OUR POWER WOES | Addressing the Peak Demand

Pumped storage schemes store energy using two interconnected reservoirs with one at a higher elevation than the other. Water is pumped to the upper reservoir during daytime using solar energy and during periods of peak demand of energy water from the upper reservoir is released, generating electricity as it passes through turbines to the lower reservoir
OUR POWER WOES | Addressing the Peak Demand
Come winter and we would continue to suffer both the scheduled as well as unscheduled power cuts. However, last winter the power situation was well managed and generally the load shedding was within acceptable range. File: Mubashir Khan/ GK

Every summer one used to read the news about the augmentation of our power transmission and distribution infrastructure with the concluding remarks suggesting that the power supply scenario will see a vast improve in coming winter.

Come winter and we would continue to suffer both the scheduled as well as unscheduled power cuts. However, last winter the power situation was well managed and generally the load shedding was within acceptable range.

However, the goodwill created by JKPDD during the winter seems to have been lost in the last few weeks because of heavy and unannounced load shedding particularly during peak hours.

It is only very recently that the power supply situation has shown improvement.

Author

One of the key issues in supplying uninterrupted power is the high demand during peak hours. It is time our power engineers seriously explore the various alternatives to address our future energy demands and ensure uninterrupted 24x7 power supply.

One of the possible solutions towards addressing the peak energy demand could be to explore the construction of hybrid pumped storage schemes - traditional pumped storage schemes but with the pumps being energised by solar power plant rather than by power from the grid.

While all of us are generally familiar with hydro power and solar power it might be worthwhile to briefly explain what a pumped storage scheme is and how it works.

A pumped storage scheme is a type of hydro power plant which, in simple terms, has two reservoirs (one at the top and another at the bottom) and its turbines are designed to also act as pumps.

Reversible pump-turbine/motor-generator assembly in the scheme which can act as either a pump or as a turbine depending on the use one wants to put it to. A pumped storage scheme is capable of generating electricity or of pumping water (from lower reservoir to upper reservoir).

When the demand for energy is high the scheme is operated as a generating station wherein it generates electricity as water flows, through the turbines, from upper reservoir to lower reservoir where the water is then stored till it is pumped back into the upper reservoir.

During the period of low demand (when surplus energy is readily available) the scheme is operated as a pumping station. Energy supplied by an external source (i.e. the grid) is used to pump water back from the lower reservoir to the upper reservoir to be eventually used for generating energy during periods of high demand. In that respect pumped storages act as giant battery packs or power bank since they can store energy and release it when needed.

Pumped storages have been in use in west since last 130 years and there are some such schemes in India as well - a large, pumped storage scheme (1000 MW) is nearing completion in Tehri, Uttarakhand.

Unlike the plains, our mountainous topography and terrain is particularly suited to construction of reservoirs required for pumped storage schemes. The reservoirs could be located on tributaries of our rivers or other topographically and geologically suitable locations.

Though pumped storage schemes are a net consumer of electricity they have several advantages particularly their ability, like any hydroelectric plant, to respond to potentially large electrical load changes within seconds. Traditional pumped-storage facilities are very attractive in a differential tariff regime where non peak period energy is cheaper than peak period energy.

In our context while in summers the energy situation generally is not bad, in winter months, particularly in Kashmir valley, we suffer the double whammy in that we have a huge increase in demand coupled with very low generation from the hydro plants.

In such a scenario we are unlikely to ever have surplus energy from the grid to pump the water from the lower reservoir to the upper reservoir so as to operate a pumped storage scheme in generation mode during peak periods.

To make energy available for pumping we could set up solar power generating facilities in the vicinity of these reservoirs which will provide the required energy during the daytime (non peak period) to pump the water up from the lower reservoir into the upper reservoir.

Since a different source of energy is used for pumping hence the term hybrid pumped storage schemes is used. During the daytime solar panels would generate the power required to pump water from lower reservoir to the higher reservoir.

The same water would then be released to generate energy to augment the grid power supply to address the demand of the two daily peaks; morning peak from say 7 am to 8.30 am and evening peak from 6 pm to 10 pm.

As a matter of fact, in one of my earlier articles on flood mitigation in Kashmir valley I had suggested construction of a series of small dams or reservoirs in cascade on the main rivers as well as on their tributaries which could provide flood moderation.

These same reservoirs in cascade could be suitably designed to act reservoirs for pumped storage as well. In fact, these reservoirs would be like multipurpose schemes in that they would help in flood moderation, sediment control and at the same time augment our power generation particularly in periods of peak demand.

Besides, the area around them could be developed as recreational and tourist spots.

Some may argue that since during winter the days are short (hence shorter duration of day light), that days are more gloomy or cloudy (less intense daylight) and that during snowfall the solar panels would be covered by snow, all of which are likely to reduce the operational efficiency of the solar power facility.

While all the above are very relevant, one can always find ways and means of mitigating the impact of these concerns.

Disclaimer: The views and opinions expressed in this article are the personal opinions of the author.

The facts, analysis, assumptions and perspective appearing in the article do not reflect the views of GK

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