Electricity generation in the UK is changing. While the country is still heavily reliant on coal and gas – particularly in the industrial sector – low carbon electricity generation in the UK overtook electricity generation from fossil fuels in the period January to March 2019 (1). That is 48% of electricity was from clean sources: 6% being imported, 18% from nuclear and 24% from renewable energy such as wind and solar generators, giving Brits even more reason to constantly discuss the weather!
The nature of the wind and sun means the UK cannot rely solely on them to match generation to demand. Currently, peak demand is met by gas, coal, electricity from abroad which comes into the UK’s National Grid via the interconnectors (large electricity cables under the sea from France, Netherlands, Germany, Denmark and Norway) and storage. A 100% renewable energy powered electric grid would struggle when everyone in the country wants to turn on their kettle, charge their electric vehicle or even just see which couple take home the £50k on Love Island… This is set to only intensify thanks to the electrification of everyday life, including the cars and heating of the future probably going to be powered by electricity.
July 2019 was one of the hottest months on record in the UK. Even our northern Durham and Hamilton offices saw highs of 28 and 29 °C (2)! With hotter days, comes more air conditioning, one of the most power-hungry appliances in our buildings. Demand for electricity for fans, fridges and air conditioning will increase if temperatures rise. People are looking to renewables to provide the bulk of the extra electricity demand.
There are two sides to the solution for more low carbon electricity: On the supply side, batteries, pump storage hydro stations and other storage technologies need to be built to store excess energy for peak-demand periods. Engineers are developing solar and wind energy generators that regulate themselves to provide a steadier output to the Grid (3). On the demand side, more and more strategies are being devised to regulate demand; these include increased on-site generation (especially for big organisations) and smart meters to help homeowners monitor and control their consumption.
Wind generation in Scotland is at a record high; at full capacity, when the wind is blowing constantly and strongly enough, it is able to power two Scotlands on wind power alone (4). Banks Renewables’ Kype and Middle Muir wind farms play a key part in this.
A crucial issue for the National Grid is how you get the electricity from where it is generated to where it needs to be? Unfortunately, the UK’s windiest spots are not currently next to the areas with the highest population density. New Grid connections have to be created move the electricity from the wind, solar farms and storage systems, to the Grid which then supplies it to the end user. This is a massive infrastructure upgrade. New substations, overhead lines, underground cables are just some structures that have to be built beside new energy generating developments.
Another major issue in transitioning to a more renewable energy powered Grid is inertia and frequency. Electricity grid inertia refers to the kinetic energy in the Grid. This energy is contained in generators and motors at power plants and factories which rotate at the same frequency as the National Grid. Electricity grid frequency is the nominal frequency, of the oscillations of alternating current (AC) in the National Grid, transmitted from a power station to the end-user.
The National Grid operates at a frequency of roughly 50Hz, much deviation from this and there is a major risk of a blackout. Inertia, traditionally provided by large gas and coal power stations with a relatively constant power output, stabilises the system around this frequency (5).
A power cut on Friday 9 August 2019, which affected nearly one million people across England and Wales, raised questions about the current capabilities of the National Grid. The National Grid has assured Ofgem, consumers and the Government that its ‘systems performed as they should have’ in response to the power cut.
Power stations have “black-start” contracts to reboot the grid if a full black-out does occur. A black start is the process of restoring an electric power station or a part of an electric grid to operation without relying on the external electric power transmission network to recover from a total or partial shutdown. An approach based on combining numerous providers in one black-start contract has been suggested in order to help the energy generation transition. Another idea is that battery storage starts to provide black-start, as has been proven to work in California in May 2017 (6). The Government could also choose to keep the required minimum of gas and coal fired power stations on the Grid for black start situations.
The increased demand for electricity to power our cars and heating / cooling systems needs to be managed carefully. To prevent electric vehicle owners coming home from work and plugging-in to charge their cars at the same time, energy providers are developing apps that will let EV users charge at off-peak times at a lower tariff. Using Vehicle-to-Grid technology, car-owners could also sell this electricity back to the grid if they do not need to use charge still left in their car’s battery at the end of the day. This is a potentially useful source of power to balance peak demand in the Grid given that many cars are parked 95% of the time (7). There is, of course, the option to opt out of the scheme if the owner is going on a long drive. Also charging stations are going to be able to ‘talk’ to each other and with energy suppliers so that there isn’t a surge in demand, so that energy providers can continuously adapt to the market (8).
Reaching the 2050 net-zero target will require massive amounts of behind-the-scenes investment and work from energy generators to get electricity from renewable sources to the end user. It is an interesting time to be in the energy sector in the UK.
1. Roger Harrabin, “Clean electricity overtaking fossil fuels in Britain”, BBC News online, 19 June 2019. https://www.bbc.co.uk/news/science-environment-48711649.
2. The “Time and Date” weather watch website, https://www.timeanddate.com/weather/uk/glasgow/historic?month=7&year=2019.
3. Drax, “Balancing for the renewable future”, Drax.com, 6 July 2018, https://www.drax.com/energy-policy/balancing-renewable-future/).
4. Harry Cockburn, “Scotland generating enough wind energy to power two Scotlands”, The Independent online, 19 July 2019. https://www.independent.co.uk/environment/scotland-wind-power-on-shore-renewable-energy-climate-change-uk-a9013066.html.
5. Brendan Coyne, “As solar generation makes history, National Grid starts to feel the burn”, theenergyst, 26 March 2017, https://theenergyst.com/as-solar-generation-makes-history-national-grid-starts-to-feel-the-burn/.
6. Liam Stoker, energy-storage.news, 4 June 2018, https://www.energy-storage.news/news/national-grid-wants-uk-storage-to-provide-black-start-next-year.
7. David Morris, “Today’s Cars are Parked 95% of the Time”, Fortune, March 2016, https://fortune.com/2016/03/13/cars-parked-95-percent-of-time/.
8. OvoEnergy, “Vehicle to Grid: Your electric car as a power station”, https://www.ovoenergy.com/guides/electric-cars/vehicle-to-grid-technology.html.