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Nikhil Vinay posted: Many do not consider hydro power as renewable energy. Why is it so? 2 years ago

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Narasimhan Santhanam . Excellent question, Nikhil.

However, I might have to add a small rider - and it has to do with the term Renewable...because, this term and the term Alternative are sometimes used interchangeably...though technically they mean completely different things.

You see, most (if not all) industry professionals do not consider hydro power to be an alternative source of energy, and rightly so, because hydro power has been a conventional source of energy for very long - in fact, in many countries, the first units of electricity over a century back were generated from hydro power plants.

Thus, clearly, hydro power plants (small or large) are not alternative energy power plants.

But, are they renewable? Without a doubt, yes. Water is a renewable resource, and hence, it is a no-brainer that so is energy dependent on water.

So, folks are wrong when they do not include hydro power under Renewable Energy. They are however absolutely correct when they exclude it from Alternative Energy!

Here's a related post I put in the blog I run - Cleantech Guide. You might be interested in reading it when time permits.


Divya Prabha M.V . I have also heard about reservoirs associated with large hydro-electric projects being a major source of CO2 emissions. So hydel power is not exactly as green as we think it is. Please comment Like

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Gayathri Kumar posted: Why has biomass gasification based power generation not worked well for Indian villages even though IISc implemented many projects? 2 years ago

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Narasimhan Santhanam . @Gayathri - excellent and timely question. Thousands of Indian villages have little or no power, and the chances of the power grid reaching them anytime soon are remote.

So what are the quicker options to electrify these villages?

It necessarily has to be based on distributed energy sources.

Surely, solar can be thought of, and it is indeed being implemented in many villages. At the same time, solar is not a complete solution unless you include a lot of costly batteries as part of the package.

This is where biomass gasification comes in. Biomass power is firm power. And biomass gasification can work on small scales, using waste agro residues or forest residues available in the village. Looks like a perfect fit, doesn't it?

It indeed is.

But how come many of these small biomass gasifier based power generation projects in hundreds of Indian villages have failed?

Well, don't blame it on the biomass, and nor on the gasifier.

The failure of these projects have to do mainly with the poor maintenance of the system.

You see, biomass gasification based power generation works as follows: The biomass is fed to a gasifier, which gasifies the biomass and produces what is called as the Producer Gas, a low calorific value, organic gas. This gas can be fed to gas engines, power generators similar to diesel engines or natural gas engines. The producer gas engine generates power.

Simple. Or is it?

The gasifier in itself is a sturdy piece of equipment which requires little maintenance. But that is not the case with the gas engine.

The Producer Gas contains significant amounts of biomass tar. This can clog the filters of the gas engine - remember, the gas engines were originally built for natural gas and biomass, neither of which have biomass tar in them.

Anyway, the higher the amount of tar in the producer gas, the higher is the frequency with which the filters in the gas engine get clogged.

All these essentially imply that there needs be a regular cleaning of the filter of the gas engine. Now, while this is not a complex operation, it still needs a bit of training.

Such training, and subsequent maintenance, were what were lacking in the case of villages in India that were running the small scale gasifiers. Owing to their small size, it was difficult or impossible for a professional industrial team to visit hundreds of villages regularly just to clean the filters. The only way would have been to train the villages and form a self help group within the village who had the capability to undertake this maintenance work themselves.

Such a local training and sustainable maintenance has been attempted in a few villages, and I understand in these villages the gasifier based power generation programs have been successful. However, there are many villages that still depend on external experts to maintain the gasifiers, and in most of these villages the gasifier no longer operates.

Not a great story to write home about, but there it is.

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Pruthiraj Swain posted: Is Hydrogen based fuel cells comes under renewable sources of energy ? 2 years 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.


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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Divya Prabha M.V posted: Are the costs of battery storage coming down? How much will it be by 2020? 2 years ago

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