Energy Storage, Fuel Cells and Green Hydrogen

Prerequisites

• Renewable Energy Technology: why solar and wind are intermittent.
• Chemistry in Everyday Life: oxidation, reduction and electrolysis are the chemistry behind batteries and hydrogen.
• Mineral Resources of Chhattisgarh: Katghora lithium, the state’s link to the battery story.

The Hook: Sunshine at 8 p.m.

Why it matters: Prelims asks how batteries and fuel cells work, the colours of hydrogen, which minerals batteries need and the targets of the Green Hydrogen Mission. Mains GS-II asks about storage and hydrogen as enablers of the energy transition.

Why Storage Is Needed

1. Intermittency: solar follows the day; wind follows seasons (strongest in the south-west monsoon).
2. Mismatch of timing: demand peaks in the evening, after solar output falls. Grid planners call the resulting net-demand curve the “duck curve”: a dip at midday and a steep ramp at sunset.
3. Grid stability: the grid must hold its frequency close to 50 Hz. Storage can inject or absorb power in seconds.
4. Firm renewable power: pairing solar with storage lets a project supply power round the clock, like a conventional plant.

Types of storage

Pumped Storage Projects (PSPs)

graph TD
    A["Surplus power (noon solar)"] --> B["Pump water from lower reservoir
to upper reservoir"]
    B --> C["Energy stored as
potential energy of water"]
    C --> D["Evening peak: release water
through turbine"]
    D --> E["Electricity back to grid"]
    E --> F["Water returns to
lower reservoir"]
    F --> B

• The same machine works as a pump (using power) and as a turbine-generator (producing power).
• Round-trip efficiency is roughly 70–80%: some energy is always lost, but cheap noon power is turned into valuable evening power.
• India (as of May 2026, CEA): 10 PSPs with about 7,425.6 MW in operation, about 15,870 MW under construction. The largest operating plant is Pinnapuram (1,680 MW, Andhra Pradesh); others include Sardar Sarovar (Gujarat), Tehri (Uttarakhand), Srisailam, Purulia (West Bengal), Nagarjunasagar and Kadamparai (Tamil Nadu).
• Off-river (closed-loop) PSPs build two reservoirs away from a main river, reducing ecological impact.
• Strengths: long life (decades), large scale, proven technology. Limits: suitable hilly sites, land, long construction time.

Batteries (बैटरी)

A battery stores energy as chemical energy and releases it as electricity through redox reactions. Each cell has an anode (negative), a cathode (positive), an electrolyte that carries ions, and a separator. During discharge, electrons flow through the outer circuit while ions move through the electrolyte. Charging reverses the process.

Battery energy storage systems (BESS) are large banks of batteries, usually LFP, connected to the grid or to a solar park.

The critical-minerals problem

Li-ion batteries need lithium, cobalt, nickel, graphite and manganese. India imports nearly all of its lithium and cobalt, mostly as finished cells. Responses include critical-mineral auctions, overseas acquisitions through KABIL, recycling, and chemistries (LFP, sodium-ion) that avoid scarce metals.

Chhattisgarh angle: Katghora (कटघोरा) in Korba district was India’s first lithium block to be auctioned (June 2024). Do not describe it as a producing mine. The state’s coal-and-steel economy makes storage and hydrogen important for its own transition.

Fuel Cells (ईंधन सेल)

A fuel cell converts the chemical energy of a fuel (usually hydrogen) and oxygen directly into electricity, without burning it.

• At the anode, hydrogen splits into protons and electrons. Electrons flow through the external circuit (the current); protons pass through the electrolyte membrane; at the cathode they combine with oxygen to form water.
• The only exhaust is water vapour, so a hydrogen fuel-cell vehicle has zero tailpipe emissions.
• A fuel cell keeps producing power as long as fuel is supplied; a battery must be recharged.

Battery EV vs fuel-cell EV: a battery EV stores electricity directly and is more efficient overall; a fuel-cell EV refuels in minutes and carries more energy for its weight, which suits long-haul trucks and buses.

Hydrogen (हाइड्रोजन) as an Energy Carrier

Hydrogen is the lightest element. It carries more energy per kilogram than any fuel, but very little per litre as a gas, so it must be compressed, liquefied or converted into another compound for storage. It is an energy carrier, not a primary source: energy must be spent to make it.

The colours of hydrogen

Electrolysis

Electrolysis uses electricity to split water: \( 2\,\mathrm{H_2O} \rightarrow 2\,\mathrm{H_2} + \mathrm{O_2} \). It is the reverse of a fuel cell.

Storing and moving hydrogen

• Compressed gas in high-pressure tanks.
• Liquid hydrogen, cooled to about −253 °C, which costs a lot of energy.
• Carriers: convert it to green ammonia or methanol, or bind it in liquid organic carriers, then recover it later.
• Problem: hydrogen leaks easily (tiny molecule) and can make some steels brittle (hydrogen embrittlement).

Uses

Analysis for Mains

Storage: the missing piece of the transition

1. Without storage, more solar means more midday surplus and a steeper evening ramp, forcing coal plants to cycle up and down.
2. Pumped hydro offers cheap, long-life bulk storage; batteries offer speed and can be sited anywhere. They complement each other.
3. Challenges: cost; mineral imports; fire safety; recycling; long project timelines for PSPs.
4. Policy tools: VGF for BESS, PLI for cells, storage obligations for distribution companies, time-of-day tariffs that reward evening supply.

Green hydrogen: promise and caution

1. Promise: decarbonises “hard-to-abate” sectors (steel, fertiliser, refining, shipping) that electricity alone cannot easily reach; cuts gas and ammonia imports; export opportunity.
2. Caution: green hydrogen is still costlier than grey; electrolysis loses a large share of input energy; it needs water (about 9 litres per kg of hydrogen in theory, more in practice) and huge renewable capacity; infrastructure for storage and transport is new.
3. Right use: use hydrogen where direct electrification is hard, and use batteries and direct electricity where it is easy.

Memory Tricks

Don’t Confuse

Common Mistakes

Practice

All questions below are original practice questions written in CGPSC style. They are not previous-year questions.

Level 1: Foundation

1. The only exhaust from a hydrogen fuel cell is ________.
2. Hydrogen produced by electrolysis using renewable electricity is called ________ hydrogen.
3. The largest operating pumped storage project in India (2026) is ________ in Andhra Pradesh.

Level 2: Prelims MCQs

Q1. Consider the following statements about hydrogen:

1. Most hydrogen produced today is made from natural gas by steam methane reforming.
2. Under India’s Green Hydrogen Standard, green hydrogen must have emissions of not more than 2 kg CO₂-equivalent per kg of hydrogen.
3. A fuel cell produces hydrogen by passing electricity through water.

Which of the statements given above is/are correct?

• (a) 1 only
• (b) 1 and 2 only
• (c) 2 and 3 only
• (d) 1, 2 and 3

Q2. Match List I (Hydrogen type) with List II (Production route):

• (a) A-2, B-1, C-3, D-4
• (b) A-3, B-2, C-1, D-4
• (c) A-2, B-3, C-1, D-4
• (d) A-2, B-3, C-4, D-1

Q3. Which one of the following is the main reason lithium iron phosphate (LFP) batteries are preferred for grid-scale storage?

• (a) They have the highest energy density of all battery types
• (b) They are safer, last longer and need no cobalt or nickel
• (c) They store energy in liquid electrolytes held in external tanks
• (d) They work without any electrolyte

Q4. Which of the following ports were recognised as green hydrogen hubs by MNRE in 2025?

1. Deendayal (Kandla)
2. Paradip
3. V.O. Chidambaranar (Tuticorin)
4. Jawaharlal Nehru Port (Nhava Sheva)

Select the correct answer using the code given below:

• (a) 1 and 2 only
• (b) 1, 2 and 3 only
• (c) 2, 3 and 4 only
• (d) 1, 2, 3 and 4

Level 3: Mains Answer Writing

Q1. (60 words) What is a fuel cell? How does it differ from a battery?

Q2. (150–200 words) “Energy storage is the key to India’s renewable energy future.” Discuss with reference to the technologies available and the policy support.

Quick Revision Table

Key Takeaways

What’s Next

• Nuclear Energy: reactors, the fuel cycle and India’s three-stage programme
• Energy Resources — Quick Revision: the whole chapter on one page
• Industries and Transport (Geography): steel and fertiliser, the big future users of hydrogen
• Environmental Pollution and Waste Management: e-waste and battery waste rules