Storm Diana brought travel chaos to road, rail and airports, but the clouds did have a silver lining: the strong winds helped set a renewable energy record.

Windfarms supplied about a third of the UK’s electricity between 6pm and 6.30pm on Wednesday, a time of peak energy demand. Output hit a high of 14.9GW, beating a previous record of 14.5GW.

The milestone coincides with the official opening on Friday of E.ON’s Rampion windfarm off the coast near Brighton, which is the first in the Channel and can power about 350,000 homes.

Blustery weather has buoyed wind output in the past few days, with National Grid reporting thousands of wind turbines were the UK’s No 1 source of power across Wednesday and Thursday, at about 32% of generation. Gas power stations are usually top.

Windfarms have moved from a niche source of electricity generation a decade ago – when they supplied less than 2% – to a cornerstone of Britain’s power mix, at nearly 15% of supply last year.

Quick guide Offshore windfarms in the UK Show Hide How important is offshore wind power to the UK energy system?

Offshore windfarms generated 8% of the UK’s electricity in 2018, according to estimates by trade body RenewableUK. The UK has more offshore wind capacity than anywhere in the world, with 37 projects made up of nearly 2,000 turbines. There is nearly 8GW of capacity today, 1.3GW of which was added in 2018. Another 5GW is already committed to. The UK has 44% of all European offshore wind power capacity. What obstacles has wind power faced?

The first subsidies awarded to offshore windfarms promised developers a guaranteed price of up to £150 per megawatt hour, or roughly three times the wholesale cost of electricity. Such steep subsidies would not be sustainable but cost reductions in the industry have seen that figure drop to as low as £57.50. The offshore wind industry has previously been criticised for not using enough UK contractors and suppliers. What is the economic benefit to the UK?

The industry employs around 11,000 people. One of the side effects of offshore wind’s growth has been an injection of money and jobs into coastal towns that in some cases have big pockets of economic deprivation. Ports have been upgraded and new maintenance facilities built, such as the one at Newhaven in East Sussex for the first windfarm in the English Channel. The different parts of turbines are made across the UK, from the Isle of Wight to Hull. What does the future hold for offshore wind power in the UK?

The industry has a target of growing today’s 8GW capacity to 30GW by 2030, which, if achieved, would see offshore wind power supplying more than a third of the UK’s electricity. The government has put a £557m pot of funding aside for subsidies for renewables in the next few years, most of which is expected to be taken up by offshore windfarms. The industry is also hoping for export opportunities for UK firms, as new markets grow in the US and Asia.

The 400MW Rampion project is one of four big offshore windfarms to come online this year, along with a 92MW windfarm in Aberdeen Bay, a 353MW windfarm off the Suffolk coast and a 659MW windfarm off Cumbria, which is the world’s biggest.

More vast schemes are in the wings, with a 588MW windfarm in the Moray Firth due to become fully operational next year. The title of world’s largest windfarm will be taken by a 1,218MW project off east Yorkshire a year later.

Emma Pinchbeck, the executive director of the industry body RenewableUK, said: “It’s great to see British wind power setting new records at one of the coldest, darkest, wettest times of the year.”

Onshore windfarms are cheaper and provide more power than those offshore, but the government has blocked them from competing for subsidies.