Tidal Lagoon - Energy from the Ocean, UK Gov is putting money in it

[coppice]

Using the tidal and pumped water generators for storage a 100% renewable grid is plausible, even with the solar/wind/wave power being unreliable because you can store sufficient energy in the tidal (short term storage to match solar output for instance) and pumped storages to ride out the lulls in production from other sources. Its already done here in Australia on a substantial scale with the mountain based hydro.

Don't conflate pumped storage with tidal power. We know all about pumped storage, as it has a long track record. If you have the right geographical features in sufficient quantity it is the only proven high capacity storage system around. If you could economically construct sufficiently big lakes you could even ride over the kind of huge lulls in output which wind farms give you. Few places have the necessary geography, though.

Tidal is very different. It has value, although limited value, as an energy source. Tidal is very unsuitable as a storage scheme. As I said, its a resonant effect and you have to go with the flow, or lose most of its capacity.

Tidal can be looked at as a pumped storage with a trivially small head, and yes as I keep pushing its a trade between storage capacity and energy production. As per the post above there is a huge untapped potential in both and is not constrained by a lack of suitable places to build (local nimby outrage is a problem with any large development).

Try looking an Tom Murphy's breakdown - http://physics.ucsd.edu/do-the-math/2011/12/can-tides-turn-the-tide/ - of the potential for tidal power, and see if you can find any serious flaws in his arguments.

[coppice]

If you could economically construct sufficiently big lakes you could even ride over the kind of huge lulls in output which wind farms give you.

Think about those water storage facilities and how your enemies could use them against you in a time of war.

I think most modern infrastructure is highly vulnerable in times of conflict, even to the limited kinds of attack terrorists might use. Can you really power a modern society from anything which is robust against attack?

[Someone]

Using the tidal and pumped water generators for storage a 100% renewable grid is plausible, even with the solar/wind/wave power being unreliable because you can store sufficient energy in the tidal (short term storage to match solar output for instance) and pumped storages to ride out the lulls in production from other sources. Its already done here in Australia on a substantial scale with the mountain based hydro.

Don't conflate pumped storage with tidal power. We know all about pumped storage, as it has a long track record. If you have the right geographical features in sufficient quantity it is the only proven high capacity storage system around. If you could economically construct sufficiently big lakes you could even ride over the kind of huge lulls in output which wind farms give you. Few places have the necessary geography, though.

Tidal is very different. It has value, although limited value, as an energy source. Tidal is very unsuitable as a storage scheme. As I said, its a resonant effect and you have to go with the flow, or lose most of its capacity.

Tidal can be looked at as a pumped storage with a trivially small head, and yes as I keep pushing its a trade between storage capacity and energy production. As per the post above there is a huge untapped potential in both and is not constrained by a lack of suitable places to build (local nimby outrage is a problem with any large development).

Try looking an Tom Murphy's breakdown - http://physics.ucsd.edu/do-the-math/2011/12/can-tides-turn-the-tide/ - of the potential for tidal power, and see if you can find any serious flaws in his arguments.

That discussion is focusing on just the extractable energy, rather than capacity for energy storage. Using those same calculations at less than half the available tidal range the hypothetical Severn Barrage should be able to reliably release something in excess of 10GWh over the 4 hour evening peak electrical load every day of the year. With all the benefits of the fine grained and fast slewing power supplied by hydro setups.

Investing in (ideally pumped) tidal and pumped hydro is the enabling storage technology to back solar/wind/wave/water flow plants.

[coppice]

Try looking an Tom Murphy's breakdown - http://physics.ucsd.edu/do-the-math/2011/12/can-tides-turn-the-tide/ - of the potential for tidal power, and see if you can find any serious flaws in his arguments.

That discussion is focusing on just the extractable energy, rather than capacity for energy storage. Using those same calculations at less than half the available tidal range the hypothetical Severn Barrage should be able to reliably release something in excess of 10GWh over the 4 hour evening peak electrical load every day of the year. With all the benefits of the fine grained and fast slewing power supplied by hydro setups.

Investing in (ideally pumped) tidal and pumped hydro is the enabling storage technology to back solar/wind/wave/water flow plants.

So, you didn't actually read it.

[Someone]

So, you didn't actually read it.

I read it and used their calculations! But they discuss energy harvesting of tidal power, which as they conclude is globally a small amount of energy available compared to other sources. But as an energy storage it has merit for the UK (along with pumped hydro), last time I looked this is a thread discussing the UK investment into tidal power, they are uniquely positioned to extract much higher than average energy from tides which:

• could be time shifted or pumped to cover peak requirements, at the cost of reducing its energy capability
• can be ramped at extreme rates
• is able to be scheduled with extremely high availabilty and certainty

[coppice]

So, you didn't actually read it.

I read it and used their calculations! But they discuss energy harvesting of tidal power, which as they conclude is globally a small amount of energy available compared to other sources. But as an energy storage it has merit for the UK (along with pumped hydro), last time I looked this is a thread discussing the UK investment into tidal power, they are uniquely positioned to extract much higher than average energy from tides which:

• could be time shifted or pumped to cover peak requirements, at the cost of reducing its energy capability
• can be ramped at extreme rates
• is able to be scheduled with extremely high availabilty and certainty

Are you sure you read it? As well as looking at  capacity, and how the UK, France and a few other spots are nicely positioned to be able to harness that capacity, he looks at the horrible effects of trying to time shift. Anything more than a small time shift massively reduces capacity. Its estimated that a Severn barrier could provide 5% of the UK's electrical energy, and people hand wave about other inlets being used. They hand wave because those other inlets are much weaker propositions for development. 5% is pretty good for a single source of energy, especially one you can rely on for output you can predict years in advance. However, you only get that if you work in sympathy with the tides. You don't get 5% and be able to choose when you get it. Its either/or.

[Someone]

So, you didn't actually read it.

I read it and used their calculations! But they discuss energy harvesting of tidal power, which as they conclude is globally a small amount of energy available compared to other sources. But as an energy storage it has merit for the UK (along with pumped hydro), last time I looked this is a thread discussing the UK investment into tidal power, they are uniquely positioned to extract much higher than average energy from tides which:

• could be time shifted or pumped to cover peak requirements, at the cost of reducing its energy capability
• can be ramped at extreme rates
• is able to be scheduled with extremely high availabilty and certainty

Are you sure you read it? As well as looking at  capacity, and how the UK, France and a few other spots are nicely positioned to be able to harness that capacity, he looks at the horrible effects of trying to time shift. Anything more than a small time shift massively reduces capacity. Its estimated that a Severn barrier could provide 5% of the UK's electrical energy, and people hand wave about other inlets being used. They hand wave because those other inlets are much weaker propositions for development. 5% is pretty good for a single source of energy, especially one you can rely on for output you can predict years in advance. However, you only get that if you work in sympathy with the tides. You don't get 5% and be able to choose when you get it. Its either/or.

I've seen suggestions of the UK having somewhere around a 60GW peak load, and suggest from the calculations I and others have done that the Severn Barrage when shifted could provide around 4% of that peak. Which when you think about it is only 0.5 to 1% of the total energy delivered to the grid.

Add in some pumping to take out "excess energy" during periods of excess generation and you could probably do better than 10% of the peak load, which would reduce the energy harvesting to deliver even less than 0.5% of the total energy, but it allows those intermittent sources to be utilised with high availability and certainty.

[coppice]

So, you didn't actually read it.

I read it and used their calculations! But they discuss energy harvesting of tidal power, which as they conclude is globally a small amount of energy available compared to other sources. But as an energy storage it has merit for the UK (along with pumped hydro), last time I looked this is a thread discussing the UK investment into tidal power, they are uniquely positioned to extract much higher than average energy from tides which:

• could be time shifted or pumped to cover peak requirements, at the cost of reducing its energy capability
• can be ramped at extreme rates
• is able to be scheduled with extremely high availabilty and certainty

Are you sure you read it? As well as looking at  capacity, and how the UK, France and a few other spots are nicely positioned to be able to harness that capacity, he looks at the horrible effects of trying to time shift. Anything more than a small time shift massively reduces capacity. Its estimated that a Severn barrier could provide 5% of the UK's electrical energy, and people hand wave about other inlets being used. They hand wave because those other inlets are much weaker propositions for development. 5% is pretty good for a single source of energy, especially one you can rely on for output you can predict years in advance. However, you only get that if you work in sympathy with the tides. You don't get 5% and be able to choose when you get it. Its either/or.

I've seen suggestions of the UK having somewhere around a 60GW peak load, and suggest from the calculations I and others have done that the Severn Barrage when shifted could provide around 4% of that peak. Which when you think about it is only 0.5% of the total energy delivered to the grid.

Add in some pumping to take out "excess energy" during periods of excess generation and you could probably do better than 10% of the peak load, which would reduce the energy harvesting to deliver even less than 0.5% of the total energy, but it allows those intermittent sources to be utilised with high availability and certainty.

If you only want to cope with the peak demand for a small part of the day, why not do it with gas turbines? They would be far less costly, whether you measure cost by dollars, or by how much energy you need to sink into building the system. If it only supplies 0.5% of total energy, the carbon cost is no big deal, and its not going to materially contribute to fossil fuels running out. If you are going for the huge cost of a Severn barrier surely you want some material benefit from it, like materially affecting the rate at which fossil fuels are consumed. For that you need to extract all the energy you can.

[Someone]

If you only want to cope with the peak demand for a small part of the day, why not do it with gas turbines?

The energy produced from the tidal plant has a nominally low marginal cost, where as open cycle gas turbines for peaking can have utilisation rates of 1% or less to only make profit when the market prices reach exceptional levels. Regardless, the important point I keep pushing is:
Tidal storage (and pumped hydro) is one opportunity to store energy and eliminate the intermittent issues of solar/wind/wave/water current generators
It fits in with a diversified generation base, alone it may seem silly but no conventional plants offer storage capability so they cannot be compared without considering the storage as part of the package. The return on investment of pumped storage is shorter than conventional plants, the UK investing in tidal power (pumped or not) is a great investment.

[coppice]

If you only want to cope with the peak demand for a small part of the day, why not do it with gas turbines?

The energy produced from the tidal plant has a nominally low marginal cost, where as open cycle gas turbines for peaking can have utilisation rates of 1% or less to only make profit when the market prices reach exceptional levels. Regardless, the important point I keep pushing is:
Tidal storage (and pumped hydro) is one opportunity to store energy and eliminate the intermittent issues of solar/wind/wave/water current generators
It fits in with a diversified generation base, alone it may seem silly but no conventional plants offer storage capability so they cannot be compared without considering the storage as part of the package. The return on investment of pumped storage is shorter than conventional plants, the UK investing in tidal power (pumped or not) is a great investment.

I give up. You are conflating pumped storage with tidal power again.

[Someone]

I give up. You are conflating pumped storage with tidal power again.

Tidal power can store the energy until it is required (at a reduced capacity). The power delivery can be planned around the other generators due to its extremely high availability and certainty, and its able to rapidly ramp up/down to closely follow demand cycles.

Or the additional costs to make it pumped are very low if its designed in when built. Then you can not only store the energy from the tidal power but also excess energy from other sources.

Either way tidal energy is able to store energy and deliver it when its needed most, or it can run as a predictable but intermittent generator. Market forces will determine which of these modes it would operate in but the existing data suggest that it would be more profitable as a peaking plant, and more profitable again if pumped.

[tom66]

I think most modern infrastructure is highly vulnerable in times of conflict, even to the limited kinds of attack terrorists might use. Can you really power a modern society from anything which is robust against attack?

Exactly - at least solar and wind are distributed across a large area, so I'd actually say they're less vulnerable than say a nuclear or coal plant providing several % of grid demand.

[rolycat]

If you could economically construct sufficiently big lakes you could even ride over the kind of huge lulls in output which wind farms give you.

Think about those water storage facilities and how your enemies could use them against you in a time of war.

No problem, we'll just send 617 Squadron to blow up their dams

Well, we could if it hadn't been disbanded due to lack of aircraft 

[Mechanical Menace]

No problem, we'll just send 617 Squadron to blow up their dams

Well, we could if it hadn't been disbanded due to lack of aircraft 

Manned aircraft are a hangover of a time long gone. Drones and guided missiles, preferably launched from  submarines, are the way forward. No one who would go to war with us could stop them

[Someone]

Don't worry, it's gone past talking and I'm just shouting at them

[dannyf]

I think most modern infrastructure is highly vulnerable in times of conflict, even to the limited kinds of attack terrorists might use.

The vulnerability is different. For a power plant, you can shut it down and deal with its consequences through regulation (rolling blackouts for example).

For a large dam, your choices are limited to lowering the water levels prior to an attack (presumably your attack) - your enemy can see that as a signal for a pre-emptive attack, or to live with a potential flooding by enemy attack.

[tggzzz]

Exactly - at least solar and wind are distributed across a large area, so I'd actually say they're less vulnerable than say a nuclear or coal plant providing several % of grid demand.

That is exactly correct. I've said it before, that is the reason why the National Grid considers wind and solar capacity to be more reliable and requires less spare capacity margin for them.

Reference please.

The grid always has a certain amount of spare capacity ready to dispatch should something go wrong or there be an unexpected surge.

Scandalously currently at a record low of 4%-5%.

Of course intermittent sources won't change that one iota, since the same capacity is required to cover their intermittancy - even though the capacity will be underutilised and thermally cycled.

With say wind the risk of losing 1000MW instantly is almost zero, because an individual turbine might only contribute a few tens of megawatts at most. It's a bit more complicated than that but basically accurate.

The key weasel-word there is "instantly". That makes your statement true, but also makes it irrelevant and disingenuous.

The probability of losing almost all of the UK wind capacity is 100%, no matter how much is installed. That is not theoretical, it is measured practical reality.. Thus if you have, to pick an arbitrary figure, 30GWpeak wind power, then you must have 30GW of other idle plant ready to be ramped up. The 5% chance of losing 1GW is pretty trivial by comparison!
References: the Narional Grid graphs in https://www.eevblog.com/forum/chat/tidal-lagoon-energy-from-the-ocean-uk-gov-is-putting-money-in-it/msg627043/#msg627043 and  http://www.jmt.org/wind-analysis-report.asp

[tggzzz]

Note that the IEEE is a highly respectable organisation...

A partial eclipse of the sun headed for Europe next Friday has grid operators in a tizzy.
...
“It’s a very, very big challenge for the transmission system operators in Europe,” says Enrico Maria Carlini, Head of Electric System Engineering for National Dispatching at Rome-based Italian transmission system operator Terna.
...
it poses a, “serious challenge to the regulating capability of the interconnected power system.”
...
That’s the equivalent of turning off 30 big coal or nuclear power stations.
...
Grid operators in the U.K. are less concerned about a solar deficit than their colleagues on the Continent. Solar is barely 2 percent of their power supply (compared to nearly 7 percent in Germany)

Read and understand the full article http://spectrum.ieee.org/energywise/green-tech/solar/solar-eclipse-will-test-grid-ops-in-europe?utm_source=feedburner&utm_medium=feed&utm_campaign=Feed%3A+IeeeSpectrum+%28IEEE+Spectrum%29

[coppice]

Read and understand the full article http://spectrum.ieee.org/energywise/green-tech/solar/solar-eclipse-will-test-grid-ops-in-europe?utm_source=feedburner&utm_medium=feed&utm_campaign=Feed%3A+IeeeSpectrum+%28IEEE+Spectrum%29

Although its from the IEEE, I'm not sure how much faith to put into even that article. It read like something fair and balanced, until I got to "Since much of the U.K.‘s solar capacity is installed in Scotland...". The text then treats Scottish PV power as a substantial source of power. Scotland has a lot of installed renewable capacity, but its almost all traditional hydro power and wind. Everything I've read says they have less than 150MW of installed solar PV capacity. With Scottish levels of insolation its output during most days in spring is probably <20MW. Its insignificant

[G7PSK]

Problem in the UK is cold foggy days in winter = NO wind and no sun which adds up to No power and due to the size of the UK this can be over most of the country so how ever good the grid management is you cannot rely on solar and wind alone there has to be a big enough supply from other sources to keep the country running sometimes for several days at a time. If you have that it makes for very uneconomical running of both the renewable's and the gas,coal or nuclear plant.
Martin Lorton mentioned something recently about large solar farm destabilising the grid as well due to sudden fluctuations of output which cannot be picked up fast enough by other generation means.
The only way we are going to get the amount and reliability of supply is going to be from thorium reactors.

[tggzzz]

Read and understand the full article http://spectrum.ieee.org/energywise/green-tech/solar/solar-eclipse-will-test-grid-ops-in-europe?utm_source=feedburner&utm_medium=feed&utm_campaign=Feed%3A+IeeeSpectrum+%28IEEE+Spectrum%29

Although its from the IEEE, I'm not sure how much faith to put into even that article. It read like something fair and balanced, until I got to "Since much of the U.K.‘s solar capacity is installed in Scotland...". The text then treats Scottish PV power as a substantial source of power. Scotland has a lot of installed renewable capacity, but its almost all traditional hydro power and wind. Everything I've read says they have less than 150MW of installed solar PV capacity. With Scottish levels of insolation its output during most days in spring is probably <20MW. Its insignificant

That's fair; it is essentially a "journalistic" article rather than a statement of record in a learned journal. I too was a little surprised about the statement about solar in Scotland - it deserves some scrutiny. I've since blundered into other articles which raise the question of what will happen, none of which are significantly more informative.

I will be keeping my eye out for statements about what actually happened, and what was necessary to avert "disaster".

However, the article does illustrate that intermittent sources, however predictable, are not sufficient for a reliable grid, as some (one?) on this forum seem to believe. And that's true whatever timescale is chosen for the predictability/intermittancy.

[tggzzz]

Problem in the UK is cold foggy days in winter = NO wind and no sun which adds up to No power and due to the size of the UK this can be over most of the country so how ever good the grid management is you cannot rely on solar and wind alone there has to be a big enough supply from other sources to keep the country running sometimes for several days at a time. If you have that it makes for very uneconomical running of both the renewable's and the gas,coal or nuclear plant.
Martin Lorton mentioned something recently about large solar farm destabilising the grid as well due to sudden fluctuations of output which cannot be picked up fast enough by other generation means.

But but but "there's always wind somewhere". Isn't there? Please say there is. (Oh alright, )

The only way we are going to get the amount and reliability of supply is going to be from thorium reactors.

Nah. There's no "one true way", although they are indeed beguiling.

[Someone]

The only way we are going to get the amount and reliability of supply is going to be from thorium reactors.

Or having a large percent of the peak capacity available in storage, such as water. Just having dispatchable power from hydro or tide power is a good first step to reducing the cycling of thermal plants, and as storage is added to the grid the reliability will rapidly increase. Average capacity factor will plummet but thats not a problem when the marginal cost of the generation is close to zero.

[tom66]

Average demand on the UK grid is about 40GW so we'd need around 960GWh to run us through a whole day with nil renewables. That's approx 11 milllion Tesla 85kWh packs fully cycled... Hmmm... anyone got a few trillion quid behind the sofa? (£16,000/pack)

I think pumped storage would work a little better! But the problem is where to put it? There are only a few places it works really well, like Dinorwig in Wales and I think there are a few plants in the Scottish highlands.

Unfortunately, England - relatively speaking - is really quite flat!

[tggzzz]

I think pumped storage would work a little better! But the problem is where to put it? There are only a few places it works really well, like Dinorwig in Wales and I think there are a few plants in the Scottish highlands.

Unfortunately, England - relatively speaking - is really quite flat!

Cruachan, which is tiny.

But we do have quite a few mountains. (And for convenience we'll ignore that they are just 2000ft peaks and useless w.r.t. dams).

I've often wondered if you could flood large areas of Scotland and use them as high-volume low-height storage schemes. A good way to soak up (ho ho) all the wind power in the NW