Shifting the ‘coalpost’ for climate change

At the Indian Institute of Science Education and Research, Pune, Dr. Ramanathan Vaidhyanathan, a young assistant professor at the Department of Chemistry, has set his sights on solving a small aspect of the complex task of cleaning up coal.

For a while, Dr. Vaidhyanathan worked in Canada and, along with his collaborators, searched and tested a variety of materials that could improve the efficiency of extracting maximum, clean energy from coal while also ensuring that none of the attendant carbon dioxide escaped into the atmosphere.

Findings in journal

What he proposes, along with team of international colleagues, is an alternative set of materials to scrub toxic carbon dioxide off the coal when it is burnt to produce heat and move turbines to generate electricity. A good way to do that, as futurists propose, is to first burn the coal with extremely hot steam and separate the resulting hydrogen — that’s used as non-polluting fuel — from the effluent carbon dioxide. Their work appears in this week’s issue of the Science Advances journal.

The efficiency of the process rests on specialised sponges, which are subject to cycles of high and low pressure; Dr. Vaidhyanathan and his colleagues have zeroed in on a construct of nickel and isonicotinic acid that they claim is twice better than the best such ‘sponges’ being tested anywhere in the world. Additionally, he says, their recipe is simpler and faster to manufacture and, being relatively impervious to moisture, more long-lasting.

Dr. Vaidhyanathan’s approach might appear to be a long shot given the expenses involved. The best that most coal-fired power plants in India currently do is wash the coal to reduce its ash content. To even contemplate cleaning coal with Dr. Vaidyanathan’s ‘scrubbers,’ before it is burnt, requires precisely the kind of investments that the country’s scrappy negotiators are trying to get developed countries to make at fora such as the recently concluded United Nations Climate Change Conference in Paris.

For cleaner coal

The big message for India from the deliberations was that it, too, being a rapidly growing economy and among the world’s top polluters, had to do its bit to use cleaner fuel.

While India may have committed to massively investing in solar technology and put in place a ‘coal tax’ of Rs. 200/tonne, coal is set to be the mainstay of India’s energy mix until 2030. Due to this, the international pressure to use cleaner coal would only increase in the years to come.

“I’m fairly confident that given the quality of researchers that we have in India and approaches that are being tried out in other labs, we will be able to have a feasible pilot project in the near future,” says Mr. Vaidhyanathan.

For one, the promise of his test results rests entirely in the predictable confines of his laboratory. “There’s a long way to go. Most importantly, we haven’t actually used commercial-grade coal to test whether the carbon dioxide is being separated as much as we have tested in our labs,” he says.

Then there remains the daunting challenge of what to do with the carbon dioxide that has been segregated from the coal. A. Damodaran, professor of Economics and Social Sciences at the Indian Institute of Management, Bangalore, said in a presentation that capturing, transporting and storing the CO from a new gas- or coal-fired power plant would increase the cost of electricity generated by that plant by 37-91 per cent.

This translates into a CO mitigation cost of $30-91/tonne, making so-called carbon capture and storage a “comparatively high-cost method” for mitigating carbon emissions.

Experts familiar with India’s trajectory vis-à-vis adopting new technology for coal plants say that carbon capture techniques appear expensive and that India would be unlikely to adopt them until other countries take to it and attain demonstrably greater levels of efficiency. “India’s coal plants have over the decades reached 30 per cent efficiency,” says former Power Secretary P. Umashankar, “and the best we can hope for with advanced supercritical plants is 40 per cent. For the near future, I don’t think India will concentrate much beyond these.” The key challenges would be in transporting the collected carbon dioxide and finding safe locations to bury it.

Dr. Vaidhyanathan, however, says that there are mitigating solutions to these problems. Carbon dioxide weeded out from the coal using his ‘sponge’ can be used for a variety of other industrial applications including extracting oil trapped in the ground as well as creating new compounds.

Are those in charge of India’s coal-fired power plants listening?

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Printable version | Apr 15, 2021 4:30:10 AM |

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