Solar heating in industries gaining ground

For long, India has rather been obsessed with generating electricity from the sun's energy — with billions of dollars committed for subsidising solar power — but in the process the country had lost sight of one of the most primordial applications of the sun rays —heating.

But now, there appears to be a renaissance. From domestic companies to multi-national corporations, from industries that need to dry spices and fish to those in the automotive sector, solar heating is slowly gaining ground.

Technology-wise, it is no big deal (unlike solar-electricity). Nor does it take too much of space — in fact, most of the heating systems are rooftop-based. All it takes is a toughened sheet of glass with a black-painted corrugated metal sheet screwed under it, with an inch gap between the glass and the sheet. Air in this recess is heated, which can be sucked off for either direct use, or for further heating.

Such a system was installed last year at TI Cycles, the bicycles division of Tube Investments of India Ltd. The Ambattur plant needs hot air to dry the paint on the cycle frames. Instead of heating air at ambient temperature, say around 40 degrees, to the required 110 degrees, the plant uses the rooftop solar collector first to heat air to about 85 degrees.

Last year, TI Cycles installed the rooftop solar collector spending Rs 21 lakh, and (after factoring in the Government subsidy and tax benefits) the payback is three years. After three years, the company would save Rs 3.5 lakh worth of furnace oil annually. “After the successful try-out, TI is examining other applications,” says Mr V. Santhanam, Head of Operations — Chennai Plant, TI Cycles.

Solar collectors

“Solar collectors' make sense for all heating applications where the level of temperature is not critical,” notes Mr Santhanam. They are especially useful to pre-heat air, so that a lesser amount of energy is needed to heat air to the desired level.

In the recent past, a number of companies have installed solar collectors. They include tractor manufacturer TAFE, sanitaryware maker Roco (for its Alwar plant, where hot air is needed to dry the moulds), and multi-national companies such as Caterpillar and Visteon. “Demand has been picking up in the recent years,” says Dr Chidambaram Palaniappan, an academic-turned entrepreneur, whose company, Sun Best, is one of the leading producers of solar collectors in India.

Dr Palaniappan says that there is a big potential in the fishing industry, for drying fish. The conventional method of drying fish is to lay them under the sun, but such “unhygienic ways” will not do in future, he observes. Last year, the Government of Kerala gave Dr Palaniappan a contract to put up a fish drying unit — at the Saktikulangara fishing harbour, near Quilon. The facility was built to both European and American standard specifications, to aid exports. It has since caught the attention of the Government of Oman, which is in talks with the Kerala Government for putting up a (much larger) facility in the country.

A solar collector-based fish drying facility of a capacity of 500 kg a batch, according to Dr Palaniappan, will cost (net of subsidies and tax benefits) Rs 14 lakh, which will be paid back in two years.

Industries and fisheries are but a few areas where solar heating can be applied, but it is really left to the imagination of entrepreneurs to use sun's power. For instance, Sintex Industries is learnt to have secured a contract from the Defence, to put up doubled-walled, reinforced plastic shelters in remote, hilly areas, (where it is difficult to take other kinds of building material to). It is learnt that solar-collector-based room heating is being contemplated.

The potential in agriculture is immense. Substantial energy saving in drying spices and fruits could be brought about by using solar collectors. Quoting Tata Energy Research Institute (TERI), Dr Palaniappan says that as much as 17.50 lakh kilo litres of furnace oil (or equivalent fuel) is used in low temperature heating. He says a third of it could be saved by solar collectors.

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