Electricity prices - what next?

No one has yet described how our offshore wind (much of which may well go offline today due to strong winds) can ever provide this 24/7 supply, deal with surges, or rapidly changing supply conditions, like the end of a TV programme when hundreds of thousands of kettles are turned on at once.

Isn't that the same issue when we had mostly thermal (coal and nuclear) stations that were incapable of rapid adjustments in output - the solution then was to build the likes of the Dinorwig pump-storage system - specifically designed to deal with events like 'TV pickup' - even in the days of just 4 TV channels and so much greater 'synchonising of kettles' it seemed to work well, even if they had to resort to closely watching the TV for the exact timing of the start of the advert break and keep the turnbines 'spinning in air' for a few minutes beforehand to minimise the start up time. As far as I know it's still there and still working (along with a few other smaller sister plants).

If there's spare wind capacity, then a similar if a little slower effect can be achieved by altering the angle of the turbine blades to catch less wind, but keep the whole thing pointing into the wind as normal. The blades can then be returned to their normal operating position within a few tens of seconds to increase generation.

Shorter bursts of demand can also be fed from battery storage systems (there are already several multi-10s-of MW/MWh sites in the UK).

    - Andy.

Yes they do that Andy, but there is a windspeed where the blades must be locked with brakes to pevent damage. That is the problem, the range of variable pitch, particularly at low wind speeds. The efficiency of blades is in reality quite small at low wind speeds, but this is a critical area to collect power and affects the entire machine design. Making the blades suitable for higher speed makes the low end much worse.

The aerodynamics of turbine blades is rather more sophisticated than this impression would suggest. Let me also point out some incoherence in the formulation of this contribution: "windspeed where the blades must be locked ... that is the problem... particularly at low wind speeds." 

There appears to be a few points here and each one makes up the UK energy equation. At the moment we have;

Nuclear; excellent for base load requirements providing the foundation using traditional mechanical generators which can provide frequency control. These base load due to the time to start-up and shutdown. Most of these will be leaving us in the next five or six years. Building new is problematic because the UK is so small and typically they are built in the middle of nowhere. There is much made about new nuclear stations and perhaps one of the biggest obstacles is the obsession with large generators. I came out of the nuclear industry and always wondered why no one looked at the reactors in the submarines as a small modular generating unit after all the technology to deal with expired ones has been around for a good while and their size is manageable.

Wind; on when available but because it is using invertors the output wave form is constructed by pulsing and because it does not have inductive or capacitive characteristics it is not good for frequency control. The UK is windy and I believe they can be counted upon most of the time even if they are quite maintenance intensive.

Pump Storage;  high capacity fast run-up but later on it needs to draw power back to return the water to the upper reservoir.

Waste burners; these have been a real boom over the past few years, paid to take the waste and paid for the electricity. Other than that they are basically like early 20th century chain grate boilers with conventional turbines. The emissions are quite nasty.

Coal; there is still some out there but start-up is rather long. It is still used when margins are tight as they have been regulated out of the market.

Gas Turbines; these are now the backbone for flexing to UK demands. Fast to start-up (around 1.5hours), efficient across varying outputs so they can be held at low MW ready to ramp up and meet demand. If there is a shortfall in wind it is normally these that pick it up.

Biomass; I am not sure what the environmental difference between this and coal really is other than a few million years of maturing.

Hydro; not geographically good for the UK.

Photovoltaic; these are in the UK both as farms and used by the domestic consumer. Not particularly good in the UK but I understand that the original intention of these was to fill building roof spaces which cannot be a bad idea.

Foreign interconnectors; basically getting someone else to make it for you but again the different frequencies and conversion to dc to transmit brings the invertor issue back. Obviously if the country you are importing from is short they will not export it to you. Possibly not reliable if there is an energy crisis.

Battery storage; I am sure the technology has moved on but I had nothing but bad experiences with UPS systems. I have been involved in motor generator sets in the past and they were very good.

One thing the UK only dabbled in was combined heat and power (using power station waste heat to provide heat to dwellings) but the UK has always had an obsession with large generating plants and not small local generation. I always thought it was a good idea but believe the CEGB got its fingers burnt somewhere in London and had to pay for the installation of a lot of alternative heating systems when a station closed.

One of my colleagues once mentioned starting to make coal gas again and putting the waste back in the ground a bit like carbon capture.

Another thought is to improve transmission methods and import more electricity in the form of solar as there is a lot of desert out there with regular 12 hours of daylight but it is some distance away.

The one thing I am not keen on is the UK getting so fixated on its green targets that we actually have energy prices so high that industry and the domestic consumer suffer and we become a nation in decline.

Selected comments where I disagree with your take:

Nuclear: The nuclear industry has externalities which I have detailed and you have not acknowledged. SMRs are in fact trendy (see RR), but the externalities don't go away, and some problems come in addition.

Wind: why focus on details such as invertors and such like? Obviously a contingent view.

Waste burners: as you say, emissions-poor.

Coal: please get with elementary climate science. Climate is supremely important; coal-generation is the worst.

Gas: better than coal, but an interim source only.

Biomass: you are unsure about the difference between biomass and coal? Trees absorb carbon; you burn trees; the new trees absorb the carbon you generated. This cycle is, if you do it right, less than a decade. Letting trees degrade into coal and burning the coal is, shall we say, a rather longer cycle, much longer than the concerns of climate scientists.

Storage (batteries) is going to work. I think in twenty years our future selves are going to wonder what the fuss was about. Our (grand)children are also going to wonder why we persisted with such primitive technologies as were common in 2022.

Peter - I am afraid you have not understood my remarks about turbines, It is at high speeds of wind that they have severe problems and have to be held stationary. At low speeds they generate little power, the operating range is fairly narrow and they manage about 25% of nameplate capacity averaged over long periods. Various people have calculated the battery capacity required to make them useful as a 24/7 supply and it is about 25 days X 50 GW, which is about 30,000 GW hours. Such a battery would cost around 9 X 10 to the power 15 dollars, rather a lot of money! ($300/kWhr). It would also require perhaps 70GW of turbines put somewhere. Even the largest 5MW size would need 14000 turbines, rather a lot as each needs several hundred acres to be clear of the neighbours.

To add to David's post.

On windless days the turbines actually use electricity to stop flat spotting the bearings.

To add to David's post.

On windless days the turbines actually use electricity to stop flat spotting the bearings.

Windless days off the UK coast must be very rare indeed, especially in the North Sea. I don't think that I have ever seen the Solent completely flat.

By contrast, I have seen a sea state of zero (and even no weather) in the Persian Gulf, but then, of course, they have solar.

Funny enough, October 2021 I was sailing off Brightlingsea to Ramsgate, well motoring as there was zero wind. My skipper mentioned this was not unusual. I'm sure somewhere there's  some data showing the wind performance of the North Sea Turbines.

I have motored all the way to France before now, but that doesn't mean that there was no wind, just not enough.

I have a fairly good idea about nuclear sites, I spent over twenty years working as an engineer (admittedly magnox and AGR) at two stations. I know the issues with large scale generation so the SMR bit is not just "trendy". Most of the issues and waste are derived from the handling of spent fuel and reactor circuit maintenance whether it is the fuel itself or the materials that get contaminated during the activities. SMRs manage some of this by at least minimising the number of contaminated sites, it takes around 120 years to fully decommission a nuclear site waiting for activity to decay sufficiently.

I currently work as a CCGT site which does not make me a wind specialist but technically we are an old inefficient site by modern standards but we do make good money filling the gaps when the wind does not blow. I know a little about wind generation and the fact that their output is not at 50Hz, hence the invertor bit and I also know that our old gas CCGT can make good money out of frequency control when the wind is good because they cannot do it! If you go to G. B. National Grid status (templar.co.uk) there are some good graphs showing monthly and yearly the data from each generation type and the lack of wind generation during various months when the wind is too weak or too strong is quite evident.

Biomass is interesting but I remain cynical, so far it has not been a great success and ethically when there is a new dash for something we get it from places we should not be. The recent business of palm oil is evidence of this where rainforest was torn down because there was easy money to be made. I also understand that some of the mining for materials to make batteries is not to good either. One of my biggest dislikes is people waving a green flag to say how good the UK is now (we shut all the coal stations) when what actually happened is we stopped manufacturing and have our stuff manufactured outside the UK in countries burning coal. In my opinion if we are importing those goods then those emissions are ours.

The information I was trying to pass across was how the current energy mix is made up in the UK and perhaps also put across how unblessed we are in the UK. Britain was built on coal which, as I have been reminded, is not particularly popular.

I said my bit on nuclear; the big externalities remain; I think you agree; so I won't address it further here.

The bit about you performing frequency control for turbines; days were, the turbine people would tell you "that's what you're for!" The issue with APC on the farm itself is that it reduces output and thereby revenue with no parallel compensation; economically speaking it is a pure negative for a windfarm operator. However, nowadays when it needs to be done it is done. Could it be you make money out of it because the wind farm can make *more* money by outsourcing it to you?

I think it reasonable to wonder about biomass in the UK. Germany has lots and lots of forest, and one may burn wood for heat even in urban areas (though exactly why typically-sensitive Germans ignore the ensuing particulate pollution is one of life's little mysteries). For individual buildings there are very efficient wood-burning boilers which are claimed to be ecologically better than gas; but the installation currently costs significantly more than an efficient gas boiler by some 3-4 times (you need storage for EN 14961-2 conformant fuel and a feeder, as well as room for it). There are cogeneration biomass boilers for individual buildings, but I don't know anybody with experience with one. I also don't (yet?) see growing around me the masses of willow and poplar one needs in order to get the short cycle in biomass energy. 

Hm On my farm a few years back we planted 60,000 willows for biomass on about 2 ha for about 10 properties heating requirements. When they were about ready to harvest the value of them was quoted to me at £10 / tonne cut! Aparently after I sold the farm the new owner dug them all up taking many weeks with a big digger, because he wanted to use that very wet land for horses. All I can say is idiot and poor horses, they do't eat reeds! Why this was done is a complete mystry as those trees would provide enough wood for 10 houses continuously for ever, and there was lots more land (many acres) much more suited to horses. In the UK wood does not conform to EN14961, it more sensibly used as nice simple logs. You can get pellets but they are very expensive. A friend of mine had a nice wood chip boiler but it only really worked properly with factory made pellets because the auto-feeder tended to jam up with real wood chips. He sold the house and now lives in warmer climes, probably a good idea!