# Sensible heat storage: Correlation Prices it moves with, and why Source page: https://www.materialinsights.org/energy/e_sensible_heat/correlation/ Sensible heat storage keeps heat in water, rock, sand, concrete or molten salt by raising its temperature. Costs depend on the cheap storage material, tanks and insulation, and on the gap between cheap and dear energy. No public price Sensible heat storage has no public monthly price series: Built into plants and buildings; no separate market price. #### What its price moves with Commodity [K Potash](https://www.materialinsights.org/commodities/potash/)Molten salt Solar thermal plants store heat in a mix of sodium and potassium nitrates. Potassium nitrate relies on potash, so filling a large salt tank ties storage costs to fertiliser markets that farmers also draw on. Not enough overlapping price history to measure. Chemical [HNO3 Nitric acid](https://www.materialinsights.org/chemicals/nitric_acid/)Nitrate salts The nitrates in solar salt are made with nitric acid or mined from natural nitrate deposits. Nitric acid follows ammonia and gas costs, which feed into the price of molten salt. Not enough overlapping price history to measure. Commodity [Stn Crushed stone](https://www.materialinsights.org/commodities/crushed_stone/)Storage medium Rock beds and sand batteries use crushed rock or sand, among the cheapest materials available. Their low cost makes them attractive for storing industrial heat at large scale, where tank and insulation costs dominate. Not enough overlapping price history to measure. Commodity [H₂O Water](https://www.materialinsights.org/commodities/water/)Storage medium Hot water tanks are the commonest heat store, from home cylinders to large tanks in district heating. Water is cheap, so the cost lies mainly in the tank, insulation and space. Not enough overlapping price history to measure. Energy [CSP Concentrated solar power](https://www.materialinsights.org/energy/e_csp/)Main user Concentrated solar power plants pair mirrors with molten salt tanks so they can keep generating after sunset. Their growth is the main driver of demand for very large heat stores and nitrate salts. No public price for concentrated solar power, so the link is explained in words only. Energy [EH Electric heating](https://www.materialinsights.org/energy/e_electric_heat/)Charging Electric heaters charge many stores using cheap off-peak or surplus renewable power. Cheap resistance heating makes storing heat simpler and cheaper than storing electricity itself, which is why industry is testing heat batteries. Not enough overlapping price history to measure. How to read these numbers **Correlation of monthly changes** (the number in the coloured pill) compares how much each price moved, month by month, since 2006 or the first month both series exist. It runs from −1 to +1: near +1 the two usually rise and fall in the same months, near 0 there is no link, and a negative number means they tend to move in opposite directions. Above 0.7 is strong, 0.4 to 0.7 moderate, 0.2 to 0.4 weak. **12-month changes** compare year-on-year moves, which shows whether two prices share the same cycles even when the month-to-month noise differs. **Price function** is a straight-line fit of the two prices on logarithmic scales: price ≈ k × (partner price)^β. β is how much this price moves, in per cent, for a 1% move in the partner over the whole period, and R² is the share of the variation the fit explains. Two prices that both drift up with inflation can fit well without any real link, so read it together with the monthly correlation. **Lead or lag** checks whether the monthly correlation is clearly higher when one price is shifted by 1 to 6 months. Correlation is not cause. The reasons on each card explain the economic link; the numbers show how strongly it has shown up in prices. Proxy series are US producer price indexes or related prices and can blur the real link. Data: World Bank Commodity Price Data (Pink Sheet), October 2026; US Bureau of Labor Statistics producer price indexes, IMF primary commodity prices and US EIA prices via FRED, Federal Reserve Bank of St. Louis, retrieved November 2026. Calculations by this site. ## Other sections - [Summary](https://www.materialinsights.org/energy/e_sensible_heat/index.md) - [Overview](https://www.materialinsights.org/energy/e_sensible_heat/overview/index.md) - [Science and technology](https://www.materialinsights.org/energy/e_sensible_heat/sg-sci/index.md) - [Engineering and performance](https://www.materialinsights.org/energy/e_sensible_heat/sg-eng/index.md) - [Economics](https://www.materialinsights.org/energy/e_sensible_heat/sg-econ/index.md) - [Impact and additionality](https://www.materialinsights.org/energy/e_sensible_heat/sg-impact/index.md) - [What to track](https://www.materialinsights.org/energy/e_sensible_heat/tracking/index.md) - [Relationships](https://www.materialinsights.org/energy/e_sensible_heat/links/index.md)