The Swansea tidal lagoon will still happen despite delays, the man who conducted an independent review into tidal energy has predicted.
Charles Hendry backed the £1.3bn project in his government-commissioned review published in January 2017.
The UK Government is yet to give the go-ahead, but the Welsh Government has said it will offer “substantial investment”.
But Mr Hendry argued the delay implied the project would still happen.
“The fact the government hasn’t said no is a cause for optimism,” he said.
“I think the easiest thing for a government would have been to say quite early on in the process of reviewing my conclusions, to say we’ve looked at it alongside our other priorities, and this really isn’t the time to do it – they haven’t done that,” he added.
“We’ve had distractions such as a general election, ministerial changes. So inevitably, it has taken the government some time to reach its conclusions, but I still think the case is compelling.”
Critics of the project argue it is too expensive, and will tie bill-payers into topping it up for almost a century, even though new technologies are likely to have emerged by then.
The lagoon is also expected to cost the government £123 per megawatt hour for the first 20 years, although it will reduce over time.
This total is more expensive than the £92.50/MWh at the Hinckley Point C plant in Somerset and two offshore wind projects in England and Scotland which have won strike prices of £57.50/MWh for 15 years.
Even if the finances are sorted, developers still need a marine licence to build it. But anglers in the area are worried about the impact the lagoon’s 16 large turbines could have on fish and other wildlife.
Much of the delays over the scheme’s approval have been over whether it will provide “value for money”.
But Mr Hendry said the £1.3bn cost would equate to “less than 50p a year” per household and it would “be some of the cheapest power” the UK would ever have, once the original capital investment has been paid off.
However, that is expected to take half of the lagoon’s lifetime, which could be more than 120 years.
Mr Hendry was also buoyed by First Minister Carwyn Jones’ promise to investment in the project, which he said would generate more money for Wales as the Welsh Government would take partial ownership of the lagoon.
He also said it would make a “significant difference” to the chances of the project going ahead.
“I still think the case is compelling. And I think this is something that future generations will say ‘thank you for doing it, Wales has led the world’.”
Rob Stewart, leader of Swansea City Council said: “We’ve always said in this region we can’t rely on others to do stuff.
“If the UK government won’t help us with this, if they can’t see the value of fixing energy prices and renewable forms of energy long term then they need to get out of the way and let us get on with delivering it and we will look at other ways to do that.”