Design Blueprint: A Hydrogen Power-to-Gas Store for a Small Town: Electrolyser Rating, Compressed-Gas Mass, Storage Volume and Full Round-Trip Loss for Five Thousand Usable Kilowatt-Hours

Design blueprint derived from the source paper (DOI 10.5281/zenodo.24173865): This paper sizes a hydrogen power-to-gas storage system for a small town requiring weekly balancing between windy and calm periods. The duty calls for 5e+03 usable electrical kilowatt-hours delivered at a rated power of 600 kilowatts. Working from a stated specific energy of 600 watt-hours per kilogram, an energy density of 450 watt-hours per litre, a usable depth-of-discharge fraction of 0.95, and a round-trip efficiency of 38 percent, the calculation gives a gross stored energy of 5.26e+03 kilowatt-hours, an active-store mass of 8.77e+03 kilograms, a complete system mass of 1.49e+04 kilograms, and a complete system volume of 1.99e+04 litres (19.9 cubic metres). Full discharge at rated power lasts 8.33 hours, and a full recharge takes 10.7 hours at the stated charge power. Losses amount to 5.29e+03 kilowatt-hours per complete cycle, appearing as heat at average rates of 248 kilowatts during charging and 318 kilowatts during discharge. Standing loss is 0.01 percent of the stored energy per day. Life is limited by the calendar limit, giving 5e+03 effective full cycles, about 20 years at the assumed cycling rate, and a lifetime delivered throughput of 2.5e+04 megawatt-hours. All values are computed from the stated assumptions; the system is a design study and has not been built or measured. Status: SIMULATED, NOT MEASURED. Status: DESIGN BLUEPRINT — SIMULATED, NOT MEASURED — NOT BUILT. All numbers are simulated values from the source paper's computation, deposited with this blueprint as compute.py and results.json. AI-use disclosure: Dave, an AI research system, assisted with the computation and drafting under the author's direction; author of record William Alexander Aldred.