The balancing of energy supply with demand on the UK National Grid is performed by ELEXON and as a result they provide a live snapshot of the power generated to match that demand by fuel type. I have been monitored this since December 2016. Peak demand in general occurs around 6pm and I use this value to compare the relative importance of different energy sources to energy security. The values provided by ELEXON are for centrally ‘metered’ power supply and do not include smaller ‘feed-in’ sources. Feed in sources are mostly household solar panels, solar farms, and small wind farms. The University of Sheffield began estimating Solar power around the end of 2017 based on their regional insolation/capacity model. I have been monitored this solar value since the beginning of 2018. In addition unmetered ‘feed in’ wind farms are estimated to add ~46% to the larger metered wind farms. This correction is applied to the overall results below.
Peak demand in winter still exceeds 50GW despite energy saving measures. Nuclear Power provides a stable baseline of about 8GW. Coal generation remains essential to meet demand during winter months, however most of the bulk generation balancing is now met by Gas. Wind power is extremely variable, but remained strong this winter and contributed an average 10.5% of peak demand or about 4.5GW. Maximum output at 6pm was ~12.5GW, while a record 14GW was recorded in the morning of March 17. This was also due to upgraded power transmission from Scotland to England. Solar Energy contributes essentially nothing during winter, and only becomes a significant factor after April and during daylight. Bio fuel has grown since 2016, but this growth is dominated by the DRAX turbines converting from burning coal to burning wood chips.
After November 2017 the demand curve is matched by the sum of all the fuel components, whereas before then there is an apparent small shortfall. I don’t have an answer as to why this is the case, but can only guess that the fuel figures were a little too low before November 2017. The Solar component apparently carries the supply of power beyond real time demand. That is because the effect of solar is to reduce the national demand curve through localised feed-in. However this ‘hidden’ solar is plotted here for comparison to the metered contributions from other fuels.
The week 31 May-5 June 2018 saw almost no wind across the UK, but instead a lot of sunshine. Here are the results for that week.
Total net Wind output fell as low as 0.05GW on Friday 1st June. Such lulls are not only restricted to Summer months. During the 2013/14 winter wind output fell below 0.2GW at 6pm on three separate occasions. For this reason the UK will need to keep in reserve an equal Gas capacity to that of all installed Wind farms simply to cover such lulls. Nor is it really feasible to store such huge amounts of energy. To cover one day without any wind (5GW) would need store 120GWh (430 TJ) of energy. This is 5 times larger than the bomb that destroyed Hiroshima. The largest Battery storage so far is the one that Elon Musk’s Tesla built in Southern Australia which can store 130MWh of Energy. Unfortunately this is a factor 1000 to small. The cost to the SA government for its installation was around AUD 100 million. Nuclear power looks cheap in comparison!