Stockholm, June 14, 2011 — A tenfold increase in the global production of heat and electricity from geothermal energy is possible between now and 2050, according to a report from the International Energy Agency.
Renewable sources of energy such as wind, solar and geothermal will have to comprise a much greater share of the global energy mix in the coming years if the level of carbon dioxide in the atmosphere is to be kept below 450 parts per million — a key threshold in limiting global temperature increase to 2°C, which leaders agreed to at the UN climate change talks in Cancun in 2010.
The IEA says that through a combination of policy actions that encourage the development of untapped geothermal resources and new technologies, geothermal energy can account for around 3.5 percent of annual global electricity production and 3.9 percent of energy for heat by 2050 — a substantial increase from current levels of 0.3 percent and 0.2 percent, respectively.
One key area of action for governments identified in the report is the introduction of incentive schemes that will encourage the development of geothermal technologies that are not yet commercially viable. These include feed-in tariffs, which are payments to anyone who generates electricity for a grid using renewable sources of energy.
A third proposed area of action outlined in the report focuses on overcoming the barrier of obtaining permits, which are necessary for all new geothermal plants.
To date, efforts to extract geothermal energy have concentrated on areas with naturally occurring water or steam. (The water or steam, commonly found near tectonic plate boundaries and often associated with volcanoes and seismic activities, is easily accessible as the permeable rock in the earth's crust is already fractured).
However, the vast majority of the world's geothermal energy within drilling reach, which can be up to 5 kilometers, is found in rock that is relatively dry and impermeable. These areas, which are found all over the world and contain insufficient water for natural exploration, are known as hot-rock resources.
Currently, technologies that allow energy to be tapped from hot-rock resources — the best known is enhanced geothermal systems — are still in demonstration stage, but the IEA report suggests that governments should provide sustained and substantially high research, development and demonstration resources to plan and develop at least 50 enhanced EGS pilot plants during the next decade.
With these systems, a well is drilled deep into the ground, typically below 1.5 kilometers. Water is then injected into the well at sufficient pressure so as to create fractures in the rock. Other wells are then drilled in order to suck up the water, which has been heated by the hot rocks.