Geothermal energy has been around forever, used as a heating source across the world. Today it has surfaced as another renewable resource, with advancements in drilling technology bringing down costs and opening new areas to development.
 |
| Will Pettitt |
In conjunction with the feature article on geothermal in the May 2019 issue of POWER, we sought opinion from a leading expert in the sector: Will Pettitt, executive director of the Davis, California-based Geothermal Resources Council.
POWER recently interviewed Pettitt to get his opinion about the future of geothermal energy:
What can we expect with regard to global growth in geothermal energy? Are there any regions where significant growth is expected?
Pettitt: Geothermal energy, I believe, has a really exciting and bright future. Geothermal power is a renewable energy that provides flexible baseload. It can provide the electricity grid with resiliency, reliability, and stability as we transition to more and more renewable fuels.
It is a stable 24/7 power source with capacity factors [higher than] 70% in practice, higher than any other power resource except nuclear. It can also be ramped up or down, so is flexible to give power when it’s needed and can help balance the grid when intermittent renewables come on or off.
Pettitt: The U.S. is the largest producer in the world but other countries are also doing well at developing their resources. The greatest developers of power over the past 10 years have been Turkey and Indonesia, followed by the U.S., Kenya, and New Zealand. In the USA we have about 3.6 GW of installed geothermal capacity. We have about 1.2 GW being developed. A recent study at NREL estimates there will be 6 to 11 GW installed in the USA by 2050 using today’s technologies and depending on the policy environment.
What are some of the technological advances we can expect to see that will support the growth of geothermal energy?
Pettitt: The geothermal industry also has great existing technologies, and new technologies being developed that will allow easier and more efficient access to resources. We also have talented people who are passionate about the technologies that we have, the renewable-energy mission, and the future of our industry. Geothermal energy is therefore well-placed to be a facilitator of the transition to renewable energy.
Enhanced or Engineered Geothermal Systems (EGS) offer a game-changing landscape for geothermal energy. If EGS is successful then more than 100 GW of power is conceivable in the USA alone according to government studies. In the U.S., current power production is limited to the western states with California being the largest producer and having the largest geothermal field in the world. However, the earth is hot everywhere it’s just how deep we want to drill and how the economics stacks up. If commercial EGS becomes viable then we can tap into that resource almost anywhere.
In my view there are three technology pieces that need to come together for EGS to be successful: 1) creating and maintaining the reservoir so as to ensure sufficient permeability without short circuiting; 2) bringing costs down on well drilling and construction; 3) high-temperature downhole equipment for zonal isolation and measurements. These technologies all have a lot of crossover opportunities to helping conventional geothermal be more efficient.
How important (or not important) are government subsidies to the growth of geothermal?
Pettitt: What we need to do as a renewable energy industry is appreciate that we need all sources of renewable power to be successful and that intermittent sources of power need the baseload sources to get to a 100% renewable portfolio. Geothermal therefore needs to be collaborating with the solar, wind and biofuel industries to make this happen.
Research projects into EGS are being performed all over the world. In USA there are two large projects funded by the DOE’s GTO (Geothermal Technologies Office) and by Bill Gates’ Breakthrough Energy Ventures. DOE’s FORGE EGS experiment is based in Utah. They selected the site last year and will now embark on five years of operating the site and performing research, development and experimental tests on technologies needed for commercial EGS. The DOE recently released their R&D roadmap for FORGE. The DOE is also funding other research projects that aim to develop conventional geothermal resources such as improving exploration techniques and development of Deep Direct Use.
What are the environmental concerns with regard to geothermal?
Pettitt: The IEA (International Energy Agency) notes that pre-development risks are an important factor in securing financing for geothermal projects. They see strong growth in Latin America and Caribbean because geothermal technology generates stable, CO2 emissions-free baseload power. Additional growth worldwide could be seen with faster commissioning of the projects, mainly in emerging economies.
What types of companies are likely to invest in geothermal power? Where will investments come from, and are there other opportunities for the geothermal sector?
Pettitt: There are many other technologies that add value to geothermal power plants and can help facilitate greater deployment. For example, Berkshire Hathaway Energy, among other companies, is looking at the recovery of lithium through solution mining the geothermal brine. The supply of lithium is becoming of national importance as battery markets and technologies develop. The Salton Sea geothermal field in Southern California is shown to be very cost competitive and could produce a significant portion of the world’s lithium demand.
Other similar opportunities include:
- Production of hydrogen – for fuel cells.
- Desalinization – for drinking water or to replenish lakes and reservoirs.
- Hybrid production with solar – solar plant helps cover the operational energy consumption at warmest part of the day.
- Co-production with oil and gas – as many operations are remote and in deep, hot, reservoirs.
- Energy production for mining – as many hard rock mines are in similar locations worldwide to geothermal resources.
