Maybe, just maybe, they will be so busy fighting each other that the "project" will quietly die and in the meantime somebody will build a few nuclear power stations, which will solve the energy problem, won't harm the environment and save the Severn estuary from the UK version of 3 Gorges dam.

...that the chair of the SDC commission is Jonathon Porritt (ex-FoE, Green party member and ex-Trustee of the WWF)?

14bn on a tidal project that will provide 4% of our power needs... and we spend only a few million a year funding ITER and the like. Priorities?? anyone???

the problem is that building a dam might actually reduce the tidal level in the severn, thus reducing the power it actually creates...I'd like to see them using tidal stream generation in the estuary instead. It won't create nearly as much energy but it's guaranteed and if it doesn't work it's easy to remove again.

You mean someone that actually knows and cares about the issues they pertain to. How novel!

Three Gorges Dam.

Bristols a sh!t hole anyway so it cant do any more harm.

Do the birds at risk taste good with a helping of tata's and veg? No? Well there you go then.

This is based on an average figure, but (being tidal power) is actually produced during two 4 hour periods every 25 hours. According to the SDC, this is easily smoothed out by building suitable storage facilities (which I'm sure have been factored into the costs).

Perhaps they could just use the unwanted off-peak energy to pump water back over the barrage and then reuse it at peak times? Oh, hang on a minute ...

<RANT>

I have found over the years you can't please the greens.

I have yet to see a viable solution to power generation they are happy with:

Coal pollutes,

Gas Pollutes,

Nuclear pollutes

and wind turbines are an eysore

Now they say tidal power might upset the animals ?

I had one complain to me about the simple act of washing your hands after visiting the mens room

The arguments were:

Towels pollute by detergents when washed

Paper towels are a waste and bad for the environment

Hand dryers waste electricity and dump more heat into the atmostphere.

Which brings me to the latest bandwangon that make me laugh

CO2,

Why ?

Because I see so many people not wanting to been seen to as the only ones not doing something about an issuse

that they jump on the bandwagon before looking and the scientific background

But the biggest joker in the pack is by far paying to pollute aka carbon offsetting

I am all ears what is your solution ?

Go back to living in caves and chewing on leaves ?

Hey have you ever investigated how much CO2 you exhale ?

Care to stop breathing ?

Thought not

Strikes me that some people just aren't happy unless they have something to complain about ;o)

</rant>

As far as I'm aware, the Severn barrage has been in development for the better part of thirty years. I thought that the whole idea had been dropped back in the early 90' s due to fears that it would turn the whole Severn estuary into a giant stinking swamp. Oh well, bad ideas never die....

I just wonder what sort of brainless people are out there. Since when is tidal power renewable?

Mark this well.

The tide is the result of a complex interaction beween the moon the sun and the earth. Gravity pulls on each object in this system however water is mobile and moves to form tides. The energy for this movement comes not from the sun or the moon, they are just vectors in this process. The energy comes from the rotation of the earth. The earth rotation has been slowing through time. To take energy form the tide is not to utilise wasted energy but is the extraction of additional energy from the earths rotation. We are treading on very dangerous ground if we believe this will have no effect. Slowing the earth will increase the temperature range of the whole earth and will render parts uninhabitable.

A nuclear holocust would be less damaging.

If this goes through we can all look forward to the Severn becoming a huge semi-stagnant pond of industrial waste, oil and fertiliser slopping gently back and forth; smearing a turbid slick of fermented sewage from Middle England, Cardiff, Newport and Bristol across the beaches of Minehead and Weston Super Mare.

Sounds a major improvement to the region.

It might improve the beach at Weston-super-Mud. No tides mean nothing being washed up by high tide, no reason for joyriders to dump cars on the beach for a laugh, and no danger of idiots/toddlers getting into difficulty in the mud when the tide comes in faster than you can walk.

"it would be to destroy 75 per cent of the existing intertidal habitat, an area that is protected by international law."

It's good to be Green. Or Brown. Or Bush, Cheney, Blair or similar assorted warmongers and eugenicists. Not.

@ David Sidebotham

What you say is technically correct, but I don’t think it is significant compared to the naturally present sources of fluid motion and impedance. Take the world’s vast oceans, the movement of which is constantly being impeded by the irregular ocean beds, do you believe a few resistive estuaries even compare? What about the lava underneath the earth’s crust?

A bit less over-dramatic pseudo science please!

"WE WANT TIDAL POWER! But don't stick it anywhere that will impact on the environment..."

What a pack of morons.

Like our clean green hydro power - I'm old enough to remember the protests at damming the Clutha River for a hydro power station. It's less polluting than Huntly's coal-fired plant but it does flood an entire river valley.

There's no such thing as a truly "green" power supply. Wind mills - I've seen a wind farm, they take up a lot of space and don't look very scenic. Photovoltaic - you've got to mine the minerals to make the cells. And so on.

The average greeny lives in some kind of lala-land where tidal power can be harnessed continuously using small, unobtrusive generators that won't impact upon the local environment and somehow converting the energy to electricity (read "robbing the waves of energy") is not going to have a spill-over effect.

Too much recreational herb, I suspect.

It is said there's no such thing as a free lunch - this is true of energy production too.

If we all make the effort to reduce our energy usage, then less power generation capacity will be needed.

The saddest thing about the whole wave/tidal power debate is that the invention most likely to provide efficient and low-impact energy, Salter's Edinburgh Duck, has never been properly tested despite having been invented in the 1970s.

I happen to think that the power turbines (windmills) enhance the landscape.

That the house prices where I live on the bank of the River Usk is going to Skyrocket!!! Wait for it to be built... Sell up quick...Move to a mansion in New Zealand! Get out quick before the water Stagnates!

is it always the worst possible 'renewable' schemes that are put forward first?

What an awful waste it would be to throw a dam across the severn, and then only get power when the tide is running one way, at peak times. Anyone care to explain how they will 'store' the generated power for the remaining (majority) of the time?

Every other scheme, (such as the 'artificial lagoon' method) generate power in both directions, and do very little damage to the surrounding area.

As has already been pointed out, tidal energy is not renewable in that it essentially comes from the kinetic energy of the Earth's rotation relative to other gravitational bodies (of which the Sun & Moon are the only significant ones as far as tidal forces are concerned).

However, as has been pointed out, the idea that somehow we will a significant effect on the Earth's rotation by exploiting tidal power is simply wildly wrong. Doing a simple bit of maths would show the real effect to be insignificant in the extreme, and that is making the assumption that the energy so generated would not have been wasted anyway by tidal drag (in fact it is precisely this effect that is already slowing down the Earth).

Of course on that basis, it is not a renewable source. However, the same applies to any energy source - Solar, WInd, Bio-energy - they all come by indirectly from the nuclear reactions in the Sun using a resource that will eventually run out. A more reasonable, and practical, definition of renewables as far as human activities is concerned is that it is energy sources that we will not accelerate the depletion of by exploiting them. For example, we won't somehow increase the depletion of hydrogen in the Sun by generating electricity through solar panels. Even then it is not simple - some forms of such power generation can exploit the use of distinctly finite resources, such as precious metals or natural habitat (see bio-energy). Unfortunately, as many people are noticing, so-called renewable energy resources are far from zero-impact and some, especially bio-fuels, have the potential to be extremely destructive. The tidal barrier scheme is one such.

As for the guy who says Jonathan Porritt bot knows and cares about his subject, well he cares, and maybe his knowledge is there, but his convictions tend to blind him to rational analysis in many cases. Witness his now rather fundamental disagreements with James Lovelock (who really does know what he's talking about).

A few facts to add:

There are already existing storage systems in the UK energy grid.

The Severne estuary is in fact something of a desert in terms of marine life, because of the extremely opaque water. The tidal barrier will partially (but not completely) allow more sediment to settle, thereby increasing light penetration in the water. This is likely to improve the marine habitat.

The tidal barrier will reduce but not eliminate the tidal range on the inland side, by about half. Much of the wetland areas will be preserved (although altered).

Really the only reason it hasn't been built before now is the cowardly way the UK government deals with large-scale infrastructure investment (i.e. it doesn't).