Geothermal energy plant at The Geysers near Santa Rosa, California, USA (Photo: NREL)
Geothermal energy, or heat from the Earth, is an abundant form of renewable energy that can be used in small or large scale applications. Its exploitation is expanding rapidly throughout the world, proving particularly attractive for countries without easy or affordable access to other forms of energy. A number of IEC TCs (Technical Committees) prepare International Standards for components or systems central to the development of geothermal energy.
The heat is on – everywhere…
Geysers are the most visible and best known naturally occurring form of geothermal energy. These are holes in the ground from which columns of water heated underground to above boiling point by the earth’s heat are ejected violently out of the earth’s surface, together with steam. Much of the hot water is trapped in permeable and porous rocks under a layer of impermeable rock, so forming geothermal reservoirs.
Although these well-known phenomena can be observed in a few places of volcanic activity, such as Iceland (from where the name geyser originates) or in the Yellowstone National Park in the US, geothermal energy is present everywhere. Its potential is being harnessed increasingly in a growing number of countries for a wide range of applications, from heating buildings to producing electricity in power plants, and in CHP (combined heat and power) cogeneration.
Power-hungry industries warming up to renewable energy
Many countries ramp up their electricity production from renewable sources, including from geothermal energy, to cut consumption of fossil fuels and emissions of greenhouse gases.
One country which produces 100% of its electricity from renewable sources, Iceland, sees this resource, provided mainly by hydropower and geothermal energy, as a major asset for enticing energy-intensive industries to relocate plants to the country.
Iceland produces five times more energy than it needs for domestic consumption, according toLandsvirkjun, the country’s national power company. This spare capacity, coupled with low and stable energy tariffs, has attracted industries such as aluminium smelting (where energy, i.e. the cost of electricity, represents between 30% and 40% of production expenses) and metallurgical grade silicon metal production.
Data centres represent another rapidly developing energy-intensive sector and are moving into areas where cheap renewable energy and favourable climatic conditions can be found. Data hosting company Verne Global has set up a data centre in Iceland that uses 100% renewable energy. It claims that environmental cooling and intelligent design result in a reduction in cooling costs of at least 80%.
IEC role
IEC standardization work is essential to the development and correct operation of geothermal energy systems, even if the technologies may not be as well developed as with other renewable energies.
For geothermal heating used in buildings and in other applications, heat pumps play a central role in transferring heat from the soil and pumping it to another area inside the building where it is heated or cooled over a circulating coil system and is then transferred on to provide hot water, heating or cooling (using a heat exchanger). International Standards for heat pumps are prepared by IEC SC (Subcommittee) 61D: Appliances for air-conditioning for household and similar purposes.
Steam turbines are central to electricity generation from geothermal sources. IEC TC (Technical Committee) 5: Steam turbines, created in 1927, prepares International Standards for these (seearticle on steam turbines in this e-tech).
IEC TC 2: Rotating machinery, prepares International Standards with regard to specifications for rotating electrical machines, a category that includes motors and generators. Work from many other IEC TCs and SCs involved in the preparation of International Standards for energy generation, transmission and distribution is also central to the development and proper operation of the geothermal energy power chain, just as it is for other energy sources.
Written by Morand Fachot for our e-tech Magazine. To find out more check out our e-tech article.
