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Relevance: GS Paper III — Science & Technology, Renewable Energy Source: The Hindu

1 · The Breakthrough

Imagine trapping sunlight in a bottle and releasing it as heat months later. A team led by Prof. Grace Han  and Prof. Kendall Houk did just that, publishing their work in Science in early 2026.

They used a lab-engineered molecule called 2-pyrimidone, inspired by how our DNA reacts to sunlight. When hit by ultraviolet (UV) light at 300 nanometres, this molecule folds into a tight, high-energy shape called a Dewar isomer. It traps the sun’s energy inside its chemical bonds for months.

Impressively, it stores 1.65 megajoules per kilogram (MJ/kg)—which is nearly double the energy density of a standard lithium-ion battery (0.9 MJ/kg)!

2 · How “MOST” Energy Storage Works

Molecular Solar Thermal (MOST) technology turns a liquid molecule into both a solar panel and a battery. Sunlight forces the molecule to fold like a coiled spring. It stays locked in this shape until a tiny chemical trigger makes it snap back, releasing the trapped energy as pure heat.

DNA Inspiration
Turning sunburn into a battery
When UV light hits human skin, it damages DNA by twisting its “pyrimidine” bases into folded Dewar shapes. Scientists copied this exact shape-shifting trick, turning a natural biological problem into a brilliant energy-storing solution.
The Shape-Shifter
Trapping energy at 300 nm
At 300 nm (ultraviolet light), the flat molecule folds into a strained 3D shape. The extreme tension in its chemical bonds acts like a locked vault, holding the sun’s energy for a long time without leaking heat.
Heat on Demand
Boiling water in one second
How do we get the heat out? Adding a tiny drop of hydrochloric acid (HCl) acts as a key. In a lab test, this triggered the molecule to snap back, heating water to a boiling 100°C in just one second!
The Catch
Only drinks UV light
Currently, the molecule only absorbs UV light, which makes up just 4-5% of sunlight. Also, some energy escapes before the molecule can fully fold. Scaling this up cheaply is the next big challenge.
  • Why India needs this: India’s solar capacity hit 155 GW by May 2026, but storage remains tough. A lithium-free liquid battery is perfect for off-grid cooking and water heating in sunny states like Rajasthan and Ladakh.
  • A perfect match for rooftops: Standard solar panels use visible light. Because this liquid only drinks UV light, both technologies can share a roof without competing for the same sun rays.
  • Safer than Lithium: Lithium-ion batteries leak electrical charge and can catch fire. This liquid stores energy safely in chemical bonds at room temperature, with zero electrical leakage.
  • India’s floating solar potential: A June 2026 report by the National Institute of Solar Energy (NISE) notes India’s floating solar (FSPV) potential is around 102 GW, contributing to a massive total solar potential of 3,445 GW.

UPSC Prelims Quick Facts
Molecular Solar Thermal (MOST) A system where a molecule absorbs sunlight, changes shape to store it, and later releases it as heat.
Isomerisation When a molecule changes its physical shape without changing its chemical formula.
Pyrimidine bases & Dewar isomer Pyrimidine bases are building blocks of DNA. A Dewar isomer is the folded, high-energy shape they take when exposed to UV light.
Megajoule (MJ) A unit of energy. This new molecule stores 1.65 MJ/kg, double that of commercial Li-ion batteries.
NISE & Omkareshwar Park NISE is India’s top solar research institute (not a statutory body). Omkareshwar (MP) is India’s largest floating solar plant.

MCQ Practice
Q. Consider the following statements about MOST energy storage:

  1. The 2-pyrimidone molecule absorbs sunlight, folds into a Dewar form, and stores energy inside its chemical bonds.
  2. 2-pyrimidone is a natural alkaloid extracted from a plant, which makes this storage system highly biodegradable.
  3. Unlike regular solar panels that generate electricity, a MOST system releases solar energy directly as heat.

Which of the statements given above is/are correct?
(a) 1 and 2 only    (b) 2 and 3 only    (c) 1 and 3 only    (d) 1, 2 and 3
Answer: (c) 1 and 3 only

  • Statement 1 — Correct: It absorbs UV light (300 nm) and changes into a high-energy Dewar shape to trap the energy.
  • Statement 2 — Incorrect (UPSC Trap): 2-pyrimidone is not an alkaloid or a plant extract. It is a completely synthetic (lab-made) nitrogen compound inspired by the structure of human DNA.
  • Statement 3 — Correct: While silicon solar panels make electricity, a MOST system releases heat directly, which is highly useful for boiling water or cooking without needing grid power.
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