In the previous column on Anthropocene (see The Hindu, dated September 12), we had discussed how the huge rise of carbon dioxide and other greenhouse gases has led to global warming. Here we highlight some of the remedial measures being taken, wherein fossil fuels can hopefully, and soon, be replaced by renewable and thus sustainable methods for energy production.
The main source of energy for all industrial and manufacturing processes during the last 250 years has been coal. Today, we produce about eight million tons of coal across the world, and burn it off as fuel. At this rate, all the coal in the world will be gone in 150 years. Besides solid coal, we also use liquid petroleum and natural gas as fuel for generating energy. We use up 70 million barrels of petroleum daily. The total amount of crude oil on earth today is about 1.7 trillion barrels, which, too, will be finished off in 53 years. These three fossil fuels are ‘use it and lose it’ types, not renewable.
Burning these carbonaceous fuels has rapidly damaged the earth by increasing the levels of the resulting carbon dioxide (CO2) surrounding our earth. Carbon dioxide would not escape, being locked in by the gravity of the earth. And since it lets sunlight through to warm the earth, but does not release the warmth emitted by the earth, it bounces it back on us. This greenhouse effect has rapidly warmed the earth and its atmosphere, slowly melting icebergs, raising sea levels and endangering island populations. This has led to what geologists have now declared as the start of a new epoch in earth’s history, a man-made one termed Anthropocene, thus ending Holocene. The danger is clear; what can we do about it? Having been shocked into realisation, we can think new, or even some time-tested, thoughts. Scientists are thinking about several possibilities and, in fact, putting them into action. The first is to reduce (and totally forego) fossil fuels, and use what are termed renewable energy sources, also called sustainable energy sources. These are clean, produce no greenhouse gases, consume no water and do not need large amounts of land. The very first successful step towards such realisation was in helping the ozone layer heal: The amount of ozone in the atmosphere and stratosphere above the earth was getting depleted, thanks to the use of some gases (such as Freon) used as refrigerants. Ozone, which forms a layer above the earth, effectively absorbs ultraviolet radiation, which can harm life forms on earth through oxidation. The ozone layer is thus a protective filter. But refrigerant gases, upon decomposition, react with and deplete the levels of ozone. Thanks to the Dutch Nobelist Paul Crutzen, who made us realize this harmful effect of Freon and similar gases, we have now replaced these gases by much safer ones, and the ozone layer is slowly turning back to normal levels.
We have also started replacing carbonaceous fuels by renewable and sustainable ones. One of them is the conversion of the energy we receive from the sun into electricity. Here, we use solar panels made up of materials that convert light into electricity (photo-voltaic cells, made of layers of silicon, gallium arsenide, cadmium telluride or other materials). Indeed, India is ranked number 1 in the world in utilising solar panels to generate electricity. Today, we are generating over 8,000 MW of power across the country, with Rajasthan, Tamil Nadu and Gujarat in the lead. This will grow more in the coming years. Scientists, both in India and abroad, are continuously working for better and better photovoltaic material to use in such solar panels. The second step is using wind energy through the use of wind turbines to generate electricity. Here, China leads the pack, producing about 150,000 MW of power; India is second with 25,000 MW. This site <http://www.gwec.net/wp-content/uploads/2012/06/Global-Installed-Wind-Power-Capacity-MW-%E2%80%93-Regional-Distribution.jpg> is worth reading.
The third is the use of ocean tides, and the exploitation of the difference in temperature between the surface of the ocean and in deeper layers. Using the tides, we can generate mechanical energy and the temperature difference for thermal energy production. Recall that about 70 per cent of the earth’s surface is covered by oceans. This site < http://www.renewableenergyworld.com/ocean-energy/tech.html> gives an easy-to-read example of such use of ocean energy. While Japan leads the rest in this area, India has just started. The Atlantis Resources Corporation plans a tidal power farm with a capacity of 50 MW with the possibility to increase it to more than 200 MW in Gujarat. When complete, this farm will be the first of its type, not just within the country, but also in Asia.
The fourth and still growing way is the use of microbial fuel cells, wherein waste water is used by bacteria to generate electricity. This field is in its infancy and needs to be developed further. It is clear that the world has learnt at long last. It is also notable that quite a number of scientists and innovators are researching into additional ways to improve the efficiency of these methods. Here is an opportunity for Indian scientists and technologists to think of additional ways to green energy.
D. Balasubramanian
dbala@lvpei.org
