To reach the point where geothermal energy makes up 10 – 15 percent of the nation’s power, significant investments in the technology will be needed. But according to Anderson, the investment is sound: “Once geothermal plants are live, the power is predictable. And predictable power is what we want.”
Geothermal energy in the United States has the potential to have an installed capacity of 100,000 megawatts (MW) within the next 50 years, according to a report published by an interdisciplinary panel lead by MIT. That’s the total peak energy consumption of France. Given that potential, will we see geothermal energy become a greater part of our power mix?
The current (pdf) installed capacity of geothermal energy in the United States is 3,187 MW, which is more than any other country in the world. Geothermal energy is an attractive energy option, given that plants have low emissions, operate constantly and generate high rates of electricity – in some cases, even outperforming coal-fired power plants.
Yet geothermal energy is not competitive with wind and solar.
The reason, says Brian Anderson, professor of Chemical Engineering at West Virginia University and co-author of the MIT report, comes down to cost: “Exploring a potential geothermal site is expensive, and there is a level of uncertainty in the exploratory phase. An exploratory well costs at least a few million dollars.”
But although the investment costs are hefty, once the site has been evaluated and a plant constructed, “that’s when the payback comes,” says Anderson. “The plant is generating electricity over 90 percent of the time.”
The environmental impacts of geothermal are minimal as well, says Anderson (the report notes that microearthquakes are a possibility but the authors feel it is more an issue of public perception). The biggest concern is water usage, particularly in places like California and Nevada, where the majority of U.S. geothermal plants are located. To mitigate this, some plants come equipped with binary cycle systems, which transfer the heat from the water to a different liquid, and then re-inject the water into the ground.
When it comes down to it, “we need champions in all areas of energy,” says Anderson. Geothermal energy complements intermittent energy sources, like wind and solar, because it generates energy constantly, and would make a good addition to the smart grid.
For now, wind and solar remain more popular options because the exploratory phase is much cheaper, projects can easily be scaled, and their placement is versatile – solar and wind can be installed offshore or onshore, in cities or the country, on rooftops or farms.
The US could be producing 32 million times more geothermal electrical power than it does at present.