# Regenerative braking and motion recovery: Correlation Prices it moves with, and why Source page: https://www.materialinsights.org/energy/e_regen_braking/correlation/ Regenerative braking reuses the drive motor as a generator, so its cost lies in motors, inverters and somewhere to store the energy: batteries, supercapacitors or flywheels. Its value rises with electricity and fuel prices and with stop-start duty. No public price Regenerative braking and motion recovery has no public monthly price series: A feature inside vehicles and drives; not sold or priced alone. #### What its price moves with Energy [EV Electric and hybrid vehicles](https://www.materialinsights.org/energy/e_evs/)Main use Every electric and hybrid car recovers braking energy through its motor, extending range. Growth in electric vehicles is therefore the main driver of this technology. Regenerative braking has no price series, so no statistics are shown. Not enough overlapping price history to measure. Energy [Rail Rail traction](https://www.materialinsights.org/energy/e_rail_traction/)Main use Electric trains and metros feed braking energy back into overhead lines or onboard stores, saving a large part of their power where stops are frequent. Metro systems in India and elsewhere specify it as standard. Not enough overlapping price history to measure. Energy [SC Capacitors and supercapacitors](https://www.materialinsights.org/energy/e_supercaps/)Energy store Supercapacitors absorb and release braking energy in seconds and survive millions of cycles, which suits buses, trams and cranes. Their cost and energy density decide how much braking energy can be kept. Not enough overlapping price history to measure. Energy [LFP Lithium iron phosphate batteries](https://www.materialinsights.org/energy/e_li_lfp/)Energy store Lithium iron phosphate batteries store braking energy in buses, hybrids and electric cars and tolerate frequent cycling. Falling battery prices have made regenerative systems cheaper to fit. Their long cycle life suits the constant charging and discharging that braking recovery demands. Not enough overlapping price history to measure. Energy [Mot Electric motors and drives](https://www.materialinsights.org/energy/e_motors/)Core machine The same motor that drives a vehicle or lift acts as a generator under braking, so no extra machine is needed. Motor and inverter cost, rather than any special part, sets the price of recovery. Not enough overlapping price history to measure. Commodity [REE Rare earths](https://www.materialinsights.org/commodities/rare_earths/)Magnet material Permanent-magnet motors, which recover braking energy efficiently, use neodymium magnets. Rare earth supply, dominated by China, therefore affects the cost of many regenerative systems; rare earths have no price series here. No public price for rare earths, so the link is explained in words only. 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_regen_braking/index.md) - [Overview](https://www.materialinsights.org/energy/e_regen_braking/overview/index.md) - [Science and thermodynamics](https://www.materialinsights.org/energy/e_regen_braking/rc-sci/index.md) - [Engineering and integration](https://www.materialinsights.org/energy/e_regen_braking/rc-eng/index.md) - [Economics and contracts](https://www.materialinsights.org/energy/e_regen_braking/rc-econ/index.md) - [Impact and additionality](https://www.materialinsights.org/energy/e_regen_braking/rc-impact/index.md) - [What to track](https://www.materialinsights.org/energy/e_regen_braking/tracking/index.md) - [Relationships](https://www.materialinsights.org/energy/e_regen_braking/links/index.md)