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Key advantages of Enhanced Geothermal Systems
What are the advantages of EGS technology?
Conventional geothermal applications, except for geothermal heat pumps, rely on the geological coincidence of water-bearing, hot permeable rocks occurring at economically accessible depths. This is a comparatively uncommon situation, and constrains the usable resource because it is site-specific and distributed unevenly among countries. The Hot Dry Rock (HDR) / Enhanced Geothermal Systems (EGS) concept aims to utilise the vast amount of heat stored in the Earth's crust which is not accessible by conventional geothermal technology. Hot Dry Rock comprises a huge amount of useful heat stored in rocks that are technically accessible but lack the natural permeability necessary for heat extraction. Moreover, such heat stores are much more widely distributed and so offer a geothermal potential to many countries where conventional resources are absent. Even in those areas where good conventional geothermal resources exist, there is usually a much greater volume of heated rock than can be exploited with current techniques. The importance of this ‘potential’ resource can be judged by noting that cooling one cubic kilometre of rock (which is about the scale of a geothermal reservoir) by 1°C will provide the energy equivalent of 70 000 tonnes of coal.
The U.S. Geological Survey has calculated that the heat energy in the upper 10 kilometers of the earth’s crust in the U.S. is equal to over 600 000 times the country’s annual non-transportation energy consumption. It is likely that no more than a tiny fraction of this energy could ever be extracted economically. However, just one hundredth of 1% of the total is equal to half the country’s current non-transportation energy needs for more than a century, with only a fraction of the pollution from fossil-fuelled energy sources. Experts estimate that up to 6 GWe in the U.S. and 72 GWe world-wide could be produced with current (i.e. conventional geothermal) technology at known hydrothermal sites. With enhanced technology, these estimates increase to 19 GWe and 138 GWe.
What specifically does it offer the EU?
The EU's long-term objective is to ensure a sustainable energy supply based on Renewable Energy Sources (RES). EGS could contribute significantly to total EU energy supply and may be easily integrated into existing electricity infrastructures in most European countries. EGS would offer a clean and secure energy supply: