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Identifying alternatives to petroleum

Wednesday 15 June 2005, by SACHITANAND*N.N.

For the short and medium term, India should further exploit its coal deposits using clean technology, speed up Railway electrification, and popularise biodiesel.

THAT PETROLEUM is a fast depleting energy resource is a given. Due to very limited domestic deposits, our import dependence on petro-fuels is projected to rise from the current 70 per cent to 90 per cent by the end of this decade.

A partial solution to the crisis is to use fuel extenders such as ethanol or methanol. Gasohol, a mixture of ethanol and gasoline, was used during the Second World War and has been in use in Brazil from the 1970s. Many American automobiles are now equipped to run on E85, a mixture of 85 per cent ethanol and 15 per cent gasoline.

Gasohol has higher octane or anti-knock properties than gasoline and burns more slowly, coolly, and completely, resulting in reduced emissions of some pollutants. But it also vaporises more readily, potentially aggravating ozone pollution in warm weather. In India, the use of gasohol can be controversial. Ethanol is usually obtained by fermentation and distillation of maize, wheat, potatoes or sugarcane and in India these crops are more valued as food.

Perhaps the best bet for India of an alternative transport fuel from renewable sources is biodiesel. It is a clean burning mono-alkyl ester-based oxygenated fuel made from vegetable oils or animal fats.

Biodiesel’s fuel characteristics exceed that of petroleum diesel in terms of cetane number and lubricity. It offers higher power, more fuel economy and lower engine wear. It is a much cleaner burning fuel with the emissions containing virtually no sulphur, substantially lower carbon dioxide and cancer-causing aromatics such as polyaromatic hydrocarbons. Some alternative fuels are criticised for consuming as much energy to make the fuel as the fuel contains. In the case of biodiesel, every unit of energy needed to produce it results in 3.24 units of fuel energy.

While soya oil is the main source of biodiesel in the United States, in India experiments are being carried out on non-edible oils from the jatropha and honge (Pongamia pinnata) plants. The advantage with these plants is that they can thrive in drought-prone areas. However, what has still to be established is the productivity from commercial plantations - whether there is enough land available for such commercial plantations in India and whether the biodiesel will be cost-competitive.

The impending oil crisis can also be mitigated by changing the balance in our freight transport. Because of the large tonnages moved by a rail rake, diesel consumption per tonne of freight transported by rail is much lower than by road. Unfortunately, today more freight is being moved by road than by rail due to the inefficiency of our Railways.

Between 1951 and today, the Railways’ share of freight carried has come down from 90 to 40 per cent. Further, if rail track electrification is speeded up, the reliance on diesel locos can be reduced. As on March 31, 2004, Indian Railways had brought 16,960 km of track under the electric traction system, 27 per cent of the total network.

The popularity of an energy source is dependent on availability, convenience, and cost. Petroleum has ruled the roost since its discovery as a source of energy, particularly for transport, because of its convenience of use, easy transportability (it has the highest energy density per unit volume at normal temperatures and pressures) and, till recently, relatively low cost. These user-friendly properties of petroleum have in the past militated against the deployment of alternative energy sources.

Solar energy, for example, is available only during daytime and is highly diffused. The average insolation incident over India is about 5.5 kWh/sq. metre a day over a horizontal surface. Making the silicon panels used to convert incident solar energy to electrical energy is very expensive. The conversion efficiency of these panels with current technology is around 10 to 15 per cent, which means 1 sq. metre would yield only 0.6 to 0.8 kWh a day. Thus, electricity from solar energy is, as yet, viable only for distributed small power applications. However, for low temperature applications such as cooking or heating bath water, solar heat energy has become a competitive source.

Electricity from wind energy has been touted as a promising alternative to fossil fuel-based electric power. In the last 20 years, the cost of wind power has fallen by 90 per cent due to improvements in wind turbine design and increase in individual wind turbine capacities. In some countries of West Europe, installed wind power capacity is touching 25 per cent of total power generation capacity. But that is because the average annual wind speed in those countries is high. The energy that can be tapped from wind is proportional to the cube of the wind speed.

In India, however, average wind speeds over the year are low, barring some places. The gross wind energy potential in India has been estimated at 45,000 MW. However, the technical potential is limited to a mere 13,000 MW. The utilisation of this potential has been low - only 1870 MW as on March 31, 2003. This is because land acquisition for installing large-scale wind power farms is a major issue in India. Then again, wind power is not a solution for mobile applications.

The closest competitor to petroleum in terms of energy per unit volume is another fossil fuel - coal. India is comfortably placed here, with hard coal reserves of 246 billion tonnes of which 92 billion tonnes are proven. At a current offtake level of 375 million tonnes per annum, the proven reserves alone should last us for nearly 300 years.

The downside is that Indian coal is very high in ash content (around 40 per cent), leading to a huge solid waste disposal problem after it is burnt. Direct burning of coal to produce energy also results in atmospheric pollution with the gaseous oxides of carbon, sulphur and nitrogen.

The solution to this lies in the gasification of coal, which is a process of converting coal partially or completely to combustible gases using high temperature steam, air or oxygen. The inorganic material in the coal is converted to an easily disposable glassy slag. In a type of power plant called an integrated gasification combined-cycle (IGCC) facility, the overall thermal efficiency can reach 50 per cent as against 35 per cent achieved in a conventional coal-burning power plant. The high temperature gasification process strips out pollutants like sulphur and mercury. A number of IGCC power plants have come up recently in the West. NTPC has recently announced a joint venture with BHEL to set up a 100 MW IGCC power plant at Dadri near Ghaziabad.

The other coal-usage strategy that is being studied now in a number of coal rich countries such as Australia, the United Kingdom, Spain, China and Russia is in situ gasification (ISG) of coal seams. The major environmental advantages of ISG are minimal disturbance of the surface and utilisation of the underground cavities left after gasification to sequester carbon dioxide that arises from burning the product gases in the combined cycle power plant. But the process is still in the experimental stage.

Use of nuclear power

Nuclear power has been strongly advocated, especially by past and present personages of our atomic energy establishment, for base load power stations. Unfortunately, there has been tremendous cost and time overruns in the past in establishing nuclear power stations in the country. Against a goal of putting up 10,000 MWe of nuclear power capacity by the year 2000, only 2770 MWe had been installed. The Nuclear Power Corporation of India Ltd. has very ambitious plans to install 20,000 MWe of nuclear power generation capacity by 2020 but, if past performance is any guide, this is a pipe dream.

Also, despite the fact that nuclear power stations have very low polluting emissions compared to fossil fuel power stations, there is a groundswell of public opinion against nuclear power due to radiation hazard fears.

Fuel cells (devices that convert chemical energy to electrical energy) show a lot of promise as an alternative to petro-fuels for transport applications. The fuel is a hydrocarbon like methanol or hydrogen itself. However, due to complexity of design and high cost of materials used, such as platinum catalysts, the estimated cost of existing PEM (Proton Exchange Membrane) fuel cells is $1,500-$3,000 per kW. In comparison, a conventional automotive internal combustion engine costs $50-$100 per kW.

The current Bush regime in the U.S. is laying its bets on hydrogen as the fuel of the future. However, due to its very low density and very high volatility, hydrogen presents a number of technological problems with respect to storage, transport and use. Moreover, there is still no low energy way of extracting it from its most abundant source - water.

In sum, for the short and medium term extending to the next 20 years, India’s salvation from the oil crisis lies in further exploiting its coal deposits using clean coal technology, quickly enlarging the Railway electrification programme and popularising biodiesel.

See online : The Hindu

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