Prof D Chandrasekharam

Coal, formed from organic matter, is a reservoir for significant quantities of  gases.  Methane is an important gas since it supports economic development of a country next to oil and natural gas. In fact, methane is considered as a hazard by the coal miners since it catches fire in the mines causing damage to life and property, disturbs the mining activity and reduces the economy of the mining operation.  Methane that is freely ejected in the coal mines, during and after the mining activity, is called coal mine methane (CMM). Underground coal fires that are common around the world is caused by this gas. Methane as such is a GHG that is harmful to the atmosphere and is 21 times more potent than CO₂! If this same methane is captured and stored, then it becomes  a tremendous energy source. This has been realized over the last few decades and technology is available now to extract methane from underground coal formations/beds. With declining oil resources, countries are frantically looking for other sources of energy to substitute oil. Methane is also generated from animal dung. The gas generated from the later escapes to the atmosphere while the methane trapped in the coal can be extracted and used for generating electric power with out polluting the atmosphere. What it means to a common man is, where ever there is coal there will be CBM. It is true!.  Major coal reserves occur inUSA,Australia,Indonesia,Russia,China andIndia.

 Until 2006 Chinawas using 1.4 billion cubic meters of CBM ( about 3 % of natural gas consumption) and is targeting an output of 10 billion cubic metric meters by the year 2015! CBM is one of the major thrust area projects in China’s current five year plan.USA has already extracting CBM and the maximum up tapped resources lie inAlaska(30 trillion cubic meters ??). Australiais second in the CBM production list fooled byChinaandIndia.Russiahas the maximum CBM resource, estimated to be of the order of 80 trillion cubic meters!

 It is not possible to extract to entire methane available in the coal formations. This very similar to oil exploitation. Complete extraction means, a few more households can be supported and a few more industries can be supported! Off late scientists and technologists are trying to take duel advantage in extracting CBM through pumping CO₂ into the coal beds. This way large amount of methane can be extracted from coal beds and at the same time, CO₂ that is harmful to the environment, can be stored in these coal beds. The CO₂ pumped into the coal beds will flush the methane by squeezing the pores filled with methane.  As said above, the advantage of this method is while extracting methane, CO₂ can be sequestered  in to the coal beds. This is one way of protecting the atmosphere and control global warming.

Methane commonly occurs in coal as a) adsorbed gas in the micropores, b) adsorbed into the molecular structure of coal, c) as free gas in the voids, cleats and fractures and d) also as dissolved gas in groundwater occurring in the coal beds.  CO₂ and coal have strong affinity! CO₂ can enter the finest pores in coal and get firmly adsorbed. When adsorbed, it releases methane from the coal beds. Coal can adsorb more CO₂ than methane and CO₂ is preferentially adsorbed onto the coal structure than methane, generally in the ratio of 2:1. But this ratio varies depending on the rank of the coal i.e. on the organic matter and mineral content, i.e. vitrinite, of coal. Published results on the maceral-CO₂ adsorption content show that telecollinite, a type of maceral has a suitable structure to adsorb maximum amount of CO₂. Pressure also plays an important role in CO₂ adsorption in coal.  Experimental results reported in the literature on coal-methane-CO₂ adsorption properties show that the CO₂/methane ratio is more at 20 bars than at 27 bars.  Adsorption is more under supercritical condition ( about 100 bars and 30 °C).

 While adsorption is the main mechanism of  methane retention by coal,  both adsorption and absorption are the main mechanism of CO₂ retention by coal.  Perhaps absorption of  CO₂ into the organic structure makes the coal to swell like phlogopite mica thereby changing the structural properties of coal. CO₂ ( 3.87Ã…) has a smaller molecular diameter than methane (4.09Ã…). This mechanism squeezes the methane out of coal. Many adsorption models involving adsorption of methane and CO₂ on coal do not consider this aspect.

 Methane is the cause for underground coal fires. The coal seams keep burning for years and controlling such fires is still a technological challenge. But in one way such fires are blessing in disguise as they provide a continuous heat source that can be utilised beneficially.

 For example, several coal seams in Raniganj, Jharkhand and Biharare burning underground. Coal mine fires are due to primary combustion (of methane) when oxygen and water are introduced through cracks and unsealed shafts. These coal fires continue through several years.  Most underground coal fires exhibit smouldering combustion and may only involve relatively small amounts of coal capable of burning in the presence of small amount (2%) of oxygen.  To give an example of the magnitude of this hazard, in USAthere are nearly 600 coal mine fires burning over a period of 80 years. Other under ground coal mines that are burning is located in Russiaand in several east European countries.  These fires are located at shallow depth and the depth in many cased do not go beyond 400-500 m.  Till now this heat energy available is not put to use. Heat exchanger technology commonly used in geothermal power generation can easily be adopted in regions where under ground coal mine fire is common and perennial.  Continuous heat source from burning coal seams underground will provide continuous electric supply. This method controls underground coal fires, controls CO₂ emission and generate electric power to million rural homes. We have the know how and need will power to implement it!! 

Extracting CBM by CO₂ injection into coal formations has several advantages and has the best solution to mitigate global warming!!

While pumping CO₂ in to coal formations needs technological breakthrough, capturing CO₂ is also a  “technology intense” process. Thus Carbon capture and storage (CCS) has attracted world wide attention during the last few decades as a major option to reduce carbon dioxide emissions.  Research in this field is being carried out by several countries and the technology is at various levels of development and in some they are in demonstration phase.  During the 2008Hokkaido summit, the G8 countries endorsed the recommendations by the International Energy Agency (IEA) that large scale demonstration projects in widely varied industrial sector settings need to be carried out by 2010. The aim of this exercise is to understand the uncertainties related cost, reliability and technologies related CCS.  

 It takes millions of years for oil, gas, coal and other natural resources to accumulate/form. It is a natural geological process that no one can duplicate.  One may be able to do it at a laboratory scale. For example, we may be able to produce oil, gas or coal in a laboratory over a few tens of year. But is it possible to produce billion barrels of oils by such laboratory process and supply the world.  This is one of the items in a wish list of humans. The present situation demands that large volumes of CO₂ need to be pumped in to geological formations within a short period of time so that the Earth’s atmosphere can be saved and several species on earth can be protected.  One has to wait and observe how far this can be achieved by the current and future technologies!

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.

“Green Building” seams to be back in the news with a media report recently show casing a green building, eco-friendly building, that reduces coal based electric power consumption. Lower energy consumption and cost savings upto  55 % . The design of the building is based on solar water heaters, solar PV for out door lighting, water conservation methods ( wastewater treatment and recycling of water) and recharge of aquifers, lead free tiles and lead free paint, using smoke-less chullahs etc. etc. These homes are designed by eight well thought materials that is supposed to give the consumer savings upto 55 % in utility bills. However, the response to such buildings, as per the media reports, from the builders and customers seam to be poor. The reason- cost and payback period.  On the lighter side…. One can not expect urban women to use smoke less chullahs in the kitchen!!! On paper these designs look good and give very attractive numbers. But the customer and the builders know the inner details of such buildings and the cost and the demand. These data and designs are good for a research paper or an article in a design magazine,
or can be experimented with in rural and remote inaccessible areas , where lighting two bulbs itself a matter of privilege. For a more holistic view the designers and builders have to learn a lot from Chinese and the European builders where cost and energy savings that in turn reduces CO₂ emission. 

A four member, upper middle class family needs minimum of 500 kWh of electric power per month to have a comfortable living. This is without the luxury of having air-conditioning, microwave and limited use of Geyser system,. This will meet the bear minimum for the family. Extending this to a housing complex with 50 apartments, the minimum electric power requirement will be of the order of 40 kWe ( assuming the electric supply is from coal based power plants). Installing solar PV system over such housing complex is feasible but the cost of unit of power will be prohibitive (~ 37 US cents). Even with subsidies, the unit cost ( ~24 US cents) can not be brought down to  single digit!! The area required to generate such power based on solar PV will be about 3000 sq.ft ( assuming a PLF of 0.18 but this is not so always and the average PLF can be about 0.08).  Of course at least 10 invertors are required. Any surge of power will trip the system. The buildings will not have air conditioning system……..that was considered a luxury a decade ago but it has become necessity now with the amount of dust particles floating in any major urban city and radiation from the buildings ( green cover is fading away!!.

 Clean Development Mechanism is an excellent instrument for India to raise above all the non-OECD countries in reducing  carbon emissions, earning carbon credits, improving the environmental and GDP growth in the next two decade provided it uses energy source mix and exploits its geothermal potential to its maximum. In order to exploit the potential barriers that obstruct the development of this energy source should be overcome and create or improve policies on sustainable renewable energies like those adopted by other countries like China. 

 According to a paper presented at the World Geothermal Congress 2010, held in Bali, geothermal energy should be integrated in the development plans, and decisions should not be taken exclusively from a purely market point of view. The national authorities will have to take advantage of the benefits of CDM and focus should be on two domestic targets: 1) Preparation of a plan for an extensive coordination of the national electricity markets and to develop regional wholesale electricity markets. This limits the negative impacts of uncertainties, both, with respect to the markets and to technological performance; 2) Internalize the social costs of the so-called negative externalities of energy production. One way to do this is to impose fine for the activities that contribute to air pollution (this is being implemented in several countries as “carbon tax). Then social advantage of “clean energy” thus becomes visible. But this is easier said than done in countries like India where the polluters are often the large industries that play an important role in the economic growth of the country as well as holding control over major policy related to energy in the country. Political will and determination to induct modern technological innovation for the socio-economic growth of the country is very essential to make countries like India to be at the top of non-OECD countries.

 Green building can be built by utilizing earth’s internal heat through geothermal heat pumps for space heating and cooling. Instead of installing solar heaters for hot waters, solar PV for lighting, using chullahs for cooking, installing biogas plants in the buildings, avoiding lead tiles and paints in the buildings, straight away 33% of electric power from coal power can be offset through geothermal. Cost is comparable to coal based electric power and urban elite can enjoy their comfort and still save carbon dioxide emissions and help the country to earn CER amounting to several millions of euros (World Geothermal Congress, 2010). Carbon trade with OECD countries can be avoided.

 GHP Systems can be bought off the shelf and there is sufficient knowledge base available in the country. Perhaps the NGO who showcased the green building should have known the existence of such systems in the world. We should provide what is feasible and adoptable easily to the consumer rather than suggesting high end solutions to the builders. Leave the wastewater treatment systems to central agencies. Maintaining such systems will add to the cost of the utility bills. When an easy alternate system that can create a green building without compromising comforts and routine is available why go for systems that needs time and energy of the urban residents during the week ends!

 Space cooling and heating on an average consumes 33 % of coal based power. Similarly additional 13% can be save from food sector (refrigeration). By adopting geothermal based green building, straight away 33% of coal based power usage can be offset thereby reducing CO₂ emission by about 234 billion kg (World Geothermal Congress, 2010).

The Myanmar earthquake of magnitude 6.8 (USGS) that occurred near Kengtung, on 24 March 2011 at 13.55 UTC (7.25 pm IST), was a major earthquake of recent times in this region. The depth of focus reported was 10 km. According to the Chinese seismological observatory, the magnitude of the earthquake was 7.0 with the focus located at a depth of 20 km. The epicenter is located within Myanmar near the boundary of the three countries- Thailand, Vietnam and Myanmar.

 

The Seimological office in Myanmar recorded more than 6 after shocks of M5.0 and over 60 aftershocks of M<5. A major threat was to Srinagarind dam located in Thailand boardering Myanmar. However the dam was not affected.

 The earthquake resulted due to left-strike-slip movement of the Indian and Sunda plate along the Sagaing fault, a major N-S fault with a slip rate of 18mm/y. The Sagaing fault is a very active fault that hosted several earthquakes in the past including the 6.9 magnitude earthquake of February 1991.  The movement of the Indan plate with respect to the Sunda plate is about 45mm/y. The Sagaing faults continues south and transform into a series of transform faults in the Andaman Ses, east of the Narcondam and Barrend island volcanoes and joins ultimately the Sumatra fault. It is interesting to note that this fault was a loci of five major volcanic activity. Extint volcanic cones lies along the fault.

 Kengtung city was worst affected and a hospital in Tarlay was damaged. Over all deaths reported was 65 and 111 were injured.  390 houses were damaged, 14 monasteries and 9 gov. buildings were destroyed. 

The Chinese border (Yunan province) lies about 80 km from the epicenter. According to a local report from China and Myanmar, nearly 6500 people were affected in Yunan provinces by this earthquake.

The 8.9 magnitude Honshu earthquake of March 11, 2011,   occurred due to thrust faulting within the Japan trench. The tectonic configuration of Japan and its surroundings is very complex with 4 plates meeting just below Japanese islands. The islands lie over four plates: the Pacific, North American, Eurasian and Philippine sea plates. The Pacific plate  subducts into the Eurasian plate, the junction of these two plates lie just beneath Hokkaido and Honshu. This is the main Japanese trench and the rate of subduction of the Pacific plate is about 83 mm/year. The length of the Pacific plate is about 2000 km. Thus the geological and tectonic settings of the Japanese islands is very complex and at any given point of time one of these four plates move/thrust giving rise to major earthquakes. The depth of focus of the earthquakes varies from 700 km to 25 km or less.  The eastern margin of the Japanese islands, along the subduction zones is the loci of several active volcanoes.  The 1400 m high Shinmoedake volcano, located over this foci in Kagoshima Prefecture, Kyushu (southwest Japan) has become active after the Honshu earthquake throwing ash and rocks to a height of 4  km.

Earthquakes of this magnitude is not uncommon in and around Honshu. This is not a rare event that occurred at this site.  Over nine earthquake of magnitude >7 occurred in this area since 1973.  An earthquake of magnitude 7.8 struck in an area 260 km north of the 3/11 earthquake in the year 1994. This earthquake caused injuries to 700 people.  Similarly in 1978, an earthquake of magnitude 7.7 struck 35 km south west of the current 3/11 event. This caused injuries to 400 people. Besides this, 8.4 magnitude earthquake of Sanriku in 1933, 8.3 magnitude earthquake of Tokachi in 2003 are note worthy earthquakes in this region. All these earthquakes occurred due to thrust faulting below the Japanese Islands.  Between 9^th March and 11^th  March, 2011, Honshu experienced several foreshocks of magnitudes of  7.2 to 4.2. before the 3/11 earthquake. The main shock was followed by > 100 aftershocks and the after shocks are still rocking the region.

We have  witnessed two devastating earthquakes of magnitudes 9.1 ( Sumatra)  in 2004 and the recent 8.9 magnitude earthquake of Honshu accompanied by tsunamis. The Honshu tsunami occurred even before Sumatra tsunami faded out of our memory. The Sumatra earthquake occurred due to thrust faulting, similar to the one occurred in Honshu, where 1600 km long ocean plate fractured with a slip of 15 mts. The land near Banda Ache was lifted to a height of about 30 m. The tsunami generated due to this major event caused over 250000 deaths in Indonesia, Sri Lanka and India and causing dislocation of population in several coastal regions bordering the Indian Ocean. In the case of Honshu earthquake, the lateral shfit currently estimated is about 8 m. More data on the slip amount is being calculated. Both the earthquakes are shallow with the focus depth placed between 25-30 km. But the dimension of Sumatra earthquake and tsunami is larger by several factors compared to the Honshu earthquake. The Sumatra tsunami could travel 3500  km from the source caused devastating damage. A similar features was expected from Hnashu tsunami but the energy of the waves attenuated even before they could reach the nearby islands. The wave height measured at Hawaii islands, located at a distance of 6300 km from the epicenter was about 0.7 m.  

Majority of the earthquakes over Honshu occurred due to slip at shallow levels. The buildings in Japan are built strictly according to the codes. This is the reason one could see pictures in the television where tall structures in Tokyo were swinging at the time of the earthquake and returned to its normal poison. The death toll due to  earthquake in Sendai is far less compared to that due to the tsunami. We have to learn a lot from the Japanese civil engineers about making tall earthquake resistant structures. We do have codes on papers. Only an earthquake of magnitude half of that of Honshu will be able to prove how strong these structures are!!

The recent events all along the Pacific rim only demonstrates the dynamic changes that are taking place within the internal Earth system. We have a long way to go to  understand the dynamics of this system. Earth Sciences need to be given priority at school level itself, like other countries, to generate state-of-art younger generation of earth scientists to tackle such natural disasters in future. As far as Indian coast is concerned, the east coast is more vulnerable to tsunami related disasters as the coast is in line of sight of the grate Andaman-Nicobar-Sumatra – Sunda arc system. The west coast is not facing such arc system and hence chances of tsunami related disasters occurring are minimum. Only normal faulting, as evident from several earlier faults events, is a cause of concern, both on shore and off shore of the west coast, as reported in 1985 based on an integrated geophysical and geological analysis.