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OWOE - Blog
Gung-ho for Geo
September 22, 2019

Guest blog by SA Shelley: No doubt about it, the world runs on energy (and money). Nearly 80% of all the world’s energy is still provided by coal, oil and gas though this fossil fuel proportion of the energy mix is now shrinking and in just under 10 years, the world's energy mix will look markedly different. I hope that in addition to coal, oil and gas the OWOE reader is familiar with some of the other large energy sources such as nuclear, wind, solar, hydro and wave. Here at OWOE we try to bring useful and relevant knowledge and ideas about energy to the reader, and one big potential and virtually zero carbon energy source that has been overlooked by a lot of people including the OWOE bloggers is geothermal energy. Well no more. After a bit of research this OWOE blogger has gone gung-ho for geo for good reason.

In short, geothermal energy basically arrives in two flavors, geothermal heat pump (GHP) and supercritical reservoir energy (CRE). GHP uses the earth as a heat source or sink for heating and cooling (think of heat pumps for residential use). CRE uses high temperature water or steam from a hot reservoir to drive generators to produce electricity. The key benefits of geothermal energy are:

  1. It is renewable— the rate of energy extraction can be balanced with a reservoir's natural heat recharge rate
  2. It can provide baseload power 24 hours per day / 7 days per week, regardless of weather conditions
  3. It is domestically and locally available almost everywhere
  4. It has a very small footprint—CRE power plants are compact; using less land per GWh (404 m2) than coal (3642 m2), on shore wind (1335 m2) or solar PV with center station (3237 m2)
  5. It has the very low total life cycle CO2 emissions: four times less than solar PV and six to twenty times lower than natural gas.
  6. It consumes less water on average over the lifetime energy output than the most conventional thermal (coal and gas) generation technologies

In addition, developing geothermal energy can make use of a lot of oil and gas technology and provide jobs for oil and gas workers who might soon enough find themselves in the next oil and gas downturn.

The Case for the United States In terms of GHP, currently about 2 million homes in the United States use it for heating and cooling. However, the DoE has calculated that by using existing technology and business practices there is enough thermal geothermal energy in the continental United States to heat an additional 26 million homes (Fig. 1).

Fig. 1: Percentage of U.S. homes using GHP for heating and cooling

In terms of CRE current and potential electricity generation, the potential to add 23 times the current CRE power to the U.S. grid is possible using current technology and business practices (Fig. 2).

Fig. 2: Electrical power production using CRE

This CRE is clean, baseload, 24 hour energy. Turn it on and it provides power, rain or shine, wind or none. 

The Case for California Thinking about California, there is about 3.2 GW of installed CRE and 16.7 GW potential CRE. It gets really interesting if we compare the potential geothermal power in California (16.7 GW) to the potential wind energy offshore California (58.7 GW ) Let's compare the proposed Morro Bay wind farm rated at 765 MW to an equivalent onshore CRE plant that provides baseload power. Since 765 MW is the rated power of the wind farm that means that the average power output per day will be less. Giving the Morro Bay wind farmers the benefit of technology, let's say that they achieve a capacity factor of 50% offshore, meaning that an equivalent, baseload CRE plant only needs to be rated at 425 MW at 90% efficiency to produce the same amount of power each day. In terms of land or ocean space area required (Fig. 3) the differences are significant.

Fig. 3: Surface area required for equivalent electricity production

The offshore wind farm CAPEX is four times more expensive than an onshore CRE that produces the equivalent amount of power (Fig. 4). Adding operating and maintenance costs, the large offshore wind farm economics get worse.

Fig. 4: CAPEX required for equivalent electricity production

In terms of secondary enviro-economic impacts, such as on fishing activities offshore or potential interference with whale migration, going offshore with large, expansive wind farms in California will be a losing proposition compared to a CRE plant on shore. Geothermal plants with their small local footprints are also designed to minimize any effect upon the local ecosystem.

As presented before on OWOE, it really should be obvious that California does not need large, expensive floating offshore wind farms, not yet, and not for another 10 or 20 years. However, California will soon need a few small offshore wind farms with low numbers of units that feed both into the energy grid and into secondary renewable energy and resource systems.

The Global Case for Geo Returning to geothermal energy for power production, the global potential is also huge (Fig. 5).

Fig. 5: Global electrical power production using CRE

In some places, most famously Iceland, there is an abundance of geothermal energy literally bubbling to the surface. Fully 66% of all of Iceland's primary energy is supplied by geothermal with heating and electricity production being the two largest consumers of this geothermal energy.  Kenya generates about 47% of its electricity using geothermal power plants. In 2018, Turkey added about 219 MW of geothermal power to its grid and has plans for much more in the future. Almost every country has some good potential for geothermal energy and many have started to develop that potential (Fig. 6; see

Fig. 6: Top 10 Countries with installed geothermal power in 2018 (source:

A GW of power may not seem like a lot in the United States but in places like the Philippines and Indonesia it is a lot and helps towards sustainable economic progress.

Then of course there is Canada, where the socialist governments are completely blind to geothermal energy and all of its associated very low carbon, renewable potential. They fight too much over historical technologies and cannot see the future among the steam.

Blatant Blogger Recommendation The world needs to be a little more gung-ho for geo.

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