Innovative use of carbon dioxide for sustainable supermarket refrigeration

She is exploring the potential use of carbon dioxide as a natural refrigerant in supermarket freezers, instead of relying on global warming chlorofluorocarbons banned under the Kyoto climate change treaty. Colombo believes the system will result in 40% lower emissions and greater efficiency.

The thermodynamic qualities of carbon dioxide as a refrigerant were exploited by Colombo to build a dual system delivering a chill temperature of minus two degrees as well as freezing capabilities.

If we switch to natural refrigerants like carbon dioxide, we significantly reduce emissions caused by refrigerant leakage. Carbon dioxide can, because of its thermodynamic properties, provide two temperatures in one system: a cool system and a frozen temperature.

Dr Ina Colombo, Research Fellow

Reclaiming Discharged Temperature

In developing a prototype, Dr. Colombo faced a particular challenge of tackling high-pressure issues that reduce system efficiency. But, by reclaiming the discharged temperature, that could be as high as 160 degrees, she turned this limitation into advantage, providing hot water and air conditioning.

The feasibility study she prepared demonstrates she can get a discharged temperature of 120 degrees to reduce supermarket carbon emissions by 40%, with a 30% reduction from using a natural refrigerant like carbon dioxide. Then it's possible to get a further 10% saving by making the system more efficient.

I doubled the efficiency by first reclaiming the heat and making it more efficient. We needed to prove we could get that temperature in order to get the benefits.

Says Dr Ina Colombo,

She is now training engineers to develop a work force that is able to use the new system and complete equipment tests for refrigerated cabinets under the British Standard. The training for engineers is key, as the law is pushing for a natural refrigerant and specialists like Dr Colombo are being looked to be able to deliver to the industry a robust system.

Pace Engineering Services a manufacturer of refrigeration systems part sponsored her research project, as did Tesco by providing access to supermarkets for benchmarking.


Ina came to LSBU in 2001 from her native Guadeloupe. With a background in refrigeration and mechanical engineering, she completed a building services course and then an MSc in Sustainable Energy systems as she was keen to contribute to reducing global warming greenhouse gasses. Professor Graeme Maidment, who teaches in the Department of Urban Engineering and founded the Centre for Refrigeration and Air Conditioning in 1999, invited her to consolidate her background and skills by doing a PhD in Sustainable Refrigeration supported by a grant from the Engineering and Physics Science Research Council (EPSRC).

Ina Colombo had previously secured job placement as energy manager at the House of Commons, and had worked at AMEC, the engineering consultancy, as a building services project manager. She later became sustainability consultant with the Building Design Partnership (BDP), an international practice of architects, engineers, urbanists and designers.

Now an executive member of the Institute of Refrigeration, Dr Colombo is shaping a young engineer network through workshops. She invites PhD students to demonstrate their projects and industry experts to give presentations. Speed networking events enable students to interact with experts from different fields.

Supporting Black and Minority Engineers

Dr Colombo is a driving force behind Transition Rendezvous, a project designed to attract more Black and minority students into engineering through the Association of Black Engineers. She is also developing a scheme to get Black and minority students to act as mentors to encourage secondary school students into engineering through the "Making Engineering Hot" (BeH) campaign.

LSBU is very well located and you have your life around here. I live around my University, and my work placement was around my study. AMECs offices are down the road in Borough, the House of Commons is 10 minutes away and BDP is just on the other side […] LSBU has a multicultural environment with so many nationalities, but we work together. This can be very different to academia in other countries where everybody is kind of an individual. We are a group at South Bank.

Dr Ina Colombo, Research Fellow


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