A Density-Capped Compressed-Air Energy Storage Vessel

The module set out in this paper is a density-capped compressed-air storage vessel intended for shifting wind generation into evening demand at a small installation. Its operating principle is that a steel vessel stores energy as compressed air, and its working pressure is set so that the stored density sits at a stated, very small fraction of the density bound, giving an explicit and auditable margin in the design basis. The design is computed from stated assumptions throughout; it is simulated, not measured, and no prototype results are reported. The headline result is a usable stored energy of 0.7 GJ, obtained with charge pressure of 20 MPa with a computed efficiency or performance coefficient of 55 per cent where that measure applies, for a unit of mass 9.8e+03 kg whose characteristic scale is a vessel volume of 12 m^3. A parameter sweep reported in the Results section shows how the output moves when the principal variable is changed, and the density of the working material, 238 kg per cubic metre, sits about 55.6 orders of magnitude below the neutron-carrier density bound of 9.72e+57 kg per cubic metre, so the bound enters this design as a sizing ceiling and a margin statement rather than as an operating condition. The limitations are stated plainly: round-trip efficiency is limited by compression heat loss; the isothermal figure is an upper estimate and the usable figure already discounts it substantially. Status: SIMULATED, NOT MEASURED.