The International Energy Agency (IEA) is urging greater use of geothermal energy because of its ability to provide critical baseload power that’s available all over the world, reliably every day of the year.
Geothermal presently supplies a miniscule amount of the world’s energy compared to its potential, according to IEA’s report, "Technology Roadmap: Geothermal Heat and Power."
Geothermal could increase 10-fold by 2050 with strong policies and incentives.
IEA’s report says that through a combination of actions that encourage the development of untapped geothermal resources and new technologies, geothermal energy can account for 3.5% of annual global electricity production and 3.9% of energy for heat (excluding ground source heat pumps which the report did not consider) by 2050 – a substantial increase from current levels of 0.3% and 0.2%, respectively.
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.
"This would be an important contribution to global efforts of reducing carbon emissions, using a reliable source of energy that is available all over the world, every day of the year, as it does not fluctuate with the weather or season," says IEA Executive Director Nobuo Tanaka.
The report is the latest in the IEA series of technology roadmaps, which aim to guide governments and industry on the actions and milestones needed to achieve the potential for a full range of clean energy technologies.
Untapped Areas, Emerging Technologies
Although there’s been active geothermal exploitation for more than a century, those efforts to extract geothermal energy have concentrated on areas with naturally occurring water or steam, often found in volcanic areas.
However, Milou Beerepoot, the report’s author and a senior analyst at the IEA, notes that a large share of such ‘low hanging fruit’ remains unexploited in developing and emerging economies. She says efforts should be expanded to solve economic and non-economic barriers that hinder further exploitation in these countries.
Moreover, she observes that geothermal energy can also be extracted from many deep aquifer systems, of which there are many all over the world. These resources can typically be reached at a depth of 3 kilometres and produce temperatures in excess of 60ºC. Use of these aquifers is expected to grow quickly, reflecting their wide availability and increasing interest in their use for both heat and electricity.
In addition to these untapped areas, the vast majority of the world’s geothermal energy within drilling reach – which can be up to 5 kilometres – 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 (EGS) – are still in the demonstration stage. The IEA report recommends that governments provide sustained and substantially high research, development and demonstration resources to plan and develop at least 50 EGS pilot plants during the next decade.
With these systems, a well is drilled deep into the ground, typically below 1.5 kilometres. Water is then injected into the well at sufficient pressure so as to create fractures in the rock. Other wells are then drilled to pump up the water, which has been heated by the hot rocks. "If these enhanced geothermal systems are developed further, this will significantly open up global exploitation of geothermal resources," says Ms. Beerepoot.
Incentives, Permits and Databases
Key areas of action for governments identified in the report are establishing targets and economic incentives for mature and nearly mature technologies as well as for advanced technologies that are not yet commercially viable.
They also recommend streamlined and time-effective permit procedures, which are necessary for all new geothermal plants.
In addition, the report stresses that publicly available databases, protocols and tools should be developed, which could be used to assess, access and exploit geothermal resources and thereby accelerate its development. "[This] requires co-operation among geothermal and hydrocarbon industry groupings, national authorities and research institutes," writes Ms. Beerepoot.
The risk of finding insufficient temperatures or flow rates can be addressed by more competitive and advanced drilling technologies as well as advanced resource and assessment technology. Financial instruments such as risk guarantee schemes can also reduce geothermal development costs.
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