Energy has become the key requirement for development but at the same time over consumption of energy poses grave threat to the precious ecosystem. Today, most of energy is produced from fossil fuels. But do we have enough coal to last even 50 years? Then what about emission of CO2, and related green house gases and their effects? Without giving serious thought to these issues, planners world over are sanctioning more coal-based power plants.

According to Government estimates we are already producing about 1,35,000 MW power, majority of which is through coal-based plants. In India, present generating efficiencies are between 50 and 60%, while in other developed nations, it is nearly 85%. Simply put, merely enhancing efficiency can yield nearly 33,000 MW of more power. And if we can minimize our high Transmission and Distribution losses, we can save another 40,000 MW. The government plans to generate 45,000 MW in the next two years and assuming that this increase is without addressing the efficiency issue and T&D losses, we will be losing 65,000 MW! With such trends, production of more energy will only mean more loss, and this is a loss to the public exchequer, and so it concerns everyone.

Nevertheless, we now need to look beyond reducing losses and maximizing efficiency and think beyond the fast depleting fossil fuels. Practically every river is dammed, thus exhausting the hydroelectric option as well. The coal burning power plants are already facing acute fuel crunch of various sorts and magnitudes and plant load capacities are also depressed.

Oblivious to this fact, our planners are 'dedicating' 4000 MW coal-based super Thermal Power Plants (TPPs) to every state. And this despite the various reports of coal-based plants posing health hazards to the locals. In USA alone, deaths associated with such power plant pollution are estimated to be about 150,000 per year. Literature abounds with data establishing that crop yield too is drastically affected by the pollution.

With reference to coastal power plants, it is a well documented fact that fish catch is reduced near TPPs. One estimate indicates that around Tuticorin, fishermen lose nearly Rs 65 crore worth of fish catch annually.

Fortunately for us all is still not lost. The world can turn to renewable sources and be rolling in energy which is both pollution-free and sustainable.

Table 1: Renewable Energy potential in India

(Source: MNRE, India)

Wind Energy

Off Shore wind farm at Blåvandhuk, Denmark.
It has 80 wind turbines and a total capacity of 160 MW

Wind Energy has made its presence felt in our country and even some of the bigwigs are generating enough wind power to run their units. According to Indian Wind Energy Association our installed wind power capacity is around 9587 MW, fourth largest in the world. While in many foreign countries, wind farms are being established in the sea, it could be a problem if governments do not lift wind power during monsoon, as has happened in Tamil Nadu. The government would need to ensure that there are adequate planning and grid interactions.

Small Hydro Electric Energy

Hydroelectric generation is still one of the most popular and 'cheapest' methods of electric generation. But in India most of the rivers are dammed and many more are targeted for construction of small as well as big dams.

However, in the recent past 'Run of the River' method of energy extraction is becoming popular, and judicious use can generate huge quantity of power even in remote areas without construction of dams. In Karnataka alone, it is estimated that nearly 5533 MW of power can be generated through mini hydro plants around Western Ghats, and total production for the entire range of Western Ghats could be well over 15, 000 MW.

Sri Ratnaker, an ingenious innovator of Chikkamagalore district, has established over 273 trouble-free small units by now. In many parts of Western Ghats such units can run for 10 months in a year. This technique should be used to the maximum.

Solar Energy

Decades ago, it was envisaged that India would become a superpower by using solar energy. But this has not been the case so far. With reference to solar energy, we have 5000 trillion kWH/year capacity.

Present options available for harnessing solar energy are bit costly, at least initially, so the whole world is awaiting a major technological breakthrough. Some of the important options are Solar Central Tower, Solar Troughs, Parabolic Dish, Solar chimney and Solar Ponds.

Central Tower Solar Thermal Power Plant technology, since 1988, has been running on a very elementary technique. Focussed Sunrays on a central tower through an array of mirrors, generate steam at high temperature and pressure at 15000C and run turbines. The technology was costly but recent advances made in Spain have resulted in considerable reduction in cost. This patented technology includes independent tracking system using separate small photovoltaic panels on each Heliostat (Reflector mirror).

Solar Central Receiver

Another commercially popular technique is the Parabolic Trough Collector systems. The system can even store heat for generating electricity at night. Here, arrays of long parabolic trough like reflectors focus sunlight on a pipe at their center housed in a tube, containing heat transfer medium. This medium heats up to about 4000C and is used to generate steam which runs turbine. Here too, considerable cost reduction has been achieved by tracking systems.

Parabolic Trough Power Generator

Parabolic Dish system consists of fairly large parabolic dish type collectors with modified Sterling Engine at the focal point, coupled to an Alternator to generate electricity. Generally it comes in smaller capacity ranges of 5 to 10 kW. Cost of unit is rather high, but could be very helpful in remote areas.

Parabolic Dish Generator

Solar Chimney is a very promising low cost solar power generating system. It works on the simple principle that hot air moves up. Cost of installation is fairly low and comes in a variety of capacities. In India efforts are on to install a plant capable of generating 200 MW in Rajasthan. In China some villages are already getting electricity from such chimneys.

Solar Chimney of Spain

Solar Pond is another interesting type of solar collector. A suitable sized pond is taken with layers of salt water of different concentrations. As a result heat trapped by higher density salt layer at bottom is prevented from surfacing because density gradient obstructs convection currents. Thus the lower areas of pond remain very hot at over 950C. Suitable engine is used to extract this heat to generate electricity. In Israel at Bet Ha-Arava, 5 MW of power was generated in a pond of about 250,000 sqm area. In India too, smaller salt gradient ponds have been experimented with, but problems arose in controlling algal growth in upper layers of water.

Solar Pond

BHEL has gained considerable expertise in Dish type solar devices. Survey indicates that various types of Solar Thermal plants have so far been tried in India.

Establishing smaller power plants has another advantage - it helps tremendously in reducing transmission losses. Many power engineers feel that one cannot control the vagaries of nature, and hence solar technology cannot be relied on. Of course it is true, but no one is insisting that the existing power plants be scrapped or replaced with solar. In fact, major advantages of solar technology is that it is non polluting and decentralized, so that large number of villages can be electrified, which is impossible if we go for only super thermal plants. Another important advantage is that these power plants can easily meet the demand during peak hours. This is a major benefit since the deficiency in power supply is calculated on the basis of peak demand.

But our government has been very conservative in sanctioning Alternate Power plants. Statements issued by MNRE officials such as "Companies are coming up with offers of huge capacity of 50 MW and more, but we cannot sanction them without verifying if they would be able to deliver," leaves one surprised and confused. If the company is unable to 'deliver' the amount of electricity it claims it can, it should be the problem of the company. Unless, of course, our Government is offering fabulous subsidies even before installation, as is being done for Small Hydro Electric entrepreneurs.

Cost of solar thermal power has been estimated to be between 12 to 60 cents/kWh as mentioned in the Table 2.

Table 2: Summary of Solar power generation alternatives

(Based mainly on Dr Nazish Qureshi's paper)

Solar Photovoltaic is not new, and a lot of small and large photovoltaic systems are now in use. Extensive use of these panels for remote area lighting and even pumping water should be recommended. Right now the cost is on the higher side, but nanotechnology is sure to reduce the cost further. Inventors world over are dreaming of evolving solar vehicles and availability of low cost solar cells will make this dream a reality. Most of the Indian states now have provisions for feedback of excess power produced by private enterprises to the grid and get paid. So, solar photovoltaic installations can get early payback. In fact Central Electric Authority has taken initiative to install grid interactive photovoltaic system on the roof of one of their buildings.

We should also encourage use of Solar Cookers to cut down green house gases and indoor pollution. Significantly use of even one solar cooker would cut down emission of one ton of Green house gases per year.

Biomass Energy

Generating power using waste Biomass, on a large scale is not attractive, and would be another source of pollution. But on a smaller scale at village level, it could be viable.

Bio fuels

Biodiesel and Bio alcohols are the highly hyped alternative fuels but lot of impracticality remains attached with them. To start with, it requires large area to grow bio fuel plants.

Wave Energy

Wave Energy, i.e. extraction of electricity from ocean waves, is still in its infancy, though scientists have been trying to harness wave power since 16th century. One of the largest Wave energy system commissioned recently is in Portugal, and they have preferred to use PELAMIS system. The three units of PELAMIS generate about 2.5 MW at the cost of 4.5 million Euros. But many a new type of low cost systems are emerging. A system dubbed as 'Anaconda' is considered as next best low cost Wave Harnessing system. Wave power generation too is subject to some vagaries, so a couple of inventors, including the author of this article, are contemplating on storing wave energy in such a manner that electricity can be generated perpetually day in and day out.

PELAMIS Wave energy harnessing system

Technology to harness energy from tides has progressed much. A strong barrage has to be constructed at places where river meets ocean, and as tides rise and fall, water passing through barrages turns generator both ways to produce power. In our country not much interest has been shown on account of cost considerations as well as environmental constraints.

Sources like Geothermal, trapping energy from high speed wind flow at very high altitude through generators tied to huge kites, are exotic and formidably costly.

Whatever may the source for power production, one should never forget that the energy sources are not unlimited. For a sustainable future we have to impose limits on growth of both population and industrial pollution.

References
1. Dr Nazish Qureshi http://www.geocities.com/pemnq/home.html
2. Shankar Sharma 2008, 'Impact of power sector on social and environmental issues: remedies' in "Lake 2008", 22 Dec - 24 Dec. Indian Institute of Science, Bangalore.
3. Internet sources on Central Power receivers, Solar Trough, Parabolic Dish, Solar chimney, Solar Pond Wind mills and solar cookers.
4. Energy (r)evolution, EREC, Green Peace 2006
5. Ashok Kundapur, http://www.solcooker.net