Not only was December 2015 the UK’s wettest month on record, but it was also exceptionally stormy. Bad news for many, but great news for the country’s wind power and hydro generators.

In fact, storms Desmond, Eva and Frank meant that throughout December, more than 19% of Great Britain’s (not the UK’s – as Northern Ireland is not included in the underlying data) electrical energy came from wind, solar and hydro combined. That’s the highest ever figure for a calendar month.

It was an exceptional end to an unusual year that saw several new records set within Britain’s power sector as the transition from dirty to clean energy continued. Here are a few of the most notable outcomes.

Record breaking renewables

Wind, solar and hydro – the weather-dependent renewables – together generated 14.6% of Great Britain’s electrical energy in 2015, the highest ever annual amount. Wind stormed (literally) past the 2014 record to break through the 10% milestone. Solar more than doubled to 2.5%.

… especially in December

Dr Grant Wilson

The weather-dependent renewables of wind, solar and hydro peaked at 22% of Britain’s electrical energy generation over the week of Christmas (the grey line in week 52 on the chart above) – another record.

… and June

June saw the highest ever daily percentage of solar generation, peaking on Sunday June 7 at 8.9% – another new record.

The previous day, June 6, was both sunny and windy, which meant at 2pm solar, wind and hydro were generating more than 40% of British electricity. Coal may also have dropped to a record low at the same point.

Gas overtook coal

Dr Grant Wilson

Natural gas generated more than a quarter of Britain’s electricity throughout 2015. It was enough to return gas to top spot, but still far below its 46% peak six years ago. Coal continued its decline.

Fuel sources became even more diversified

As recently as 1990, Britain still relied on coal to generate more than 70% of its electricity. But things have changed a great deal since then as natural gas and more recently renewables have provided more options.

British energy is now more diversified than ever. In fact, averaged over 2015, no individual fuel source provided more than 30% of the electricity generated – the first time this has ever happened.

Power sector emissions lowest for decades

More renewables and less coal means that when the UK’s Department of Energy and Climate Change release their greenhouse gas emissions statistics for the power sector this March, 2015 will be the lowest value recorded since 1990.

A rough estimate (using this data) puts the emissions somewhere between 105 and 110 million tonnes of CO 2 equivalent. This is at least a 45% reduction from the power sector since 1990 – the country is making significant progress towards decarbonisation.

Where next? It’s very possible that 2016 will see coal generation drop below nuclear for the very first time since Britain’s (and the world’s) first nuclear plant came online 60 years ago.

The underlying data of the differing fuel types and imports/exports is available from Elexon and National Grid websites for each half hourly period of the year. This analysis adds these values together to provide a total for each period. The percentages presented here are then calculated using this total, and it is likely that these can slightly differ from other analyses (including that of DECC) due to a different methodology or by using different estimates of embedded wind or solar generation.