In the UK it has almost become an accepted truth in the media that new nuclear power is needed because there is no other practical or cheaper way to balance fluctuating wind and solar power.
A simple way to see it is that you can't provide temporary supply with a plant that's meant to be running all the time... It will already be running (or be unable to run for unrelated technical reasons)
Electricity to consumers in the UK are inordinately high in part because the highest marginal cost wholesale pricing mechanism is dominated by gas. Taking gas pricing into a new “out-of-market” mechanism would serve two vital purposes. First it could and should anticipate paying for the use of gas to provide capacity and not MWs. Second it would immediately cause the price of electricity to better reflect the cost of renewables, reducing electricity prices to domestic and business users alike. This would make not just economic sense, but political sense by demonstrating that decarbonising the electricity supply is a benefit today, not just jam tomorrow.
Thank you for the rational approach to maximising emissions reduction in the most economical way possible.
Step 1 should be get to 100 percent renewables 95 percent of the time with, as you note, open cycle gas filling in during the occasional dunkelflaute.
Meanwhile, as you also note, you pursue various forms of step 2: electrifying everything possible and making all our infrastructure as efficient as possible.
Finally, and also simultaneously, you pursue step 3: building long-term storage (such as closed-loop pumped hydro) and step 4: continuing to research and develop new and alternative generation and storage technologies.
The vast sums saved by abandoning nuclear would buy a lot of steps 2, 3 and 4!
I accept all of the arguments, but as a non-specialist I do also watch what decisions are being made else where. In China, which is arguably the most climate aware country in the world, they are putting a lot of investment into nuclear, mostly standard U fission, but also SMRs and Th-fuelled MSRs. For a multitude of reasons they are able to drive down the cost and build-times of conventional nuclear whilst their research programs deliver on a time scale that the US and Europe struggle to match. The significant thing is they drive their nuclear program forward in parallel with wind and solar, rather than as alternatives.
A further point that is being missed, one in favour of steady nuclear, is the changing shape of the demand curve. Presently it is a curve above and below a base load; the absolute minima is during the early hours, rising when everyone gets up, flattening or even dropping slightly during the day then peaking in the evening. The gas demand curve is much the same.
Electrification of transport will push up over night demand, flattening the curve. Heat pumps can’t heat water to the temperature required to warm a property quickly, they’re far more effective if left running continuously. Pushing gas heating to electricity will raise and also flatten the demand curve.
The same applies for industrial energy; high energy processes run near continuously.
The end result looks to be a demand curve that is of lower amplitude and much higher base, diurnal variation will be a far smaller percentage of base load than at present. Flattening the demand curve gives lower rates of change in demand, all of which suits nuclear to the tee.
The issue that is being missed here is that Net Zero isn’t about decarbonising today’s grid, it’s about replacing all primary energy with electricity. The patterns of demand that we see today will not remain the same, transport in particular will drive up overnight demand as will industrial demand — steel, cement, chemicals run continuously. As the demand curve flattens base load increases making nuclear an ideal solution.
Wind is nowhere near cheap enough, especially when one factors in the cost of balancing, storage, inertial reserve and contingency, all of which are externalities ignored when costing wind, but carried by the grid and passed on via higher consumer prices.
As for gas balancing wind, in the medium to long term the suggestion does not hold up. Once gas is replaced as a primary energy source then volumes that will be required to provide even 10% on UK electricity will not justify the maintenance of the pipeline infrastructure to import it. As that infrastructure is retired it will not be replaced, leaving no gas whatsoever. That’s not a UK decision; it’s one in the hands of those countries from which we import gas.
The better solution is to go all in for nuclear, backing large reactors with multiple SMRs — the correct focus being not on “small” but “modular” — with PSH — which is fast response and highly flexible, to cover the time it takes to ramp them up.
Sorry, but wind, despite its vocal proponents, is distraction. We could never build and, even more importantly, indefinitely maintain enough wind capacity to meet UK demand AFTER net zero is reached. We know nuclear works and we know from countries that maintained a nuclear programme that it can be built on time and budget, we just haven’t done enough to rebuild the UK’s skills and supply chain. Climate change is too pressing an issue to faff around with “renewable” solutions that have yet to demonstrate their ability independently to power an entire nation.
But you accept my point that Net Zero involves removing hydrocarbons as a source of primary energy from the economy as a whole, forever? And the consequence that North Sea gas infrastructure (and LNG re-gas terminals), the operation and economics of which rely on continuous demand, will not be replaced?
Gas might conceivably be stretched out a few more years if we were (i) to allow more UKCS gas fields to be developed; and (ii) add a lot of localised gas storage to the OCGTs being proposed to balance renewables and the CCGTs proposed to ensure continuity of supply during periods of low wind. But that's (a) very expensive; and (b) isn't zero carbon by anyone's definition. Trying to set off that CO2 is a non-starter; we couldn't grow forests fast enough. Using CCS (even pre-combustion) is both very expensive and energy inefficient; OCGT's are, what, 30% efficient at best? Add CCS and I doubt they'd make 20%.
As a permanent solution you can't rely on gas to back wind generation. And if you can't back wind generation, what are we going to do in a fully electrified economy. Please don't say storage is the solution. It's great for diurnal peaking, but it doesn’t stack up economically or environmentally for long term, seasonal smoothing. There simply aren't enough high valley and glens to build sufficient long term PSH to meet, say, seven day's UK demand today, let alone what demand will be post whole economy decarbonisation. Were we to try the environmental damage to the Highlands, Cambrian and Cumbrian mountains would be horrific. Equally, the demand for rare earths etc. for battery storage (even if allowing for near 100% recycling) already imposes unconscionable environmental costs; we shouldn’t be exporting these as we do.
So what is the solution? I've read your article on SMRs and cannot concur with your analysis. There's only one that we know can work and for which future technology pathways are clear; nuclear. The reason I suggest big plants backed by SMR and limited PSH is not that SMR's are small, but that they are modular. You can add, say, 200 - 600MW by turning on a plant and their (relatively) low thermal mass allows them to be ramped up and down far more quickly than large nuclear.
I have done a blog post about the 'primary energy fallacy' - you don't have to replace hydrocarbons with an equal amount of renewables. See 'How small increases in renewables produce big cuts in carbon emissions' https://davidtoke.substack.com/p/how-small-increases-in-renewables As for battery materials, you are using a straw man when you say that lithium batteries are not good to use for long term storage. We don't argue that. Batteries are becoming more and more economic for short term storage. In addition to that grid forming inverters can and are being efficiently used. See for example 'Grid-Scale Battery Stabilizes Scottish Power Supply Its advanced inverters quickly inject power and current' https://spectrum.ieee.org/grid-scale-battery-scotland
The role of the new nuclear is NOT to pick up the slack when wind + solar aren't generating, it's to provide a large baseload, so that it won't be necessary to build so much wind + solar + batteries. Nuclear can provide 50-80% of minimum load, wind + solar + batteries pick up the rest, gas fills in any remaining gaps. Nuclear is needed because without it you need to cover gigantic amounts of land with panels / windmills. Why do that, when nuclear is more reliable and safer?
Also regarding costs, Sizewell C is an abomination, the costs of which have ballooned disproportionately. But this is a UK thing not a nuclear thing. South Korea are building nuclear at a tenth of the cost. In the UK, any big government or capital project has gigantic cost overruns, pointing to systemic UK issues in permitting and procurement. Those issues need to be solved anyway.
The problems with nuclear power are partly a problem with construction in general, and not to be waived away by a comparison with South Korea. This is inaccurate anyway relying on a 'factoid' which does the rounds. South Korea is catching up with the west in having increasing construction tomes for nuclear power. The latest power plant to come on line took 11 years from construction start to generation anyway. See https://world-nuclear.org/nuclear-reactor-database/details/shin-hanul-2. See my comments on how nuclear power has become so expensive here: 'Why nuclear power plant are so expensive, especially in the West' https://davidtoke.substack.com/p/why-nuclear-power-plant-are-so-expensive
Unfortunately, the reply not visible in the public dialogue so I have taken the liberty to republish it below as it raised some interesting points of discussion. David stated:
“It’s all very well raising issues but the point is that Sizewell C will make very little if any difference to any of these. Voltage and frequency control will come from grid forming inverters which are very cheap pieces of spinning metal required at small volumes compared to total generators capacity. You seem to miss completely my point that gas leakers will provide occasional generation during low wind/solar, which surprises me since it was the central point of the blog post. The clean power plan relies mostly on fixed rather than floating wind turbines. There are large amounts of batteries already coming on line to provide intra-day balancing a lot of the time.”
The UK Electricity generation sources and supply network must be designed to cater for the worst-case situation. For a system comprising a very high percentage renewables the worst-case would be a European wide wind drought of which there have been two since 2010/11. The Winter Freeze wind drought in 2010/11 lasted for 42 days. In this situation it would be negligent to assume that interconnectors could help out. Northern Europe would be in the same boat and Norway might be reluctant to release energy from hydropower if their dams were low. (There is some political resentment in Norway that Norway is selling is hydro energy to Europe at market process which increase the cost of electricity to Norwegians)
As an engineer/analyst I was fully aware of the concept outlined in your post of using Gas to meet 5% of demand. Indeed, it was this percentage that prompted the questions about storage. If gas is to provide just 5% of energy demand and wind power the remainder then with a wind load factor no better than 50% then this will require significant intraday and interday storage.
The UK currently uses some ~900–1,000 GWh/day. A 30-day wind drought would currently require some 23 TWh of storage if the UK was 95% supplied by wind power. The need for storage will increase over time due to UK electrification and the increased penetration of EVs and Air Source Heat Pumps. There is no experience of storage at TWh scale anywhere worldwide.
================================
I concur that UK government policy is for mainly offshore fixed bottom turbines.
The capital costs of floating wind turbine and 4th generation nuclear are similar. After taking into account the cost of storage and transmission network upgrades the full cost of nuclear energy per MWh is lower.
4th generation nuclear is not intermittent, it will have 90% availability, it can be sited on existing power station sites and it can meet some of industry’s needs for heat energy in manufacturing which is some 60% of the size of total electricity demand.
So rather than putting all eggs into one basket maybe the UK government should promote 4th generation nuclear instead of niche product floating wind power which when sitting 10 miles or more in the North Sea has little utility when compared with a 4th generation nuclear sitting on an industrial estate delivering electricity and heat to its occupants.
Finally, there are a couple of technical points in your post that seem wrong. I will comment separately on each of them.
BESS are useful for short-term grid balancing (intra-day) and for next day storage, but are not suited for multi-day or seasonal backup. Worldwide they are used for next day storage with capacities up to ~3GWH (0.003 TWh) discharging over four hours.
They cannot meaningfully support UK electricity needs during a 30-day low-wind event in winter which needs in excess of 20TWh.
David, you described grid forming inverters as “very cheap pieces of spinning metal”. This is not correct.
Grid-forming inverters (GFIs) are power electronic devices that convert DC electricity from sources like solar panels, batteries, or wind turbines into AC electricity, while also establishing and maintaining the grid voltage and frequency—just like a traditional synchronous generator.
There is no worldwide experience of using them at Giga Watt level. The largest deployments have been 300MW and 500MW. It is estimated that they add 2-3% to the cost of a wind-farm.
There are technical challenges of GFI including: coordination of multiple GFI, harmonic emissions, compliance with regulatory grid codes, and the complexity of network control strategies. These challenges will be magnified with increasing usage of independent GFIs on a national network.
I have a few questions about this world future world where more than 90% of UK electricity is to be provided by intermittent renewables.
1) What mechanisms will be used for providing voltage and frequency stability and have they been proven at utility level scale.
2) Who will pay for these stability mechanisms and where do the costings appear in the plan. They are not included in the Levelized Cost of Electricity (LCOE) for renewables
3) What is the scale (say of peak and average demand) of very long-term storage (more than 4 days) needed to provide both capacity (GW) and long-term supply (TWh) in times of wind drought
4) What types of storage will be used for the very long-term storage (more than 4 days) that will be needed and have they been proven at utility level scale
5) Who will pay for these storage mechanisms and where do the costings appear in the plan
6) There have been three wind droughts since 2010, the worst was the Big Freeze in 201/11 where the average daily wind load factor at the time fell below 7% for 42 successive 42 days at a time when the usual monthly load factor was around 24%. Will renewable and storage deliver reliable power for each minute of the day during a 6- week period such as this.
7) The scale of wind turbines planned is huge, 43-50 GW offshore (the UK has about 15GW now) A significant proportion of the later build will need to use floating turbines. AR6 strike prices indicate they are about 2.5 times the cost on fixed bottom turbines. When combined with the associated network enhancement costs what is the anticipated total cost per MWh?
Surely the cheapest and easiest way is to manage demand? Discretionary demand (most of it) is met when power is available. Nuclear power might not be v. good at filling gaps, but it is essential nonetheless.
Great blog. I was not aware that CCGTs are less flexible than OCGTs. Is that universally true? Here in Austria, as well as a few other countries I have been following, I also note that gas production springs in for short spurts when the sun goes down and not enough wind is available, BUT, I also note that in those periods of course the spot price shoots up (obviously making the gas-produced electricity profitable), and that in turn motivates the production of electricity from gas plants EVEN if a countries needs are being more than met - i.e. export is also being promoted. I guess one could argue that if a neighbor needs the electricity than so be it, but I simply wonder about the climate-related efficacy. Its one thing to argue we need the gas-turbines to spring in when there are not enough renewables available, but its another to note the overriding economic factor - as long as the spot price shoots up, gas-turbines will be used.
CCGTs can respond reasonably quickly but their conversion efficiency goes down by a lot when stopping and starting. This makes them less effective than OGCTs which are cheaper
I attended an online event yesterday at which East Midlands Nuclear set out their proposals for nuclear power generation in the region. I posed the following question, which (not surprisingly) due to shortage of time did not receive an answer...
"Nuclear power has, up to now, been regarded as providing reliable power for base load. This has suited the characteristics of reactors and the capital dominated economics of nuclear power that demands a high and maintained load factor. In an age where variable renewables are taking the lion's share of generation, how will nuclear play a compatible part in balancing the grid? If stored hydrogen and gas turbines form a significant part of the answer, the economics will be highly questionable."
The following was a supplementary question, that also went unanswered...
"The East Midlands, or more specifically the EMCCA/D2N2 Area is trailing behind the UK in its rate of decarbonisation [35.5% reduction in GHGs from 2005 to 2023 according to the ONS, compared to the UK's 45.8%]. Can the East Midlands afford to have an energy strategy in which principal elements come on stream so far into the future and/or are very speculative?"
Thanks David for another excellent factual article exploding the myth that we need nuclear to "keep the lights on". Here at STAND (Severnside Together Against Nuclear Development), where we have been fighting nuclear power since the 80's, we are facing the prospect of 3 Rolls Royce "small" ha ha "modular" ha ha reactors on the old Oldbury site. We quote you often on our website and you are a great source of information.
We are having a public meeting on 17th October in Lydney where Jonathon Porritt will be one of the main speakers. We'd love to have you too! (only 8hrs 20 mins by car according to RAC route planner!). Keep up the good (essential) work!
I would just add - if and when BECCS (for example Drax, running two biomass units at a total of roughly 1.2 GW) comes on-line, the intention is to maximise 'negative emissions', and that requires that they generate with a high load factor. The resultant additional 'firm' power on the grid on top of nuclear would curtail even more weather dependent renewables. Go out to 2050 when it's suggested BECCS might be storing as much as 80million tonnes of CO2 per year and we'd need as much as 10GW of BECCS generating capacity, running baseload. What role for nuclear then?
A model looking at a hypothetical 10 GW UK wind fleet (which is a significant portion of current capacity) found that:
* Power is below 20% of available power for 3,448 hours (20 weeks) in a year.
* Power is below 10% of available power for 1,519 hours (9 weeks) in a year.
* Of the hours below 10% of maximum, 1,178 hours (78%) occur in events that continue for 6 hours or more.
These figures from the model suggest that wind output can be very low for a substantial portion of the year, and these low-output periods can be prolonged.
Of course there would be many other times where it is well below 100%. The gas percentage in your scenario would be more like 30%.
If you look at the grid power sources every half hour for the current year you will see the trend. I cannot attach the document as there is a copyright stamp.
A simple way to see it is that you can't provide temporary supply with a plant that's meant to be running all the time... It will already be running (or be unable to run for unrelated technical reasons)
Electricity to consumers in the UK are inordinately high in part because the highest marginal cost wholesale pricing mechanism is dominated by gas. Taking gas pricing into a new “out-of-market” mechanism would serve two vital purposes. First it could and should anticipate paying for the use of gas to provide capacity and not MWs. Second it would immediately cause the price of electricity to better reflect the cost of renewables, reducing electricity prices to domestic and business users alike. This would make not just economic sense, but political sense by demonstrating that decarbonising the electricity supply is a benefit today, not just jam tomorrow.
Great idea in principle. The devil is in the detail, as they say.
Thank you for the rational approach to maximising emissions reduction in the most economical way possible.
Step 1 should be get to 100 percent renewables 95 percent of the time with, as you note, open cycle gas filling in during the occasional dunkelflaute.
Meanwhile, as you also note, you pursue various forms of step 2: electrifying everything possible and making all our infrastructure as efficient as possible.
Finally, and also simultaneously, you pursue step 3: building long-term storage (such as closed-loop pumped hydro) and step 4: continuing to research and develop new and alternative generation and storage technologies.
The vast sums saved by abandoning nuclear would buy a lot of steps 2, 3 and 4!
A bad way? A virtually impossible way, surely?
I accept all of the arguments, but as a non-specialist I do also watch what decisions are being made else where. In China, which is arguably the most climate aware country in the world, they are putting a lot of investment into nuclear, mostly standard U fission, but also SMRs and Th-fuelled MSRs. For a multitude of reasons they are able to drive down the cost and build-times of conventional nuclear whilst their research programs deliver on a time scale that the US and Europe struggle to match. The significant thing is they drive their nuclear program forward in parallel with wind and solar, rather than as alternatives.
A further point that is being missed, one in favour of steady nuclear, is the changing shape of the demand curve. Presently it is a curve above and below a base load; the absolute minima is during the early hours, rising when everyone gets up, flattening or even dropping slightly during the day then peaking in the evening. The gas demand curve is much the same.
Electrification of transport will push up over night demand, flattening the curve. Heat pumps can’t heat water to the temperature required to warm a property quickly, they’re far more effective if left running continuously. Pushing gas heating to electricity will raise and also flatten the demand curve.
The same applies for industrial energy; high energy processes run near continuously.
The end result looks to be a demand curve that is of lower amplitude and much higher base, diurnal variation will be a far smaller percentage of base load than at present. Flattening the demand curve gives lower rates of change in demand, all of which suits nuclear to the tee.
The issue that is being missed here is that Net Zero isn’t about decarbonising today’s grid, it’s about replacing all primary energy with electricity. The patterns of demand that we see today will not remain the same, transport in particular will drive up overnight demand as will industrial demand — steel, cement, chemicals run continuously. As the demand curve flattens base load increases making nuclear an ideal solution.
Wind is nowhere near cheap enough, especially when one factors in the cost of balancing, storage, inertial reserve and contingency, all of which are externalities ignored when costing wind, but carried by the grid and passed on via higher consumer prices.
As for gas balancing wind, in the medium to long term the suggestion does not hold up. Once gas is replaced as a primary energy source then volumes that will be required to provide even 10% on UK electricity will not justify the maintenance of the pipeline infrastructure to import it. As that infrastructure is retired it will not be replaced, leaving no gas whatsoever. That’s not a UK decision; it’s one in the hands of those countries from which we import gas.
The better solution is to go all in for nuclear, backing large reactors with multiple SMRs — the correct focus being not on “small” but “modular” — with PSH — which is fast response and highly flexible, to cover the time it takes to ramp them up.
Sorry, but wind, despite its vocal proponents, is distraction. We could never build and, even more importantly, indefinitely maintain enough wind capacity to meet UK demand AFTER net zero is reached. We know nuclear works and we know from countries that maintained a nuclear programme that it can be built on time and budget, we just haven’t done enough to rebuild the UK’s skills and supply chain. Climate change is too pressing an issue to faff around with “renewable” solutions that have yet to demonstrate their ability independently to power an entire nation.
multiple SMRs? doubt this very very much. They are a marketing illusion really. See my commentary specifically on this at https://davidtoke.substack.com/p/why-small-modular-reactors-do-not
But you accept my point that Net Zero involves removing hydrocarbons as a source of primary energy from the economy as a whole, forever? And the consequence that North Sea gas infrastructure (and LNG re-gas terminals), the operation and economics of which rely on continuous demand, will not be replaced?
Gas might conceivably be stretched out a few more years if we were (i) to allow more UKCS gas fields to be developed; and (ii) add a lot of localised gas storage to the OCGTs being proposed to balance renewables and the CCGTs proposed to ensure continuity of supply during periods of low wind. But that's (a) very expensive; and (b) isn't zero carbon by anyone's definition. Trying to set off that CO2 is a non-starter; we couldn't grow forests fast enough. Using CCS (even pre-combustion) is both very expensive and energy inefficient; OCGT's are, what, 30% efficient at best? Add CCS and I doubt they'd make 20%.
As a permanent solution you can't rely on gas to back wind generation. And if you can't back wind generation, what are we going to do in a fully electrified economy. Please don't say storage is the solution. It's great for diurnal peaking, but it doesn’t stack up economically or environmentally for long term, seasonal smoothing. There simply aren't enough high valley and glens to build sufficient long term PSH to meet, say, seven day's UK demand today, let alone what demand will be post whole economy decarbonisation. Were we to try the environmental damage to the Highlands, Cambrian and Cumbrian mountains would be horrific. Equally, the demand for rare earths etc. for battery storage (even if allowing for near 100% recycling) already imposes unconscionable environmental costs; we shouldn’t be exporting these as we do.
So what is the solution? I've read your article on SMRs and cannot concur with your analysis. There's only one that we know can work and for which future technology pathways are clear; nuclear. The reason I suggest big plants backed by SMR and limited PSH is not that SMR's are small, but that they are modular. You can add, say, 200 - 600MW by turning on a plant and their (relatively) low thermal mass allows them to be ramped up and down far more quickly than large nuclear.
I have done a blog post about the 'primary energy fallacy' - you don't have to replace hydrocarbons with an equal amount of renewables. See 'How small increases in renewables produce big cuts in carbon emissions' https://davidtoke.substack.com/p/how-small-increases-in-renewables As for battery materials, you are using a straw man when you say that lithium batteries are not good to use for long term storage. We don't argue that. Batteries are becoming more and more economic for short term storage. In addition to that grid forming inverters can and are being efficiently used. See for example 'Grid-Scale Battery Stabilizes Scottish Power Supply Its advanced inverters quickly inject power and current' https://spectrum.ieee.org/grid-scale-battery-scotland
The role of the new nuclear is NOT to pick up the slack when wind + solar aren't generating, it's to provide a large baseload, so that it won't be necessary to build so much wind + solar + batteries. Nuclear can provide 50-80% of minimum load, wind + solar + batteries pick up the rest, gas fills in any remaining gaps. Nuclear is needed because without it you need to cover gigantic amounts of land with panels / windmills. Why do that, when nuclear is more reliable and safer?
Also regarding costs, Sizewell C is an abomination, the costs of which have ballooned disproportionately. But this is a UK thing not a nuclear thing. South Korea are building nuclear at a tenth of the cost. In the UK, any big government or capital project has gigantic cost overruns, pointing to systemic UK issues in permitting and procurement. Those issues need to be solved anyway.
The problems with nuclear power are partly a problem with construction in general, and not to be waived away by a comparison with South Korea. This is inaccurate anyway relying on a 'factoid' which does the rounds. South Korea is catching up with the west in having increasing construction tomes for nuclear power. The latest power plant to come on line took 11 years from construction start to generation anyway. See https://world-nuclear.org/nuclear-reactor-database/details/shin-hanul-2. See my comments on how nuclear power has become so expensive here: 'Why nuclear power plant are so expensive, especially in the West' https://davidtoke.substack.com/p/why-nuclear-power-plant-are-so-expensive
David posted the following response to the seven questions raised in my post https://open.substack.com/pub/davidtoke/p/why-new-nuclear-power-is-a-bad-way?r=51aelu&utm_campaign=comment-list-share-cta&utm_medium=web&comments=true&commentId=142551373
Unfortunately, the reply not visible in the public dialogue so I have taken the liberty to republish it below as it raised some interesting points of discussion. David stated:
“It’s all very well raising issues but the point is that Sizewell C will make very little if any difference to any of these. Voltage and frequency control will come from grid forming inverters which are very cheap pieces of spinning metal required at small volumes compared to total generators capacity. You seem to miss completely my point that gas leakers will provide occasional generation during low wind/solar, which surprises me since it was the central point of the blog post. The clean power plan relies mostly on fixed rather than floating wind turbines. There are large amounts of batteries already coming on line to provide intra-day balancing a lot of the time.”
The UK Electricity generation sources and supply network must be designed to cater for the worst-case situation. For a system comprising a very high percentage renewables the worst-case would be a European wide wind drought of which there have been two since 2010/11. The Winter Freeze wind drought in 2010/11 lasted for 42 days. In this situation it would be negligent to assume that interconnectors could help out. Northern Europe would be in the same boat and Norway might be reluctant to release energy from hydropower if their dams were low. (There is some political resentment in Norway that Norway is selling is hydro energy to Europe at market process which increase the cost of electricity to Norwegians)
As an engineer/analyst I was fully aware of the concept outlined in your post of using Gas to meet 5% of demand. Indeed, it was this percentage that prompted the questions about storage. If gas is to provide just 5% of energy demand and wind power the remainder then with a wind load factor no better than 50% then this will require significant intraday and interday storage.
The UK currently uses some ~900–1,000 GWh/day. A 30-day wind drought would currently require some 23 TWh of storage if the UK was 95% supplied by wind power. The need for storage will increase over time due to UK electrification and the increased penetration of EVs and Air Source Heat Pumps. There is no experience of storage at TWh scale anywhere worldwide.
================================
I concur that UK government policy is for mainly offshore fixed bottom turbines.
The capital costs of floating wind turbine and 4th generation nuclear are similar. After taking into account the cost of storage and transmission network upgrades the full cost of nuclear energy per MWh is lower.
4th generation nuclear is not intermittent, it will have 90% availability, it can be sited on existing power station sites and it can meet some of industry’s needs for heat energy in manufacturing which is some 60% of the size of total electricity demand.
So rather than putting all eggs into one basket maybe the UK government should promote 4th generation nuclear instead of niche product floating wind power which when sitting 10 miles or more in the North Sea has little utility when compared with a 4th generation nuclear sitting on an industrial estate delivering electricity and heat to its occupants.
Finally, there are a couple of technical points in your post that seem wrong. I will comment separately on each of them.
Battery Energy storage systems (BESS)
BESS are useful for short-term grid balancing (intra-day) and for next day storage, but are not suited for multi-day or seasonal backup. Worldwide they are used for next day storage with capacities up to ~3GWH (0.003 TWh) discharging over four hours.
They cannot meaningfully support UK electricity needs during a 30-day low-wind event in winter which needs in excess of 20TWh.
For further information see: https://docs.google.com/document/d/1WvMSTf2dp0AHVtUfi1oOMD_ev6ilycaA2r_Mx5wNmcQ/edit?usp=sharing
Grid Forming Inverters (GFI)
David, you described grid forming inverters as “very cheap pieces of spinning metal”. This is not correct.
Grid-forming inverters (GFIs) are power electronic devices that convert DC electricity from sources like solar panels, batteries, or wind turbines into AC electricity, while also establishing and maintaining the grid voltage and frequency—just like a traditional synchronous generator.
There is no worldwide experience of using them at Giga Watt level. The largest deployments have been 300MW and 500MW. It is estimated that they add 2-3% to the cost of a wind-farm.
There are technical challenges of GFI including: coordination of multiple GFI, harmonic emissions, compliance with regulatory grid codes, and the complexity of network control strategies. These challenges will be magnified with increasing usage of independent GFIs on a national network.
There is more detail about GFIs in this document here: https://docs.google.com/document/d/1mMOFU3xyt93Zqi6t4UVMUNpcv6Et7C7oIqAkULCfZ90/edit?usp=sharing
I have a few questions about this world future world where more than 90% of UK electricity is to be provided by intermittent renewables.
1) What mechanisms will be used for providing voltage and frequency stability and have they been proven at utility level scale.
2) Who will pay for these stability mechanisms and where do the costings appear in the plan. They are not included in the Levelized Cost of Electricity (LCOE) for renewables
3) What is the scale (say of peak and average demand) of very long-term storage (more than 4 days) needed to provide both capacity (GW) and long-term supply (TWh) in times of wind drought
4) What types of storage will be used for the very long-term storage (more than 4 days) that will be needed and have they been proven at utility level scale
5) Who will pay for these storage mechanisms and where do the costings appear in the plan
6) There have been three wind droughts since 2010, the worst was the Big Freeze in 201/11 where the average daily wind load factor at the time fell below 7% for 42 successive 42 days at a time when the usual monthly load factor was around 24%. Will renewable and storage deliver reliable power for each minute of the day during a 6- week period such as this.
7) The scale of wind turbines planned is huge, 43-50 GW offshore (the UK has about 15GW now) A significant proportion of the later build will need to use floating turbines. AR6 strike prices indicate they are about 2.5 times the cost on fixed bottom turbines. When combined with the associated network enhancement costs what is the anticipated total cost per MWh?
Surely the cheapest and easiest way is to manage demand? Discretionary demand (most of it) is met when power is available. Nuclear power might not be v. good at filling gaps, but it is essential nonetheless.
demand side managment or ‘flexibility’ is important in the case of any supply-side mixture
Great blog. I was not aware that CCGTs are less flexible than OCGTs. Is that universally true? Here in Austria, as well as a few other countries I have been following, I also note that gas production springs in for short spurts when the sun goes down and not enough wind is available, BUT, I also note that in those periods of course the spot price shoots up (obviously making the gas-produced electricity profitable), and that in turn motivates the production of electricity from gas plants EVEN if a countries needs are being more than met - i.e. export is also being promoted. I guess one could argue that if a neighbor needs the electricity than so be it, but I simply wonder about the climate-related efficacy. Its one thing to argue we need the gas-turbines to spring in when there are not enough renewables available, but its another to note the overriding economic factor - as long as the spot price shoots up, gas-turbines will be used.
CCGTs can respond reasonably quickly but their conversion efficiency goes down by a lot when stopping and starting. This makes them less effective than OGCTs which are cheaper
I absolutely agree with you on this, David.
I attended an online event yesterday at which East Midlands Nuclear set out their proposals for nuclear power generation in the region. I posed the following question, which (not surprisingly) due to shortage of time did not receive an answer...
"Nuclear power has, up to now, been regarded as providing reliable power for base load. This has suited the characteristics of reactors and the capital dominated economics of nuclear power that demands a high and maintained load factor. In an age where variable renewables are taking the lion's share of generation, how will nuclear play a compatible part in balancing the grid? If stored hydrogen and gas turbines form a significant part of the answer, the economics will be highly questionable."
The following was a supplementary question, that also went unanswered...
"The East Midlands, or more specifically the EMCCA/D2N2 Area is trailing behind the UK in its rate of decarbonisation [35.5% reduction in GHGs from 2005 to 2023 according to the ONS, compared to the UK's 45.8%]. Can the East Midlands afford to have an energy strategy in which principal elements come on stream so far into the future and/or are very speculative?"
Thanks David for another excellent factual article exploding the myth that we need nuclear to "keep the lights on". Here at STAND (Severnside Together Against Nuclear Development), where we have been fighting nuclear power since the 80's, we are facing the prospect of 3 Rolls Royce "small" ha ha "modular" ha ha reactors on the old Oldbury site. We quote you often on our website and you are a great source of information.
We are having a public meeting on 17th October in Lydney where Jonathon Porritt will be one of the main speakers. We'd love to have you too! (only 8hrs 20 mins by car according to RAC route planner!). Keep up the good (essential) work!
Agree with your arguments here David.
I would just add - if and when BECCS (for example Drax, running two biomass units at a total of roughly 1.2 GW) comes on-line, the intention is to maximise 'negative emissions', and that requires that they generate with a high load factor. The resultant additional 'firm' power on the grid on top of nuclear would curtail even more weather dependent renewables. Go out to 2050 when it's suggested BECCS might be storing as much as 80million tonnes of CO2 per year and we'd need as much as 10GW of BECCS generating capacity, running baseload. What role for nuclear then?
That is a huge amount of gas.
Modelled Data:
A model looking at a hypothetical 10 GW UK wind fleet (which is a significant portion of current capacity) found that:
* Power is below 20% of available power for 3,448 hours (20 weeks) in a year.
* Power is below 10% of available power for 1,519 hours (9 weeks) in a year.
* Of the hours below 10% of maximum, 1,178 hours (78%) occur in events that continue for 6 hours or more.
These figures from the model suggest that wind output can be very low for a substantial portion of the year, and these low-output periods can be prolonged.
Of course there would be many other times where it is well below 100%. The gas percentage in your scenario would be more like 30%.
Well you’ll have argue with the Committee on Climate Change whose analysis implies that they’ll be about 5% gas residual. That’s what my post says.
If you look at the grid power sources every half hour for the current year you will see the trend. I cannot attach the document as there is a copyright stamp.
https://open.substack.com/pub/chrisbond/p/hows-it-going-ed?r=kv235&utm_medium=ios