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Geo-Thermal

Geo-Thermal Energy

Geothermal Energy is heat stored in earth crust and being used for electric generation and also for direct heat application worldwide since beginning of last century. USA, Philippines, Indonesia, Mexico, Italy and Iceland are leading countries availing commercial exploitation with world production 12000 MW [1]. For harnessing Geothermal energy in the country the Ministry of New & Renewable Energy (MNRE) has been supporting R&D on exploration activities and Resource Assessment during last 25 years. This includes formation of expert groups, working group, core group and committees in addition to providing financial support for such projects and for resource assessment. MNRE is targeting for deployment of Geo-thermal capacity of 1000 MWth in the initial phase till 2022. Resource Assessment is being planned in 2016-2017 for public domain.  

The objective of the programme is to assess the potential of geothermal resources in the country and to harness these resources in two distinct categories namely

(i) Power Production

Government of India, Ministry of New and Renewable Energy (MNRE) contemplate major initiative in RDD&D of Geothermal technology for harnessing the geothermal energy in the country for the period 2015-17. Geothermal electricity generation is site and technology specific and India is in Low Geothermal Potential Region with low/medium heat enthalpy [12]. Government is planning to encourage the demonstration projects at the first stage to assess the technical viability of the project before going to the commercial models.

Various resource assessment carried out by GSI, UNDP and NGRI under aegis of CEA,UNDP & MNRE established the potential 10600 MWth /1000MWe spread over 340 hot springs across seven Geothermal provinces/11 states [2][14]. The average rough capital cost on not exceeding basis stands 30 Cr per MW (Rs 12 per KWhr) [18]. As per the international reports a 1 MW Geothermal Power Plant generates about 8.3 Millions Units (MU) per MW per annum [13] compared to Solar 1.6 MU per MW, Wind 1.9 MU per MW and Hydro 3.9 MU per MW [15].

Comparison chart of Geothermal with other RE technologies is provided below

S.No Renewable Resource Cost per MW[15] Avg Units produced Per MWe Per Year[15]   Levellised Tariff Costby CERC 2014[15] Ratio of Capital Cost to the total Generation
1 Geothermal Rs 30.0 Cr[20] 8.3 MU* Rs 12.0 ** Rs 36.1
2 Solar Thermal(with storage) Rs 25.0 Cr 2.01MU Rs 11.8 Rs 124.3
2 Solar PV Rs 6.91 Cr 1.66 MU Rs 9.42 Rs 41.6
3 Wind Rs 6.03 Cr 1.93 MU Rs 5.76 Rs 31.2
4 Hydro Rs 7.35 Cr 3.90 MU Rs 3.80 Rs 18.8

 

*D Chandrasekharam, IIT Mumbai, 9th Biennial International Conference Paper [18]

** As per the submitted report to MNRE byf Dr. A. Absar, Formar Director of Geological Survey of India.

(ii) Ground Source Heat Pumps (GSHP’s)/ Geo-exchange Pumps.

Ground Source Heat Pumps (GSHP’s) use the earth's relatively constant temperature between 16 - 240C [16] at a depth of 20 feet to provide heating, cooling, and hot water for homes and commercial buildings. GSHP harvests heat absorbed at the Earth's surface from solar energy. The temperature in the ground below 6 metres (20 ft) is roughly equal to the mean annual air temperature [17] at that latitude at the surface It uses the earth as a heat source (in the winter) or a heat sink (in the summer). GHP’s is effective in all kind of climate zones or can be deployed anywhere in India on 24 x 7 bases. This Technology is being used worldwide from last 50 Years [3]. According to the reports published in the World Geothermal Congress 2010, the installed capacity of GSHP in the world is 52.7 GWt  up to the year 2013 [4] . More than 3 million GSHP units of capacity 7 kW to 35 kW (24 000 to 120 000 Btu/h) [19] installed worldwide in 43 countries[5].The leading countries using this technology are USA, Sweden, Germany, Switzerland, Canada, Japan and China [6].

Government of India, Ministry of New and Renewable Energy (MNRE) contemplate initiatives in RDD&D of Geothermal technology specifically for the purpose of cooling, drying, space heating, greenhouse cultivation, Industrial processes, Cold Storage, Poultry & Fish Farming, Mushroom Farming, Horticulture etc. MNRE is also working in collaboration with BEE on increasing the efficiency by more than 50% of conventional HVAC system by retrofitting /replacing the cooling towers (Air cooled) by Energy Star qualified Geothermal Heat Pumps [3][7].

The basic principle on which the GSHP works is "refrigeration cycle". The refrigerant carries the heat from one "space" to another [8]. The heat pump's process can be reversed. The earth is the main source and sink of heat. In winters, it provides heat and summers it takes the heat. The common two types of GHPs in use are 1) earth-couple (closed loop) system that uses sealed pipes/tubes-placed vertically or horizontally, through water or a mixer of water and antifreeze circulates transferring heat to and from the earth and 2) water source (open loop) system where water from the underground aquifer pumps water to the heat exchanger[9]. Between the two, earth coupled GHPs are very popular because they are very adoptable. Use of GSHP can bring down substantially consumption of expensive electricity cost which is in the range of Rs 8-10 per unit at present.

Although ambient temperature in India varies drastically from -100C to 500C but temperature beneath the earth remains constant throughout the year on 24 x 7 bases between16 - 24 0C[16]. It uses the earth as a heat source (in the winter) or a heat sink (in the summer) [10]. The earth’s constant temperature maximizes GHP’s COP or EER and remains unaffected with rise in= ambient temperature of surrounding whereas the EER decreases with increasing air ambient temperature in conventional HVAC systems. Commercially available HVAC systems have COP of 3 to 4 while GHPs have greater than 6 [11] and the EER values upto 27 [16].

All stake holders like HVAC Contractors & Suppliers, Food Processing Units Manufactures, Builders & contractors, Cold storage, Green House Manufacturer, Hotel/Restaurants Owners, Industry owners, Social Institutes, Schools Owners are encouraged to come forward for deployment of Geothermal Heat Pumps in India and suitable Demo grant will be provided on case to case basis.

Presentation on Geothermal Energy at RE-Invest

References:

  1. Renewable 2014 Global Status Report
  2. http://www.portal.gsi.gov.in/pls/gsipub/PKG_PTL_STATIC_PAGES.pShowUnpubRepResults_GNRL?inpTheme=1110&inpState=&inpSource=
  3. Comparative Energy Performance between a Geothermal Heat Pump System and an Air-to-Water Heat Pump System for Heating and Cooling in typical conditions of the European Mediterranean Coast
  4. Installed Capacity of Geothermal Heat Pumps to More than Double by 2020,
    http://www.navigantresearch.com/newsroom/installed-capacity-of-geothermal-heat-pumps-will-grow-by-nearly-150-percent-by-2020
  5. http://www.geothermal-energy.org/pdf/IGAstandard/WGC/2010/0007.pdf
    http://dnr.wi.gov/topic/Wells/documents/GeothermalTrendsandEmergingTechnology.pdf,
    http://www.iea.org/publications/freepublications/publication/Geothermal_Essentials.pdf
  6. http://en.wikipedia.org/wiki/Geothermal_heat_pump
  7. http://www.proudgreenhome.com/videos/new-geothermal-technology-boosts-hvac-energy-savings/
  8. https://www.youtube.com/watch?v=QE_rvxzLJcU
  9. https://www.youtube.com/watch?v=uVDBRQvBVso
  10. https://www.youtube.com/watch?v=_oyKhhcTrcs
  11. http://www.scirp.org/journal/PaperDownload.aspx?paperID=29014
  12. http://www.earthscienceindia.info/pdfupload/tech_pdf-1255.pdf
  13. http://www.geothermal-energy.org/pdf/IGAstandard/WGC/2010/3501.pdf
  14. http://mnre.gov.in/file-manager/UserFiles/Geological-Survey-of-India-Atlas.pdf
  15. http://www.cercind.gov.in/2014/orders/SO354.pdf
  16. http://www.imd.gov.in/doc/climate_profile.pdf,
  17. http://www.ogpl.gov.in/catalog/annual-and-seasonal-mean-temperature-india#web_catalog_tabs_block_10
  18. http://www.spgindia.org/spg_2012/spgp530.pdf
  19. http://www.nrcan.gc.ca/sites/oee.nrcan.gc.ca/files/pdf/publications/infosource/pub/home/heating-heat-pump/booklet.pdf
  20. http://costing.irena.org/media/2769/Overview_Renewable-Power-Generation-Costs-in-2012.pdf

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