geothermal Resources Council (GRC) Annual Meeting & Geothermal Energy Association (GEA) Geothermal Energy Expo in Portland, Oregon, Dave Olsen of the California Independent System Operator Corporation (CAISO) said that base loads are becoming a problem. In fact, the closure of the San Onofre Nuclear Generation Station (SONGS) actually made the grid much more stable, and allowed for greater use of solar and wind power. This was because too much power was generated during the mid day, when power demand is at its lowest. Unfortunately, noon time is when solar electricity production is at its peak. Even with additional storage and grid modernization, there will still be an overproduction of electricity during this time and more base load power plants will only exacerbate the situation.

CAISO Duck Curve Showing Midday Overgeneration
CAISO Duck Curve Showing Mid Day Overgeneration

In fact, base load power plants will have to operate more flexibly to maintain grid stability. They will have to provide ancillary services like spinning reserve that activate when power demand surges and deactivate when electricity demand falls. This is usually met using pumped storage hydroelectric power plants were possible, but in many instances gas and diesel power plants take up this role, resulting not only in higher costs but more greenhouse gas emissions.

Using geothermal power for this role is already being done. The Hawaii Electric Light Company (HELCO) uses an old geothermal power plant, Ormat’s Puna geothermal project. Puna is able to increase or decrease electric production based on demand by making good use of its governor valve to blow off steam as needed. Since geothermal royalties are usually based on power generated, and diesel cost is already high, it makes much economic sense to use geothermal power in this role. This is in addition to its lower carbon footprint.

Henceforth, the geothermal industry should no longer settle into its base, it should be more flexible and open minded in working with other renewable energy developers.

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