The IEA enables innovation through a wide range of international Energy Technology Initiatives, or ETIs1. Through the ETIs, more than 6,000 experts from over 50 countries work together to accelerate advances in energy technologies.
Electricity generation from high-temperature geothermal heat is the only renewable energy source that can provide continuous, base-load power for many years with no fuel costs and with minimal environmental impact. Geothermal steam can be used in district heating networks or for industrial processes, and the lower-temperature heat from the ground can be used for building heating and cooling. Policies and measures to support geothermal include economic incentives such as feed-in tariffs, tax incentives and renewable portfolio standards.
The goal of the Implementing Agreement for the Co-operative Programme on Geothermal Energy Research and Technology (Geothermal IA) is to provide a framework for international co-operation on R&D. Activities include information sharing; developing best practice on the use of technologies and techniques; exploration, development and utilisation of geothermal; and producing and disseminating authoritative analysis and databases. There are currently 15 Contracting Parties, including Iceland and Mexico, as well as five Sponsors.
Geothermal wells are more expensive to drill than oil and gas wells, and these costs increase according to the depth. These costs can represent more than half of the capital cost for a deep geothermal power project. Therefore reducing these costs is a primary focus for the industry.
The goal of one Geothermal IA project, Advanced Geothermal Drilling and Logging Technologies, is to develop a better understanding of these complex processes in order to identify opportunities for reducing these costs.
Geothermal drilling practices for wells destined for direct use (low temperature) and electricity generation (high temperature) require careful planning and design to reduce the time to full exploitation.
Technical challenges due to siting, water or steam quality and composition, and equipment; physical constraints such as the large diameter of the wells; and the unique character of each well, even wells in close proximity, are also important factors to consider. The project also considered indirect costs relating to the need to re‑inject fluids to maintain pressure. Optimal design criteria were established for a number of parameters, including drilling and completion programmes; drilling practices for cost avoidance; problem diagnosis and remediation during slim-hole drilling; trouble avoidance, well testing; geophysical logging; and preserving the wellbore.
Costs and risks of emerging technologies, in particular deep drilling, were explored. Drilling with casing was highlighted as a best practice as it reduces time spent and has been used successfully to drill through unstable formations. Expandable tubes and feedback processes were also examined. The results of the project, including case studies, are compiled in the Handbook of Best Practices for Geothermal Drilling, available free from the Geothermal IA website.
* Photo courtesy of Sandia National Laboratories.
For more information: www.iea-gia.org
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