# Pressure and flow recovery

Turning surplus gas or water pressure into power.

Source page: https://www.materialinsights.org/energy/e_pressure_recovery/

Recovery and reuse · Pressure, motion and waste fuels · No. 131

- Recovery and reuse
- Waste energy: Pressure
 Recovery and reuse · Pressure, motion and waste fuels · Foundation · Energy

A ceramic rotor in desalination plants hands brine pressure back to incoming seawater at up to 98% efficiency.

Chart: Illustration: Pressure and flow recovery

##### Where it comes from

Chart: Map of where it comes from

Wherever pressure is thrown away across a valve, a turbine or exchanger can catch it: city gas stations dropping 70 to 20 bar, water mains, and brine leaving reverse osmosis membranes.

##### Three things to know

1. Gas cools about 0.5 C per bar as it expands, so one modelled 2 MW expander needed 1,980 kW of extra preheat.
2. Compressors turn 80-93% of their input into heat; a 100 bhp unit's recovered heat saved about USD 6,975 a year.
3. Small in-pipe hydro is slow to pay: Manitou Springs in Colorado expected 12 to 14 years.

##### The journey

1. 1 **Surplus pressure**Gas mains, water pipes or RO brine
2. 2 **Bypass loop**Turbine sits beside the old valve
3. 3 **Expander or exchanger**Pressure becomes shaft work or transfers directly
4. 4 **Preheat**Gas must be warmed as it expands
5. 5 **Output**Electricity, or cheaper fresh water

##### Go deeper pick a tab to open it in full

## Other sections

- [Overview](https://www.materialinsights.org/energy/e_pressure_recovery/overview/index.md)
- [Correlation](https://www.materialinsights.org/energy/e_pressure_recovery/correlation/index.md)
- [Science and thermodynamics](https://www.materialinsights.org/energy/e_pressure_recovery/rc-sci/index.md)
- [Engineering and integration](https://www.materialinsights.org/energy/e_pressure_recovery/rc-eng/index.md)
- [Economics and contracts](https://www.materialinsights.org/energy/e_pressure_recovery/rc-econ/index.md)
- [Impact and additionality](https://www.materialinsights.org/energy/e_pressure_recovery/rc-impact/index.md)
- [What to track](https://www.materialinsights.org/energy/e_pressure_recovery/tracking/index.md)
- [Relationships](https://www.materialinsights.org/energy/e_pressure_recovery/links/index.md)