We're in all sorts of bigger trouble if we need a back up power source for tidal power and when exactly was the last time you went to the coast and there were no waves? Sure I've seen it in Hudson's Bay, but not anywhere around the UK.

..unless serious money is spent on bulk electricity storage systems (and I haven't a clue what, if any, technology can handle this task) the UK Govt will miss its carbon reduction targets by a huge amount.

If the estimates I've seen about uranium reserves are approximately right, then nuclear can't take up the slack, so best we restart the fast breeder reactor programs as well.

This has huge potential knock-ons: where does the money for this expensive and necessary R&D come from? Maybe cancelling the Navy's new carriers and pulling out of Iraq would cover it.

"Power in national-grid quantities is very hard to store meaningfully - it normally has to be generated as needed"

Without wanting to elevate this sentence to the point where using the word "meaningfully" to apply to storing power can be criticised as the nightmarishly unsuitable blandity it is, I would mention that one could use the excess power to pump water in a hydroelectric power plant back to the upper reservoir, stored and ready to rush down for the end of Eastenders.

Yes, of course tidal power generation systems average well below 'peak' output due to the nature of the source. What's your point?

With installations all around the country, all feeding the grid, supply smooths out. Then we're simply down to how much per MW it will cost in 5-10years time

Carbon fuels will only go up in price, now we are at the beginning of the end of oil, gas & coal supplies, with decreasing stocks vs. accelerating demand (my girlfriend's an oil trader, sorry), whilst the cost of electrical & mechanical engineering resources will be fairly predictable for decades. Also, economies of scale will drive down the installation & management costs per MW of wind/wave/tidal, not to mention the inceasing efficiency in propeller designs that are increasing the output per device thus further decreasing cost/MW.

And in case you've missed all that fuss on the telly, we're killing the planet too, which is why wind/wave/tidal power is a good idea.

Thank god there are people investing in these schemes right now. Why the downer on tidal power anyway... your dad a miner? Place green hat firmly back on head please.

Lecture over.

"Specialist barge is unavailable" thats a good wording, of "we actually buckled the legs when we hit a sand bank, that was where it shouldn't be" according to the 18oo's sea chart.

If the propeller is extracting power from the medium it is in instead of transmitting power to it, is it still called a propeller?

Surely it doesn't have to be Nuclear or hyrocarbon based backup. They can be renewable!

I can think of at least one example of storing power in grid like quantities, in Ireland there's a hyroelectric dam (near Glendalough, Co. Wicklow) which is already does this.

Aside from generating power from water flowing from a man made lake to a natural one, at night it takes surplus power from the grid and pumps water back up to the top lake again, ready for the morning surge.

I've seen one example of a system that would store the ridiculously high levels of energy needed to compensate for non-continuous power sources like wind, wave Sun or tide.

I saw it in a documentary years ago, so I can't remember the name or the site where it was implemented. It works thus: During low-demand periods, excess generator capacity is used to pump water into an elevated reservoir. When peak demand is hit, this water is allowed to run downhill, through a turbine, into a lower-lying reservoir. The turbine, of course, is linked to a generator.

As used today, it allows you to build a power station with a capacity just a little more than enough to service -average- load, instead of -peak- load, which represents a lot of over-capacity. But it could also potentially be used with a non-continuous power sources in mind.

Of course, it relies on obliging geography. You can't just use a water-tower as your elevated reservoir, not if you want to store useful amounts of energy. You need something lake-sized, sitting on top of a mountain. And the pumps and turbines are expensive, high-maintenance machines. And there is bound to be some power losses, too. (Darned 2nd law of thermodynamics!)

But it is at least one possibility.

people obviously havn't played enough sim city, it's a well known fact that all green power sources seem like a good idea when you only have one house to power but if you want to power that city boy o boy you sure can't afford to do it with wind and solar power - even if you can afford to cover half the map in power tiles.

Knock all that junk down and build a nice efficent nuclear powerplant - thankyou very much.

Internet superhero

Go look up http://easytide.ukho.gov.uk for different ports around the country. There might be enough variance to not have a dead time.

The tides are delayed as they travel around the coast. If you ignore the wind, the delay for a given point is constant, however a strong wind with or against the tide can delay peak tide by upto about 1hr (tides take 12.5 hours to complete a cycle). UK tides are calculated in advance for 30 years by determining the tide for one location (Newlyn, Cornwall IIRC), and then adding the offset for other locations.

Thus, if you have multiple sites, then you are virtually guaranteed continuous power generation.

Luckily the tides around the UK do not all go up and down together. As any sailor will tell you, it can be high tide in one place, but go a hundred miles up the coast and the same high tide can be hours later. So we won't need quite so many of those nukes...

In the Channel Islands (some of the biggest tides in the world) we are looking forward to the day when we can use the electro-dollars reaped from supplying 5% of the UK's electricity to replace the income from the finance industry that Gordon Brown is busily trying to strangle!

@Anonymous Coward, post 1: Did you read the article? It explains why there are high-flow and zero-flow tidal currents. And when we have zero flow, that's when we need "backup for the tides". Mr Page is not worrying about the moon vanishing off into space and all tides actually stopping!

@Robert Grant: Pedant! :-) I sent a similar message re: reservoirs which hasn't shown up yet. It probably will have by the time *this* message is posted.

@2nd Anonymous Coward, post 4: Is there enough variation around the country so that there will be no troughs in the supply curve? I doubt it! And you'll still need a huge over-capacity installed, if you need generators all along the coast. And just who was arguing that green energy supplies weren't needed?

@Simon Baker: That must have been an "oops!" moment. :-)

Oh, yes. And do you have the faintest idea how much power loss would be garnered trying to transmit power from across the length of the country? There's a damn good reason why low-power generators are only useful locally, and your green hat is considerably less efficient as an insulator than a few hundred miles of wire. Only give lectures in a subject you have knowledge of, if you please. Unless of course you're going to tell me you've invented a stable, ductile, room-temperature superconductor. In which case I will be the first to applaud.

Just a few comments - there are no doubt many more that could be said...

1)One pilot plant doesn't automatically mean the cost comes down massively by the second. Ref learning factors. Wind power was similarly extremely expensive at the start.

2)Cost of building a tidal stream generator includes project costs, development, and the connection to the grid. If a tidal farm is built the costs of all of these reduces massively as a proportion of overall costs. Parts have to be designed and built purely for this project, with no economies of scale.

3)Storage of power at these levels is irrelevant. You don't store, you switch off the hydrocarbon capacity so it doesn't generate. Cycling of the power plant is sub optimal but when it's on a scale of hours that doesn't matter, the cost in fuel savings more than covers this. Tidal power is reliable enough that you don't need to have extra capacity idling in case the supply drops.

Seriously, that's one of the most poorly informed pieces I've read in a while...

As I vaguely recall it from 'o'-level geog, there was a system somewhere in the UK which used the 'pumping water up the hill' idea.

Perhaps some of you guys out there have more info?

Re: can it still be referred to as a propeller?

Course it can be - you just need to think of it as inside out - the sea is propelling the generator :)

Or like a jet engine which combusts externally... er I think I'll have a lie down.

There's a fairly accurate article about the Dinorwig pumped-water storage setup on Wikipedia at http://en.wikipedia.org/wiki/Dinorwig_power_station

I was on a tour of the place a few years back when the man at the control desk said 'shall we wiggle the National Grid up and down a bit?' and demonstrated how Dinorwig's output is used to regulate the frequency of the mains supply in the UK.

It's nice to know that the government is so willing to invest in renewable power but would it not make more of a difference to go to the other end of the chain and help people to insulate their homes properly, establish regulations to ensure that all new build is thermally efficient and so on? This is somewhere that the a bit of regulation can have a lot of leverage but for whatever reasons the government chooses to shy away from it and place the onus for action on the homeowner at every turn.

If supply is a problem and it is relatively simple and inexpensive to reduce demand then surely someone here is barking up the wrong tree.

There's to of them near Llanberis Snowdonia.

Quite a good tour if you're in the area as well.

They've got Europes largest man made cavern

http://www.fhc.co.uk/dinorwig.htm

You're thinkin of one of the hydro plants on Loch Awe methinks.

Gentlemen

- you're telling me about tide times, that spent eight years as a bridge watchkeeping officer at sea?

Yes the times of high water do vary around the UK. But in essence the flow of the UK tides is the Atlantic flowing in and out, and it's tidal stream - water flow - that Sea Gen needs. The places where the company think it could site turbines are very restricted to begin with, and a lot of them have similar timings despite being widely separated as they are still responding to the same thing - the moon's effect on the Atlantic Ocean.

For example, look at today's times of maximum rate-of-change of height (the UKHO don't seem to be offering stream atlases online, sadly, but this will be a good approximation of the time of best stream flow).

Muckle Skerry (that's up in the mouth of the Pentland Firth, just south of the Orkneys; ripper tidal streams there*, good for SeaGen) - best times: 0300 and 0900

The Lizard, Cornwall (again, good fast tides) - best times: 0300 and 0900

Oops. Opposite ends of the country; same times.

Given that the range of possible locations (five knot tides in places you can sink piles - and won't block traffic) is very restricted, you'll really struggle to distribute turbines around so that you get a steady feed to the national grid overall. If you can do it at all you'll seriously limit the overall potential of the idea, which is already quite limited. And then you've still got a bad snag in that you'll suffer massive transmission losses piping your juice across the country from the fast flowing places to the slow flowing ones.

And then the times of the tides can be seriously changed by strong winds - which the SeaGen lads conventiently ignore - which will rot up your careful placement and balancing scheme fairly often even if you could do it. So you'll still need backup anyway!

Given that the whole thing's economically unflyable to begin with, trying to balance out the power surges by siting is going to er, blow it out of the water completely. Perhaps I should have put all this in the article, but I thought people would check if they had the idea.

PS - ad hominem guy - no my dad was not a miner. We won't get into yours.

*My ship nearly got turned round once by the eddies there. Not a big ship, but even so.

I visited this place a while ago: http://www.fhc.co.uk/dinorwig.htm

They were proud to claim 40% efficiency, much more than coal fired power stations. Except when you realise they are storing energy (40% efficiency = they're losing 60% of the energy pumping the water back) vs creating energy (ok, converting to electricity for those pedants!).

That said, I agree with the above comments about ecomomy of scale and the fact it'll reduce demand elsewhere in the system. Storage is only really needed if we (fat chance) go 80% renewable soon or peak demands, yes, the end of Eastenders.

As mentioned elsewhere, there are a number of viable energy storage systems that can be used to smooth output or extend the service hours of renewable sources.

Flow batteries show promise in storing and releasing energy by means of reversible chemical reactions, and these can be scaled to very large sizes. Kinetic energy or potential energy systems such as flywheels and pumped gravitational systems are already viable and potentially applicable to renewable sources.

Aren't there some places where currents run continuously, the straights of Gib' rings a bell, does such a thing exist around the UK?

Today, here and now, in 2007, we are about as wasteful of resource as it is possible to be. So, in 200 years time, when our kids kids kids kids are scratching around looking for stuff to burn, a fraction of the power we consume today for a couple of hours a day might be considered a luxury.

It's worth remembering, we haven't yet managed to create an energy source. We have harnessed some energy (mainly by burning stuff), and using that energy we have managed to convert inert things into stored energy, but the amount of energy we create is a fraction of what we poured in to create it.

Hydrogen looks good, as long as we have colossal amounts of energy available to create the amount of hydrogen we need.

Nuclear is seen as a good option once we have finished burning the planet from under our feet, but what a price there is to pay in the long term. Our kids kids kids kids might prefer a couple of hours of weak tide energy a day, but we might not give them the choice.

I don't consider myself a treehugging greenie, but I don't mind facing facts.

Storing energy tends to be massively inefficent.. pumping water back up a hill wastes a whole lot of energy, but there is also the problem of having the water to pump up the hill, having the hill etc etc.

A possibly better way is AIr compression... works in much the same way- compressthe air, and then use it to run turbines when needed... the nice thing is that you scale up or down the facility, and build it practically anywhere.

There are already two pilot projects underway- one in the US, one in Germany... (This was in the economist 2-3 weeks ago).

Alex

... while the Oil companies are laughing all the way to bank.

If anything, the amout of Oil on tap has increased... while prices increase, and the tax-man rips us off with a new excuse to make us feel guilty!

The more that this scare-mongering continues, the more we'll pay for Oil - while some Oil-barons and govts mint money out of us.

In short, don't believe the hype.

Diversity is key, so tidal, wind, hydro and solar are all providing backups for each other, but there are energy storage solutions.

Flow batteries are coming down in price rather nicely. They are great as extra storage can be added just by adding tanks.

http://en.wikipedia.org/wiki/Flow_Battery

There are already deployments next to wind farms to provide close to 100% uptime.

And regards using hybrid cars, extra petrol isn't required as the whole idea of a plug-in hybrid is that it gets charged from the mains to handle the first few 10s of miles. So, during peak usage charge can be drawn from the car and into the grid, and then over-night (for instance) the car's batteries are charged for the next day.

Ian

There is more than enough variablity in the tide times,

heres two major ports, with the tides for today

Falmouth HW <00:00 LW 06:09 HW 12:12 LW 19:03

http://easytide.ukho.gov.uk/EasyTide/EasyTide/ShowPrediction.aspx?PortID=0005&PredictionLength=7

Lowestoft HW 04:46 LW 10:57 HW 17:30 LW 23:36

http://easytide.ukho.gov.uk/EasyTide/EasyTide/ShowPrediction.aspx?PortID=0141&PredictionLength=7

Thats about 4hr50 difference. Ideally you want 6hrs/num_stations between the sites.

I can't find a website that gives the raw tide differences, this will make it clearer that it takes the tides several days to go around the UK.

I was in tongue biting mood and about to move on (thinking I might take The Register off my favourites since this article isn't the first with an obvious bias) when Mr Page chips in.

You may be an expert at watchkeeping bridges but I don't think you've got your head around renewables. In case you hadn't noticed, there's not going to be much option in the not too distant future (things like cold fusion nothwithstanding) so we'll have to get by with some pretty drastic energy conservation plans (probably 80-90%).

If you plan to keep fossil fuel generators I'd like to hear where you suggest their fuel's coming from.....Russia's about the only realistic future supply for our gas generators and they've just started sending long range bombers over to shake us up a bit. And the Mid East is going to be busy supplying the real world powers USA, China and India.

And claiming something is 'economically unflyable' says absolutely nothing about the subject, burning huge amounts of valuable hydrocarbons will certainly come to be viewed as economic madness.

And tides are not just water sloshing in and out, when ocean basins, the coriolis effect and planetary vorticity are factored in you get a tidal wave rotating around an amphidromic point which does give a large variation to tide times (especially in the north sea).

Yet you STILL haven't addressed the fact that you don't store the energy, you turn off existing hydrocarbon plant which turns on again later. You aren't saving in capacity, you're saving in fuel. Same thing that happens now in the UK as a matter of fact, on a huge scale as day/night patterns shift. Or the fact the costs are likely to come down massively. Your article reads as though you have a very fixed idea already in your mind about tidal power (and renewable as a whole?) which ignores quite a lot of the theory and practice of a national grid.

So I wonder what the ecological impact of taking that much energy out of the local tidal system is in regards to currents etc... Tidal barrages like Cardiff are an ecological catastrophe of course - imagine the effect of damming the Severn of course, but if the turbines are big enough to take a reasonmable perecentage of the tide energy then its going to affect the ecology some, not to mention shore erosion... And incidentally I wonder about silt... As th current is reduced by the props it will drop silt, and then...

I can't help but notice nobody has used any Alternating Current related puns. Just thought I should rectify that.

With more smart electricity consuming devices in the system you don't need as much pumped and battery storage to cope with variable output renewable generators while maintaining grid stability. Smart consumption started with those concrete electric storage heaters which are switched on at certain times of the day and night and switched off during peak demand times. Charging electric cars could be made cheaper if there is a longer timespan to charge them over, and they charge up only when the cheapest electricity is available. This concept ideally requires signals sent to smart consuming devices by the grid control centres, to turn them on and off as needed.

At least there were a few encouraging facts in there. I guess I can just let my eyes glaze over for the "you can't make money at it so it can't work so we'll just keep doing what we're doing and making money and.... live happily ever after somehow" parts. Spew out all the reasons why it can't work that you want, Lewis. Doesn't escape the fact that it *has* to work somehow - that is if you don't want to go back to being pale hairy cavemen. Oil won't last forever, flow is most likely declining right now, so I'm happy to hear that anyone is working on solutions. I suppose I can keep reading the many environmental articles like this on el reg, and mining the actual news out of them, while ignoring the fatuous commentary from backwards jerks like you. Does turn my stomach a bit, but I won't delete the bookmark just yet. If I thought there was any point in arguing with someone like you then I would, but it would just be tiring. Good on you those who do attempt it.

To the guy who mentioned insulating homes, you obviously don't live in one or you need to pay attention. If you talk to any builder of new homes, an extension or loft conversion company or almost any one else, they will tell you just how difficult it is to keep up with the ever changing regs for home insulation. Also the gov are going round sticking 15cms or more of insulation into the lofts of OAPs in an effort to eventually get out of having to pay them a cold weather supplement. Insulation and making homes more energy efficient is definately part of the answer but certainly not the whole of it. ALL alternative energy sources are worth investigating and considering even if only to disprove some of them as non-viable. During world war II the most incredible and unlikely things were looked at and considered and it is amazing how many of them paid dividends.

@Colin Miller

Lewis picked two places with strong tidal flows. Probably he picked the two strongest in the UK. What makes you think there are useful tidal flows at Falmouth and Lowestoft? If they don't both have strong tides their relative timing doesn't matter a toss.

@Robert Grant, Stuart Van Onselen, Mike Banahan, ChriZ, Sweep et al.

If you're aiming for 20% renewables, you'd best have a similar storage capacity: Murphy will ensure that sme night we'll have a windless period everywhere that coincides with slack water most places on the coast. In 2004 the total power generated during the year was 345 GWh, so to replace the 20% renewable contribution we need 72GwH. Lets say that we need 20% of that (14.4 GWh) to cover peaks and long, low output periods. Dinowig's maximum capacity is 1.44 GwH (288 MW for 5 hours). We might just about manage to fit another 9 Dinowigs in these rather flat islands, but I wouldn't count on it and ther's no coverage for increased renewable share ot increased demand

@Alex D

Would you really want a huge very high pressure air tank in the vicinity? I wouldn't. It would be incredibly dangerous.

@Ian Oliver

The vanadium flow battery is the most developed flow technology, but its energy density is low (and hence it is large) and fairly expensive. The largest unit so far built is only 2 MWh capacity. Where will we put the other 7,200 units we need to get 14.4 GWh capacity? Can we afford to build them?

Oil.

No major discoveries have been made this decade. Don't forget that new finds reported by OPEC countries are probably ficticious. Here's why. OPEC rules limit national production rates to a proportion of declared reserves, so when an OPEC country wants to raise its output it conveniently "finds" more oil.

Uranium

Good idea, but according to van Leeuwen and Smith there is only enough uranium ore in the world to generate nuclear power at the current rate for "several decates" at most. As I said earlier, nuclear power is not a long term prospect unless we can get fast breeder reactors or fusion to work. Fast breeders have been abandoned and fusion has been 10 years away since the '50s, so don't hold your breath.

Bottom line

More work needs to be done very soon on bulk electricity storage, fast breeder reactors and large-scale energy conservation.

Expect effective energy conservation to have a major effect on our lifestyle. At a minimum it will affect housing, commuting and travel patterns and methods, town planning and transport of goods.

It sounds like the proponents of this system are fit to be tide!

Martin

Sam and Zedee have their minds disconnected - the propellor is propelling the alternator. I direct all your attentions to the comment by breakfast, the likes of which keep me attracted to El Reg. I would not switch to another site for all the joules in Britain, ie any other one amp would be a second, watt?

The problem with articles like this is that it looks at one project in isolation. The truth is, we need alternative energy research and [more importantly] implementation.

If you took a power station and did a cost / payback analysis, you probably would not bother. Cost / benefit yes. Wave, wind, solar, methane et al, all fall into this category.

We need alternatives, so, bite the bullet and pay the bill.

P.