Through a combination of actions that encourage the development of untapped geothermal resources and new technologies, geothermal energy could account for around 3.5% of annual global electricity production by 2050 (a considerable increase from current levels of 0.3%) the International Energy Agency (IEA) says in a report released on Tuesday.
The report, titled “Technology Roadmap: Geothermal heat and power,” is the latest in the IEA’s series of technology guides, which provide parameters for government and industry on actions and milestones needed to achieve cleaner energy technologies. Previous reports have profiled nuclear power, carbon capture and storage technologies, and smart grids.
The IEA says that for more than a century, efforts to harvest geothermal energy have been centered on areas with naturally occurring heated water or steam, found often in volcanic areas. But a large share of “low hanging fruit” remains unexploited in developing and emerging economies, the IEA says, suggesting that efforts should be expanded to solve economic and non-economic barriers that hinder further exploitation in these countries.
Geothermal energy can also be extracted from many deep aquifer systems, of which there are many all over the world, the IEA says. These resources can typically be reached at a depth of 3 kilometers and produce temperatures in excess of 60C. Use of these aquifers is expected to grow quickly, reflecting their wide availability and increasing interest in their use for both heat and power.
In addition to these untapped areas, 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. Technologies that allow energy to be tapped from hot rock resources—including enhanced geothermal systems (EGS)—are still in the demonstration stage. But governments should provide sustained and substantially high research, development and demonstration resources to plan and develop at least 50 EGS pilot plants during the next decade, the IEA says.
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 pump up the water, which has been heated by the hot rocks.
Key areas of action for governments identified in the report are the establishment of targets and economic incentive schemes for mature and nearly mature technologies as well as for advanced technologies that are not yet commercially viable. Another proposed area of action outlined in the report focuses on the need for 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 their development.
“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,” the IEA says. “Financial instruments such as risk guarantee schemes can also reduce geothermal development costs.”
Sources: POWERnews, IEA