The first major trial of dynamic demand devices is to start in January, with Npower installing more than 3,000 fridges containing them in customers’ homes.
Dynamic demand has long been promoted as a way of lowering the need for back-up power generation (ENDS Report 377, p 12).
The technology allows appliances such as fridges to adapt their electricity usage to the needs of the national grid. A microcontroller in the appliance monitors the grid’s frequency, allowing appliances to detect periods of high demand and switch off. The technology can be fitted to any appliance with a duty cycle, such as air conditioning units or water heaters.
In December, Npower announced it had signed an agreement with dynamic demand developer RLtec to run an 18-month trial. Npower will give 300 of its customers fridges fitted with devices in January; another 3,000 will receive them in September.
National Grid will monitor the impact of the trial on the grid and assess its affect on the need for back-up generation.
The energy regulator, Ofgem, has approved the trial as a ‘demonstration action’ under the carbon emissions reduction target (CERT). The target requires energy suppliers to achieve a set amount of carbon savings through improving the energy efficiency of customers’ homes or providing them with micro-renewables (ENDS Report 379, pp 37-38).
Demonstration actions are trials of new products expected to reduce CO2 emissions, but where the reduction is unknown. Ofgem allocates the energy supplier a CO2 saving based on the trial’s cost.
In November, the Department of Energy and Climate Change issued a report on dynamic demand’s potential.1 This is based on modelling by the Centre for Sustainable Electricity and Distributed Generation (SEDG) at Imperial College, London.
Dynamic demand devices could replace 728-1,174 megawatts of back-up generation if installed in 40 million devices, the report says. Currently, National Grid pays for 1.3 gigawatts of back-up plant to cover for demand spikes or power outages at a cost of about £200 million a year. By lowering the need for back-up plant, dynamic demand could save 0.68-1.74 million tonnes of CO2 per year depending on the generation mix, the report adds. Each device would save National Grid £0.70-£5.60 per year in balancing costs.
The report stresses these estimates are based on "generic, simplistic models of refrigerators and the generation system", and says trials are needed. Several questions about the technology are outstanding, it adds, such as the potential for appliances to sustain their response for long enough and the synchronisation impact of devices.
RLtec has already undertaken laboratory trials of a "significant number" of its devices, according to Andrew Howe, the company’s chief executive. These have shown impacts on the grid and CO2 "roughly in line" with SEDG’s report, he said.
RLtec is working with a major fridge maker on the trials. Interestingly, the company’s business model does not rely on CERT to pay for the devices. "Any appliance installed with these devices can provide a service to the grid," Mr Howe said. "Our business plan focuses on that energy balancing service and being paid [by grid operators] for that. We are not focusing on the carbon benefits."
National Grid is devising rules to allow dynamic demand companies to provide it with "firm frequency response" services.
RLtec is looking at commercial users of refrigeration, air conditioning and other appliances, as well as the domestic market. It is about to start a trial on supermarket refrigeration systems. However, Mr Howe would not reveal further details.
Two thirds of the savings have come from improving insulation in customers’ homes and 27% from providing energy-efficient light bulbs. CERT has yet to provide a boost to micro-renewables - 71 ground source heat pumps have been installed, but nothing else.
The Department of Energy and Climate Change will issue details of how the expanded CERT will work in January.