Geothermal Energy Set to Increase Market Share
With fossil fuel prices well above historical average, geothermal energy is likely to increase substantially its share of the energy mix, according to Oxford Analytica.
Geothermal energy can be used to produce electricity, to provide heat and hot water for direct applications and indirectly by using geothermal heat pumps. Unlike wind and solar photovoltaic (PV), geothermal electricity is base load — ie, it is available 24 hours a day, 365 days a year with capacity factors often above 90% .
The world geothermal potential from conventional geothermal sources has been estimated at 70 gigawatts (GW). If engineered geothermal systems (EGS) technology becomes technically viable — a process where water is pumped to extreme depths to produce steam — geothermal energy potential could double to 140 GW. A recent Massachusetts Institute of Technology (MIT) study suggests an even higher world EGS potential. It found that EGS could supply the United States alone with 100 GW of electricity within 50 years.
As with all renewable energy sources, interest in geothermal development has increased with rising fossil fuel prices and global warming concerns. For example, the US Geothermal Energy Association reports that current US geothermal development projects are scheduled to more than double US geothermal electricity capacity in the next few years. In Germany over 100 areas are being explored for their geothermal potential.
Other countries are also increasing their geothermal capacity. In Xianyang, Shaanxi province, a Chinese and Icelandic partnership is replacing coal fired heating with a geothermal district heating system, which has the potential to become the biggest such system in the world.
In many cases geothermal proves to be very competitive with other sources of energy, especially if renewable energy incentives are available. Recent cost experience has shown that costs for geothermal electricity production typically range from 4.5 to 7.3 cents per kilowatt-hour (kWh).
Currently, geothermal development is restricted to areas where natural hydrothermal systems are available for utilisation. Such systems are mainly located along the Pacific Ring of Fire, along the Atlantic Ridge, in the African Rift Valley and in isolated places of high heat flows. Advances in technology in recent decades have enabled the production of electricity with lower temperature resources using binary technology. This has increased the feasible area for conventional geothermal energy production in countries such as Germany that before were not viable for geothermal electricity production but are now building geothermal plants.
If EGS becomes technically viable, geothermal energy could be harnessed everywhere in the world and no longer be limited to a few selected areas. The main technical barriers to EGS are increasing flow rates and sustaining high heat flows within the engineered reservoir for sustained periods of time. Work to overcome these barriers is being conducted in both Europe and the United States. Australia is at the forefront of these efforts with multiple private firms with millions invested in EGS development.
Conventional geothermal systems are utilised worldwide but rising drilling costs are affecting geothermal economic viability. For EGS development, the next few years will be critical in deciding whether the added influx of interest and investment will be enough to prove the EGS concept, lower costs and thus make geothermal electricity available worldwide.
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