Alternatives to HCFCs in the Refrigeration and Air Conditioning Sector 65 S ection 02 The measurements from the plant were logged on site and a model of the plant built up in a simulation tool “CyperMart” developed by the Department of Energy, Royal Institute of Technology in Stockholm. Calculations of the TEWI value show the impact of how the electricity is produced. The factor used for power generation depends on the production mix. The average for Sweden is low due to the fact that most of the electricity in the country is produced from nuclear or hydroelectric power plants. Also the Nordic mixture is low for the same reason. The European production mix results in a significantly higher value as the production is more dependent on fossil fuels. I ndirect system R-404A D irect system supercritical COCO2 Region S weden N ordic E urope S weden N ordic E urope CO2 kg/kWh 0.041 0.15 0.50 0.041 0.15 0.50 Indirect emissions 165 312 604 800 2 016 000 192 290 703 500 2 345 000 Direct emissions 317 856 317 853 317 856 336 336 336 T otal emissions 483 168 922 656 2 333 856 192 626 703 836 2 345 336 D irect/total 65.8% 34.5% 13.6% 0.2% 0.0% 0.0% Fig. 2.20 TEWI calculations for the supercritical system and an indirect system with R-404A. The leakage rate was assumed to be 12% for the indirect R-404A system and 15% for the direct CO2 system. The installation cost of the CO2 installation was, as stated by supermarket owner, approximately 20% higher than the indirect R-404A plant. The LCC analysis based on a 10 year perspective showed an 18% higher cost with CO2 than for indirect solution. The conclusions made in the survey were that with the technology installed in this plant (2006) the CO2 system was more expensive and could be expected to have a slightly lower efficiency than the theoretical reference system used for comparison. Since the original installation of this plant there has been an ongoing development of supercritical as well as cascade systems with CO2, so the situation is changing. Also, the installation in this plant has been modified and the manufacturer, Green&Cool, claims that the average COP of this plant now is better than a conventional R-404A indirect plant. It is also expected that the price on CO2 components and systems will decrease relative to conventional technologies. It should always be considered that in refrigeration and air conditioning there are many technical options and climate as well as possible heat recovery can drastically change the outcome of any comparisons. Neither the CO2 solution selected nor the indirect R-404A system used in this comparison might be considered the lowest cost or most energy efficient options in a particular market (author’s comment). The local climate and need for heat recovery will have an impact on the comparison of different technologies. In general, the carbon dioxide process as a one –stage supercritical process will have relatively better COP at low ambient temperatures. In the case where there is a need for high temperature in the heat recovery this is often beneficial for CO2 in a comparison with conventional alternatives.