March 25, 2014
Tapping The Energy In The Earth’s Hot Core
It’s the moment a DIY man or woman dreads. You dig out that old electric drill to fit a new shelf in the kitchen. Then, just as you are drilling your last hole, there’s a bang and a flash. The power goes off and if you are lucky, you have avoided electrocution, but what you have done is zap the main cable buried and hidden in your wall. That’s bad enough, but imagine for a moment that you are drilling into the Earth in a multi-million dollar project looking at exploiting geothermal energy. As you drive the drill deep into the Earth’s crust, you suddenly break through into a “magma chamber.” In effect, you have just tapped into a pocket of the Earth’s molten core. Inside is the magma itself – rock that is so hot it has melted or become semi-solid with a temperature in the region of 2,000° Fahrenheit. You have opened up a hole through which the very stuff of volcanoes is trying to escape. What do you do you now?
Well, that question has only been asked twice in these circumstances and the answer was very different in each case. Back in 2005, workers at Ormat, one of the world’s biggest geothermal producers, were drilling a mile and a half deep inspection well in Hawaii when they hit a magma chamber. Magma contains gas as well as molten rock and once released it loses gas and heat rapidly. In this case the magma rose about 20 feet into the drill hole before solidifying. Although other holes were drilled in the area with the same result, they were all allowed to solidify. They were then were capped with concrete plugs and are now being studied and monitored for seismic activity.
The second time this happened was at Krafla in Iceland in 2008 and 2009 when the Icelandic Deep Drilling Project (IDDP) again discovered a magma pocket. But it is only now that scientists have confirmed that, in spite of the considerable capital costs involved, they reinforced the hole with steel and concrete to keep it open and have been looking at ways to tap the geothermal energy from the magma. The bottom of the hole was kept perforated. It was then allowed to heat slowly, producing superheated steam capable of driving turbines.
Iceland already uses hydro and geothermal sources to supply almost all its electricity and uses geothermal heat to warm the vast majority of its buildings. The country has the highest electricity production per capita of any country in the world. But this discovery of a new source of geothermal energy is of a totally different order. The borehole is capable of producing vents of steam at an incredible temperature of up to 1,000°F. If this energy could be tapped efficiently and safely, it opens up the possibility of a whole new geothermal power source. It is thought that this one borehole alone could produce 36MW of electricity, which is over half that produced by a large geothermal power plant nearby.
The IDDP believe that they have discovered a way to harness the energy of the Earth’s molten core and this could “in the near future lead to a revolution in energy efficiency in high-temperature geothermal areas of the world.”
Image Credit: Thinkstock