Drilling Doesn’t Always Need to be Dirty

Monday, May 6, 2013 12:43
Posted in category Technical How-To's

Geothermal EnergyAt the Geothermal Energy Association conference (GEA) in New York, many compelling presentations conveyed the benefits of this relatively obscure renewable energy source. Its benefits go beyond simply limiting harmful emissions, which are largely associated with conventional energies. Geothermal energy supplies a consistent source of electricity, unlike some other renewable energies, which makes it attractive to investors. Despite high capital costs due to exploration of geothermal sources, operating costs for geothermal remain low. This is due to not requiring fuel after the power plant is constructed.

The high cost of renewable energy is a common argument against building such power plants in developed countries, and this misconception also keeps many investors away. Yet, at the GEA conference it was shown that even lesser developed countries, such as Kenya (202 MW of installed geothermal) and El Salvador(204 MW), have already begun to install significant amounts of geothermal. Furthermore, if the levelized cost of a power plant is taken into account, including capital and operating costs, geothermal energy is the cheapest source apart from wind; the latter being an intermittent source. One must wonder why many more developed countries have not yet taken to this kind of energy?

Is it a Reliable Energy Source?

Geothermal energy is a renewable energy found abundantly around the globe. The technology takes advantage of the earth’s subterranean thermal energy. It has been used to produce heat for humans for thousands of years (think Roman bathhouses). Using geothermal energy for electricity began in Italy in 1904 in a plant in operation since then.

Today, twenty-four countries around the world employ geothermal energy to produce energy on a large scale. Total geothermal energy used worldwide is estimated to be 11,224 MW (GEA 2012). The top four countries utilizing geothermal are the U.S.(3,386 Megawatts), Philippines(1,904 MW), Indonesia(1,222 MW), Mexico(958), and Italy(883 MW). These numbers are not small considering it takes 1-2 Megawatts to power 1,000 homes. Yet, geothermal electrical energy in the U.S.only accounts for about 3% of all its renewable energy sources. However, an additional 5,150-5,523MW are under commission or “in the pipeline” (GEA estimate).

How does it work?

Geothermal energy is, by the nature of the technology, completely dependent on unmovable resources—the location of reservoirs beneath the earth’s crust. Wherever geothermal reservoirs happen to lie beneath the earth’s surface, there is potential to tap into its energy. However, new research has allowed developers to use geothermal energy in many more places in the world because it is now possible to tap into reservoirs with much lower temperatures and still produce electricity (by using what is called a binary plant).

Three types of electrical geothermal energy exist: flash, dry steam, and binary (as well as some hybrids). In a flash plant, water and steam are separated at the earth’s surface, with the steam used to power a turbine, which in turn creates electrical energy. In a dry steam plant, steam already exists and thus a separator is not required. Binary geothermal plants, employing new technology, require much lower temperatures (300 Fahrenheit as opposed to 500+ for the others). In this type of plant, the hot water is used to heat another “working fluid”, (such as pentafluoropropane), which can reach higher temperature more easily than water. The evaporating water (or steam) is mimicked by these working fluids to drive a turbine the same as a conventional geothermal plant.

Geothermal technologies tied to production of electrical energy are not feasible in many parts of the world which are far away from hot water reservoirs. However, the constant temperature of the earth’s core provides another ingenious way to heat and cool buildings (thermal energy), using the same concepts. Geothermal heat pumps (GHPs) pull heat down from a building during the summer; while in the winter, heat is driven up. This system can be used in virtually every corner of the globe to regulate building air temperatures and to produce hot water.

Bringing Light to Africa

Geothermal KenyaIf Kenya can develop geothermal energy on a grand scale, the technology is most likely proven and financeable. The Kenyan government has been largely responsible for the recent success of geothermal development projects. Through the Geothermal Development Company, (an autonomous state-owned company formed in 2009), the government mitigates the risk of geothermal plants; financial risks often impossible for the private sector to absorb.

This helps secure much needed foreign direct investment, without which would stymie exploration and procurement. Another clever policy tool employed by the Kenyan government was setting the import duty on renewable energy equipment and accessories to zero. This lessened the burden of importing expensive parts from around the world for renewable energy plants.

Geothermal energy in Kenya already accounts for nearly 16% of its total supply. Africa was once considered The Dark Continent, but may soon be lighting up with help from geothermal energy and other renewable energy sources. Indeed, Kenya is an integral part to Africa’s energy revolution.

Drill, baby, Drill!

What if developed countries began to seriously consider geothermal as a reliable, efficient, and sustainable energy source? Unlike other renewable energies, such as wind and solar, geothermal energy is not intermittent; meaning that a geothermal power plant can replace a coal or natural gas power plant quite easily.

New policy tools can help alleviate the burden of upfront exploration costs for geothermal energy, as the government of Kenya has done. And although the U.S. government and other governments of developed countries with geothermal energy promote, and in some cases subsidize geothermal energy, it is often confused with other renewable energy technologies. The confusion lies in the assumption that geothermal energy is like wind or solar energy, and is thus relatively new and unreliable.  Whereas the reality is geothermal needs policy that can attract new finance schemes, while also pushing further technological research (research which recently helped develop binary plants).

 

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    Kyle S Herman

    Kyle S Herman

    Kyle gained a Masters in International Studies from the University of San Francisco and completed a traineeship at the International Network for Sustainable Energy in Aarhus, Denmark. He then created his own non-profit organization, the Coalition for Renewable Energy, to continue promoting renewable energy policy domestically and abroad. Currently he works for the Council on Global Security and Governance to advise ambassadors to the U.N. on socially responsible investments in developing countries.