19 April 2016 12:49:10 IST

Using fly ash creatively to limit damage to the environment

Fly ash bricks

The fly ash generated from coal-burning can be used as agricultural nutrients or to make bricks

A startling data point that I chanced upon recently: in the April-September period of 2015, 132 thermal power plants in India ate up 252 million tonnes of coal. That’s a lot. If you want to store 252 million tonnes of coal you’d need a space that is 10 feet high, one mile wide and 20 miles long.

In burning 252 million tonnes of coal, we Indians would have put 720 million tonnes of carbon dioxide in the atmosphere. As I have mentioned in these columns earlier, these greenhouse gases are, in terms of their effect, like an enormous block of stone that will one day surely fall and kill all under it.

However, this column is not about that. It is about another problem, one that is closely linked, but fortunately is twinned with a solution. It is this: these 252 million tonnes of coal produced 83.64 million tonnes of ash. (I know they say ‘67.8 per cent of all statistics are made up on the spot’ but, believe me, these are Government of India figures.)

The coal that we dig up in this country is very mucky — a third of it doesn’t burn. What doesn’t burn turns into ash. Disposing 83.64 million tonnes of ash is an enormous problem. The only positive thing about the ‘83.64 million tonnes of ash’ is that it is not as bad as the 92 million tonnes that the thermal plants produced in April-September 2014.

What can you do?

So what can you do with this ash? Apparently, a lot. To start with, you could use it to fill the holes made in the ground while mining coal. But if the coal mine is near a water body, the ash — which could contain poisonous material like mercury, arsenic and lead — may present a problem.

You could also use the ash in laying roads and building embankments. And you could use it to make bricks. All this is common knowledge and so the stuff is being put to these uses.

But the problem is that 83-odd million tonnes is so huge an amount that, despite best efforts, the country could utilise only 56 per cent of it. The rest lies in huge ponds. Ash is very fine dust. So, come a gust of wind, it will merrily rise up; and ashosphere is not something that suits mankind.

If this problem is this big today, imagine what will happen when India doubles or even trebles its coal-fired power plant capacity. In addition to power, coal is also used in making some other materials, such as cement — and the grey residue is something to reckon with.

Fly ash and its other uses

Then, again, every problem is an entrepreneurial opportunity. Scientists have known that fly ash (as it is called) also contains nutrients useful for plants and you might, where possible, use it for nourishing soil.

A recent publication of the Central Electricity Authority — the one that comes out with all the numbers — notes with dismay that the use of fly ash in agriculture and wasteland development “has large potential but the utilisation is below expectation.”

It attributes this to fears that fly ash may contain toxic or radioactive substances, but stresses that research projects sponsored by the Fly Ash Unit of the Ministry of Science and Technology “indicate that there are no adverse effects in using fly ash in agriculture”. Apparently, the small amounts of nutrients in fly ash are good enough for helpful microorganisms to grow.

So inasmuch as the ash is a problem, it is also an opportunity. It is cheap and, they even pay you to dispose of it. It is conceivable that pretty soon there will be a crop of fly ash start-ups or, who knows, even a new public sector company styled ‘Fly ash Corporation of India.’