Oxygen and PSA
How much electricity does a PSA oxygen plant use?
How much electricity does a PSA oxygen plant use per cubic metre of oxygen?
Short answer
Published guidance puts a conventional PSA oxygen plant at about 1.2 kWh per cubic metre of oxygen: a 2020 WHO COVID-19 rule of thumb gives 1.22 kWh ±5% per m³ of total flow, and PATH about 1.2 kWh per Nm³ at 65 psig. The figure depends on design and delivery pressure.
Published figures
| Source | Figure | Conditions |
|---|---|---|
| WHO, Oxygen sources and distribution for COVID-19 treatment centres (2020) | 1.22 kWh ±5% per m³ of total flow | Rule of thumb for PSA plants; WHO advises using the manufacturer's technical specification for a detailed estimate |
| PATH and CHAI (2021) | About 1.2 kWh per Nm³ produced | Conventional PSA plant at 65 psig; rises with higher service pressure and with cylinder filling |
| PATH and CHAI (2021) | About 0.39 kWh per Nm³ of total flow | VSA plant at 2.7 psig |
| Fraunhofer IKTS | At least 0.9 kWh per Nm³ | Small PSA plants below 100 m³(STP) of oxygen per hour |
What drives the number
- Compressor pressure. The ULTRAOX datasheet (2022) states that every 1 bar increase in compressor pressure adds 7% to total electricity consumption, which is why the pressure drop between the compressed air and the oxygen outlet matters.
- Control of the compressors. The same datasheet states that if the system is not calculated correctly, more than 20% of the installed power is also consumed when the compressor switches out of its load cycle.
- Variable speed. ULTRASCREW, the compressor of ULTRAOX ST plants, has an optional variable speed version that its datasheet rates at up to 35% energy savings.
- Purity setting. The Global Fund purity note (2024) explains that a plant specified at 95% (±1%) needs larger equipment than a 93% (±3%) plant for the same flow, with higher power consumption.
- Compressed air demand. The ULTRACON table lists, for every generator size, the compressed air it consumes at 93% and 95% purity, which is what the compressors must supply.
- Cylinder filling. PATH notes that consumption increases when the plant also fills cylinders.
The ULTRAOX ST datasheet notes that compressor power and pressure can vary with the service conditions required by the facility, so the electricity figure for a given plant comes from its sizing rather than from a single published ratio. VSA plants use less energy per cubic metre but produce oxygen at much lower pressure and often need a booster compressor to feed a hospital pipeline, according to PATH.
More questions
Does a VSA plant use less electricity than a PSA plant?
PATH and CHAI (2021) give about 0.39 kWh per Nm³ of total flow for VSA at 2.7 psig against about 1.2 kWh per Nm³ for conventional PSA at 65 psig, but VSA output often needs a booster compressor to reach pipeline pressure.
Why does delivery pressure matter?
Compressor energy rises with pressure: the ULTRAOX datasheet (2022) states that each extra bar of compressor pressure adds 7% to total electricity consumption.
Sources
- WHO, Oxygen sources and distribution for COVID-19 treatment centres, interim guidance (4 April 2020)
- PATH and CHAI, Oxygen Generation and Storage: Pressure/Vacuum Swing Adsorption Plant (July 2021)
- Fraunhofer IKTS, Energy demand of oxygen membrane plants
- Global Fund / Build Health International, Briefing Note: PSA Plant Oxygen Purity (3 April 2024)
- ULTRAOX datasheet 2022, p. 5
- ULTRAOX ST datasheet, p. 5
- ULTRASCREW datasheet, p. 2
- ULTRACON datasheet, p. 3
Ultra Controlo figures come from its technical datasheets. Third-party facts were read at the source on the date shown.