31 Aug 2016 20:35 IST

Has waste to energy issue been cracked?

Maybe the solution lies in having many smaller plants processing some homogenous kind of waste

We, as normal people, generate a heck of a lot of waste. We dump this somewhere, which causes certain problems. But instead, if we burn this waste, we not only destroy it but also generate useful energy!

Yawn! I’ve heard this many, many times before, and I’m sure you have too.

This is the principle of waste-to-energy, or simply W2E. It never ceases to amaze me. A W2E device is something like a magician’s box — put in some worthless stuff — anything that can be burnt — and out comes something extremely valuable in the form of gas! Any residue left in the box, such as ashes, can also be useful. In this instance, it can be used as fertilisers.

The elusive tomorrow

The world has been talking about this for years now, and each conversation on the topic makes it appear as though “The time of W2E has now come!” But the ‘time’, much like ‘tomorrow’, is always round the corner, never fully in our grasp.

In 2014, the Ministry of New and Renewable Energy, which probably didn’t want to come across as a department which hasn’t done its bit for the business, constituted a ‘Task Force’ to delve into this and find out what exactly is going on. The report speaks about the volume of ‘municipal solid waste’ India generates — 62 million tonnes — and, “What a valuable resource this waste is!”… and so on and so forth it goes.

But two years down the line, guess what we have? As of the end of July 2016, India has 115.08 MW of W2E plants that feed electricity into the grid, and another 161.39 MW-equivalent that people put up to use the energy themselves — making it 276.47 MW in total.

So where are we going wrong?

As the Task Force notes, there are a number of issues leading to the failure of the W2E movement. But the biggest among them is the lack of assured burnable, good quality waste supply. Also, if one builds a big plant — big in this context being around 5 MW — he/she has to keep feeding the beast, or the venture will collapse economically.

Then there is the issue of the type of waste used. If the feedstock contains non-combustible garbage, there is a problem. In bio-methanisation plants, there is an added issue — if you overfeed the bacteria, the reactor will turn acidic, in turn killing these micro-organisms.

While these might look insurmountable, a careful analysis will show that there is a way to handle the issues. Instead of a big multi-MW plant, located at some corner of the city (where locals won’t be close enough to mind its presence), if you could have many smaller plants processing some homogenous kind of waste, the problem may be solved.

For instance

The Taj Coromandel hotel in Chennai has attempted this, and it looks like it will be a commercial success. The hotel bought a bio-reactor and put it on its premises on the rear side.

The feedstock consists of the food waste that comes in from their kitchen and restaurants. So that takes care of the supply issue. And the feedstock is homogenous, and in order to keep it that way, the hotel feeds only organic wastes, leaving out meat and fish that might have bones.

Each morning, the reactor is loaded and it keeps giving methane all day long. The gas is then collected and piped to the kitchen, to substitute costlier LPG.

Returns

Bengaluru-based GPS Renewables, which makes the bio-methanisation plants, says the mid-range (500 kg of waste per day) costs ₹30 lakh, and the investment will be paid back in four years.

A notable feature of the GPS Renewables reactor is the complete monitoring system, which enables the company to track every machine sold, from its central office in Bengaluru. At the first sign of acidification, the company sends an alert, stopping it.

When I visited the plant at Taj’s premises last month, I said to myself, “Oh my God! This could be the answer to the bio-methanisation W2E jinx. The small plants, locally generated homogenous waste, energy being consumed right there — this is the way to go.

GPS Renewables says in the few months it has been in the business, over 30 pieces of equipment have been sold. There is good demand from practically all hotels as well as educational institutions, for their canteen wastes.

There are many other W2E companies out there. The big ones have failed, but by some accounts, the small ones are doing fine. Only, they don’t get talked about. It looks like we are on the cusp of a bio-methanisation revolution. In the near future, there ought to be a bio-methane producing equipment everywhere in the country.

If the recent experience of GPS Renewables is anything to go by, the revolution may have just begun.

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