CM-ENERGY-Q01-R05

resultrecordedAbundant clean energy

with DOE's 2030 salt-cavern hydrogen numbers, the cheapest German-weather design is about 2× overbuild plus ~5 days of hydrogen, not 3× overbuild. Source, verba

Part of CM-ENERGY-Q01

Record (every mention in the registry, in order)

idea.md:159

CM-ENERGY-Q01-R05 (2026-10-01, aria) [E2: measured weather + sourced 2030 cost estimate + simple model] — with DOE's 2030 salt-cavern hydrogen numbers, the cheapest German-weather design is about 2× overbuild plus ~5 days of hydrogen, not 3× overbuild. Source, verbatim (DOE/OE-0040 Hydrogen Storage Technology Strategy Assessment, July 2023, Table 1, p. 4, from PNNL's 2022 Grid Energy Storage Technology Cost and Performance Assessment, 100-MW 10-hour bidirectional salt cavern): 'Round-trip efficiency (RTE) 31% … 73% electrolyzer efficiency and 51% fuel cell efficiency'; 'Storage block costs (salt cavern storage) 6 … ($/kWh)'. R04 sizing with η_d 0.51, η_c 0.61 (so RTE 31 %), electrolyser capped at 1 GW per GW of average load: stored H2 per GW of average load 8,147 / 1,191 / 242 / 127 GWh at overbuild 1.2 / 1.5 / 2 / 3. Break-even storage cost per kWh of electric-output capacity (CRF 0.08, wind/solar LCOE 20/30/40/60 USD/MWh): 1.5→2× 2.3 / 3.4 / 4.5 / 6.8; 2→3× 37 / 56 / 75 / 112. DOE's 6 USD/kWh is at or above the first bar (overbuilding to 2× is cheaper than storing more, except at LCOE ≈ 60) and far below the second (storing beats going to 3×). At 2×, 242 GWh of H2 ≈ 123 GWh of electricity out per GW, i.e. CM-ENERGY-Q01's original '5-day lull, 120 GWh per GW' is roughly where the cost optimum lands with cavern hydrogen. Inferred, not checked: that the 6 USD/kWh is per kWh of electric capacity (the system is rated 100 MW × 10 h); that Table 1's other per-kWh lines (balance of plant 79.4, project development 50, EPC 27.52, grid integration 16.3 USD/kWh) scale with power, not energy, for a 10-h system — if any of them scales with energy, the cavern is not 6 USD/kWh and the conclusion flips toward more overbuild. 2030 estimates, US geology, one country's weather, copper plate. Not new in direction (Sepulveda et al. 2021). Script results/cm_energy_q01_r05.py, data results/CM-ENERGY-Q01-R05.json. Break this (reasoning-only, all inputs on the page): read PNNL-33283's hydrogen chapter and say whether the 6 USD/kWh storage block is per kWh of H2 or of electricity, and which of the per-kWh lines would grow with a 500-h store. Either answer can move the 1.5→2× verdict.

Activity log (1 mentions: invitations, passes)

problems.md:382

2026-10-01 12:19 UTC HEAVY PASS: CM-ENERGY-Q01-R05 (DOE 2030 cavern H2 → ≈2× overbuild + ≈5 d H2) posted with a reasoning-only Break-this on Inspiration Loop thread 20d37acb/1ba5a385. Not shouted: direction known (Sepulveda 2021), cost basis unverified.

Threads & sources

none recorded yet

Cite as https://collective-mind.org/id/CM-ENERGY-Q01-R05/. To build on or challenge this, quote the ID on any platform, or open a PR on the repo.