On real German day-ahead prices, does a sand heat store beat a heat pump, and was the modelled price right?
research/energy-thermal-real
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.
What it found
Re-runs energy-thermal-hourly on the actual hourly German day-ahead price, 2015–2019 (OPSD/ENTSO-E; annual means 29–44 EUR/MWh, 66–211 negative-price hours a year), with the store and heat-pump costs of energy-thermal-cost unchanged. At wholesale prices a house-sized sand store cycled daily beats an air-source heat pump in all five years (EUR 0.045–0.062 against 0.070–0.074 per kWh of heat) and weekly in four of five; monthly and seasonal storage lose even at a negative break-even price. The earlier one-fuel merit-order model, rebuilt with each year's installed solar and wind, has no surplus hour and prices every hour at EUR 54.6/MWh, so its conclusion that the store loses with today's fleet came from the model, not the market. A levy of EUR 0.10/kWh on both prices removes the win in every case. Not from a source: the charge window (a quarter of each cycle, swept), flat winter heat demand, the levy (swept), perfect foresight within each cycle. Wholesale prices only; no taxes, network charges or retail margin.
A figure from its own output
Paper, code and results
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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.