How much can the sand store's heat exchanger cost before a heat pump wins again?

research/energy-store-hx

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.

6 tests

What it found

The sand-store versus heat-pump comparisons leave out the equipment that takes heat out of the sand. No sourced sand-to-water exchanger price is in the cost table, so the price (EUR per kW of peak discharge) is solved for rather than assumed: the break-even at which the store stops beating the air-source pump on German prices and ERA5 weather 2015–2019, house scale, 45 °C sink. Weekly cycling survives an exchanger of 211, 241 and 274 EUR/kW in 2015–2017 and 123 in 2019; 2018 loses even with a free exchanger. Daily cycling survives 460–901 EUR/kW. At 100 EUR/kW the exchanger adds 0.0032 EUR/kWh. The break-even halves if the house is sized for 1,000 full-load hours. Not from a source: the exchanger price (swept), the 2000-hour peak rule, and the exchanger's lifetime and O&M, borrowed from the sand charger row; the sand-side discharge limit is not modelled.

A figure from its own output

Figure produced by research/energy-store-hx: breakeven — energy-store-hx/experiments/breakeven.svg, written by the project's own experiment code.

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.