California: Leader in U.S. Geothermal Energy Production for Years to Come

With the current demand for renewable energy on the rise, California is certainly doing its part in generating its share of renewable energy from a variety of different resources. The California Energy Commission recorded the energy generation in GWh for these different renewable resources in 2010, and the results are demonstrated in Figure 1. While wind and biomass both generated over 5500 GWh, geothermal is California’s highest production renewable energy source as it produced more GWh than wind and biomass combined. About half of California’s geothermal energy production is made possible by The Geysers, the largest geothermal plant in the world.  The Geysers are located in northern California and have a “capacity of over 1100MW” [1].

Figure 1: California Renewable Energy Capacity and Generation (GWh, 2010) {1}

Having geothermal as its leading renewable energy source is beneficial to California in a couple of different ways. For instance, rather than depend on fuel, geothermal plants rely on the hot fluids that are extracted from the earth’s core; these fluids are used to drive a steam turbine and generate electricity as illustrated in Figure 2. Thus, since fuel is not needed to generate a geothermal plant, the operation expenses for the plant are low, making geothermal energy both environmentally friendly and economical. Furthermore, geothermal plants do not pollute the air; only on occasion do they release harmful gases from inside the earth. However, geothermal energy is still regarded as very clean since most of these gases can be captured [2]. Because of California’s high participation in geothermal initiatives, the state is able to receive tax cuts, and utilities can obtain Renewable Energy Credits to meet their Renewable Energy Portfolios (RPS) [2,3].

Figure 2: Geothermal Energy Process {4}

While most of California’s geothermal plants are located in northern California, the state has development plans that are expected to create new geothermal plants in the southern region. The aim of these plans is to satisfy California’s greenhouse gas (GHG) reduction goals and its RPS which orders that 33% of the state’s electrical power derives from renewable energy sources by 2020 [1]. I believe these plans are promising because according to a recent US Geological Survey the western United Stated is estimated to hold 30 GW of “undiscovered” geothermal resource [5]. If the development of southern California results in production similar or better than that of the successful northern Geysers, there is no doubt that California will continue to be the leader in geothermal energy production for years to come.

However, I do not agree with a recent article from Aol Energy that predicts that geothermal power will become the state’s baseload power [3]. While I agree that California will be creating a bigger geothermal impact in the near future, natural gas is still the state’s biggest in-state electricity provider. According to the California Energy Commission, 56.7% of the in-state electricity generation was from natural gas while only 13.9% was from renewables in 2009 [6]. The article also seemed hopeful that the state’s San Onofre nuclear power plant license is about to expire in 20 years, even though the nuclear produced 15.3% of the in-state electricity in 2009 [3, 6]. While nuclear has its disadvantages, so does geothermal energy. The biggest drawback of geothermal energy that can affect California is that the steam production from a well-established geothermal plant can suddenly decline or stop; a drought that can last about 10 years  [7]. Though leading the world’s geothermal energy production is great, California needs to be aware of the potential unreliability of geothermal before it depends on this renewable resource becoming the state’s baseload power.

The following video gives a more visual representation of the geothermal energy process for those interested:


[1] Geothermal Energy Association (GEA). (2011, October). Energizing Southern California Economy: The Economic Benefits and Potential for Geothermal Energy in Southern California.

[2] Clean Energy Ideas. (2011). Advantages Of Geothermal Energy.

[3] Carus, Felicity. (2012, January). Geothermal Could Become California’s Baseload Power: Commissioner. Aol Energy.

[4] Fin, Al. (2011, February). Incredible Geothermal Energy Potential in the United States. Oil

[5] Thurston, Charles W.  (2012, January). Accelerating Geothermal Growth Through DOE Initiatives. Renewable Energy

[6] The California Energy Commission Energy Almanac. (2011, April). California’s Major Sources of Energy.

[7] Clean Energy Ideas. (2011). Disadvantages Of Geothermal Energy.



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2 responses to “California: Leader in U.S. Geothermal Energy Production for Years to Come

  1. jkguidry

    This was an enlightening post. I was not aware that geothermal site production could suddenly decline or stop. The article on geothermal energy disadvantages also indicates that the number of suitable sites for geothermal steam extraction are limited. If a limited number of suitable sites for steam extraction exist, then as energy demand increases, geothermal will contribute a continually decreasing percentage of the overall energy being provided. These disadvantages lead me to think that geothermal works well as a supplemental energy source, but cannot be relied upon as a primary energy source.

  2. altheokay

    Everything has a tradeoff… But, with their plans to tap into multiple sites across the state I would guess that they will become less sensitive to that. The Geysers, for instance, consists of at least 15 power plants and has multiple taps per plant, and it looks like they are developing methods to “recharge” used sites. If you start digging around on this site, there is some info about the efforts: . Of course it is the company owning the plants writing this, so they are a little biased, but I am sure as research continues on geothermal energy, they will find more ways to offset the potential losses. I would still want to keep my energy sources diversified though…

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