Power is flowing from the Shetland Isles to mainland Britain for the first time as the UK’s most productive onshore windfarm comes on stream.

SSE says its 103-turbine project, known as Viking, can generate 443 megawatts (MW) of electricity, enough to power nearly 500,000 homes.

Shetland is the windiest part of the UK, which means it will be rare for the blades, which reach a massive 155m at their tip, not to be spinning.

Chief executive Alistair Phillips-Davies told BBC News a “significant acceleration” in renewable energy infrastructure is now urgently needed if the UK is to meet its climate change targets.

“We need to do a lot more of these projects, a lot more offshore wind projects as well, to make sure that we can decarbonise the energy system,” he said.

But critics of windfarms – and the pylons required to carry the electricity they generate – say a new era of mass industrialisation for private profit will ruin swathes of the British countryside.

SSE has built a 160-mile long undersea cable to carry the power from Viking to Noss Head, near Wick, on the Scottish mainland.

The company said it has invested more than £1bn in the windfarm and cable projects, and plans to plough another £20bn into renewables by the end of the decade.

Mr Phillips-Davies said that would amount to “the biggest construction that we’ve seen since the Second World War.”

“Shetland’s got a great wind resource. This is the first of the really big wind farms that may be built here. There’ll be more projects to come,” he said.

The UK’s Energy Secretary Ed Miliband said Viking was “a crucial part” of reducing the UK’s reliance on “volatile fossil fuel markets, boosting our energy independence and protecting consumers.”

The Labour government has set a target for 100% of the UK’s electricity to be generated from renewable sources by 2030, phasing out gas-fired power stations.

Ministers have promised to accelerate the development of wind, hydrogen and carbon capture projects by investing £8.3bn over five years in a publicly-owned power company called Great British Energy.

The Conservatives have previously said that GB Energy is a “financial black hole” which will funnel taxpayers’ money “into reducing risk for multi-million pound energy companies.”

Mr Miliband also claims the Viking project will ensure “hundreds of thousands of homes in the Shetlands and right across the country will benefit from cheap, homegrown energy,” but that is hotly contested on the archipelago.

Moraig Lyall, chair of the environment and transport committee of Shetland Islands Council, said annual household bills in the islands were often more than double the UK average of £1,700 and showed no sign of falling as a result of hosting Viking.

“People look out their windows now, they see all these turbines that are generating lots and lots of energy, but they’re not seeing the benefit here,” she said.

“They’re still sitting in their homes having to decide, can I afford to put on my heating, and so people are justifiably angry about that.”

She added that islanders were also worried about Viking’s impact on the landscape; the peat bog environment on which it was built; and tourism.

Like most renewable projects it will generate a “community benefit fund” but islanders say the gains will be small – about £72m over 25 years – in comparison to the revenue from the windfarm.

There has also been anger on the island that the windfarm operator has received more than £2m already in “constraint payments” which pay for it not to generate power.

These payments are made during times when the amount of energy being generated exceeds the capacity of the network to transfer it where it is needed – mainly England.

The process of transferring the power is also causing concern on the mainland too.

Some communities are objecting to plans by SSE and others to erect large pylons to transmit electricity from new renewable projects to cities and towns throughout Scotland, England and Wales.

“Somebody needs to police the line between net zero ideology and rampant commercial opportunism,” said Kate Matthews of Save Our Mearns, a group campaigning against SSE’s plans to install 66 miles (106km) of new pylons from Kintore in Aberdeenshire to Tealing in Angus.

“Angus and Aberdeenshire are looking at 10 to 20 years of industrialisation, so constant building, constant applications, thousands of acres of battery energy storage, thousands of acres of solar turbine hydrogen plants,” said Ms Matthews.

“We’ll be paying the price for generations. It will be unrecognisable,” she added.

Ms Matthews said “the rest of the UK doesn’t know what’s coming,” with plans for new pylons in Essex, Lincolnshire, Yorkshire, the Lake District, parts of Wales, and elsewhere.

Ministers have also pledged to reform planning laws to make it easier and quicker for big projects to gain consent.

Mr Phillips-Davies of SSE said that was vital, pointing out that it took 20 years for Viking to go from inception to blades turning, 16 years of which were on paper.

He is calling for both the UK and Scottish governments to streamline and accelerate their planning processes so projects can be approved or rejected within 12 months.

He points out that Berwick Bank in the outer Firth of Forth, which would be the world’s largest offshore windfarm, has been waiting for consent from the Scottish government for nearly two years.

It’s not just renewable energy companies which have worries about the pace of the transition from fossil fuels to greener sources of power.

In Aberdeen, the home of the UK oil and gas industry, there are concerns that the UK government is putting jobs at risk.

“This is already a sector which is paying three times the tax of the wider economy,” says David Whitehouse of the industry body, Offshore Energies UK, formerly Oil & Gas UK.

Producers currently pay a tax rate of 78%, including a windfall tax brought in after Russia’s invasion of Ukraine caused a spike in the oil price.

Mr Whitehouse says he is also concerned about the removal of tax breaks for investment.

He warns of a potential “shutdown of investment” which he says could have consequences for thousands of jobs and implications for “the very supply chain that we need to deliver a successful domestic home-grown energy transition”.

“We’re starting to see resources, key equipment, drilling rigs and personnel leave the basin,” agrees Steve Bowyer, North Sea general manager of oil and gas producer, EnQuest.

“We actually want to grow in the UK but we need the right fiscal conditions to drive that growth,” he adds.

Mr Bowyer says his firm will be “watching very closely” what Chancellor Rachel Reeves does in her autumn budget and how she engages with industry “over the next six to 12 months” as it considers where to invest in future.

“There’s a risk of causing irreparable damage to the industry and the UK economy if we don’t see proper engagement, collaboration and action to put in place an appropriate fiscal regime,” he added.

The government insists it will protect North Sea jobs for decades to come while also ensuring a smooth transition to renewable energy.

But it is clear that ministers face pressure and scrutiny from the oil industry on one hand and the renewables sector on the other.

Going green is not without its challenges.