Q2 2019: Power system records

by Dr Iain Staffell – Imperial College London

The last three months have seen another 24 records broken by Britain’s power system.

We saw the first ever day with a carbon intensity below 100 g/kWh, the share of fossil fuels fell below 10% for the first time ever, and demand for electricity fell to its lowest level in 25 years. 

The tables below look over the past decade (2009 to 2019) and report the record output and share of electricity generation, plus sustained averages over a day, a month and a calendar year.¹ Cells highlighted in blue are records that were broken in the second quarter of 2019. Each number links to the date it occurred on the Electric Insights website, allowing these records to be explored visually.

As reported in Article 2, renewables supplied more than half of electricity for a whole day for the first time, providing 55.3% of Britain’s electricity on June 30th. This beat the previous record of 49.4% set last autumn. Peak output from renewables also edged up from 22.4 to 22.7 GW, boosted by a new record for solar panel output.

Nuclear output fell to its lowest levels in a decade. Monthly average output fell to 4.4 GW in June, down from a previous low of 5.2 GW set back in 2014. Both instantaneous and daily-average output fell below 4 GW for the first time since records began.

Coal also had its worst ever month, averaging just 28 MW output in May, from over 10,000 MW installed. This is a fall of three-quarters on the previous lows seen last summer. Coal supplied just 0.1% of Britain’s electricity during May.

Fossil fuels supplied less than 10% of Britain’s electricity for the first time ever, falling to a 9.5% share in the afternoon of May 26th. The lowest ever one-day average share of fossil fuels also fell by nearly four percentage points to 15.4% on the same day. 

Imports and exports continued to break previous records after the Nemo link to Belgium opened. Britain got closer to having imported a fifth of its electricity demand overnight on May 18th.

Britain had its first ever day with a carbon intensity below 100 g/kWh.  June 30thaveraged 97 g/kWh, down from the previous record of 104 g/kWh set last summer.  Junealso saw the lowest monthly demand for 25 years, at 29.4 GW. The lowest value seen in recent times was 29.6 GW back in August 2017.

1: The annual records relate to calendar years, so cover the period of 2009 to 2018.

2: Note that Britain has no inter-seasonal electricity storage, so we only report on half-hourly and daily records. Elexon and National Grid only report the output of large pumped hydro storage plants. The operation of battery, flywheel and other storage sites is not publicly available.

Authors: Dr Iain Staffell, Professor Richard Green, Dr Rob Gross and Professor Tim Green.