Gas separation technologies for energy production (ICSC-331)

Distillation column and main heat exchanger for air separation – credit: Adobe Stock (Par yarm sasha)


Oxygen (O2) separation is an energy-intensive process. Any improvements that can be made to enhance the performance of air separation units (ASUs) and reduce their cost can have a large impact on the introduction of net zero technologies in industrial and power generation applications. This report assesses recent developments in the performance of cryogenic ASUs applicable to oxyfuel, integrated gasification combined cycle (IGCC) and industrial applications, including an assessment of sensitivities to oxygen purity and to scale. It also reviews research into state‑of‑the‑art ASU technologies which offer potential for step-change improvement in ASU performance.

Cryogenic air separation remains the preferred technology for producing high-purity oxygen and nitrogen and is the most cost-effective technology for high-production rate plants with volumes of over 5000 tO2/d per single unit achievable. Continued development and optimisation are driving the specific energy of oxygen production down towards the medium-term target of 120–140 kWh/tO2 in an oxyfuel application, with heat integration and oxygen purity being key drivers.

Chemical looping-based air separation offers potential advantages in terms of reduced energy demand provided oxygen carrier mechanical durability and material issues can be overcome. Electrochemical oxygen as a valorised co-product to renewable hydrogen from water electrolysis seems set to increase significantly in importance through to 2050. There are also opportunities to combine aspects of air separation technologies themselves to improve oxygen separation efficiency and hence overall cost.


Gas separation technologies for energy production

Report Author(s)

Greg Kelsall

Report Number




Publication date

1 June 2024