28 Mar 2019 19:38 IST

Smart tech makes renewable power affordable

Technology advancements are largely responsible for the fall in prices of solar and wind power

The highlight of the developments in the renewable energy industry in India in the last two years is the incredibly steep fall in prices of electricity sold by the renewable energy companies (called ‘developers’) to the electricity distribution companies (called ‘discoms’, such as Tata Power Distribution, BSES Rajdhani and Tangedco).

Renewable energy in India comes almost entirely from two sources – solar and wind. (Interestingly, power from large hydro electric dams is counted as renewable energy all over the world, but not in India.) The tariffs for both solar and wind power have fallen drastically, for different reasons. Solar rates have plummeted because prices of the modules — the dark blue panels that face the sun — have fallen precipitously, because of over-production of these panels in China, causing a price-hammering glut.

Sharp fall in prices

To illustrate, towards the end of 2015, solar modules sold at 43-45 US cents a watt, and solar prices then were around ₹5 in India — indeed, when a now-defunct company called SunEdison won a bid quoting ₹4.63 a kWhr, it was roundly criticised as being foolish. But now, module prices have crashed to 22-25 cents and, correspondingly, solar electricity prices have dropped to around ₹2.50 a unit of electricity.

The reason for the fall in wind power prices is different. Till two years back the prices at which wind power developers would sell their electricity to discoms used to be fixed by the State electricity regulator. But since 2017, the method of fixing prices changed — a system of auction began, so that whoever offered to sell at the lowest prices got an opportunity to put up wind plants. As developers tried to outbid one another, prices crashed. Earlier, fixed prices used to be between ₹4 and ₹6. Now, market-determined prices are ruling around ₹2.84.

Now, the question is, how are the developers able to quote such low prices and still (apparently) survive? One part of the answer is that the market itself has grown and so there is a bigger pie to be carved out from. As each developer’s slice becomes bigger, he can afford to sell power at lower prices.

But there is another important reason – which is the essence of this article. It is ‘technology’.

Taller towers, longer blades

In the days of yore, windmills were mostly quaint contraptions standing, typically, along coastlines, or near water sources, their arms waving madly in the wind. Initially, they pumped water or pounded grain; but, for the last half century, their sleeker, modern-day cousins have been producing electricity. (Any circular motion can be harnessed to disturb a magnetic field inside a generator, and when you cut magnetic lines with a good conductor of electricity, electricity flows through the conductor.)

Later they just made the windmills taller. That helped because taller windmills had longer blades, and the longer the blade – obviously – the larger the circle they swept and there is a very direct relationship between the swept area and electricity produced.

So the initial windmills of the early 1990s had blades about 13-15 metres — today the blades are a good 80-90 metres long. (Oh yes, they weigh a lot — about 100 tonnes each is typical, which means the tower would need to support 300 tonnes of just blade weight alone.) The towers have kept growing taller. Today’s towers are 120 metres in height, and they are making them even taller. Newer technologies for erecting towers have emerged — for example, the lower two-thirds could be concrete, while the top third could be tubular steel.

The smart tech edge

Thus we had an era of taller windmills that could be put up profitably even in areas not-so-windy. But today’s windmills are a great deal smarter. Things have moved way beyond just physical parameters such as height and blade length, which posed only mechanical problems that are easier to solve.

Today we live in an era of digital wind farms. They have become IoT-based. There is a lot of data science behind the operation of a wind farm today.

The first generation digital wind farms took data from either satellites or microwave about, say, upcoming weather or wind-flow direction, to adjust the orientation of the wind turbine. Then things became more hi-tech.

Imagine a wind turbine sitting on the top of a 120-metre tower with its three blades, like the tri-star logo of Mercedes Benz. Now, at any point in time, the tip of the blade that is standing vertical, or perpendicular to the earth, is the highest point of the machine, right? A sensor at the tip of the blade senses the quantum and direction of wind-flow and communicates it instantly to the blade that is next to assume the vertical position. The follower-blade will automatically adjust its orientation so that it catches more wind. This happens dynamically, all the time, and over a year, the additional electricity generated because of the rapid, real-time corrections in orientation gets the developer more bang for his buck.

Optimised farms

If this is an individual machines, imagine a wind farm, with rows of windmills. The first row gets the full blast of the flowing wind, the second receives only the ‘wake’ from the first row, and the third even less. With IoT connectivity, the machines calculate the optimum speed of rotation of the blades, so that the output of the entire farm is optimised, even if the first rows have to slow down a bit.

With improvements in material sciences, such as carbon composite fibres for turbines and super-conducting generators that can ferry out a lot more electricity, things are set to improve further.

Without such advancements in technology the low prices of wind power would not have been possible. The windmill is no longer the dumb giant that Don Quixote tilted at; it is a majestic, smart manifestation of technology that commands respect.

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