Prof D Chandrasekharam

International Energy Agency (IEA), located in Vienna, has clear objectives of  1) securing member countries with ample supply of all forms of energy in case of oil supply disruptions; 2) promoting sustainable energy policies that support country’s economic growth and protect the environment; 3) support collaboration between countries on matters related energy technology, future energy supply, protection of environment through developing advanced low carbon technology; 4) improve methods to conserve energy and improve energy efficiency and 5) evolve solutions to mitigate global energy challenges through dialogues with member and non member countries and industries and international organizations.  These advantages are enjoyed by all the member countries that include Australia, Austria, Belgium,Canada,Czech Republic, Denmark, Finland, France, France, Germany,Greece, Hungary, Ireland, Italy, Japan, Republic of Korea, Luxemberg, theNetherlands,New Zealand, Norway, Poland, Portugal, SlovakRepublic, Spain,Sweden, Switzerland, Turkey, U.K., USA. The European commission participates in all IEA’s deliberations.

In the Foreword note of the recently released IEA’s “ Technology Roadmap: Geothermal Heat and Power”,  Nobuo Tanaka, Executive Director, stated “ Without decisive action, energy related emissions of CO₂ will more than double by 2050 and increased oil demand will heighten concerns over the security of supplies. We must and can change our current path; we must initiate an energy revolution in which low carbon energy technologies play a leading role……Emerging geothermal technologies that extract energy from the hot rock resources found everywhere in the world hold much promise for expanding the production of geothermal power and heat” The road map brought out by IEA after several rounds of workshops and meeting across the continents clearly envisions geothermal energy as the main energy sources by 2050.  By this year, according to the road map, by 2050 geothermal electricity generation could reach 1400 TWh/y amounting to 3.5% of global electricity generation and geothermal heat could contribute 5.8 EJ /y by 2050.

Recognizing the need to ‘accelerate the development technologies to provide clean and sustainable energy and mitigate climate change through reduced carbon dioxide emissions’, G8 countries, China, India and South Korea, in 2008, expressed desire that IEA comes out with a road map with the above aim.

The heat from the Earth’s interior to the surface is continuous and constant. Thus heat convection/conduction is in operation since 4.5 billion years and will continue for millions of years, similar to the heat radiated from the Sun. Considering this time scale, this energy is renewable as for as life on Earth is concerned.  Hydrothermal circulations utilizes this heat through established convective systems while EGS utilizes induced convection technology using water or carbon dioxide to extract the heat.  Literally energy can be extracted at any point at any given time on Earth.  The title “The future Beneath our feet”,   a green energy documentary by the British council telecasted on WE day is quite appropriate in this context. But then one should know how to go about it.  Whether it is electricity or heat, many science and engineering disciplines and techniques are needed  especially for resources assessment, reserves assessment, and means to access this source (s). This expertise is not any body’s cup of tea and demands deep knowledge of geology & geophysics and teamwork.

With in couple of years, EGS will be perfected and countries should be in a position to utilize this source to offset carbon dioxide and black carbon emissions. EGS with GHP will reduce substantial dependence on imported oil and coal energy sources. Developing countries will benefit immensely.  By this time, low enthalpy resources will play a major role in energy sector. According to IEA analysis the cost of a unit electric power from EGS will be much lower relative to other renewables and this comes with CO₂ and BC discounts!! This is value addition and further reduces the unit cost. According to IEA “ ETP 2010 puts geothermal energy in competition with all other zero or low carbon technologies to delineate the economically optimal energy mix leading to specified global energy related CO₂ levels by 2050. The ETP 2010 BLUE Map scenario describes how energy economy may be transformed by 2050 to achieve the global goal of reducing annual CO₂ emissions to half that of 2005 level”.

Countries across the world have already implementing methods to make EGS the future energy source.  For example, DOE US believes that EGS has enormous potential and the present Govt. has  requested a large chunk of funds from US Department of Energy to support Geothermal.  Europe, realizing the potential of geothermal is planning to revise the tariff structure. According to the German Renewable Energy Federation, by the year 2020 Germany will have new geothermal power plants and escalate the power production to 625 MWe. This will be twice the amount currently being generated.

In China, geothermal is expected to reach about 69 million tons of standard coal equivalent ( ~ 560 000 GWh) by 2015 accounting for 1.7 % in the country’s overall energy consumption. The amount of utilizable shallow geothermal energy resources is equivalent to 350 million tons of standard coal annually ( that could generate ~ 3 million GWh). This could offset mining 250 million tons of standard coal and 500 million tons of carbon dioxide.

A recent publication, “The Future of Geothermal Energy – Impact of Enhanced Geothermal Systems (EGS) on the United States in the 21th Century“, determined a large potential for the USA recoverable resources > 200,000 EJ, corresponding to 2,000 times the annual primary energy demand. An EGS power generation capacity of >100,000 MWe could be established by the year 2050 with an investment volume of 0.8 – 1 billion USD. The report presents marketable electricity prices, based on economic models that need to be substantiated by EGS realizations. Since the temperature increases with depth is everywhere, in future EGS could generate electric power in our backyard. Initial hiccups will be there for any projects- whether it is oil exploration, space exploration, submarine exploration. Such hiccups provide large data for perfecting the technology. EGS is no exception. The technology is being perfected with the commissioning of 1.5 MWe pilot EGS power plant in Francefollowed by the CooperBasinproject in Australia. EGS plants, once operational, can be expected to have great environmental benefits (negligible CO2 emissions). A recent paper presented at the World Geothermal Congress 2010, Bali, Indonesia, states that India’s EGS resources is equivalent to 3.133 x 10²² BTU. Some environmental issues like the chance of triggering major earthquakes is unfounded. There is an ongoing media hype about earthquakes possibly being induced by EGS projects. One of the leading American Geothermal Company believes “fears to appear overblown”. Curt Robinson, Executive Director, Geothermal Resources Council says “ I won’t make light of seismicity, but tornadoes are a greater threat than these micro-seismic events,” Concerns about earthquakes are realistic, but from a public hazard point of view, the earthquakes should not be a big concern since the magnitude will be around 2 to 2.5 says United States Geological Survey geologists. Human being will never feel such low magnitude earthquake even while stationary. Such small magnitude earthquakes will occur only during well stimulation period ( which will be about 2 weeks) that creates fractures for easy flow of the injected water.