The word geothermal literally means heat from within the earth. At its simplest, geothermal energy is power extracted from heat within the earth’s crust. Very deep within the earth is a layer of molten rock known as magma, from which heat is continually produced through the natural decay of uranium, potassium and other radioactive materials. The layers of rock surrounding this magma are super-heated, gradually declining in temperature as you move farther from the molten core and toward the relatively chilly surface.

Erupting volcanoes are an example of magma exploding through chambers connected to this molten layer, usually by way of seismic activity. So it stands to reason that areas with high volcanic or seismic activity have the highest geothermal resources. Yet geothermal energy is everywhere. According to the Union of Concerned Scientists, the amount of heat within 33,000 feet of the earth’s surface contains 50,000 times more energy than all the oil and gas resources in the world.

Is Geothermal Energy Renewable?

Geothermal power is not inherently a renewable resource; a geothermal resource can be depleted. However, proper plant management can transform geothermal power into a renewable resource. The key is to avoid removing more super heated water than can be replenished by natural processes or through re-injection of used water resources. (more…)

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Coal mine shafts on the brink of closure in Asturias, Spain, could be transformed into geothermal boilers to provide heating and hot water to towns nearby. Considering the 60 some-odd years of stripping the earth of coal, it’s nice to see researchers planning to use the mines for eco-friendly purposes.

Photo Credit: NIOSH

Engineer Rafael Rodriguez and colleague Maria Belarmina Diaz developed a way to estimate the amount of heat a tunnel may provide. Their goal is to make use of low-intensity geothermal energy from the internal heat of the earth.

Advantages of mine shaft boilers:

• Predictable energy production levels
• Reduction of CO2 emissions
• Not vulnerable to changes in climate, unlike solar and wind power
• Doesn’t pollute the environment
• Profitable over the long term
• Doesn’t require new development on big sites

Testing and research needs to be conducted at mines that are still in use but are on the verge of being abandoned. Once a mine is abandoned, access is cut off. However, while still active, they have easy access to the tunnels and can easily gather data about ventilation and the rock properties. They can even program the closure of some sections to use them for geothermal energy production. It’s possible to work with closed mines, but it’s not as easy to make modifications, gather data, and make improvements.

Using a two-kilometer (6,561 ft.) mine shaft, the study evaluates the temperature of the rocks 500 meters below the surface, which are 86 degrees Fahrenheit. They’re considering forcing water through tubes at 45 degrees that would return 54 degree-water for local towns to use.

As more research unfolds, you’ll know about it here.

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East Africa’s Rift Valley spans six countries, from Mozambique to Djibouti. The United Nations Environment Programme (UNEP) and the Global Environment Facility (GEF) have just completed testing for geothermal capacity in the region. Those tests have produced results far beyond expectations.

Geothermal wells able to generate up to 8 MW have been discovered. The Africa Rift Valley Geothermal Development Facility (ARGeo) puts the valley’s potential in the range of 2.5 to 6.5 GW at present technological abilities. So far only Kenya has begun tapping this renewable resource, with a goal of 1200 MW by 2015. That, however, is about to change.

ARGeo, backed by UNEP and the World Bank, will facilitate drilling in the six Rift Valley countries starting early next year. With so much energy available and Africa’s populations in dire need, leaders in the UN and Africa are ready to get drilling. (more…)

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