Grid balancing – the role of refrigeration

The recent cold spell has resulted in consumers being involved in demand side grid balancing. It has been reported that on 24 January 2023 as many as a million households in the UK with smart meters were paid by National grid ESO to switch or reduce electrical usage between 17.00 and 18.00. In return they were offered money off their bills.[1]

In the bid to become net zero, the UK grid is becoming more dependent on renewables such as wind. This is fine for many parts of the day but at peak demand times (morning and evening) there is insufficient capacity to supply enough electricity. Therefore, the current move to remunerate customers who reduce their demand is likely to continue. It is not just domestic customers who can contribute and benefit. Industry and commercial energy users can also switch down demand and benefit financially. Sometimes single companies can have sufficient reduction capacity to provide ‘virtual power plants’. In other cases, they can join together though an aggregator to provide sufficient reduction in energy consumption to the grid. As refrigeration systems and HVAC are estimated to consume ~14% of the UK’s electricity[2] there is potential for the refrigeration sector to be involved in demand side response services.

Supermarkets are already involved in demand side response. Work carried out in 2018 by the University of Lincoln showed the aggregation potential of supermarkets[3]. In the study they looked at both the impact on the temperatures in display cabinets, the impact of rapidly switching off cabinets and the impact of the increased load as they were switched back on. This affects the load on the refrigeration plant as well as the impact of rapid switch off/on on compressors and other electrical equipment. Temperature control was assessed on several replicates of 2 chiller and 2 freezer cabinet models. The authors found that the ability for cabinets to remain off was related to their design, loading, the local environment around the cabinet as well as the cabinet controls (mainly the scheduling of defrosts). This also affected the ability of cabinets to reduce internal temperatures of simulated food back down after the 30-minute demand side response period. Differences were found between cabinet models in their response to the demand side period. Differences were also seen between similar models, with some cases, product temperatures rising to unacceptable levels. This seemed to be related to how the cabinet control system operated before the demand side period.

There seems to be significant opportunity to be able to better control demand side response in some cabinets. Although the ability for cabinets to be able to cope with demand side events is currently not part of test standards, it is certainly an important factor that should be considered in the future when purchasing a cabinet. Such tests could simply be incorporated into current testing procedures to discover how robust the performance of a cabinet is during demand side events. This would enable end users to best select the most robust cabinets that can cope with demand side events. Ultimately this saves the end user money and reduces carbon emission by being able to optimise the use of renewable energy sources for the grid.

If you are interested in the potential to assess how cabinets perform under demand side response periods, please contact Judith Evans (j.a.evans@rdandt.co.uk) at RD&T.

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