Energy Sources
Geothermal
Facts
Geothermal plants are among the most expensive to build, with upfront costs ranging from $3,000/kW to $7,000/kW. As a comparison, it costs about $4,000/kW for nuclear and $2,300/kW for coal power plants. However, geothermal plants do not require a fuel supply to operate, therefore reducing the lifetime costs of the plant and eliminating the risk of fuel price spikes.
Source: “World Geothermal Generation,” Geo-Heat Centre Quarterly Bulletin. (http://geoheat.oit.edu/bulletin/bull28-3/art3.pdf)
Most geothermal plants are located on the Pacific “ring of fire,” a geographic area known for earthquakes and volcanic eruptions. The United States is the largest producer of geothermal energy, while significant development and new opportunities exist in Indonesia, the Philippines, New Zealand, Mexico, and Chile. Several European countries have smaller, but notable, geothermal resources, such as Iceland, Italy, Portugal, and Turkey.
Source: IEA. “World Energy Outlook 2010.” (http://www.worldenergyoutlook.org/)
Geothermal energy is sustainable on a global scale, but requires proper management to replace the water (emitted in the form of steam) drawn out of the aquifer. Local resources can be exhausted if production rates are too high and/or an insufficient amount of water is re-injected into the site.
Source: “Geothermal Sustainability,” Geo-Heat Centre Quarterly Bulletin (http://geoheat.oit.edu/bulletin/bull28-3/art2.pdf)
Overview
Between 1980 and 2009 world geothermal electricity consumption grew from just over 13 billion kWh to over 60 billion kWh. During the same period geothermal electricity consumption in the US tripled from around 5 billion kWh to more than 15 billion kWh. The Philippines is currently the second largest consumer of geothermal energy at nearly 10 billion kWh.
Source: US Energy Information Administration (EIA). “International Energy Statistics.” (http://tonto.eia.doe.gov/cfapps/ipdbproject/iedindex3.cfm?tid=6&pid=35&aid=2&cid=regions&syid=1980&eyid=2009&unit=BKWH)
In Iceland, where there are favorable geologic conditions and efficient hot water distribution networks, 88% of all households get their heat from geothermal energy. The hot water used in these heating systems is primarily produced in combined heat and power (CHP) plants, which generate electricity and heat at the same time. Other industrialized countries using geothermal for district heating include Germany, Austria, Denmark, Hungary, Slovakia and Belgium.
Source: IEA. “World Energy Outlook 2010.” (http://www.worldenergyoutlook.org/)
By 2035 global geothermal heat use is forecast to grow from 5 Million tonnes of oil equivalent (Mtoe) to 26 Mtoe, with the largest increase expected in the US. Geothermal heat is primarily used to heat buildings.
Source: IEA. “World Energy Outlook 2010.” (http://www.worldenergyoutlook.org/)
Although geothermal is a renewable resource, the process draws a small amount of greenhouse gases from deep within the earth that are emitted into the atmosphere. Although emissions from geothermal energy plants are only a fraction of those of fossil fuel plants, these emissions make a small contribution towards climate change and acid rain. Geothermal plants have few other environmental side effects, but in some cases have been shown to increase seismic activity.
Source: “World Geothermal Generation,” Geo-Heat Centre Quarterly Bulletin. (http://geoheat.oit.edu/bulletin/bull28-3/art3.pdf)
Source: “Seismicity Induced by Water Injection for Geothermal Reservoir Stimulation 5 km Below the City of Basel, Switzerland.” American Geophysical Union (http://adsabs.harvard.edu/abs/2007AGUFM.V53F..08D)
At an average cost of $52/MWh over the next decade, geothermal electricity is one of the most inexpensive form of renewable energy available.
Source: IEA. “World Energy Outlook 2010.” (http://www.worldenergyoutlook.org/)
In some areas, geothermal energy systems can save homeowners 25 – 70% in utility expenses compared with conventional systems.
Source: Geothermal heat pump consortium. “Geothermal heating and cooling.” (http://geoexchange.us/about/how.htm)
Geothermal exploration is expensive and risky, particularly for medium-temperature resources, which are more widespread. The failure rate in geothermal well exploration is between 20 - 40%.
Source: ” Hattenberg, Dilley, % Linnell Engineering Consultants. “Geothermal cost matrix.” (http://www.akenergyauthority.org/Geothermal/MatrixHandout_4-09.pdf)
The cost of geothermal generation is expected to decrease by just over 10% over the next 20 years, from $52/MWh to $46/MWh. Although geothermal will remain cheaper than most other renewable sources of energy, the decrease over the next twenty years is not as significant as the expected 44% decrease in the cost of solar and 24% decrease in the cost of wind energy.
Source: IEA. “World Energy Outlook 2010.” (http://www.worldenergyoutlook.org/)
Although the price per MWh will not decrease as rapidly as others, geothermal energy generation is still predicted to be more economical than any other renewable energy resource in 2030. If countries choose to put a price on carbon, geothermal energy could be the cheapest energy source available overall.
Source: IEA. “World Energy Outlook 2010.” (http://www.worldenergyoutlook.org/)
Geothermal energy is not a zero-carbon energy source, as geothermal wells emit small amounts of CO2, H2S, CH4, and NH3. However, compared with fossil fuel sources of energy the emissions from geothermal energy are quite low.
Source:Bloomfield, K. Kit, Moore,Joseph N. and Neilson, Robert M. (2003). “Geothermal energy reduces greenhouse gases.” Geothermal Resources Council: http://www.geothermal.org/articles/greenhousegases.pdf
Some geothermal plants release trace amounts of elements that can cause damage to local plant and animal life if not captured at the generation plant.
Source: "Environmental Impact of Trace Element Emissions from Geothermal Power Plants", Environmental Contamination Toxicology. (http://www.springerlink.com/content/v04exle5cey69ejg/)
Efforts to maintain site productivity can have positive side effects. For example, re-injecting water into geothermal wells reduces emissions of trace elements during generation.
Source: "Environmental Impact of Trace Element Emissions from Geothermal Power Plants", Environmental Contamination Toxicology. (http://www.springerlink.com/content/v04exle5cey69ejg/)
Countries are beginning to implement environmental safeguards for geothermal projects owing to the risks associated with induced seismicity. Projects have been stalled in California and Switzerland amidst fears that the regions could face an increase in damaging earthquakes as a result of geothermal reservoir operations.
Source: “Geothermal energy project in California is shut down.” The New York Times. (http://www.nytimes.com/2009/12/12/science/earth/12quake.html?ref=geothermal-power)
Some environmentalists consider geothermal energy to be less desirable than solar or wind owing to the environmental impact at the site, but its effect on air pollution, greenhouse gas emissions, and local ecosystems is negligible, especially when compared to fossil fuels.
Source: VentureBeat (http://venturebeat.com/2010/11/23/did-bjork-yes-bjork-get-it-right-on-geothermal-energy/)
Geothermal is one of the most secure forms of renewable energy, as geothermal plants typically have long life spans. Properly managed geothermal plants can last for several decades and generation is not dependent on climatic conditions.
Source: “World Geothermal Generation,” Geo-Heat Centre Quarterly Bulletin. (http://geoheat.oit.edu/bulletin/bull28-3/art3.pdf)
With most resources located along the Pacific Rim and in Europe, geothermal resources are found in countries that are traditionally politically stable, implying that geothermal energy will likely remain a consistent contributor to the global energy mix.
Source: “Geothermal Energy: International Market Update.” Geothermal Energy Association: http://www.geo-energy.org/pdf/reports/GEA_International_Market_Report_Final_May_2010.pdf
Source: “Political instability index.” EIU. March 2009: http://www.economist.com/node/13349331
If properly managed, geothermal wells can perform for several decades without depleting, ensuring long-term energy stability. Italy has a geothermal project dating back to 1913, while projects originally built in the 1950s are still operational in California and New Zealand.
Source: "A Brief History of the Wairakei Geothermal Power Project", Geo-Heat Centre Quarterly Bulletin (http://geoheat.oit.edu/bulletin/bull19-3/art1.pdf)
Geothermal: Opportunities
Geothermal is one of the most reliable and economical renewable energy sources.
Unlike wind, solar, and hydro power, geothermal power is not dependent on climate conditions and can provide reliable 24-hour power over a long lifetime. Additionally, it can be used to produce electricity as well as provide direct heat. Geothermal power has one of the lowest generating costs of any renewable energy resource.
New technologies could open up increased geothermal resources
Enhanced geothermal systems (EGS) have already been developed and are expected to be economically viable in more regions in the coming decades. EGS utilizes a process called hydraulic stimulation, which creates fractures in hot dry rock underneath the earth’s surface. Cold water is pumped through the fractures in the hot dry rock, heating up in the process. The hot water is then forced out of the rock through a second bore hole and captured in a geothermal plant. Effectively, EGS allows more geothermal resources to be recovered at a cost that is economically viable.
Source: “The Future of Geothermal Energy.” MIT. (http://geothermal.inel.gov/publications/future_of_geothermal_energy.pdf)
Geothermal: Challenges
Geothermal resources are located sparsely around the globe and exploration can entail significant risks.
High-temperature geothermal resources are usually located near plate boundaries or rift zones, which are often far from areas of high energy demand, requiring costly transmission infrastructure. Medium and low-temperature resources are more widespread but costlier to operate and less efficient.
Source: IEA. “World Energy Outlook 2010.” (http://www.worldenergyoutlook.org/)
Unlike other renewable energy sources such as wind and solar, prices for geothermal energy are unlikely to decline noticeably in the next 20 years.
In order for new geothermal resources to be developed, a significant amount of upfront research and development, exploration, and construction expenses will be incurred. Although geothermal still ranks as one of the most affordable renewable sources of energy, its upfront costs are among the highest and new technologies are not expected to bring costs down significantly.
Source: “The Future of Geothermal Energy.” MIT. (http://geothermal.inel.gov/publications/future_of_geothermal_energy.pdf)
Source: IEA. “World Energy Outlook 2010.” (http://www.worldenergyoutlook.org/)