A new MIT-led study suggests that geothermal power does not get the attention it deserves.
A comprehensive new MIT-led study of the potential for geothermal energy within the United States has found that mining the huge amounts of heat that reside as stored thermal energy in the Earth's hard rock crust could supply a substantial portion of the electricity the United States will need in the future, probably at competitive prices and with minimal environmental impact.
An 18-member panel led by MIT prepared the 400-plus page study, titled "The Future of Geothermal Energy" (PDF, 14.1 MB). Sponsored by the U.S. Department of Energy, it is the first study in some 30 years to take a new look at geothermal, an energy resource that has been largely ignored.
See the body of the report for cost details. I also include a couple of excerpts from the cost sections below. Also, see Figure 1.11 on page 42 which shows cost estimates for a future geothermal site at Clear Lake in Kelseyville California. Note the cost range is from about 2.8 to 4.4 kwh. That is competitive with coal's current cost. That coal electric comes with no carbon sequestration and much more mercury, particulates and other pollution than I'd like to see. Geothermal would avoid all that.
For geothermal note that drilling costs are falling due to on-going efforts by the oil and natural gas industries to develop cheaper methods to do deep drilling. But geothermal has some additional needs for technological advancement and for exploration to identify the best drilling locations.
Here is a surprise. Did you know that geothermal generates more power than wind and solar combined in the United States?
According to panel member M. Nafi Toksöz, professor of geophysics at MIT, "geothermal energy could play an important role in our national energy picture as a non-carbon-based energy source. It's a very large resource and has the potential to be a significant contributor to the energy needs of this country." Toksöz added that the electricity produced annually by geothermal energy systems now in use in the United States at sites in California, Hawaii, Utah and Nevada is comparable to that produced by solar and wind power combined. And the potential is far greater still, since hot rocks below the surface are available in most parts of the United States.
Wind blows weakly in some parts of the United States, especially in the southeast which is experiencing rapid population growth. But geothermal installations won't stop when the wind slows and the sun goes down.
The panel makes a number of recommendations:
- More detailed and site-specific assessments of the U.S. geothermal energy resource should be conducted.
- Field trials running three to five years at several sites should be done to demonstrate commercial-scale engineered geothermal systems.
- The shallow, extra-hot, high-grade deposits in the west should be explored and tested first.
- Other geothermal resources such as co-produced hot water associated with oil and gas production and geopressured resources should also be pursued as short-term options.
- On a longer time scale, deeper, lower-grade geothermal deposits should be explored and tested.
- Local and national policies should be enacted that encourage geothermal development.
- A multiyear research program exploring subsurface science and geothermal drilling and energy conversion should be started, backed by constant analysis of results.
With better battery technology add geothermal to the list of energy sources that could replace oil as a means to power ground transportation.
What about cost? The body of the 372 page report has extensive discussion of cost considerations.
Because the field-demonstration program involves staged developments at different sites, committed support for an extended period will be needed to demonstrate the viability, robustness, and reproducibility of methods for stimulating viable, commercial-sized EGS reservoirs at several locations. Based on the economic analysis we conducted as part of our study, a $300 million to $400 million investment over 15 years will be needed to make early-generation EGS power plant installations competitive in evolving U.S. electricity supply markets.
These funds compensate for the higher capital and financing costs expected for early-generation EGS plants, which would be expected as a result of somewhat higher field development (drilling and stimulation) costs per unit of power initially produced. Higher generating costs, in turn, lead to higher perceived financial risk for investors with corresponding higher-debt interest rates and equity rates of return. In effect, the federal investment can be viewed as equivalent to an “absorbed cost” of deployment. In addition, investments in R&D will also be needed to reduce costs in future deployment of EGS plants.
But one big pay-off would be to avoid construction of dozens of polluting coal plants.
Based on growing markets in the United States for clean, base-load capacity, the panel thinks that with a combined public/private investment of about $800 million to $1 billion over a 15-year period, EGS technology could be deployed commercially on a timescale that would produce more than 100,000 MWe or 100 GWe of new capacity by 2050. This amount is approximately equivalent to the total R&D investment made in the past 30 years to EGS internationally, which is still less than the cost of a single, new-generation, clean-coal power plant.
Geothermal would have a small surface footprint and would cut very little into habitat areas. Unlike biomass energy sources such as corn and cane sugar ethanol, geothermal wouldn't compete with food crops for agricultural acreage. But in order for geothermal (or solar or nuclear or wind) to displace fossil fuels for transportation uses we need better batteries. Battery technology is going to be the key to ending the era of fossil fuels without turning most of the world into crop lands.
Given the timelines discussed in the report geothermal is not much of a short term solution. Though the panel thinks development of hot sites near the surface in the western US could come sooner than the deeper sites. But if we start now to do the research and development recommended in this report then geothermal could start displacing a lot of new construction of coal plants by the 2020s. The amount of money needed to develop this option is fairly small. Why not do it?
Some 58 new geothermal energy projects are already under development in the United States, according to a November 2006 survey by the Geothermal Energy Association, GEA, an industry trade group, which says federal and state incentives to promote geothermal energy are paying off.
Anyone know how big the government incentives are for geothermal? I'm guessing California's mandate to get more electricity from renewables makes geothermal more cost effective in California than in most other states.
“This represents the U.S. geothermal industry’s most dramatic wave of expansion since the 1980s,” said Karl Gawell, GEA’s executive director. "We are seeing a geothermal power renaissance in the U.S."
These projects, when developed, would provide up to 2,250 megawatts of electric power capacity, enough to serve the needs of 1.8 million households.
Those geothermal projects combined add up to about one large nuclear power plant.
One problem geothermal has is that most of the best sites in the United States are in the west. But if geothermal electricity becomes really cheap then energy intensive industries such as computing and aluminum could relocate to near geothermal sites.