02 November 2016 12:07:07 IST

Why cleaning up is a hot idea

Pic credit: KYTan/Shutterstock

Selling ‘heat’ can help tackle the issue of waste and make electricity cheaper

The concept of selling heat is somewhat alien to us Indians. Anything that can be produced can be sold. Sometimes, things that are not produced can be sold too — such as the services of a bank or a hospital. But heat? Can you really sell heat? If yes, how?

To understand this concept of selling heat, you have to go to a cold country. Which I did, recently.

Going cold

Finland is where the sun is a foreigner and anybody who walks outside without wearing a thick overcoat can be an undertaker’s delight. Suffice it to say it is pretty cold. People can do with some help in keeping themselves warm. Which means, you can sell them heat.

But how? Simple.

Power plants produce a lot of heat. When we burn, say, coal in the boilers, we use the heat energy to convert water into high pressure steam, which in turn hits the turbines and turns them. In the case of gas-powered plants, natural gas — methane — is used, instead of steam. After the steam or gas leaves the turbines, the heat it contains is, usually, wasted.

In the cold countries, the ‘combined heat and power’ (CHP) plants use the residual heat to make hot water. Water is a carrier of heat — it can be transported, the heat sold, and the water looped back. This way, you extract most out of the fuel that you use in the power plants, and you improve the economics of the plant, which in turn makes electricity cheaper.

An example

A typical case is that of Vantaa Energy, a company whose CHP plant is situated a little outside Helsinki, Finland’s capital. The company produces and sells both electricity and heat.

The steam that comes out of the turbines heats up water to close to boiling point. This is then piped some 25 kilometres to the township of Vantaa, in insulated pipes. The township’s water supply system does not use this water, it brings its own.

The hot water piped from Vantaa Energy transfers its heat to the not-so-hot water of the town’s water supply system. The company’s water returns to the CHP plant, ready to convert to steam all over again. The town’s water, which has picked up the heat, now leaves for homes. By the time it reaches the taps and showers, it is about 65 degrees Celsius — nice and warm for a shower or a dish-wash.

Such CHP plants dot the landscape of the Nordic countries (Norway, Sweden, Finland, Denmark and Iceland.) Heat is a saleable commodity and therefore, heat produced as a by-product in a power plant can be mined for its value. What it fetches in the market can then be used to cross-subsidise the cost of electricity, keeping it low. In Finland, for instance, electricity costs around three euro cents (₹2.20) a kilowatt-hour.

Face the heat

India has around 200,000 MW of thermal power plants and the waste heat is rarely captured. Imagine how much valuable heat we are wasting! Now, you would say that while heat is a saleable commodity in the cold countries, it is not the same in a tropical country like India.

But that would not be quite right. Heat can be used for cooling too. It is technologically possible, and is being done. So the central message of this article is this: we should build a movement in this country to capture as much heat as possible from our thermal power plants and have the heat work for us.

To me, the visit to Vantaa Energy was an eye-opener. On the one hand, there is heat transported 25 km across frosty land and sold for money. On the other, the raw material used to produce energy is something we have a lot of, but have struggled to use for a similar purpose — city’s waste.

Every day, tens of trucks roll into the Vantaa plant carrying Helsinki’s waste. It helps that people segregate wastes into electronic, plastic, metal and all else, and dump them in appropriate bins.

Each year, Vantaa burns 320,000 tonnes of waste in its boilers, where temperatures go as high as 1,000 degrees Celsius, neutralising the wastes by incinerating them. Out comes heat, which is first used to make steam and thence, electricity. The remaining heat in the used-up steam makes hot water for the town.

One man’s trash…

Now, unlike ‘selling heat’, waste-to-energy (W2E) is not an alien concept to us. Yet, India has struggled with it because of many problems — the wastes here are highly heterogeneous; they are often wet; their supply is not assured due to inefficient collection system; and above all, the power produced by waste-to-energy plants is not very cheap because the heat part of it is not fully milked for its worth.

Utilities baulk at buying electricity from W2E plants either because it is costly or because the supply is irregular. The electricity is costly also because the plants are typically small — usually not more than a few tens of MW. In contrast, Vantaa Energy is a mammoth 160 MW.

We dump wastes in landfills, where it causes further problems. On the output side, we waste heat. On the input side, we waste waste. Truly, there is no rocket science involved.

It only calls for clever management. Anybody interested?