The problem with nuclear is that it isn’t very flexible in terms of ramping up and decreasing output. If you have a lot of intermittent supply (wind and solar) then you need something more flexible such as gas or a shed load of pumped storage.
There have been some developments on coal fired plants that enables them to be more reactive to demand (I’ll admit I haven’t yet read the full paper on this but I’ve mentioned it for completeness).
The Terrapower AMR has also been designed to flex it’s output more than the typical nuclear reactor. With a nominal 345MW output it can, for short periods, peak at 500MW. It does this by storing excess output at times of low demand as heat in a reservoir of molten salt (it’s primary coolant). It’s better suited to the normal variations of demand over the course of a day though and is not a solution to the variability of wind generation that can drop to near zero over days at a time.
Because marginal pricing is used, it’s usually gas that is the most expensive, as it’s switched on in order to meet demand. Research has shown that in 2021, gas set the price of UK electricity 97% of the time. But let’s avoid any protracted discussion on this; I’m sure we all agree that we need to move away from fossil fuels for the sake of the planet.
Yes, gas does set the market price 97% of the time. However it usually sets it at a value that is less than the guaranteed prices that renewable suppliers receive.
Gas plants receive the market price.
Renewable electricity operators also receive the market price but they then receive an additional top-up payment that is the difference between the market price and their guaranteed price.
Thanks - wasn’t aware Agile was available to all, last time I looked at Octopus they seemed to be offering a standard tariff possibly with more flexible ones later on once you’d been a customer for a while. I may have misinterpreted.
Assume those figures are price/kWh?
So are you effectively being paid to consume when they’re blue? How are the figure in green so low?
Or is it variation around a fixed maybe higher unit price?
Today is quite unusual having so much of what is called plunge pricing. It’s a sunny day with plenty of wind around and being a weekend there’s oversupply so it’s being given away or even better!
Agile can be horrifically expensive but on average works out to be economical. I’ve run a comparison tool for the last 3 months usage and Agile worked out slightly cheaper than the fixed deal which was already low compared to current tariffs. This is without factoring in adjustments in usage patterns, i.e. running the dishwasher and washing machine in cheaper overnight slots and avoiding expensive days for doing the washing for example.
You can get greenness forecasts which predict a few days ahead which days will be greener than others which helps with planning.
Some may say it’s not worth the faff but I find it quite rewarding and avoiding the non green days is a way of helping the environment so it’s not just the back pocket that benefits.
They really are aren’t they, along with other utility bills and council tax.
Almost 30 years ago when we moved into our home, electricity was a few pennies per kWh from memory and we’d have used loads more than we currently do, especially for lighting.
The larger living area (originally 2 rooms) had 2 ugly yet functional ceiling lights each with 3x100W bulbs. Seems incredible lighting that used 0.6 kWh. Rapidly changed to CFLs when they became available though hated them, and heavy/expensive LEDs quite early on dramatically reducing consumption for lighting (though the bulbs were very expensive at around £20 for funky Philips Master LEDs).
Back then utility bills were just bills I didn’t think about them too much, just paid them and we had much lower household income comparatively.
Approaching retirement it is pretty scary thinking how much of our income goes on council tax/utility bills and how fortunate we are that we will not have to rely on state pension alone.
One to explore in the future by the sounds of it. Looks as though it’s reasonably predictable in the sense that you have blocks of -ve/+ve for the most part rather than large changes every hour or two.
So I assume a fixed unit price which then varies every half hour?
Is it effectively real time pricing so there’d be a risk of say using a tumble dryer when you think it’s cheaper then it becoming more expensive unpredictably half an hour later, or do you get advanced pricing figures for a few hours or even the day allowing you to plan?
I’ve always wondered why everyone wouldn’t take advantage of such pricing if they could, though equally felt if everyone did by time shifting high consumption that the price fluctuations would likely flatten out over the years with less benefit to consumers.
Time shifting noisy appliances or ones you’d want to not use unattended would perhaps be tricky for many.
It seems that Octopus Agile can be used in conjunction with Octopus Labs to automatically optimise battery charge and EV charging based on the 24hr price schedule for Agile that is published around 4pm each day.
There’s no fixed unit price, it’s completely variable up to the cap of £1/kWh. Prices are set the day before and published around 4pm so no, it’s not ready time dynamic pricing which would be a PITA.
An EV tariff if you are eligible will likely be cheaper overall depending on your usage pattern. Adding in a battery to cover some or all of your peak hours usage would provide a much lower overall cost than Agile.
Thanks, don’t have an EV primarily as it would not be feasible to charge at home (at least currently). This is maybe the point I was making earlier about some of the excellent tariffs being unavailable for a large number of the population.
Wow! What a bargain. Except you then need to factor in the cost of the same amount of gas power to spool up when the sun doesn’t shine. So you have all the cost of the solar panels and associated infrastructure plus all the capital cost of the gas plant and associated infrastructure. Now this would be less than the £114 as you’d only be using gas when the plant is running but would still, even on these questionable numbers, render solar more expensive than gas.
In winter, in the UK, solar generates less than 10% of it’s “capacity” and even then in the middle of the day when demand is not at peak so the backup gas plant and will be running an awful lot of the time.
So back to the numbers. National Grid quote £41 per MWh for solar. In the AR7 auction the offer price for solar was £78 per MWh and even at that there were no bids. At £78 per MWh solar was deemed un-investable in the UK.
I’d have to do a bit of digging to confirm prices for new plant gas generation, probably from the latest capacity market figures, but I am rather suspicious of the £114 value (November 2025 cost of gas generated electricity in the UK was £52.46 pre carbon tax). They don’t break it down as to how much Carbon Tax is included in there (last year it was £27.95. I suspect that they’re projecting an increase on that (prices have already started rising in anticipation of UK joining the EU carbon trading scheme).
In summary the National Grid document is at best disingenuous, at worst outright spin. It doesn’t tie up with the reality of the cost of generation in the UK.
If you wish to gain a deeper understanding of the costs of renewables in the UK then this would be a good starter.
A little further reading on the risks of the current electricity market strategy
Maybe have a look at Octopus EV car leasing (new and used). They give you a 50% off public charging at selected CPOs with their free Electroverse card.
Ooh, thanks was unaware of that. The expensive cost of public charging must be preventing so many people from getting EVs if they can’t charge at home cheaply.
I was looking at a Tesla in late 2024 as they were offering free charging for a year with the garage close to a local supermarket I could potentially pop into while charging. Only found out about the offer shortly before it ended and time was really against me.
Charging at home will, as you say, be a huge barrier for many aspiring EV owners. There are some possible solutions for homeowners who don’t have off-road parking, including cables that can be routed under the pavement for example. That won’t work for everyone, but it shows that off-road parking is not necessarily a prerequisite.
Yes, I’ve read about some of those. Unless they were public charging points (and likely to be expensive) and not connected to the household supply our biggest issue currently would be being able to park outside the house. It was never an issue a couple of years ago, but it’s very hard to park at all these days. Cars which don’t even belong to neighbours have started appearing, often left for days or weeks, during the last year or so.
I think it’s largely due to a church hall a hundred yards away which was converted into a dozen or more flats (yes, local residents/NIMBYs objected) - the developers said none of the residents were anticipated to have vehicles as there was no parking space at the site. Sure…