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Associations
Image by Dr Andy Pearson
times higher than what is considered to be best practice performance , so clearly there is a significant opportunity for improvement .
5 . WHAT NEEDS TO HAPPEN NEXT The next steps in the journey do not depend so much on refrigerant choice , but rather on the transition that is already ongoing in the sourcing of power to run the systems . We are in the middle of a process that has two facets . We need to make our electricity supplies substantially cleaner than they are at present in order to reduce carbon dioxide emissions and we need to transfer many processes that have traditionally burned fossil fuels onto electricity as the energy driver . Both facets need to succeed : if one is successful but the other fails , we will face a climate catastrophe far beyond anything that has been seen so far . Failing to clean up the grid while transferring loads onto it is no good . Cleaning up the grid and then failing to use it to displace fossil-fuelled heating and transport will be equally bad . The relationship between decarbonisation of the grid and transition of fuel from carbon-based to electrical is shown schematically in Figure 3 , where the x-axis ranges from 1 000 gCO2 . kWh-1 on the left down to 0 gCO2 . kWh-1 on the right .
Figure 3 : the relationship between Decarbonisation and Electrification ( red indicates environmentally unacceptable outcomes , green is acceptable )
South Africa generated 238 998 GWh in 2021 according to a recent government report ( DFFE , 2024 ) with a grid emission factor of 1 013 gCO2e . kWh-1 . A further 7 268 GWh was imported , predominantly from hydroelectric systems , resulting in an overall emission factor of 985 gCO2e . kWh-1 .
This is one of the highest emission factors in the world , primarily due to the prevalent use of coal in thermal power stations which accounted for 86 % of all generation , compared to 5 % for wind and 2 % for solar . However , there is a substantial programme of renewable energy investment , known as the South African Renewable initiative ( SARi ), which aims to complete 19 GW of renewable energy capacity by 2030 . This is expected to account for 30 % of South Africa ’ s electricity needs but even this level of coverage brings additional challenges . The transmission network needs to be capable of handling energy flows in new places and new directions and supply needs to be guaranteed even when the wind doesn ’ t blow or the sun doesn ’ t shine . Coping with intermittency requires the storage of renewable energy while it can be harvested , or else the otherwise redundant old thermal plants need to be kept in service to provide backup . These options can be expensive but the total cost of this resilience needs to be factored into the overall cost of renewable energy .
Assuming that we can clean up the grid beyond the 30 % target of 2030 and we can also transition other fossil fuel users onto the network , for example replacing oil fired boilers with heat pumps and switching from internal combustion to electric vehicles , the methods of selling and buying electricity will change dramatically . The production cost for electricity , even allowing for provisions for intermittency , will trend towards zero at certain times of day , but these times will become less predictable .
The low cost of electricity does not mean that we can be complacent about system efficiency because a more efficient refrigeration plant helps to take the load off the existing grid infrastructure , so freeing it up for other uses . It will , however , make it difficult to motivate end users to pay attention to efficiency so there may be scope for some kind of incentive scheme to encourage good behaviour . This may even take the form of paying users to take electricity at certain times and to avoid using at other times , determined by whether the wind is blowing or the sun is shining . It may be possible in these cases to give a few hours ’ advance notice of times to avoid but this will require some development in refrigeration control systems , especially for process plants and it might take the form of limiting capacity rather than switching off completely . Electricity charging might change quite radically to a format where the supplier imposes a much higher standing charge , reflecting the higher fixed cost of coping with intermittency , and then the unit charge rate varies from a negative number to a positive number , allowing users to offset the high standing charge by using power at favourable times of day ( or night ). Efficiency could be encouraged by giving a certain amount of ‘ free ’ electricity and then charging heavily when that limit is exceeded .
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RACA Journal I March 2025 www . refrigerationandaircon . co . za