Chairman Emeritus Reconnect 44 – “Energy Storage for Intermittent Renewables”

My dear friends,

Our Hon’ble Prime Minister Shri Narendra Modi has been announcing to the entire world that India has scaled up its plans from Mega Watts to Giga Watts in the arena of Renewable Energy in view of its environmental sustainability. The quantum jump being mentioned is 5,000 MW to 100,000 MW (100 GW) in respect of Solar Energy and 25,000 MW to 60,000 MW (60 GW) in respect of Wind Energy by 2022.

Such an ambition is not realizable without complementary energy storage of intermittent renewables. Both the above stated renewable energies are available only for 6-8 hours/day, not matching with peak load requirements and are further subject to seasonal variations. One of the basics of Power System is that the electricity must be generated at the precise moment it is demanded. It is the ultimate “just in time” system, where long-term inventory of electricity is denied. (Electricity can only notionally be stored in Capacitors and Inductors for a short time.) It cannot be stored in significant quantities but its converted forms like chemical energy in batteries, gravitational hydro potential energy etc, are possible to be stored.

Recent Cabinet Approval on Amendments in Tariff Policy

Recently the Union Cabinet has approved the proposal of the Ministry of Power for amendments in the Tariff Policy. For the first time a holistic view of the power sector has been taken and comprehensive amendments have been made in the Tariff policy 2006. The amendments are also aimed at achieving the objectives of Ujwal DISCOM Assurance Yojana (UDAY) with the focus on following 4 E’s:

  1. Electricity for all
  2. Efficiency to ensure affordable tariffs
  3. Environment for a sustainable future
  4. Ease of doing business to attract investments and ensure financial viability

Unfortunately the 5th E i.e. Energy Storage for Intermittent Renewables has been missed out. Cost of energy storage should have been built in to the Peaking tariff. This was not expected in the present scenario when we have a common Union Minister for Power and MNRE.

Recent R&D Council Meeting of the National Wind Energy Institute under MNRE

I attended the latest (Twenty-third) meeting of R&D council of the National Institute of Wind Energy (NIWE) held at Chennai on 30.12.2015 wherein their 10-Year Vision Plan was presented.

I pointed out that the renewables like wind and solar can become 24X7 power suppliers only when the appropriate Energy Storage systems are in place and hence a thrust be given for projects in developing Energy Storage systems, for renewables.

Pumped storage is one of the most promising options for energy storage in the form of hydro potential whose assessment in India is more than 96,000 MW of which not even 6,000 MW has been harnessed so far. Almost all (>99%) of power-grid-scale energy storage in the world today is pumped-hydroelectric.

However, Pumped storage is also undergoing a conceptual transformation. Rivers and dams are no more required. Sea water can be used as pumped storage media in novel approaches and “swinging door algorithm” pumped storage becomes a big battery analog for wind farm energy storage. Even an exhausted mine can be used as lower reservoir, if you can find a small water pond at a higher elevation nearby. There are many such novel systems that would revolutionize the energy storage spectrum and need immediate focus and practical green field pilots.

It was agreed in the Committee that a new group for “Energy Storage” would be created in NIWE, reflecting it as an essential ground-breaking component in the 10-Year R&D Vision Plan.

There is no future for Wind Energy Sector (and so also the SPV) without “Energy Storage”. Its importance is more than the “Solar-PV Hybrid” which can only expand the electricity supply period in a day to an extent, not necessarily matching with the Grid demand. It may however facilitate more land space for PV.

With “Energy Storage” component, the load demand can be met much better, right from cyclic stability to daily demand pattern to even seasonal demands. Without Energy Storage component Wind Energy & SPV can never be accepted as viable options for energy supply due to their intermittent nature. The cost of energy storage system has to reflect in the peaking tariff of energy supply. Higher absorption of renewable energy round the clock on the other hand may reduce its cost of supply.

There are four basic options in Energy Storage:

  1. Mechanical→Pumped Storage (Seasonal balance), Compressed Air (Daily stability), Flywheel (cyclic stability)
  2. Chemical→Batteries, Hydrogen (Electrolysers), Fuel cells
  3. Electrical→Double Layer Capacitor, Superconducting Magnetic Coil
  4. Thermal→Heat Storage (Molten Salt), for stability in heating systems or re-conversion in to electricity

The above options may suit different sets of wind farms & SPV stations and their connecting sub-stations to supply 24×7 and more specifically as per grid demand and the environment around.

I hope, all concerned wake up to the urgent need of Energy Storage in our country!

Satyamev Jayate !!!

Best wishes and Regards,

Dr. B.S.K.Naidu

BE(Hons), M.Tech., Ph.D., CBI-Scholar, D.Engg. (Calif.), FNAE, Hon.D.WRE (USA)
Chairman Emeritus, Great Lakes, Gurgaon, NCR, New Delhi, INDIA
Former Director General (NPTI & CPRI / REL), Ex. Director (REC) / Executive Director (IREDA)

No job is small or big, the way in which you do, makes it small or big (c)

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