Clean Tech

The ‘other’ sun shines for the industry

M. Ramesh | Updated on: Jan 09, 2022

That companies have begun using solar heat for industrial purposes is a good step forward, says M Ramesh

It’s been awaited a long time and now, finally, it’s happening. The ‘other’ solar laggard is pulling up its socks.

Indian industries are warming up to the idea of using solar heat for their processes. Here is a telling data point: Till the end of 2016, India had 271 units that produced ‘solar heat for industrial processes’, or SHIP, with a total ‘collector area’ of 78,290 square metres; in 2017, the country added 36 units cumulatively spread over 15,313 sq m — the second highest in the world, only after an outlier, Oman, put up one plant as big as two-and-a-half football fields, the biggest ever.

(Background: The sun’s heat can be tapped in many ways. One is to keep a series of water tubes on a reflecting surface put on the roof; another method is to heat the air trapped between two sun-facing, flat surfaces placed one above the other with a gap in-between; yet another is to focus mirrors onto a tube carrying a liquid. Common to all these is the area of surface (‘collector’) facing the sun to pick up the energy — that is why the installed capacity is measured in terms of square metres.)

Capturing the sun’s heat energy is indisputably far more efficient (therefore, cheaper) than picking up sunlight to excite electrons on a semiconductor surface and produce electricity. Today’s best solar PV can convert around 17 per cent of light energy falling on the panels into electricity; in contrast, a solar thermal system can easily cart away 65-70 per cent of the sun’s heat to the point of application.

Also, solar thermal is cheaper to install. If solar PV costs ₹45 a watt, solar thermal can do with ₹10 less, says Siddharth Malik, Managing Director of the Delhi-based Megawatt Solutions, a leading company in solar heat. All this has been known for long, but the focus has always remained on solar PV. Why so? One reason is historical. PV systems evolved first in cold climatic zones and it was easy for India to cut-and-paste them here — more so because PV is very modular and amenable to standardisation. Electricity is also easier to dispatch whereas heat, generally, is not. The production and consumption points of heat cannot be too separate, or there would be energy loss.

Dr Satyanarayanan Seshadri, who teaches Applied Mechanics at IIT-Madras, observes that sometimes matching temperature with the process requirement could also pose a challenge. “Temperature levels can vary depending on solar radiation,” he says, noting that this may call for a back-up system. But even more than that, solar thermal systems work best if they are designed for the location. “Each system, and application needs a detailed assessment before even a proposal can be made. This is a challenge. Who will front the cost of this assessment?” poses Seshadri, who is also an entrepreneur.

But then, if the economics is sound — as in this case — solutions will be found. There comes a tipping point, when the sceptics lose.

Malik, for one, believes that such a tipping point has been crossed — as evidenced by India seeing a spurt in SHIP installations in 2017. He says that apart from awareness of solar heat reaching an “all time high”, the pricing of most fuels like diesel and LPG being market-linked, and therefore rising, has made solar thermal more attractive.

Furthermore, the supply industry has evolved over time and is now mature, says Malik. The supply chain is more organised. Until a few years ago, solar heat was mostly used by non-industrial users — typically for community kitchens of pilgrim centres, such as in Shirdi and Tirupati. As the industry began to adopt solar thermal, it imparted more “seriousness” to the business, he says.

Hatsun Agro, which makes Arun ice-creams and a host of other dairy products, uses so much of sun-derived heat in its processes that its officials quip that they make “solar ice-creams”. Mondelez (formerly, Cadbury’s India) and Reckitt Benckiser, manufacturer of the Dettol brand, were among the many companies that took to solar heat last year.

If India saw a SHIP boom in 2017, this year is likely to see an encore. Because, apart from the general rise in awareness and the maturing of the industry, there is another factor lending support — the ‘opex model’. Just as it is happening in solar, solar heat companies are now telling their customers that they are happy to sell only the energy — the investments in plant and machinery would be made by the solar companies themselves. This model, though, is not entirely new in solar thermal — years back, Chennai-based Aspiration Energy did this for Wheels India.

But again, ‘opex model’ in solar thermal is beginning to gather steam — in the case of Hatsun Agro, quite literally. In December last year, the company contracted to buy steam. Protarget, a German company, has put up a parabolic dish plant next to Hatsun Agro’s ice-cream factory near Salem, Tamil Nadu, and is selling steam at the rate of 400 kg an hour. Because the installation costs are lower (than solar PV) and the energy yield is higher, the returns are pretty good — upwards of 20 per cent on equity, according to Malik. Funds, now familiar with the opex model in solar PV, are beginning to consider thermal, he says. “Solar thermal is far more financially attractive,” says Malik.

Malik’s company, Megawatt Solutions, itself is an example of the growth of this sector. Till last year, the company had installed solar thermal solutions worth 5 MW. In the current financial year up to now, the company has installed 6.5 MW, and based on secured orders, Malik says the company will end the year adding 20 MW to its portfolio.

All this is only ‘solar heat for industrial purposes’. There is a huge ‘heat’ market out there for non-industrial uses too — for example, for district heating and cooling, and temperature control in buildings. A big push is expected to come from buildings. India has committed to follow the Energy Conservation Building Code, which proposes that, depending on floor space, solar thermal must meet 20-40 per cent of the demand for hot water.

And there is scope for going beyond solar itself, in the search for alternatives to fossil fuels. You find scintillating examples in Europe. A cemetery in Aalborg, Denmark, sells heat from burning bodies to make nearby villages warm. In Zurich, Switzerland, heat from a data centre located in an underground, disused military bunker is used to warm waters of a swimming pool. In Finland, very hot water produced by burning Helsinki city waste is piped to Vantaa, a township 25 km away, and is used to heat water supplied to residents. But for now, the good news is, companies are seizing the solar option for industrial heating. Given the compelling economics of it, the phenomenon is best captured in the words of the famous song in the Rishi Kapoor starred “Khel-khel mein”: yeh to hona hi tha (it had to happen)!

Published on July 17, 2018
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