As Storms Ciara and Dennis have battered the UK over the last few weeks they have created a lot of renewable energy, some days up to 44% of the UK’s entire electricity generation .
That amount of energy hitting the grid is creating a lot of interesting scenarios for the power network, especially at night. As the wind continues to blow during the night, the turbines continue to generate energy. However, the demand on the grid reduces substantially as people go to sleep and don’t require as much power, and opportunity for a fossil free grid arises.
For an illustration of this, take a look at the graph above for the 17th and 18th February 2020 . In the early hours of 18th February between midnight and 6am, the total demand for electricity in the UK was 30GW.
At midday on the 18th February the power demand was 41GW. This comprised of 37% wind, 21% gas, 14% nuclear, 9% imports, 8% solar, 6% biomass and 2.5% coal.
However, If we were to remove the gas, coal and solar then the rest (wind, nuclear, imports* and biomass) would be providing approximately 30GW of power.
This suggests that there should be enough capacity on the grid to power the UK grid without domestic* fossil fuels plants between midnight and 6am – providing the wind is blowing.
So why did we not have a fossil fuel free night on the 17th-18th February? The simple answer is that the grid is operated by the National Grid Plc and they run it based on market principles, and not for environmental gain. Gas and coal plants – and biomass and imports from abroad – sell their power on the UK’s electricity wholesale market and directly to large customers. Therefore gas and coal plants directly compete against biomass and imports. If the price of electricity is too low then generators will not sell their power to the grid. It is unlikely that all the gas and coal plants shutdown, whilst the biomass and imports continue to provide energy.
However, wind energy is not bound by the same market principles. Operators receive a set amount for the energy they produce independent of the wholesale market price .
The amount of wind energy in the UK is only going to increase as more wind farms are built. The current UK Government is aiming for 40GW of offshore wind by 2030, over four times the existing value . During the night of the 18th February, gas and coal were producing just under 4GW of power. In the next five years there is around 8GW of offshore wind power due to come online alone. This makes the probability of a domestic fossil fuel free night highly likely in the next few years as the new wind energy crowds out the gas and coal. Sweet dreams!
*Imports include power generated in other countries (France, Ireland, The Netherlands and Belgium) which is transmitted to the UK via undersea cables. These sources of energy cannot be guaranteed to be completely fossil free, although they are dominated by nuclear energy from France. Furthermore, if it is windy in the UK it is likely to be windy in the neighbouring countries, increasing the proportion of wind power in those countries as well.