Interest in geothermal energy hotting up!
We’ve all seen the power of volcanoes, felt the warmth of hot springs and learned the earth’s core is hotter than a hot day on Bondi Beach. Energy companies are exploiting this by constructing more and more geothermal energy plants.
What is geothermal energy?
Geothermal energy is the energy which comes from the earth’s core in the form of heat. Made up mostly of molten rock, the core is heated up by the constant natural nuclear reactions taking place. Geothermal electricity involves exploiting this energy to produce a current. Man has been harnessing geothermal energy since Roman times, with the very earliest central heating systems making the most of this power source. Now this principle has been developed to build modern and sustainable power stations.
How geothermal energy works
Most geothermal energy systems are based around the principle of drilling closer to the Earth’s core (sometimes up to several kilometres deep) and pumping down cold water which is then heated by the earth’s core. The steam given off can be used to push turbines around. The most modern of these machines –Binary cycle power plants - do not need steam at all and can push turbines round with fluid at temperatures as low as 57°C. The other two types of geothermal plant – dry steam plants and flash steam power plants – are much less efficient and require the water to be heated to a much higher temperature – between 150°C and 180°C – to be effective.
Advantages of geothermal energy
Geothermal energy is a relatively safe, stable and predictable form of renewable energy. It is better than most other forms of energy generation in several senses; it creates little pollution and requires no fuel. Furthermore, costs are also much less likely to fluctuate compared with those incurred with fossil fuels, although these depend on the abundance of other energy sources.
Disadvantages of geothermal energy
You need three thing for thermal energy:
- Suitable hot rocks
- Hot rocks at suitable depths
- Geology conducive to drilling
Without these three things, the initial building costs make little economic sense. Even suitable areas can, quite literally run out of steam for periods. Concerns surround the potential release of harmful acid-rain causing gases such as carbon dioxide and ammonia. Finally, there is a suggestion that earthquakes increase in areas where geothermal energy plants are sited, although there is little scientific evidence to support this.
Geothermal energy in Australia
Throughout much of its recent history, the Australian government has shown little interest in geothermal energy, a position echoed by many Australian companies. However, recent interest has grown, and researchers are now actively searching for the ‘hot rocks’ which could be used to generate electricity. South Australia has been described as Australia’s ‘rock haven’ and parts of Central Tasmania are estimated to have the capacity to produce up to 280MW of power.
Geothermal energy around the World
The International Geothermal Association reports 10,715MW of geothermal in 24 countries is online. The leading producer worldwide is the USA, with the largest plant situated in California. Other leading producers include the Philippines, Indonesia and Mexico.
Leading geothermal companies include Calpine, Ormat technologies, Ram power and Magma energy.
Future of geothermal energy
With many countries, including Australia, researching and building geothermal energy facilities the future is hotting up for those interested in this technology. Most interestingly, France and Germany are currently investigating the viability of tunnelling several miles into the ground to extract the maximum possible energy from sites.
Geothermal energy will become more important over coming years, but its usage will undoubtedly cause increased concern regarding its environmental and ecological impact. Governments and companies will need to bear these considerations in mind before continuing with such projects.
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