# Is an on-site PSA nitrogen generator lower carbon than buying liquid nitrogen?

Canonical: https://senseible.earth/answers/psa-nitrogen-generator-vs-liquid-nitrogen-co2

Often yes for steady, moderate purity demand, but it moves emissions into your Scope 2. PSA runs on compressor electricity; liquid nitrogen carries the supplier's air separation power and road transport in your Scope 3. Compare kWh per cubic metre at the purity you need.

## What to compare

- PSA: compressor kWh per Nm3 at your purity, from the vendor and a meter.
- Liquid: the supplier's kWh per Nm3 if they share it, plus tanker trips.
- Boil-off losses from liquid storage.

## Purity matters

Very high purity needs more air per cubic metre of nitrogen, so PSA power rises. For small or very pure loads, liquid supply may still be the better choice.

## What Senseible does here

Senseible reads electricity bills, including kVAh, demand and solar export lines, into dated records with the units, factor and year behind every Scope 2 figure.

- [Industrial gases in Scope 3](https://senseible.earth/answers/industrial-gases-oxygen-nitrogen-scope-3)
- [Compressor specific power](https://senseible.earth/answers/air-compressor-specific-power-kw-per-cfm)
- [Compressed air leaks](https://senseible.earth/answers/compressed-air-leak-cost-and-emissions)

Sources: [GHG Protocol Corporate Value Chain (Scope 3) Standard](https://ghgprotocol.org/corporate-value-chain-scope-3-standard), [GHG Protocol Scope 2 Guidance](https://ghgprotocol.org/scope-2-guidance)

Last reviewed 2026-10-22.