How far must capital costs move to flip the sand-store versus heat-pump verdict, and is that more than the price year moves it?
research/energy-store-flip
How far must capex move to flip the sand-store vs heat-pump verdict? Weekly cycling flips on a 2 to 40% store-capex change (the cost table's own vintage step is 26%); daily cycling holds to 2 to 3.5 times.
What it found
Scales the PyPSA technology-data capital costs in the cost model of energy-thermal-real and bisects for the multiplier at which a house-sized sand store and an air-source heat pump cost the same, on real German day-ahead prices 2015–2019. Weekly cycling flips at 1.16, 1.20, 1.20, 0.59 and 1.02 times the store’s table capex, so the table’s own vintage step (1.257×) alone flips four of five years; daily cycling holds to 2.1–3.5×, monthly and seasonal never come close. With capex drawn uniformly within ±h (assumed, swept 0.10–0.50), the spread across price years (sd 0.0063 EUR/kWh) exceeds the cost spread at h = 0.10 (0.0039) and falls below it at h = 0.25 (0.0098). Five years, capex only, wholesale prices; h is an assumption, labelled; all other inputs are sourced.
Paper, code and results
More in Energy supply and dense energy storage
- How much can the sand store's heat exchanger cost before a heat pump wins again?How much can the sand store's heat exchanger cost? Weekly cycling survives about 120 to 270 EUR per kW in four of five price years; daily cycling survives 460 to 900; 2018 never wins.
- Does the sand-store versus heat-pump verdict survive a modelled electricity price instead of the real one?Does the sand-store vs heat-pump verdict survive a modelled price? Mostly: 32 of 40 cells agree with real prices (21 for the flat merit-order price), but weekly cycling, whose margin is under EUR 0.011/kWh, is wrong in sign in 5 of 5 years; as a charge scheduler the model costs under EUR 0.0011/kWh.
- How much cheaper must a store's electricity be than a heat pump's for a sand heat store to deliver heat for less?How much cheaper must electricity be for a sand heat store to beat a heat pump? Sourced costs (PyPSA technology-data) on the
energy-thermalmodel: a daily-cycled store needs the pump's electricity about 2 times dearer, weekly 5, monthly 16, seasonal 120 (house); the heat lost in standby, not the sand, rules out seasonal storage. - If a sand heat store buys electricity only in the cheap hours of a German price series, when does it beat a heat pump?When does a sand heat store beat a heat pump on hourly prices? With 189 GW solar and 137 GW wind and a modelled German price series, a daily or weekly store wins in all 5 years (EUR 0.027/kWh against 0.071); a levy of 0.10/kWh or a surplus-hour price above about 20–35 EUR/MWh removes the win.
- On real German day-ahead prices, does a sand heat store beat a heat pump, and was the modelled price right?On real German day-ahead prices, does a sand heat store beat a heat pump? Yes at wholesale: daily cycling wins in all 5 years (EUR 0.045–0.062/kWh against 0.070–0.074) and weekly in 4; the earlier merit-order model was flat at EUR 54.6/MWh and wrong; a EUR 0.10/kWh levy removes the win.
- How much is a home battery worth on a time-of-use tariff if it is dispatched optimally?How much is a home battery worth on a time-of-use tariff with optimal dispatch? An LP breaks even at $867/kWh for 10 kWh behind 6 kW PV, against $674 for the best fixed rule ($742 with a 4,000-cycle life); a rolling 36 h plan matches the year optimum (
energy-touwith an optimiser).
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Produced with AI assistance (Claude). Results are from the code in this repository and are simulated or stylised unless the abstract says otherwise; nothing here implies affiliation with or endorsement by any lab, researcher or company cited. MIT licensed.