Competitiveness key to renewable energy
The San Antonio Express-News has been vocal about the need to address the climate crisis, both in editorials and in publishing “Another View” opinions. I am thankful for its willingness to bring to its readers critical information that will help constituents persuade their political representatives to take action.
Two recent “Another View” opinions are noteworthy: “The clean energy beneath our feet” on geothermal energy (Dec. 6) and “We are losing the second nuclear race” about nuclear power generation (Dec. 13).
Both opinions address a concern that is often expressed when pointing to solar and wind power — how to meet baseload generation requirements. The argument is that solar and wind are intermittent and there is a need to be able to provide energy when the sun is not shining and the wind is not blowing. Such arguments ignore the rapid advances taking place in battery storage while, at the same time, presenting future technologies that are not yet fully developed. The truth is that much research and development must be conducted in all potential clean energy technologies if we are to have a carbon-free energy future.
I am not opposed to either of the technologies presented by these opinion pieces. Quite the contrary, I applaud their presence in the discussion. I would, however, like to clarify some things related to both geothermal energy and “new nuclear” energy technologies.
As described in “The clean energy beneath our feet,” geothermal energy exploits Earth’s internal heat. However, clarification must be provided.
The authors cite that “the core of the Earth is 6,000 degrees Celsius, about the temperature of the surface of the sun” and, at least to my reading, leave the impression we can drill to the core. Nothing could be further from the truth. Earth’s outer core is more than 2,900 kilometers (1,800 miles) beneath our feet. Add to this the average thickness of Earth’s crust (the land we live on) and you have an additional 35 kilometers ( just less than 22 miles). The deepest borehole drilled to date is the Kola borehole in the Russian Arctic, which is 12.2 kilometers (7.58 miles).
So we can’t drill to the core. But we don’t have to because the deeper we drill, the hotter it gets. The rise in temperature of rocks with increasing depth is Earth’s geothermal gradient. The average geothermal gradient is 25 degrees Celsius per kilometer depth, which equates to 1 degree Fahrenheit per 70 feet of depth. The geothermal gradient varies considerably, with areas close to volcanoes and subsurface magma being much hotter while midcontinental areas are much cooler.
Those regions with high geothermal gradients, such as Japan, Iceland and portions of the United States, have long exploited geothermal energy. New advances in heat exchange materials will also permit regions with low geothermal gradients to take advantage of Earth’s internal heat. According to the Department of Energy, thermal exchange technologies provide the potential to use low-temperature resources (temperatures below 150 Celsius or 300 degrees Fahrenheit). In fact some test applications have used temperatures as low as 140 degrees Fahrenheit. A simple calculation suggests we can reach that temperature with a borehole drilled to about 10,000 feet — an easy task for the intellectual and practical experience of the petroleum industry.
What about the new nuclear? According to the MIT Technology Review, small modular reactors, or SMR, using molten salts or helium gas as the coolant are much cheaper and far safer than conventional nuclear power plants, with costs comparable to new natural gas generators. Advanced fission reactors reduce waste by using it as a fuel, and a sodium-cooled reactor that can be powered by spent fuel from a traditional reactor, depleted uranium or uranium straight from the ground (which would not be of weapons purity) is expected to be operational in China in 2023.
The drawback of fourth-generation SMR fission reactors is public perception rather than safety. The same MIT article indicates the public appears to be more accepting of fusion reactors; however, that technology is far more expensive, with no functioning model currently available to evaluate.
When I consider these and other technologies, my question is: “Who decides which technology to use?” Once passed by the peer-review process of the science and engineering communities for safety, the answer should be the marketplace.
Technologies other than fossil fuels can only be competitive in the market if a true cost of carbon pollution is incorporated into pricing. A fee on carbon would increase the cost of electricity generated by coal and gas, and make technologies such as geothermal and SMR nuclear competitive. Geothermal could specifically take advantage of expertise developed in the petroleum industry, making Texas an obvious hub for the development of geothermal energy technologies. To offset the increased costs of energy, a direct dividend can be returned to people to cover increased energy costs as the transition away from fossil fuels progresses.