Between Cardiff and Bristol is a huge resource that could generate enough renewable electricity to power the whole of Wales.

But news that a new commission is being set up to explore tidal energy options for the Severn Estuary has prompted questions about what happened the last time this was looked at.

About a decade ago a public debate on a potential Severn Barrage lasted years but the project ultimately stalled after failing to get backing from Westminster.

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Major changes since then include developments in tidal energy technology and increasing urgency in the need to move away from fossil fuels to renewable energy.

Ideas for tidal power stations in the Severn Estuary and Bristol Channel stretch back decades but the most recent one really got off the ground in 2008, when the UK government began a two-year feasibility study looking at different options before eventually deciding that a barrage from Lavernock to Brean, near Weston-super-Mare, could be the best choice.

Then in 2010 as the UK coalition government took power priorities and plans changed and funding for the scheme was dropped in September that year. The government didn’t rule out supporting the project, however, if developers could find enough private funding.

One company, Hafren Power, developed serious plans for an 11-mile long barrage and held talks with ministers at the UK Department of Energy and Climate Change.

But these plans were criticised by MPs for not having enough detailed evidence to prove the case for the barrage and concerns were raised on the impact of the local environment and local ports.

Although ministers from the department held talks with Hafren Power about how the government could support a private scheme these had stalled by 2013 and led nowhere.

One prominent supporter of the scheme was Peter Hain, former Welsh Secretary and MP for Neath.

He quit his role on the shadow cabinet in 2012 to focus on campaigning for the barrage.

He previously said: “The Cardiff-Weston Severn barrage is the single most important low-carbon, renewable energy project in Europe and should be backed by all those serious about tackling climate change.

“It would generate the equivalent of several nuclear power stations and contribute over five per cent of Britain’s entire electricity requirements.

"It would harness the enormous tidal power of the Severn estuary which has the second-highest tidal range in the world.

"Tidal energy generation has a considerable advantage over other renewable energy technologies because tides are predictable and constant. Whereas wind and solar are intermittent tidal power is continuous.”

READ MORE: ‘Decade of action’ needed to achieve a net zero Wales

The question now is whether technology, politics, and the demand for clean energy has moved on since then.

In October, Cardiff council leader Huw Thomas revealed plans for a new panel of experts set up to explore tidal energy options in the estuary, including a barrage.

The panel will be commissioned by the 'Western Gateway', a new regional group of several local authorities including Swansea, Cardiff, Bristol and Wiltshire.

At the time Cllr Thomas said: “We’re not wedded at this point in time to any solution, rather to make groundwork on the case for looking at what the options could be.”

Few details are available at the moment on the new commission but more announcements are expected soon. Meanwhile elsewhere in the world tidal energy has developed significantly since the last time a barrage was seriously considered for the Severn.

The oldest tidal power station in the world is La Rance, in Brittany in northwest France, which opened in 1966. This used to also be the world’s largest until Sihwa Lake tidal power station opened near Seoul in South Korea in 2011, a barrage built on an already existing seawall.

Both of these power stations are barrages but there are other forms of tidal power technology closer to home.

Off the north-eastern tip of Scotland the new MeyGen power station was launched in 2016 and uses giant underwater turbines to generate electricity from fast-moving tidal streams. And in Swansea plans for a tidal lagoon have repeatedly been put forward but so far without success.

Another lagoon idea, Blue Eden, would stretch between the Tawe and Neath rivers. It wouldn’t need government funding and would also include floating houses. While before Christmas, the Welsh Government ministers approved planning permission for Menter Môn’s Morlais tidal energy project, situated off the the Ynys Môn's west coast.

According to one tidal power expert at Cardiff University, Professor Roger Falconer, technology has developed since the early 2010s that could now make schemes easier to develop, including artificial intelligence and different types of turbines to allow fish to flow through.

He previously said: “This is a credible option that deserves the same attention as other options — now more than ever. This would give us complete independence and predictability. It would make a major contribution in my mind to UK Ltd energy security and Wales can play a very important part in that.”

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