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Shiv Vembadi posted: How much of the world is currently powered by renewable energy? What would be the case in 2020? 1 year ago

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Narasimhan Santhanam . Thanks for the question, Shiv. And a pretty important one too at that,

Before I answer, I would like to spell out what I mean by Renewable energy. In addition to solar, wind, biomass, geothermal and ocean based (tidal/wave), hydropower is also renewable energy, though many do not consider it while discussing renewables, owing to a confusion between alternative and renewable sources (hydro is not alternative energy as it has been a conventional source for long, but IS renewable).

If we agree on the above definition, the total installed capacity of renewable energy sources end of 2016 was around 2.3 TW (2300 GW), with hydro contributing about 60% in terms of installed capacity (about 1300 GW), and the rest of renewables contributing about 1 TW (1000 GW). Of the non-hydro renewable sources, solar and wind will claim a large share (about 900 GW).

Given that the total global installed capacity of electricity is about 6.4 TW, the total % share of renewable power capacity is about 35%, quite a substantial share. However, when it comes to power generation (and not just capacity), the share of renewable will be a shade under 20% - my best estimate is somewhere almost 20%, with hydro contributing about 16.5, wind about 2%, solar and biomass giving about 1.5% together.

So, currently, in terms of installed capacity, renewable sources of power has about 35%, and in terms of generation, about 20%.

But as you can see, the elephant in the room is hydro power. If you take hydro power from the equation, the % share of renewable energy sources to the world's electricity consumption comes crashing down to just 3.5%.
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Shiv Vembadi . Mr. Narasimhan, that's a lot of useful information. Thank you. So, if solar and wind are currently only about 3% to the total electricity demand, when do you think that could become 10% or 30%? Like

Narasimhan Santhanam . @Shiv - a difficult thing to predict. All I know in terms of formal estimate is that IEA thinks solar power will be the single largest generation source for electricity by 2050 - solar PV and CSP combined could contribute about 27% of total - Link />
Of course, 2050 is too far into the future to predict, or for that matter, bother about for the ordinary I and you.

If I were to take a guess, consider it a guess and no more, by 2020, renewables (excluding hydro) would be contributing about 4.5%-5%, and by 2025, possibly about 8%. A 10% contribution could take until close to 2030.

A 30% for solar and wind together would perhaps happen around 2040-2042, if we go with the above IEA estimates.

Prediction far into the future is a nice game isn't it? It's so far away, no one is gone to point fingers at you when I'm wrong - because it will take some 25 years to find out if if I am :-)
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Divya Prabha M.V posted: Similar to solar panels, is there good scope to have small wind turbines on rooftops in India? 1 year ago

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Narasimhan Santhanam . Well Divya, good question.

The short answer is: No.

Here's a longer answer.

While solar PV based power plants are truly modular in nature (they work as well in small sizes as they do in large sizes), the same cannot be said for the wind turbines. In most cases, I have seen that small scale wind turbines have very poor CUFs in Indian conditions. Besides, large parts of India are not exactly windy, while most regions of India get at least reasonable, if not very good, sunshine.

Finally, solar panels and solar power plants are a well established, global industry, with quality standards and warranties well in place, ensuring that the retail, distributed energy sector can reliably invest in them. Small scale wind turbine sector, on the other hand, is quite unorganized world over (even more unorganized in India), suffers from lack credible quality standards and benchmarks. All these hinder the small end user in residential or small commercial sector to invest in small wind turbines on rooftops.

While some technological advances such as vertical axis wind turbines are likely to accelerate adoption of small wind turbines on rooftops in India, I do not expect the rooftop wind power market in India to be even a small fraction of the rooftop solar panels market in the foreseeable future.
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Aravind Venugopalan . A technical limitation for wind turbines is that wind speed is much better the higher you go. Partly due to this reason, wind turbines are getting larger and larger. Like

Narasimhan Santhanam . @Aravind - yes, that too. The power generated by a wind turbine is proportional to the cube wind speed (Power = k.v^3). And as Aravind said, wind speeds are higher with altitudes, so you can see that you get a much higher bang for the buck if the blades are a higher altitude. In fact, some of today's largest MW scale wind turbines are 100+ meters high.

Unfortunately for small wind, the converse is true as well - lower the altitude, much lower is the overall generation.
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Manohar Namasivayam . @Divya @narsi

What about wind from coastal rural areas which can benefit from
such a low cost turbine,

I read about this some time ago.

Is it a viable option >?
Link
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Narasimhan Santhanam . Hi Manohar - Your idea can lend itself to a slightly different perspective...yes coastal rural areas could have more wind and hence could be more attractive for small wind turbines. Still, I doubt if rural households could afford to invest in small wind turbines (please note that the cost/kW for small wind is right now much higher than that for solar power plant, almost 1.5 times that of a solar power plant).

But as I mentioned, the fact that you have good wind even at low heights in the coastal rural areas could be used for community scale wind power plants, where perhaps with a good amount of government support, there can be perhaps 15 or 20 kW wind turbines for each village, set not on rooftops, but on some common community land. Such a community wind farm does away with rooftop structural issues, maintenance is less of an issue now that the community (and not just a single household) is involved in it, and finally another avenue in the government's Power for All mantra.

A tweak that government can try while implementing this is to have a solar/wind hybrid power plant, as we all know that solar and wind power generation are kind of complementary to each other, thus resulting in a relatively more uniform power generation over a day than solar or wind alone.

Of course, whatever I have mentioned comes under the broad scope of microgrids - though I doubt the government has considered your perspective in terms of use of small wind specifically for coastal rural areas as part of the microgrid energy source mix.
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Manohar Namasivayam . Link />
This is old news.

The product has not caught on.
@Divya will you be knowing its performance currently.
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Narasimhan Santhanam . @Manohar, I don't know what you do to your links, but they don't lead anywhere :-), I see a /> after the link which could be creating problems, so am removing it and giving your link that works - Link Like

Narasimhan Santhanam . Oh and by the way, on the YourStory link you had given @Manohar, one of the founders, Arun George had contacted me a few months before he launched his firm, as he wanted us to do a survey of the market. I really hope they are able to make some breakthrough here, but my questions and concerns on small wind turbines remain... Like

BALAJI CS . First of all Wind power is site specific whereas the solar power ,irrradince level and the expected output can be generalized to a greater extent say for a city/town.

large wind parks need a detailed Wind Resource assessment (WRA) and even for kw rated wind generators we need to have the historical wind speed pattern,elevation etcc so as to arrive the optimal design/feasibility-whereas solar PV System & modules are all standardized and one can source it from the market with ease to meet his power requirement.This factor plays a key role in limiting the spread of smaller wind turbines.However hybrid systems (wind +solar)would be much more effective provided we do the ground work thoroughly
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Divya Prabha M.V . Thanks for the answers. I also wanted some clarity on how much do these small-scale wind turbines cost. For e.g, a 1 kW solar power plant today costs about Rs.55-60 per Watt. Do wind turbines also cost around the same for such small capacities? Like

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Pruthiraj Swain posted: Is Hydrogen based fuel cells comes under renewable sources of energy ? 1 year ago

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Narasimhan Santhanam . Hi Pruthiraj. Thanks for your question.

Technically, hydrogen cannot be classified as a renewable energy source, but more as an energy storage medium.

Why?

Consider the key renewable energy sources - solar, wind, biomass, geothermal etc. These are all present in nature around us, and all we need to do is to recover useful energy out of these (electricity from solar & wind, heat & biofuels from biomass, heat & power from geothermal).

On the other hand, hydrogen is not present around us in pure form, and hence has to be generated using other forms of energy - which could be renewable energy or a fossil energy source!

So, it can easily deduced that hydrogen is neither a direct source of energy, nor can it be definitively called renewable.

However, as a storage medium, hydrogen is a great idea. Solar & wind are infirm sources, so an effective way to make them reliable is to use them to generate hydrogen and recover this energy on demand.

Hope I made sense. Thanks again for asking.
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