In March I went to see Henrik Poulsen, the boss of Dong Energy, in Copenhagen. Never heard of him or his company? You are not alone, but the chances are he is keeping your lights on. The largely unknown story of his company is worth telling because it is genuinely revolutionary.

Dong stands for Danish oil and natural gas. It was, like Shell and BP, involved in fossil fuel exploration and production. But in less than a decade it has become an 85% offshore wind company, and is divesting its coal, oil and gas interests. By 2023, Dong Energy will be very close to zero carbon. That is a pretty staggering transformation in a very short space of time.

But it doesn’t end there. This isn’t just a hymn to the glory of an oil and gas company, it’s also a paean to the UK’s “greenest government ever”. Thanks to its support, the price of offshore wind energy has dropped by half in less than two years. By the 2020s, it will be as cheap or cheaper than any other form of power generation. It’s just become much cheaper than nuclear, even taking into account the additional costs associated with the wind’s intermittency. And in any case, this is less of an issue at sea where the winds are more constant.

Talking to Poulsen made me realise that we were on the cusp of a quiet revolution. From being the most expensive form of renewable energy, offshore wind was fast becoming the cheapest form of large-scale, low-carbon generation bar none. As Poulsen said: “When you go 10 years into the future and you look back, I think we will look at these years, 2016, 2017, 2018, as the inflection point. I think we’ll look back and say wow … Something happened for wind and solar energy during those years that completely changed the dynamic.” But he also said that “without the UK government and what they have done for the past five or six years, we wouldn’t have been where we are today. I’m glad to see that it’s paying off because we’re creating a lot of jobs right now and building a local supply chain. So they’ll get their rewards, which they should.”

There’s a pleasing symmetry in fighting climate change, a truly enormous problem that remains invisible to most people in the UK, with offshore wind, an equivalently huge and equally invisible solution. But I came away from that meeting thinking that this quiet revolution needed a bit of noise and visibility. Amid the gale of bad news that has blown through 2017, this was a good news story that needed shouting about from the rooftops.

This month’s contracts for the next round of offshore wind farms to be built in the North Sea should have the champagne corks popping in No 10. They mean billions more in foreign investment coming into the UK. They will be playing a major role in regenerating regions in the north-east of the country. And they will create a thriving export market in contracts for offshore wind developments. But we at Greenpeace are not sure the government has noticed the full potential that their policies have created.

This month’s contracts for the next round of offshore wind farms mean billions in foreign investment coming into the UK

To bring it to their attention, some of the world’s biggest players, including Vattenfall and General Electric, have come together alongside environmental organisations including WWF and the Marine Conservation Society. A campaign is being launched today at Westminster with the help of creative agency Mother, which is working pro bono. They explained to us that when you’re selling the future of energy generation at 50% off, all you really need to do is get this fact in front of your customers. MPs using Westminster tube station will find it hard to miss.

The UK needs affordable and secure energy. We have to replace our obsolete power stations and meet growing demand from the electric vehicle revolution. Offshore wind, alongside a smart energy system including storage and interconnectors, should be the backbone of how the UK generates its power in future. Short term, as part of the transition, gas back up might be required (but only when needed, unless it’s green like biogas). Such a system could help us meet our climate change commitments and speed up the move to a low-carbon economy. It could provide jobs and regional regeneration as well as provide export markets. It could be the cheapest form of large-scale power available. It’s shown to be wildly popular in all opinion surveys. We urge the government to come clean on this issue and publicly admit that they got this right!

• John Sauven is director of Greenpeace