Small-Scale Compressed-Air Energy Storage for a Village or Workshop: A First-Principles Design, Efficiency and Cost Test

Design and first-principles test of small-scale compressed-air energy storage using cheap pressure vessels (repurposed LPG tanks, buried steel pipe, well casing) charged by surplus solar or wind, sized for evening lighting and phone charging for 50 households (3.00 kWh delivered per evening). SIMULATED, NOT MEASURED; nothing was built or hardware-tested. One cubic metre at 20 bar gauge holds 1.213 kWh of isothermal work but yields 0.628 kWh in adiabatic blowdown. Round-trip efficiency is 15.9 percent without heat storage and 28.3 percent with it. Levelised cost is $1.545 per delivered kWh for the buried-pipe design and $4.974 for repurposed LPG tanks (142 tanks needed), against $0.687 for lead-acid and $0.324 for lithium iron phosphate. Even with a free vessel, machinery alone costs $1.123 per delivered kWh. The paper states the narrow conditions where the design wins and the pressure-vessel safety boundaries in plain terms.