By Simon Evans

Nearly half of the UK's electricity came from renewables and nuclear in 2015, while fossil fuel's share of energy supplies hit a record low.

The latest Digest of UK Energy Statistics (DUKES) from the Department for Business, Energy and Industrial Strategy (BEIS) reveals a nation in the midst of a low-carbon transition. However, it also shows that fossil fuel extraction increased for the first time in 15 years.

Carbon Brief has produced five charts to show what happened to the UK's energy mix in 2015.

1. Fossil Decline

Fossil fuels supplied 82 percent of the UK's primary energy in 2015, by far the lowest share in records going back nearly half a century. Within that, coal use fell to 25 million tons of oil equivalent (Mtoe), down 21 percent in a year and just one quarter of the amount used in 1970.

Top: UK primary energy use by source, millions of tons of oil equivalent (Mtoe), 1970-2015. Bottom: Shares of UK energy use (percent). Source: DUKES table 1.1.1.Carbon Brief / Highcharts

The fall in coal use means it reached a new nadir, having already dropped to levels not seen since the industrial revolution. Oil and gas demand increased slightly in 2015, up 1.4 percent and 2.7 percent respectively because of falling prices and cooler weather compared to a year earlier.

2. Transport Turnaround

Overall, UK energy use increased slightly in 2015, though it continued its decade-long decline once variations in weather are taken into account. Transport energy use is now the exception to this trend, having increased for two years running as cheap oil fuels increased traffic.

UK energy use by sector (Mtoe), 1970-2015. Source: DUKES table 1.1.5.Carbon Brief / Highcharts

Domestic energy use continues to fall, with ups and downs due to the weather. It's interesting to note that reductions in industrial energy use appear to be tailing off, either because energy efficiency efforts are slowing or because output is increasing.

3. Low-Carbon Power

The speed of the UK's low-carbon transition has been particularly dramatic in the electricity sector. Nuclear (21 percent) and renewables (25 percent) generated nearly half of the UK's electricity in 2015, with renewables up five percentage points.

Top: UK electricity generation by source, terawatt hours (TWh), 1996-2015. Bottom: Shares of UK electricity generation (percent). Source: DUKES table 5.5. Carbon Brief / Highcharts

Coal-fired power generation continues to plummet, falling by a quarter in one year and by nearly half since 2012, the high point of the past two decades. Coal has fallen even further in the first half of 2016. Notably electricity generated from gas has remained steady, with renewables claiming market share from coal.

4. Renewable Rise

Wind, solar and biomass all contributed to the rising share of renewable electricity. Onshore wind generation increased by 23 percent on a year earlier, while offshore wind and biomass grew 30 percent as new wind farms were completed and Drax continued its conversion from coal to wood pellets.

The largest percentage increase was for solar, which grew 87 percent year-on-year and met around 2 percent of the UK's electricity needs for 2015. In May 2016, Carbon Brief analysis showed that solar generated more electricity than coal for a full month for the first time ever.

UK renewable electricity by source (TWh), 1990-2015. Source: DUKES table 6.1.1.Carbon Brief / Highcharts

The increases in solar and biomass electricity are unlikely to continue at such a rate during 2016. Solar installation rates surged during 2015 to take advantage of closing subsidy schemes, while Drax is unlikely to convert further coal units to biomass for the foreseeable future.

5. Maximizing Recovery

While the UK is in the midst of a low-carbon transition, that doesn't mean it has stopped the extraction of fossil fuels. In fact, combined coal, oil and gas production rose in 2015, the first annual increase since 1999. Within this increase, coal extraction fell by 26 percent year-on-year.

UK fossil fuel extraction by source (Mtoe), 1998-2015. Source: Dukes table 1.1. Carbon Brief / Highcharts

The government has made it a legal obligation to draw up strategies to "maximize economic recovery" of UK fossil fuel resources. As chancellor, George Osborne introduced a series of tax breaks designed to meet this obligation. The exchequer is actually paying some oil majors, as they can reclaim tax paid in previous years to offset the costs of decommissioning North Sea assets.

Conclusion

As ever, it's worth keeping a longer-term perspective on the UK's low-carbon transition. While last year saw record contributions from low-carbon sources, the UK still relies on fossil fuels for 82 percent of its energy and 54 percent of its power.

The UK's fifth carbon budget, recently passed into law, will require the power sector to be largely decarbonized by 2030. Meanwhile, the Paris agreement on climate change means the UK has pledged, along with almost 200 other nations, to almost completely decarbonize all energy use soon after mid-century. There's a long way to go.

And Finally…

Below, Carbon Brief has produced an animated GIF of the DUKES energy flow charts for the UK 2012-2015. It shows at a glance how the inputs and outputs to UK energy use have changed over recent years.

The flows show shares of each year's total, obscuring the overall decline in energy use noted above. Even so, some interesting trends are visible.

Note, for instance, how coal use shrinks over the four-year period, while the darker pink band showing renewable electricity inputs grows.

It's also worth noting that this year the chart is published by BEIS, the new department created in a merger of the old Department of Energy and Climate Change and the department for Business, Innovation and Skills.

This article was reposted with permission from our media associate Carbon Brief.