According to a recent paper published in Energy Policy reports that a biomass resource model developed by a UK-based school shows “that indigenous biomass resources and energy crops could service up to 44% of UK energy demand by 2050 without impacting food systems”. It is not clear whether this model accounts for the black carbon emitted by biomass fuel and its impact on the climate. BBGs are intimately related! One is a source of energy and the other is a source of global warming!! Over centuries, civilizations used firewood, biomass, and dung cake to sustain lives. For both cooking and heating purposes, this was and is the cheap and easily available stock to humans.
Excess use of any such energy sources is harmful and the consequences are being felt by the current generation.
In the current industrial era, besides the above fuels, fossil fuels like coal, diesel, and kerosene enhanced the black carbon (BC) content in the atmosphere further to our misery!! Changing weather patterns, fast retreating glaciers, droughts, flash and summer floods are the consequences of such uncontrolled BC emissions. Carbon dioxide also plays a major role but CO2 has a long-term effect while BC has a short-term effect. Coal, fuelwood, dung cake, and agricultural waste are consumed maximum in that order in India.
According to 1996-2001 data, 286 Mt (million) of coal, 302 Mt of fuelwood, 121 Mt of dung cake, and 116 Mt of agricultural waste were consumed in India. The consumption of these fuels has increased by several folds due to an increase in population and hence demand. BC emissions factor of these fuels in that order is ~ 0.8, 1.1, 4.4, and 1.3 g/kg. BC absorbs sunlight turning it into heat. Thus, a layer of BC in the atmosphere, while emitting a third of this absorbed heat back into space, keeps the earth’s surface warm. More BC in the atmosphere means more heat over the surface of the earth.
As the BC increases the earth’s surface gets hotter and hotter!! Simple logic. Thus BC causes a change in the heat input at the top of the atmosphere. This is known as “Radiative Forcing (RF)”.
According to the Intergovernmental Panel on Climate Change (IPCC) 2007 report, RF of BC is of the order of + 0.34 W/m2 while forcing of CO2 is of the order of + 1.66 W/m2 . What is Black Carbon?? The black soot, that all of us observe in our daily life, is known as black carbon (BC). BC forms due to the combustion of carbon-based fuels at high temperatures. Thus the sources of BC are fossil fuels (coal, oil, gas), biomass, agricultural waste, dung, etc.
The life of BC in the atmosphere is about a week, while CO2 lingers for several decades. Both BC and CO2 have a tremendous effect on global warming and glacier retreat. BC has strong light-absorbing property. Thus short-term control of global warming can be accomplished by controlling the BC emissions. If BC emissions is controlled then half our problems related to global warming are solved!! In developing countries like India and Africa, BC emissions emerge mainly from the rural sector while the transport sector is the main source of BC emissions in the developed countries. A high per cent of biomass and dung is used in rural regions for cooking, space heating, and consumption of such fuels is high during winters. According to a paper published in “Atmospheric Environment” in 2002, the BC (India) emissions of dung cake is 0.25 g/kg and that of crop waste is 0.47 g/kg. Another paper that appeared in the same journal in 2005 reported BC emissions of dung cake from 2.2 to 6.6 g/kg and that of agricultural waste from 0.2 to 2.4 g/kg!! The value reported by the same author also varies with time!! Perhaps such discrepancies may be related to the betterment of analytical techniques and demographic data.
Such uncertainties are (E.g. see Jr. Geophy. Res., 2004) due to extrapolation of data such as population, per capita consumption (varies by a factor of 3!), economic data, etc., and also due to over prediction of fuel-use measurements!!. Irrespective of these numbers, the truth is, India, next to China, is the leader in BC emissions!. The total BC emissions by India ( 2000 base value) as reported earlier, was 600 Gg (Jr. Geophy. Res., 2003, v,108) while in 2008 this value has changed to 1343 Gg (Geophy. Res. Lett., 2008, v. 35)!!. Thus one gets two values for per capita emissions of BC in India. One at 600 g and the second, just double this value!! It is safe to take the minimum value for all discussions. In India, maximum BC emissions is from rural areas like Leh. Leh is located at an altitude of 4500 m in the Himalayas (in Ladakh province of J & K), where the temperatures fall 15 degrees C below zero in winters. The combustion rate of all fuels is low at this elevation. Dung cake, biomass, and coal are extensively used to heat the homes and of course for cooking also. Guesthouses, the army, and affluent society use cooking gas or “Bukhari”, a device that uses kerosene ( or sometimes sawdust) to heat rooms and homes. CO, CO2, and BC are ejected out into space through an exhaust pipe. The army establishments extensively use diesel. They are located near Leh, Kargil, and other locations along the Himalayan border. The population of Leh is ~ 68,000 and with the reported per capita, BC emissions of 600 g (2000) Leh alone is contributing a minimum of about 0.04 Gg of BC annually. Similarly, Kargil with a population of 119,307 is contributing about 0.07Gg of BC to the atmosphere around the glaciers. Similar emissions figures can be assumed from other towns located at that altitude all along the higher Himalayas, extending from NW to E of India. The BC emissions from the foothill Himalayas also reaches higher altitudes.
During winter (where BC emissions are maximum) snow brings down all the BC floating in the atmosphere. This is the reason why many Himalayan glaciers appear black. It is easy to estimate the BC content in ice. Since it is possible to date ice, BC content in the atmosphere in the past can be estimated. The Gangotri glacier is retreating at a rate of 18 m/yr. This is alarming and this observation is not disputed. The real “component” that is responsible for this retreat is BC. Simulation studies conducted by Lawrence Berkeley National Laboratory in Feb 2010 showed that the major contributor (~90%) to the fast melting of glaciers is BC. How does this happen? BC deposition on a white surface like snow and ice absorbs more light and becomes warmer faster than pure ice/snow and thus enhances the melting process. If one visits the Gangotri glacier, a major part of the ice body appears dirty (black) because of small BC particles in it. BC content in ice cores recovered from ERG glacier is about 20 μg/kg. while the global average BC content in the snow is about 5 μg/kg. This is alarmingly high!! 15 μg/kg of BC in snow reduces about 1% of its albedo. This is a clear indication that the 18m/year retrieval of the Gangotri glacier is due to huge BC emissions from rural Higher Himalayan villages/towns. Since BC heats the atmosphere, it creates a local thermal anomaly thereby disturbing the normal atmospheric convection pattern that exerts tremendous influence on the precipitation. Perhaps this could be the reason for the flash flood that devastated Leh in 2010! The residence time of BC in the atmosphere is about a week while CO2’s is several decades. So BC does not accumulate while CO2 accumulates in the atmosphere. What it means is that through controlling BC emissions, global warming can be controlled within a short period. It is very easy to control BC emissions without compromising life comforts!! Thus, the Biomass model published recently should be valued in terms of the amount of BC emitted by 2050 and its effect on the arctic ice cap. The pristine Himalayan ecosystem can be protected and fast deteriorating glaciers life can be restored by tapping the huge geothermal resources available in Leh. Where are these sources…….one may ask? They are in abundance all along the entire Himalayan belt extending from Zanskar to Arunachal Pradesh.
These are hydrothermal sources throwing out hot water onto the surface with temperatures varying from 60 to 85 degrees C. The ones that are very near to the army establishments are Puga and Chumathang. Extensive exploration work has been carried on all the geothermal sites of the Himalayas and estimates indicate the power generation capacity of these sites to the order of 250 MWe.
The geothermal sites falling within the Indian territory are few but they are abundant within the Tibetan territory. The Chinese have established geothermal power plants way back during the seventies one at Yangbhajing and the other at Naqu, each generating 32 and 13 MWe respectively. Lasa is completely supported by geothermal power.
China is developing other hydrothermal provinces along the Himalayan border to support its Silk route (revived project). China convened a conference of countries located along the Himalayas to assess the geothermal potential along the entire Himalayan border. Thus China, India, Afghanistan, Iran, Taiwan had a two-day deliberation related to the hydrothermal potential of the Himalayas. Based on the outcome of the conference it immediately established an Institute in Wuhan to take forward geothermal development projects along the Himalayan border.
Geothermal power plants being an all-weather base-load electricity generator, and environmentally friendly energy sources gave huge support to the “One Belt, One Road “ project initiated by China.
China, in its report on the 13th 5-year plan (released on Jan 2017) reported that the geothermal energy (hydrothermal) potential of Tibet is 377 MWe and stated that the plan agenda includes building geothermal power generation projects in Tibet, Western Sichuan and other areas with the high-temperature geothermal resource. During this plan period, exploration and development work on geothermal resources at depths of 10 km will be carried out and actively carry out testing of hot dry rock power generation. Priority areas include southern Tibet, western Sichuan, western Yunnan, Fujian, the North China Plain, Changbai Mountain and other resource-rich areas.
The exploration work includes the establishment of 2 to 3 demonstration bases for hot dry rock exploration and development projects, form a suite of technologies, incubate related enterprises, and accumulate construction experience. Start promotion when the conditions are ripe for it. Thus China has already drawn its road map to tap the entire Himalayan geothermal energy resources. Coming to the Indian scenario, despite several proposals by M/S GeoSyndicate Power Pvt. Ltd. A Mumbai-based IITB start-up geothermal company, there were no takers from the army side. Diesel still rules the roost in Leh. China completed its exploration work and initiated projects to tap the energy.
The country has estimated that the entire belt can generate 5800 MWe (The finding were published in 2010 and 2015 at the world geothermal congress held at Bali and Melbourne). Now China has surging forward to tap the heat from the Himalayan granites to generate electricity (Known as Enhanced Geothermal Systems). Once this technology is established, The entire Tibet and other Southern Provinces of China including those establishments along the One Belt One Road route will have a huge electricity supply. That country need not rely on power generated from hydroelectric projects. Already diesel passenger trains connect Shanghai and Lasa and in a few years, one will see electric trains traversing the entre Himalayan belt…..starting from Chengdu in East China (maybe from Singapore!!) to Europe on the west). If India sits back and dreams about solar in those regions, it will become a mute spectator to the technology developments by China supported by geothermal energy sources. We will still be using diesel and Bhukaris to support our establishments and keep emitting BC while the Chinese electric train will be zooming along the Himalayan border!.
Views expressed above are the author’s own.
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