Demand response is being deployed increasingly in the commercial and industrial sector, but the large potential of the residential sector has remained hitherto untapped. Other criteria apply: comfort safeguards are a basic requirement to enable sustained participation, and the sources for flexibility are small as regards the quantity of energy but there are many of them. As such, the technology needed for residential demand response is fundamentally different from that needed at the industrial level.
With increasing renewable energy supply, the supply-demand balance is becoming increasingly difficult to maintain, because of its intermittency, necessitating new resources for demand management. Accordingly in Flanders the Linear project was developed to investigate solutions for matching residential electricity consumption with available wind and solar energy. The five-year project, headed by the EnergyVille research institute consortium, has now published its final report.
240 families participated in the demonstration, evaluating two different consumer interaction models:
● Variable time-of-use: 55 families were asked to alter their energy consumption based on dynamic tariffs, with prices communicated the day before. A home energy monitoring system was provided to give insight into their consumption, and a display was provided showing the market-priced tariffs scaled-up to the targeted wind and solar predictions in 2020.
● Automated demand side management: 185 families were equipped with a home energy management system and smart appliances, such as washing machine, dishwasher, tumble dryer, electric heating application and electrical vehicle, turning on the machines when more energy consumption was needed, or turning them off when less energy had to be used. In all there were deployed 445 postponable appliances, 15 domestic hot water buffers and 7 EVs. The systems also included features to manage the comfort of the users as well as ensure that the families could always take a hot shower and that the dishes would be ready when needed.
Smart meters were installed in 110 of the houses, while the others had standard energy meters for overall consumption and production.
For each of four business cases, Linear investigated to what extent residential demand response could offer a technical and economical solution to mitigate the effects of the increasing share of renewable energy production, while still bearing in mind user behaviour and comfort. The business cases were portfolio management, wind balancing, transformer aging, and line voltage management.
Automated demand response with household appliances
The response to the variable time-of-use tariff scheme was weak, with most families taking little account of the categories and quickly going back to their old consumption patterns. With six tariff categories, the scheme also turned out to be too complex.
The acceptance of the smart-start functionality, however, was much better. After 18 months of testing there was still no indication of user fatigue, and the participants that stopped using the system did so because of technical issues. An automated system is also preferable for energy companies as they are able to respond to changes in the weather throughout the day, whereas price controls only operate based on predictions made up to one day in advance.
Other findings are that dishwashers gave greater savings than tumble dryers and washing machines. However, absolute savings for a domestic hot water buffer are significantly greater than for white goods appliances. Further, electric vehicles performed well for the balancing case when smart charging was available.
The wind balancing business case was also found to have very limited impact on line voltage and transformer aging. Specifically, the maximum activated power demand from the smart appliances remained limited compared to the overall maximum power demand of the households.
The findings are of significance in Belgium, where the supply imbalance cost currently can be as high as €4,500/MWh (approximately 100 times higher than usual) if the network operator is forced to activate additional strategic reserves as a result of limited generation capacity. Residential demand response could help suppliers and network operators better manage these costs.