However, turning generation on or off isn't the only way the grid is balanced in the short term - turning up/down tends to be a big part of it too and most conventional generation can do that faster (sometimes a lot faster) than startup/shutdown.
Despite the insistence that Closed Cycle Gas Turbines can't react quickly, because they're by far the largest component that we could start and stop the UK does in fact very quickly increase and decrease output from the CCGTs. For example this morning 2.79GW at 0600 to 3.89 at 0700.
There are much faster options, batteries, import, even the pumped storage is seconds instead of minutes - if available, but CCGT is just not that slow to change compared to the weather. In that same period the wind power went from 10.9GW to 11.4GW. 500MW is a lot of power but it's not more than 1.1GW
https://www.oecd-nea.org/upload/docs/application/pdf/2021-12...
... most of the modern light water nuclear reactors are capable (by design)
to operate in a load following mode, i.e. to change their power level once
or twice per day in the range of 100% to 50% (or even lower) of the rated
power, with a ramp rate of up to 5% (or even more) of rated power per minute.
1.6 GW per reactor for the latest ones under construction (Hinkley Point C) and in development (Sizewell C). Each site has 2 reactors for a total of 2 x 2 x 1.6 GW = 6.4 GW.
Although this is largely just replacing the UK's existing fleet of reactors, almost all of which will have shut down by the time Hinkley Point C comes online. Of the current 5 operating UK nuclear power stations, only Sizewell B is scheduled to operate beyond 2028.
> "They will need them built in the right place, because while more power cables can be built, you can't transfer a lot of power on very long distances"
One of the reasons offshore wind has been so economic & successful in the UK is they can usually plug in to existing, redundant transmission lines left behind by decommissioned coal and nuclear power stations, which are often on the coast. It's relatively cheap to connect to the grid when the infrastructure is already there waiting: you just need to build the cables from the turbines to the shore.
The start time is long but that does not say much about the overall operations.
> Modern nuclear plants with light water reactors are designed to have maneuvering capabilities in the 30-100% range with 5%/minute slope, up to 140 MW/minute
https://en.wikipedia.org/wiki/Load-following_power_plant
and https://thundersaidenergy.com/downloads/power-plants-cold-st...
> In France, with an average of 2 reactors out of 3 available for load variations, the overall power adjustment capacity of the nuclear fleet equates to 21,000 MW (i.e. equivalent to the output of 21 reactors) in less than 30 minutes.
https://www.powermag.com/flexible-operation-of-nuclear-power...
A report from a few years back (which I'm afraid I've utterly forgotten the source) examined the data on this, and argued that as a result of this changed pattern of use, these CCGT stations were now not achieving nearly the kind of efficiency figures they were designed for, which from a carbon point of view is not good news - we might still be emitting lots of the stuff, but just not getting as much practical benefit from it as we used to.
Now, I'm not meaning to suggest that this is a disaster, or that is somehow invalidates the entire of concept of renewables, but it does point to the need to be careful about what we take to be a useful measure of progress - and that merely the quantity of supply to the grid in GWH isn't necessarily it.
And the article under discussion here is of course picking away at another strand of this same idea - when we connect these generators together, it gives rise to system-level effects, and we need to be thinking about the outcomes, both beneficial and harmful, in system-level terms as well.
(Edited for spelling.)
I think it depends on how you define unpredictable.
Wind power forecasting[1] is used pretty extensively as I understand it by all major windfarms.
[1] https://en.wikipedia.org/wiki/Wind_power_forecasting#Uncerta... [2] https://www.cerc.co.uk/forecasting/wind-energy.html [3] https://aemo.com.au/en/energy-systems/electricity/national-e...
You could just keep it spinning nonstop without a load I suppose, but for anything but nuclear it's not gonna be economical.
Wind turbine output, although variable, is also fairly predictable: so good modelling and scheduling should ensure that when CCGTs do operate, they can run as efficiently as possible and not be spinning up and down too frequently.
What you are saying is that its possible to map out in the future when power is available for generation.
The thing is, they don't really want to do it if they can save fuel by shutting down.
You'll soon end up with a burning/melted generator.
> "pump some water in a loop"
OK, but you're going to need huge pumps (1000+ MW!). Expensive.
> "or discharge through some resistors"
Again, you'll need extremely large resistors, and a way to dissipate an awful lot of heat. We're talking about a huge amount of energy here!
Nordstream 1 was 1222km, and Britpipe now, is 60km shorter.
Boston to Lisbon is 5100km. Churchill Falls (home of a giant hydro dam project in Labrador Canada which got screwed by Hydro-Quebec because the only via transit was through Quebec), would be just under 4000km subsea.
The transit contract expires in 2039 I believe...
https://xlinks.co/morocco-uk-power-project/
Surely HVDC links between Scotland and England could be built?
And then there are pumped hydropower storage project like this one with a proposed storage capacity of 200 GWh and 1.5GW of power:
In the worst case, couldn't the excess power simply be used in electrolyzers to generate hydrogen? They may not be very efficient but it's better than throwing free energy away.
But the retail buyer doesn't usually see the negative/low electricity prices of high-supply+low-demand time periods for their "inefficient" uses that should still be economic.
Maybe if variable prices encourages energy intensive demand to shift to Scotland that will help, but that’s not quick either.
Could try also melting some salt on the side.
why would this be necessary when the entirety of Great Britain is one synchronous grid?
But operating a nuclear plant in this fashion pushes up the price per MWh considerably given their very high cap-ex and op-ex. And while fuel cost is negligible for nuclear, creating more nuclear waste per useful MWh generated is a further drag on costs.
So as a solution, it "works" if the nuclear plant does not have to compete in terms of price with other sources of electricity. But nuclear fails to compete on cost even if operated continuously - it's uncompetitive with cheap, quick to deploy, low op-ex, modern tech like CC gas turbines or renewables in most western electricity markets and can only survive with government subsidy[2].
[1] https://www.nrc.gov/docs/ML0703/ML070380209.pdf [2] https://www.washingtonpost.com/business/2022/04/19/biden-adm...
Absolutely. One HVDC link between Scotland and England (actually, Wales) has already been built:
https://en.wikipedia.org/wiki/Western_HVDC_Link
And more are planned:
I suspect NIMBYism is a big part of the explanation. Airborne AC links are efficient but ugly. Underwater AC links are tolerated by Nimbies, but inefficient. So you end up with underwater HVDC links.
Because there are bottlenecks in capacity on the synchronous grid that restrict the amount of power that can be moved from north-to-south (or vice-versa).
It works out better/cheaper/easier to bypass those bottlenecks with efficient undersea HVDC links than to try and build more terrestrial AC transmission lines.
The article covers this and explains why it's not enough. Provisioning time for the links exceeds projected generation capacity increases in the Scotland.
There are electricity suppliers in the UK who offer prices linked to the wholesale price, including actually paying you to use electricity if the price goes negative. Quite useful for flexible loads such as EV charging!
https://twitter.com/DanielColquitt/status/139539635553586790...
https://www.independent.co.uk/news/uk/home-news/national-gri...
Wiki says: https://en.wikipedia.org/wiki/Australia-Asia_Power_Link
projected to begin construction in mid-2023
In January 2023, Sun Cable went into administration, the equivalent of Chapter 11 Bankruptcy.There's good reason why they are hard to throttle. For starters thermal contraction shortened lifespan; but also because the nuclear cycle itself doesn't lend itself to throttling safely - nuclear products create "retarded (?) neutrons" which are the cornerstone of a stable control system (as opposed to prompt neutrons) and also significant amounts of neutrons poisons which are normally "burned" at equilibrium steady state power levels but which accumulate if you throttle down (therefore be needing even more prompt neutrons).
My understanding is that the more you need to rely on prompt neutrons for your neutron balance the more unstable your reactor (starting them up, therefore, is delicate). Throttling the power upsets this balance by at least two different mechanism.
https://www.abc.net.au/news/2023-01-11/sun-cable-enters-admi...
First, reactors are in a stable equilibrium when operating, so one will actually increase their power by increasing the rate at which heat is removed (and v.v.). Alas, that's workable only within some small range.
A reason[1] load-following with PWRs was originally difficult is that traditionally PWRs use boron concentration in primary loop to regulate power and that can be decreased only slowly. The reason it's done that way is that it's the easiest way to ensure that power is adjusted uniformly throughout the core; if instead some control rods were partially inserted, the top part of the core would operate at lower power (and thus lower fuel burn-up) than the bottom part, which would cause compounding control issues later on.
France is using their PWRs in load-following mode by (a) having additional less absorptive control rods ("gray rods") that can be inserted fully to adjust power by smaller increments (b) more complicated schemes to decide which combination of available actuations to use to change power. See https://hal.science/hal-01496376/document for a paper that tries to optimize control designs so that power changes are more possible (and describes how the control schemes work).
Note that the total heat capacity of even just the primary loop in usual reactors is quite large: in PWRs it usually requires ~0.5s of full power output of the reactor to warm it by 1degC, so this can easily cover, say, ~5% variations for something like a minute.
[1] Another is that reactors are not stateless due to xenon poisoning.
The big problem is that energy prices are set based on the most expensive unit that needs to be turned on to meet demand. Renewables do not tend to be that during periods of low supply, as low supply of energy in the eu market generally means sub-optimal weather conditions for renewables. It is going to be either fossil fuels, nuclear, or battery. If we take out fossil fuels then that leaves battery or nuclear. Neither is very economical without subsidies. Governments (and tax paying citizens) are however very keen on grid stability and thus willing to spend a lot of money to keep it running.
This is all predicated on the market operator actually having the systems in place to signal the need for curtailment effectively, of course. That’s a whole different question.
In a certain sense one should expect lowering usage to inevitably lower efficiency, as a sort of inverse corollary to Jevon's paradox (which states that as efficiency rises, total usage does too).
That's a shame, I wasn't entirely onboard with the logistics of crossing the massive fault lines along the route .. but I admired the ambition and scope of the project.
Be interesting to see if this is the end or just a pause waiting for fresh capital.
That is not a problem, it is the incentive to have supplies available so they can be turned on.
I therefore wonder if the market couldn't be structured in a better way which would still ensure that the fossil backup generators are adequately compensated but smoothes the extra cost over the remaining cheap GWh. Something like a meditating party which is aware of the production costs and buys up the daily power and sells it on at an averaged price. There are probably good reasons why this wouldn't work, but I am too stupid to figure them out.
It's worth noting there are some demand response initiatives and the like that are approaching this from the other side - they will pay a user to not use power at particular times of high load. If you don't want to pay a premium on power, I suspect there will be providers happy to oblige, so long as you are willing to forgo the 100% service guarantee.
The UK market maybe not, but the UK could make a truckload of money selling their wind power to France to aid their old, barely running NPPs.
It really doesn't make much sense to connect Europe and North America.
[1] https://en.wikipedia.org/wiki/Ultra-high-voltage_electricity...
At this point there isn't really any part of the energy grid that governments do not subsidize. They subsidize companies that provide grid stability. They subsidize renewables that provide capacity. They subsidize the customer who buy energy. They subsidize the grid infrastructure that transports the energy. They subsidize the interconnection between countries that enables trade between countries. They subsidize the cleaning up and associated costs from pollution.
It's called pumped storage.
We dont need as much storage as people think. Solar and wind anti correlate and a vast amount of demand can be time shifted.
The problem is that building wind turbines in Britain has opportunity costs.
For simplicity: assume a status quo of 100% gas. We are burning 100 units of gas for that per year.
Now assume by building a crazy amount of wind turbines we could satisfy 95% of the UK's power demand with renewable. However, for the remaining 5% we'd need to burn 50 units of gas.
In this scenario, efficiency of burning gas drastically plummeted, but so did overall gas use.
However now the question is: for the resources invested into building all those turbines, could we have gotten a better climate bang than 50 units of gas saved?
(All numbers made up, obviously. In practice, we can probably make the economics work. Though we might need to deregulate the grid. It's crazy to pay wind turbines for not running. At least mine bitcoin or smelt aluminum or something.)
Alas, in the real world because of public opinion and political pressure, it's almost impossible to build new nuclear power plants. And those that get build are crazy expensive and overengineered, and invariable overrun their schedule and budget.
Could you at least mine bitcoin or something like that?
Building any new transmission line through densely-populated England is extremely expensive. Even if you can secure the necessary land and wayleaves, nobody wants them running near their house and spoiling the views, so significant segments have to run underground in tunnels, greatly increasing costs.
Besides, the UK is not that small when linking England and Scotland. The proposed Eastern Green Link 2 (EGL2) is 440 km long: there are many existing HVDC connections much shorter than that around the world!
It's because of this that there's a lot of talk about wild ideas like pressurizing abandoned mines and so on - there are a lot of mines around. But then we're back to the "proven technology" sticking point.
1. power available when you want it, and you can choose on the fly
2. power available when you want it as long as you know in advance
3. power available at a time that you don't choose, but you can predict
4. power available at a time that you can neither choose not predict
Moving generation up this hierarchy, or demand down it, is always going to give some benefit. Well designed power markets should make sure that there is some fair incentive for any such step.
Nowhere is currently "well" provisioned for pumped hydro given a solar and wind grid coz while they existed for over a hundred years they have never had to store that much energy. Newer, larger ones are being built around the world. Australia will be well provisioned soon.
Go back in time 10 years when solar and wind first became economic and people made similar comments about how little of it there was (1% of total power!), ignoring the unit economics completely. We are at that exact same inflexion point with pumped hydro.
What's the longest period without wind and sun you're willing to provision for before you give up and tell the population they'll have to do without electricity for a bit? A day, a week, a month? Numerically, how much storage would that actually need? How many stations, how big? You'd need over a hundred Fengnings to power the UK for a week. Where would they go? I'm all for renewables + storage but you can't handwave these questions as FUD, it's a serious problem.
I suspect that if we committed to categorically eliminating fossil fuels, including peaker plants, the first time the lights went out because the weather was bad you'd have people clamoring to build nuclear power plants. Statistically, it'll happen at some point no matter how much storage you provision.
They are expensive things, and typically not something left to popular vote.
6.5 Fengnings or equivalent should be enough for a 94% renewable grid in the UK.
It is well within the same order of magnitude.
>the first time the lights went out because the weather was bad you'd have people clamoring to build nuclear power plants
because why build a solar or wind farm this year when you can instead wait 20 years for hinkley c to be finished at FIVE times the LCOE cost?
it's absurd. the people dont clamor for nuclear power. only the military industrial complex does.
That doesn't follow at all from your article, which is about the US. You can't just extrapolate from a different country at a lower latitude with different weather patterns and vastly more space to put things like onshore wind/solar farms without running into NIMBYIsm, not to mention more hours of sunlight just from spanning 4 timezones. 6 hours of storage is not even close to enough for reliable renewable power in the UK. It wouldn't even cover a single windless winter night.
And even if we take it at face value, the scenario you linked involves masses of overbuild, over the course of nearly 30 years ("by 2050"), and still leaves 6% of energy coming from carbon combustion. If we start building nuclear plants now, even if we accept your premise that they take 20 years to build (they needn't, especially with scale), then we can get to zero carbon almost a decade earlier - and with minimal land use.
It's not like it's impossible - France went all in on a nuclear grid.
This is FUD.
You absolutely can if you are discussing orders of magnitude which we were.
Our fundamental disagreement wasnt about whether it was 8x fengnings or 6.5x but rather whether it was of the order of 65 or 6.5.
>It's not like it's impossible - France went all in on a nuclear grid.
Not impossible, just at great expense and it wasnt worth it. In 5 years less of France's electricity will be nuclear than it is now while still spending vast sums on new plants. They're officially hoping renewables will make up the difference.
The UK is leading the world in grid interconnection and offshore wind build out (though all owned by none UK entities), so if they aren’t building quickly enough I don’t know anyone who is….
Arguably, if cost effective, nuclear is best run at full output as consistently as possible, with other systems buffering that supply with demand (hydro storage, batteries, demand response, etc).
https://www.laka.org/nieuws/2022/so-how-flexible-is-nuclear-...
https://www.ianfairlie.org/news/french-report-nuclear-power-...