Solar-Powered Thermal Battery by IIT Bombay

GS3 – Science & Technology

Context

Researchers at IIT Bombay have developed an innovative solar-powered thermal battery that captures and stores solar heat in summer for use during the cold Himalayan winters.

What is a Solar-Powered Thermal Battery?

A device that stores solar thermal energy chemically for long durations and releases it as heat when needed. It uses:

• Solar thermal collectors: Capture and concentrate sunlight to heat air
• Reactor chamber: Filled with strontium bromide (SrBr₂)
• Air circulation system: Regulates chemical reactions for charging and discharging

Technology Base:

• Based on Thermochemical Energy Storage (TCES) — unlike sensible (hot water) or latent (phase change) storage, this stores energy via chemical reactions

Role of Strontium Bromide (SrBr₂)

• Why chosen?
  • High energy density
  • Chemically stable and non-toxic
  • Not explosive and environmentally safe
• Nature:
  • A white, crystalline compound
  • Also used in flares and pharmaceuticals

How It Works

1. Charging Phase (Summer – Energy Storage)

• Solar collectors heat the air
• Heated air is passed over hydrated strontium bromide
• The salt dehydrates (endothermic reaction), storing energy in chemical form

2. Discharging Phase (Winter – Heat Release)

• Moist air is passed through dehydrated salt
• Salt rehydrates (exothermic reaction), releasing the stored heat
• This heat is used for space heating, especially useful in Himalayan winters

 Significance & Potential Impact

• Seasonal Storage: Can retain heat for months, enabling summer-to-winter energy use
• Sustainable Alternative:
  • Replaces diesel heaters and firewood in Himalayan homes
  • Reduces pollution, cost, and carbon footprint
• Clean Energy Innovation:
  • Makes use of abundant solar radiation during summers
  • Ideal for remote, off-grid regions

 About Thermochemical Energy Storage (TCES)

• Working Principle:
  • Stores energy through reversible chemical reactions
  • Involves bond-breaking (charging) and bond-forming (discharging) processes
• Phases of Operation:

• • 1. Charging (Dehydration)
    2. Storage
    3. Discharging (Rehydration)

• Advantages:
  • Minimal energy loss over time
  • More efficient than conventional thermal storage for long durations
• Global Status:
  • Piloted in Germany and other countries
  • In India, practical deployment is still in pilot/testing stage