Neil Roberts, Technical Development Manager at Chemours UK, looks at the path to reducing climate change emissions from commercial refrigeration applications.
We’ve all seen the headlines highlighting the devastating effects of climate change if not enough is done to reduce the emissions that are fuelling this potentially catastrophic future but great care should be taken to avoid knee-jerk reactions that seem to be the right choice until further scrutiny reveals they were just an expensive mistake.
In a study commissioned by Chemours, independent consultants Wave Refrigeration compiled a comparison of six low GWP alternative technologies available to retailers for their refrigeration needs.
- Water-cooled (WC) integrals (plug-ins)
- Air-cooled (AC) integrals (plug-ins)
- R290 / glycol systems (secondary system)
- R134a / pumped R-744 MT (secondary system)/ sub critical cascaded LT systems
- Lower GWP (<1500) non-flammable Opteon XP40 (R449A) systems (baseline technology)
- Low GWP (<250) HFO A2L systems, Opteon XL20 (R454C) & Opteon XL40 (R454A)
- Transcritical R744 booster systems (FGB)
A detailed description of the technologies considered and full results of the study are available in a white paper published by Chemours.
The study produced by Wave Refrigeration considered each of the technologies in stores of two different sizes:
Standard supermarket ~2000m2 sales area with design loads of 160 kW medium temperature / 30 kW low temperature and
Convenience store 300-500m2 sales area with design loads of 40 kW medium temperature / 8 kW low temperature,
simulating performances in a moderate European climate (Leicester, UK). Details for other European locations are available in the Chemours white paper.
The results from this study examined the initial cost of purchasing and installation (CAPEX), the operating costs (OPEX) and total emissions (TCO2e) for each scenario to make a like for like comparison to the baseline Opteon XP40 technology, to enable end users to make the best choice of refrigeration technology to use for the future.
What’s the cost? (10-year life cycle cost)
When considering which technology to use it is normal that comparisons are made on a cost basis. For the store operator the initial cost of purchasing and installation (CAPEX) is of course a major consideration but the operating costs (OPEX) are often considered equally important and therefore a 10-year life cycle cost (10-yr LCC) taking into account CAPEX and OPEX is commonly used. On this basis it can clearly be seen (Figures 1 & 2) why HFC and similar technologies are historically the favoured choice.
Figure 1- 10-yr LCC for a standard supermarket
Figure 2 - 10-yr LCC for a convenience store
What becomes clear in this analysis is that low CAPEX options, such as air cooled or water-cooled integrals, have a significantly higher 10-yr LCC due to the relatively poor energy efficiency of this technology. It also clear that energy efficiency is the major cost over the lifetime of the system.
What about the environment? (10-year total emissions)
The measures within the regulations are all about reducing climate changing emissions to atmosphere and therefore the cost of taking measures to reduce these potentially harmful emissions is not the primary focus. The legislation is focussed on reduction of emissions and therefore the total emissions to atmosphere must be considered when choosing a sustainable technology.
Figure 3- 10-yr total emissions for a standard supermarket
Figure 4 - 10-yr Total Emissions for a convenience store
It is obvious from figures 3 and 4 why R404A has been targeted for reduction as the high GWP results in high direct emissions, even at a leak rate of just 5% per year. It is also very clear that for the low GWP (<250) options, the indirect emissions from energy consumption are by far the biggest contributor to the total emissions and is the critical factor to be considered when choosing a sustainable replacement for R404A.
In all the scenarios considered, the alternative technologies with the lowest total emissions and 10-yr LCC were those utilising the low GWP A2L Opteon XL refrigerants. With the lowest total emissions (18-20% lower than the baseline technology) and 10-yr LCC 11-21% lower than any of the other alternative technologies, the Opteon XL refrigerants are clearly the most favourable future technology choice.
Whilst the refrigerant GWP is an important factor, this study has demonstrated it is far from the only consideration and using refrigerants with GWPs <10 does not necessarily improve the climate change emissions produced during the operation of the system.
As reported in the ACR Journal (October 2019), Central England Co-operative has already taken advantage of the benefits by using Opteon XL20 technology in a new store in Langley Mill, Derbyshire. After years of investigation, the major UK retailer Asda has also embarked on a programme to introduce Opteon XL refrigerants into their estate having decided it was the only technology to meet all their required criteria:
- Match cooling performance
- Exceed energy performance
- Match system uptime (minimise risk to trade)
- Match total cost of ownership
- Match ease of installation and maintenance
And if that wasn’t enough, this study has shown that Opteon XL refrigerants provide
- Lowest 10-yr Total CO₂e emissions
- At the lowest 10-yr life cycle cost of the low GWP alternative technologies
Why would you use anything else?