Making Geothermal a Viable Energy Source Around the World
Geothermal energy is a proven “green” energy technology in areas of the world where high temperature hydrothermal sources are close to the earth’s surface, such as Iceland, New Zealand and California.
These resources, however, are scarce and rarely located near centres of major power consumption, limiting their impact on the global power generation need. Some attempts have been made to develop Enhanced Geothermal Systems (EGS) where there are no natural high temperature sources near surface.
These systems are developed by drilling a pair of deep wells (typically more than 5 km deep) into solid, non-porous rock. Hydraulic fractures are created between the wells at depth to create a “heat exchanger” in the rock.
Water is injected into one well and flows through the fractures in the hot rock to create steam, which is then produced through the second well. On surface, the steam is passed through turbines to generate electricity and the effluent can be used for district heating or industrial heating needs before the water is re-injected to become steam again.
The Enhanced Geothermal process has the potential to be developed anywhere in the world, since the earth is hot everywhere if you drill deep enough. The challenge is to overcome high construction costs for the deep wells and to make the rock “heat exchanger” more efficient.
The Enhanced Geothermal process is very similar to, but the reverse of, the SAGD process used in enhanced oil recovery (EOR). In SAGD, steam is injected in one well to heat the rock so that the liquid hydrocarbon can flow into a second well and be produced to surface. For EGS, water is injected into the rock to create steam and the heat created is collected.
C-FER Technologies has helped Alberta companies make significant technological advances to improve the efficiency, reliability and safety of circulating liquids and steam, at depth, through rock for the SAGD process.
These technologies coupled with other oilfield technologies such as multi-zone hydraulic fracturing and horizontal drilling could have a significant impact on the efficiency of Enhanced Geothermal power generation that could make it viable anywhere in the world.
C-FER can help enhanced geothermal operators evaluate technologies that could be utilized in these developments including:
- Advanced drilling techniques to build wells that maximize access to the hot rock;
- High temperature well casing systems to ensure safe, long-term well operation;
- Downhole flow control devices to optimize water injection and steam production;
- Multi-stage hydraulic fracturing to increase well productivity; and
- High temperature, downhole pumping systems to reduce operating costs.