How do I calculate the emissions of a hospital PSA oxygen plant?
A PSA oxygen plant runs on electricity, mainly its air compressor. Multiply the plant's kWh from a sub-meter by 0.710 kg CO2 per kWh, add generator diesel during outages, and divide by cubic metres of oxygen produced. Bought liquid oxygen is Scope 3 instead.
What uses power
- The air compressor, the largest load.
- Air dryer and filters.
- The oxygen booster where cylinders are filled.
PSA or bought oxygen
Oxygen made on site counts through the plant's electricity, in Scope 2. Liquid or cylinder oxygen bought from a supplier is a purchased good in Scope 3, Category 1.
Per cubic metre
Report kg CO2 per cubic metre from the plant's flow meter, and keep the sub-meter readings as evidence.
Worked example: hospital PSA plant (one month, illustrative inputs)
- Electricity: 15,000 kWh x 0.710 = 10,650 kg CO2
- Cubic metres of oxygen produced: 9,000
- Total: 10,650 / 9,000 = 1.183 kg CO2 per cubic metre
Inputs are illustrative; use the plant sub-meter and flow meter readings.
What Senseible does here
Senseible reads electricity bills (CEA grid factor 0.710 kg CO2 per kWh, CO2 Baseline Database version 21.0) and diesel, LPG and gas invoices (IPCC 2006 defaults) into a dated, fingerprinted Scope 1 and 2 record for each site. Intensity per unit uses the activity count you enter, and estimates are labelled as estimates.
Sources: GHG Protocol Corporate Standard, GHG Protocol Corporate Value Chain (Scope 3) Standard, CEA CO2 Baseline Database, version 21.0
Last reviewed 2026-10-21.