We hear a lot about the technological challenges that peak energy demand throws up for our energy grid, forgetting that our energy use is actually a very social thing. The pattern of big peaks and troughs that plays out across our grid - across each day, week and season - is the outcome of lots of people in homes, organisations and institutions simultaneously doing activities that use energy. The rhythms and patterns of these energy-demanding activities are in constant flux, influenced by complex social and cultural dynamics that go beyond just the design of buildings, appliances and infrastructures.
While peaks typically occur early in the morning and most strongly in the early evening, analysis of time use data we have undertaken in the DEMAND Centre at Lancaster University in the UK shows that there’s a lot of variation in what people do during those periods and that they’re made of different activities depending on what day of the week it is. For example, there’s more eating and drinking in peak hours on a Friday than on a Monday, and there’s less personal care and washing, because a lot more of us are out and about socialising on a Friday night. Women generally have a more fragmented set of activities at peak time than men and a greater proportion of women are spending time preparing food from 16.30 through to 19.00 when more men are at work.
More flexible working hours, more time spent commuting and changes to the opening hours and location of shops and schools have been pushing laundry towards non-peak electricity demand periods for some time. Most people now do their laundry on a Sunday whereas Friday was the most popular day in the 1970s. Early morning and late night laundry has decreased on all days of the week, perhaps because people are using tumble driers rather than getting wet laundry out of the machine ready for a full-day of drying on the clothes line. Understanding what energy is being used for at different times can inform strategies to move energy use around in time, and out of peak periods.
The ongoing shift towards an increasingly digital society also has major implications for the dynamics of energy demand, and not just in terms of the direct charging and use of the phone, tablet and computing devices that are now embedded in how we live. For instance, automatic software upgrades can cause significant peaks across the electricity grid that can overwhelm local networks if not properly prepared for. To give an example, when iOS8 was released on 17 September 2014, the UK’s internet provider Virgin Media saw its daily data traffic increase by 10%.
The data traffic associated with the distribution of automated upgrades now generates as much traffic as the entire internet in 2007. The connected car is another key example of the effects of digitalisation and ‘big data’ on energy use: as well as updating their 25 to 50 central processing units and hundreds of sensors, connected cars also send back a wealth of data to the car manufacturer about where the car is, how it’s being driven and contact details, synced from mobile phones. For example, the Mercedes Benz B-series transmits the vehicle’s mileage, fuel level, coolant level and tyre pressure every two minutes. And every unit of data transmitted, processed and stored in distant servers adds to overall energy demand.
In the face of trends like these, the challenge is to think more systemically about the why and how energy demand is changing and look beyond the traditional scope of energy policy at where opportunities and responsibilities for demand reduction might lie. As society changes, there are a wide range of strategies we might use to reduce peak load or to improve the match between demand and supply, especially of renewable energy.
Professor Gordon Walker is Co-Director of the DEMAND Centre at Lancaster University.