27
Examination of witnesses
Jon Saltmarsh, Professor Keith Bell and Dr Emily Wallace.
Q1 The Chair: Good morning and welcome to the Lords Committee on the Environment and Climate Change. Today we will be holding the first session of our new inquiry into whether the Government have a firm handle on how to fill the renewables energy gap when the wind does not blow and the sun does not shine, a weather phenomenon often referred to as Dunkelflaute.
Before we start, I remind everyone that the session will be webcast live and that a transcript will be taken and made public. Witnesses will have an opportunity to review the transcript and, if necessary, make very minor amendments. Members are reminded that they should declare any relevant interests the first time they speak, and this applies equally to all witnesses. I will take the opportunity here to say that I am a director of Peers for the Planet.
We are very grateful to our panel of expert witnesses for making the time to be with us today. Dr Emily Wallace is not quite with us, but we hope that she will be very shortly. I will ask each of our witnesses present to briefly introduce themselves. Can I start with you, Jon Saltmarsh?
Jon Saltmarsh: Hello, everyone. I am chief technology officer at the Energy Systems Catapult. I have been there for about four years, and before that I had about 10 years in what is now DESNZ, responsible for innovation, research and engineering. I am an engineer by background.
The Chair: Excellent. Can I ask you to move your chair right in front of the microphone? It is quite sensitive directionally, so that would be helpful to us.
Professor Keith Bell: Good morning. I hold the ScottishPower chair in Future Power Systems at the University of Strathclyde. I am also a co-director of the UK Energy Research Centre, where I lead the research theme on energy infrastructure transitions.
Q2 The Chair: Thank you both again very much for making the time to be with us today. The purpose of today’s session is to understand the impact of wind and sun intermittency and how potential gaps in energy delivery from renewables could be filled. Let me start by asking the first question: what is Dunkelflaute? When you address this, could you do so from a meteorological perspective and an energy sector perspective? I would be interested to know whether it is quantifiable. How is it measured and how is it defined? Lastly, how useful do you think the term Dunkelflaute is for modelling and preparing for the risk of energy shortfalls from renewables? Professor Bell, I will come to you first.
Professor Keith Bell: Yes, certainly. I will have to leave it to Dr Wallace. Hopefully Emily will get here soon to address the meteorological phenomena behind it, for example, how long it might last and how you can forecast it. From an energy system perspective, there is no set definition.
The Chair: Briefly, from your knowledge, what is Dunkelflaute?
Professor Keith Bell: When we want to make use of energy from renewable sources to meet demand—wind and solar in particular—we are subject to the variability of wind and solar. When it is not so windy or not so sunny, we have to meet the energy demand from somewhere else, at least the demand for electricity. We can see periods of time when the total available power from renewables is low. That suggests a bigger need for meeting the electricity demand from somewhere else. We could quantify this in terms of residual demand. At any moment in time, what is the demand for electricity and what is available from wind and solar? That residual demand, if you like, is the gap. If that persists over some period of time, that is clearly a bigger amount of energy that we need to find from somewhere else. That is what we can quantify and we can use modelling to do that.
We can look over different periods of time. For example, what is that gap over the worst-case day or week, two weeks or four weeks? Of course that will be subject to weather variability as well. We might be able to model weather patterns over a multi-decade period, over 30 or 40 years, depending on what the data is that we have available. Then we can look at something like the 95th or 99th percentile of that gap over those different periods of time. From there, we have to understand what the risk is of not meeting that gap. What would the consequences be? In the first instance, you would hope that demand would reduce. In that period of time, the cost of meeting that electricity demand from other sources will become increasingly high. You would expect that that would be an incentive to try to reduce your use. For example, a few winters ago, at the beginning of the Ukraine war when gas prices went sky high, we saw some industrial users of gas just stopped using it, just stopped production. Therefore, there is that element, which is not ideal, but it would be a feature of how economics works in terms of supply and demand.
Flexing to move when you use energy is possible. For a day, that is totally possible across all sectors, but for a period like five days or a week or more for the domestic sector, especially depending on electricity for heat or for transport, you cannot rely on that demand flexibility, so that gap still remains to meet that demand from somewhere else. I should also say that as a last resort you might have to rely on rationing access to electricity, such as rota electricity disconnections. The last time we did that in the UK was in the early 1970s when fossil fuel supplies were disrupted, so it is a thing that can happen.
The Chair: Excellent, thank you very much indeed. Dr Emily Wallace is with us now from the Met Office. Dr Wallace, please introduce yourself—but first I will put the first question to you, then you can go straight into the question. What is Dunkelflaute from a meteorological point of view from your perspective, and from an energy sector perspective? We would like to try to understand how it is measured and defined, and whether it is quantifiable. Lastly, how useful a term is it for modelling and preparing for the risk of energy shortfalls from renewables?
Dr Emily Wallace: Thank you, and apologies for my late arrival. Unfortunately, Paddington was not playing ball this morning.
The Chair: Thank you very much for taking the time to be with us.
Dr Emily Wallace: It is my pleasure. I am a fellow in weather and climate extremes at the Met Office and I am seconded to the National Energy System Operator as a meteorological adviser there. Finally, I am a visiting professor at the University of Strathclyde. Today I am speaking on behalf of the Met Office, an executive agency of the Department for Business, Innovation, Science and Trade. While we are best known for our UK weather forecasting service, we are also a world-renowned climate research organisation. It is from that point of view that I am talking this morning.
Dunkelflaute—Keith may well have already covered it—literally means doldrums. That is referring to a lack of wind and a lack of sunshine. The meteorological cause of this is anti-cyclones or high pressure sitting over the UK and Europe. When we think about the weather, it is useful to think in large spatial terms because that is how our weather manifests. What we are talking about in a Dunkelflaute situation is a high-pressure system sitting over the UK. Often that will be sitting over northern Europe at the same time. These are large-scale phenomena, and they often stay in place for long periods of time. High pressure means we have descending air, and that is what traps the moisture at the earth’s surface, which why we tend to get drizzle or low cloud associated with these high-pressure systems.
The Met Office refers to that as anti-cyclonic gloom. There was one last year that was long enough and dull enough for us all that the Met Office wrote a blog about when it would end. A typical feel for a Dunkelflaute event is that we are all feeling a bit tedious—and of course it has implications for the energy sector as well. The other feature that you can get with a Dunkelflaute event is cold conditions. In that case it would have more impact on the energy system. I have talked about wind, I have talked about lack of sunshine and I have talked about temperature. All of those have implications for energy systems. Obviously, the wind and the sunshine—or the lack of—will reduce the amount of generation from wind and PV on a large scale and on what we call embedded generation on our houses.
The Chair: Sorry, what was that term you used?
Dr Emily Wallace: Embedded generation, embedded PV panels on people’s roofs, which means that they are suppressing the demand. If they are operating, they are suppressing the demand from those households, as opposed to allowing the whole demand to be seen by the transmission system. The temperature relates quite strongly already to demand for electricity and demand for gas. In that sense, they are very important for our energy system. I suspect Keith may have covered this already. There is no single definition for Dunkelflaute. It is usually focused on the winter months only when we think about Dunkelflaute, which is because we have shorter sunshine hours and tend to see lower sunshine strength radiation in the winter months. For that reason, it is often thought about as a wintertime condition and that descending air trapping cloud is a wintertime phenomenon. We do not tend to see that in the summer months so much.
Meteorologically, it can be defined in a number of different ways. We can define it, as the name suggests, using wind and sunshine amounts, perhaps choosing some particular locations in the UK where we know that there is generation and looking for periods of time where both sunshine and wind are low, the 20th percentile of what is normal at that location. We can define it with just wind. On our current energy system, Dunkelflaute events are primarily controlled by the amount of wind. That is the larger factor within the Dunkelflaute, so just defining on wind is an option. The other alternative is thinking about the cold Dunkelflaute, which is arguably the more important type of Dunkelflaute because that will be increasing the demand at the same time as the wind and solar generation is depressed, so that omits sunshine from the equation.
The final meteorological way of thinking about the problem would be through pressure patterns, and looking for that high pressure. There are a number of different ways of doing that, some using AI approaches to match pressure to predefined pictures. The other would be via something like the North Atlantic Oscillation, which is a measure of the tendency for winds to come from the west or for that prevalence of westerly winds to be reduced at two ends of the spectrum. In terms of defining on energy, some of the common ways of defining Dunkelflaute would be just on generation, either observed generation from wind and solar or modelled generation taken from a meteorological condition. There are a number of translations between what the wind is doing, what the sunshine is doing and what the temperature is doing towards generation.
The other approach is through demand net renewables. This is taking again either observed or modelled demand, what we expect the demand to be, and subtracting the amount of renewable generation. High-demand net renewables mean that we have a lot of demand to be met with not so much in the way of renewables to meet that demand. It probably means that we are using gas or interconnectors at the moment. If we have low-demand net renewables or indeed negative, that means that we will not be using so much gas. That is the opposite of a Dunkelflaute.
The final way—Keith and Jon may be able to step in to describe some of the mechanics of this more than I can—would be to use something called capacity expansion models. These models are energy system models. One of the uses of them is to chart out potential pathways to meet particular conditions—for example, net zero 2050. A capacity expansion model takes, or can take, year-by-year weather conditions and build out the technologies that are required to meet demand for those weather conditions day by day. A way of defining Dunkelflaute or these conditions is something called system-defining occurrences within that modelling process, where there is a big step change in the technology that is required to meet a particular weather condition, perhaps because in the time series something as bad has not been met before. There may be some additional details that fellow panel members can add in there.
In terms of definition, the best-practice approach is take a cumulative view of Dunkelflaute, because one of the things that can be particularly taxing is if it is going on day after day. A very severe Dunkelflaute may be less important, depending on the energy system, than one that is perhaps less deep but goes on for a number of days. As I say, intensity is important. There is no specific definition for Dunkelflaute, but we do have models and data. There is a lot of rich information on what we can expect to experience today and what we can expect to experience in decades to come coming out of climate simulations.
It is that rich information combined with understanding of energy systems or energy system modelling that we can use to understand whether or not our system is resilient or what it takes for our systems to be resilient. The important part is that collaboration between the rich information coming out of climate modelling and how we apply that to energy systems. It is advocating for that data-driven evidence approach, because what matters is that it is system dependent, it is situation dependent and it is application dependent—so that rich approach is needed.
How useful a term is it? It is useful for communicating compound risk. I described that picture of the large scale and the long term, the combination that means that you might get cold at the same time. It is a term that helps us to communicate that compound aspect, so it supports having a conversation. However, it lacks the meteorological and engineering precision that we need to say whether we are resilient to a Dunkelflaute. It is not a question you can answer—it comes back to the genuine collaboration between the rich information we have about the climate and what it could do and how we build our energy system.
Q3 The Chair: Thank you very much. Jon Saltmarsh, over to you. Could you keep your remarks brief? We have several more questions.
Jon Saltmarsh: I will be very brief because my two colleagues have covered this in immense detail. I absolutely agree that it is a useful shorthand, but if you try to focus down on what we mean in terms of whether it is two weeks, one week or 24 hours, that does not help. The second point to think about is that it is not just about the supply of energy. You need to think about demand as well. Within the Catapult’s modelling, we talk about gaps rather than a Dunkelflaute, because it is not just a Dunkelflaute. You mentioned the cold weather and cold weather drives up demand. It is the gap between supply and demand that is an important bit.
It is also broader than the single event. Generally, it is defining the amount of storage that you want as far as your energy system is concerned. However, there are two ways to deplete storage, one of which is to have a long period with slightly below average wind or renewables or generation, whatever you are particularly measuring. The other is to have an intense period. In a lot of the scenarios, we see that it is not the intense period of a two-week Dunkelflaute that is the problem but the 100 days of 5% below average wind. That is important from a planning basis. You very much need to state what you mean by a Dunkelflaute and how you are measuring it. Clearly the amount of storage that you require varies dramatically, depending on your mix of renewables and firm generation. Most of our modelling would recommend a balance between renewables and nuclear. Generally, the more nuclear you put in, the higher the costs are of the overall generation, but the less storage.
The Chair: We can come on to specific technologies later.
Jon Saltmarsh: That covers all the extra points that I wanted to make.
The Chair: Excellent, thank you. Before we move on to Baroness McIntosh’s question, I want to go back to the question of a definition. We understand that some sources define a Dunkelflaut; is it Dunkelflaut or Dunkelflaute?
Dr Emily Wallace: I am afraid I am not a German speaker. I am the wrong person to ask.
The Chair: That is how I have been referring to it, but I was interested to understand whether the industry refers to it as Dunkelflaut. Anyway, we will stick to Dunkelflaute.
Some sources define a Dunkelflaute as a period of at least 10 consecutive hours in which wind and solar generation falls below 10% of installed capacity. It seems to me that a baseline definition would be useful. Is this something that you think could be useful as a baseline definition?
Dr Emily Wallace: Leading off Jon’s comment, the 10 hours would be a relatively short period to be worrying about. Some calculations done by a Met Office colleague, Gillian Kay, some time ago defined a less extreme version of a 20% wind capacity, effectively. She found that up to five weeks was possible, unlikely but possible. The one-in-40 event would be three consecutive weeks of suppressed wind at around the 20% mark. That is not that very severe—
The Chair: Has that scenario happened?
Dr Emily Wallace: That is coming out of simulations—the worst scenario that was found in the historical record of that nature.
The Chair: We will come on to that and talk about trends. Professor Bell, do you have anything to add to that?
Professor Keith Bell: Yes. I would favour looking at things from an energy system perspective, because that is what we are trying to deliver—reliable supplies of energy. What Emily called demand net renewables I call residual demand. We need to be able to quantify that and we can do that using the models. We can look at that and the risk over different periods of time, given the variability of the weather over long periods. We might define it in a 24-hour sense or one week, four weeks, or indeed—as Jon suggested—even 100 days and look at a particular infrastructure mix of where we are getting the energy from, what the demand is and the different options of that, how much we want to build and what storage capacity and so on. We can run through the models to assess the one-day, one-week, four-week or 100-day risks that we are exposed to. However, in the end we still need to make a judgment about what is an acceptable level of risk, because we cannot eliminate it completely.
Q4 Baroness McIntosh of Pickering: For that reason, no wonder we get the doldrums in autumn. Could I declare my interests? I have small shareholdings in National Grid, BP and Shell, well below the registrable amount of shares. Dr Wallace, you touched on this as a phenomenon across northern Europe. Being half-Danish, I follow the DMI, the Danish Meteorological Institute. Do you co-operate with the Danes and Norwegians, who probably have had renewables for far longer than we have, to learn from their experience?
Dr Emily Wallace: Yes, meteorology is very much a global collaboration. I am not aware of specifics, but no doubt there will be links into the DMI. In terms of the energy, it is not something that I have had specific links with before. I know that there is a lot of international collaboration in the energy sector as well, learning from other organisations.
The Chair: We will come on to further international collaboration later on. Baroness McIntosh, let us go back to your question.
Baroness McIntosh of Pickering: Mr Jon Saltmarsh, your organisation did a joint report not so long ago on the frequency, duration and severity conditions. Could you share the conclusions with the committee so that we can get that as evidence today? How effectively do you think these events can be predicted? You looked at a period of roughly every eight years; presumably from what we have heard already it is largely unpredictable, but it would help us to understand.
Jon Saltmarsh: We look backwards rather than trying to predict forwards. Probably the best data for this comes from a Royal Society report that Sir Chris Llewellyn Smith did a couple of years ago on large-scale electric storage, where he looked back over 37 years, from 1980 to 2016. He analysed the gaps in lots of different ways, identifying 22-hour gaps, which was one of the peaks of short-duration gaps, up to how many of those months we saw 20% below normal. What it identified was three years, 1997, 2007 and 2013, where there was a whole month where wind and solar output was 65% below average, and that was one of its forcing functions. We have done similar: we ended up identifying a two-week period as probably the worst situation that we saw in the eight years that we were looking at. The model that we had for generation and the mix of generation resulted in a 15 terawatt-hour gap that needed to be plugged with some form of long-duration storage, if that answers the question.
Baroness McIntosh of Pickering: That is very helpful. Does it help us predict these situations going forward?
Jon Saltmarsh: I would turn to Emily on whether past history is a forecast of the future. I do not know how climate change is likely to impact that.
The Chair: We will be coming on to that, so we can park that.
Baroness McIntosh of Pickering: Professor Bell, do you have anything to add?
Professor Keith Bell: Yes, a couple of quick things. We can model what would happen if weather conditions from the past were reproduced. To the extent that future weather patterns are similar to past weather patterns, which we know they are not because climate change is happening, we could say that a particular condition could arise. I expect that it is more difficult to say exactly when it will arise. In some of our modelling, we used 34 years of past weather, put it through a representation of a 2030 electricity system and found similar results to what Jon mentioned in terms of the scale of the gap of 10 to 15 terawatt hours.
The other thing I will quickly mention is you talked about Norway and Denmark. In a sense, Norway especially has faced these questions for a very long time, because it makes use of a lot of hydropower. It has a lot of electricity demand and most of that is met from hydropower. It has a plan for how much water it will get, what the weather will deliver in snow and rain, and plans its reservoir sizes on that basis to manage the possibility of not having enough. This issue has been a live question for it for a very long time, so when you mention collaboration, that is a useful place to look. However, I understand from talking to colleagues that there is still a lot of debate about quite how you model and assess the risk associated with this.
Baroness McIntosh of Pickering: That is very helpful, thank you.
Q5 Earl Russell: Good morning. Thank you very much for being with us today. Dr Emily Wallace, how is the Met Office working with NESO and other key stakeholders in the energy sector to understand the Dunkelflaute risk? You have given us a long introduction in your first piece, which was very useful, about different ways of defining the interaction of weather systems and building of the energy transition and different conditions. We could have a long slow decline or we could have a deep period of no wind or no wind plus cold weather. Could you say more about how you are working with the energy sector to understand, manage and predict some of these risks? For the sake of clarity, the next question will be on climate change.
Dr Emily Wallace: The energy security energy sector is extremely important to the Met Office. The thing that I say a lot is that weather is the fuel of our future system and it is no less important a vector than any other. On that basis, the Met Office has had a formal agreement with the National Energy System Operator to build a partnership to support it to have the best forecast information, the best planning information and the best information to support resilience from a meteorological point of view, and that expertise as well. On a daily basis we send observations to support demand calculations of forecasts to support generation demand forecasting at the National Energy System Operator. We have worked with the teams there, which are already using 10,000 simulations of weather to inform its winter outlook. That is the margins of electricity that we expect to see over the coming months. We have now built in some predictability information into that from innovative approaches coming out of the Met Office Hadley Centre. Beyond that, there is already use of data going much further ahead. We will come to projections in a moment, so I will not dwell on that one.
The Met Office was involved in the Royal Society report to pull the conclusions about long-duration storage beyond the historical record. One of the things we know, particularly in the case of wind, is that it is very variable and we have only been observing it for about 50 years. Therefore, we have not seen some of the combinations of weather that can be thrown at us. We have been using an approach called UNSEEN, which helps to simulate beyond what we have already seen, and that was involved in the Royal Society report. We have worked alongside the National Infrastructure Commission and the Climate Change Committee to support the calculation of adverse weather scenarios for exactly this purpose, what some of the worst conditions are that we can see for stress-testing of future energy systems.
We are also working closely with the Department for Energy Security and Net Zero. We have a channel of work there on energy security as well as the climate change work, which has been going on longer, and have a relationship with International Gas and much of the rest of the industry and the Energy Networks Association. It is a very important area for us at the Met Office.
Earl Russell: If I could summarise, there is very close collaboration, drawing on historical records, the latest technology and AI for future predictions, but risk is at the heart of what you are doing in the collaboration between yourself and NESO and the energy sector in terms of understanding weather impacts on our transition and our ability to generate.
Dr Emily Wallace: That is it. We are moving towards having the very best information from the weather side as it develops, as we get new innovation plugged into those energy system models at those critical organisations that are responsible for the resilience of our system.
Earl Russell: Do Jon Saltmarsh or Professor Bell have anything to add on this question?
Jon Saltmarsh: I do not think so. The point is that it is about risk and we need to think about it in those terms. We cannot be definitive.
Q6 Lord Jay of Ewelme: You have talked about the difficulty of prediction, which all of us entirely understand. However, one question that is often asked—at least I find is often asked—is whether the frequency, duration or severity of Dunkelflaute conditions will be or might be affected by climate change. I know that is a very broad question, but what do you think about that?
Dr Emily Wallace: As we have described, the definition is not very tight, so I will break down the components of it. We know that the variability in wind speeds will continue, so it is highly variable. That variability is much larger than any climate change signal in wind speeds. That is the first point; the variability will continue. There is not a very substantial signal for changes to wind speeds. Similarly, there is not a very substantial signal in changes to sunshine amounts. Last year was the sunniest on record for some time, but that is just natural variability. Temperature, however, which is an important part of this question, is set to rise. Through the winter, on average we will see warmer temperatures than historically. That is not to say that we will not experience cold conditions from time to time.
Lord Jay of Ewelme: Do you think that that will increase the chances of Dunkelflaute conditions?
Dr Emily Wallace: That would indicate that the chance of the Dunkelflaute conditions will not increase.
Lord Jay of Ewelme: Does anybody disagree with that assessment?
Jon Saltmarsh: I would not disagree with the assessment. The reality will be though that we will need a significant amount of long-duration storage, in the terawatt hours. At the moment we have nothing like that, and whether it increases a bit or decreases a bit will not change the overall direction to where we are trying to get to.
Professor Keith Bell: My two colleagues have summarised it very well. The important thing—and we have touched on this already—is the correlations between these different factors. Demand for electricity for heat in the future will be a big part of it. If a day is warmer, that demand is lower. If that day happens to be one where it is a bit dull, that is not so bad because the demand is lower. However, these periods where it could still be cold and you have these dark, still conditions, that is the thing that we would worry about. Jon made the point very well: from where we are now, there is still a lot to do.
Lord Jay of Ewelme: Following on from that, what other risks could lead to or amplify Dunkelflaute? We talked a bit about cold weather or hot weather or low renewables across interconnected countries or gas supply disruption. There is a tendency when talking about this always to talk about Britain, but of course the climate is not insular. Are we likely to see the same conditions in other European countries that will affect us or might we find ourselves in some way protected from Dunkelflaute when other countries suffer from it? What is your view on that?
Jon Saltmarsh: My understanding is that these weather effects would affect the whole of northern Europe, and that if we are suffering from this problem, you will probably find that our nearest neighbours, which are where we get our electricity from over interconnectors, will be in exactly the same position.
Lord Jay of Ewelme: The safest assumption to make is that we are not just talking about Britain, we are talking about northern Europe, however you define northern Europe.
Jon Saltmarsh: You need to look at interconnectors on the continental scale, taking energy from the far east of Europe over to the western side and vice versa to get a balancing out of weather effects around the country and around the continent.
Professor Keith Bell: The precise meteorological conditions and how they spread across a certain geographical area is something that Emily and her colleagues will be able to look at in detail and that is what their models already do. It is certainly true that we have to take proper account of those correlations across space as well as across time.
Dr Emily Wallace: Yes, that is beautifully summarised. As I described at the beginning, high-pressure systems tend to be very large scale. You could draw a big circle of that high-pressure system that could easily incorporate the UK and much of northern Europe. However, there is a lot of subtlety in there, which is why I am advocating for that rich data approach to the problem. To find the very worst conditions, it will be very system dependent and situation dependent. Exactly where the winds happen to be blowing will have subtleties to it, as well as that very large-scale picture.
The Chair: I have Earl Russell, Lord Krebs, Lord Trees and Lord Redwood for short supplementaries.
Q7 Earl Russell: Yes, a very short supplementary from me. I want to ask for a comment on changed winter wind under climate models. Are there any signals that we might get more periods of either 20% less wind over longer periods or periods of very low wind? Obviously our climate is changing and we have defined Dunkelflaute on past climatic conditions. Are there any other particular types of climatic conditions that could cause problems for our renewable energy sector? I am thinking about still wind and very high summer temperatures as an example.
Dr Emily Wallace: There is not a strong signal for changes to wind speeds. In that case, yes, we might see something worse than we have ever seen before, but that is not because of a strong climate change signal. There are some models that say higher, some that say lower, but generally the variability eclipses it. On other weather conditions, absolutely, yes, there is a lot of weather that stresses our energy system. Heatwaves are a great example because that will be in conjunction potentially with a lack of water, wildfires, infrastructure problems and risks. In these high-pressure systems we also often get worse air quality, because again we have that descending air and stagnant air underneath, so air quality can be a problem. I have already mentioned cold going alongside the Dunkelflaute. If you think about the health impacts as a result of that cold, you get different compounding aspects.
Q8 Lord Krebs: I should declare an interest. I used to be an adviser to Drax, the energy company. I stopped doing that last year.
This is a question to Emily. Tim Palmer has recently written an article in The Economist in which he alludes to—in addition to the thermodynamic impact of climate change, which is what you talked about—another impact there could be, which is that it changes the circulatory systems themselves, for example, altering the jet streams, and therefore it might be that there eventually is a tipping point in which the climate system, including the regional weather system, moves into a new model or new mode. Does that have widespread acceptance in the climate modelling community or is it an outlying view?
Dr Emily Wallace: It is not something that I can comment on today. I suggest that we go to our colleagues at the Met Office and provide a written response balancing all of the views at the Met Office on that one.
Lord Krebs: That would be very helpful.
The Chair: Absolutely, yes, please do ensure that reaches us.
Q9 Lord Trees: Thanks very much for coming. I am not an electrical engineer and we are trying to concentrate on Dunkelflaute in this inquiry, but I would like you to confirm what is emerging from what you have said—taking wind first of all—that the amount of electricity generated by a turbine will be related to the speed of the turbine and ergo the speed of the wind. Therefore, there is a variable continuum. Dunkelflaute is the extreme of a continuum; there are varying degrees of necessity to augment that supply. Does that also apply to solar? The intensity of radiation will affect the output of given solar capacity. It is important for us to understand that when thinking about solutions.
Jon Saltmarsh: Building on that, a lot of it is predictable. Certainly with solar we have very good models, and across the country we have an idea of how much cloud cover there is likely to be, so we can make very good predictions. Similarly, the prediction for wind is getting much better. We have ways of dealing with this for the short term with batteries and other short-term storage. The Dunkelflaute issue, as far as we were concerned, was very much more on the long-duration storage bit and how we deal with that element of it.
Q10 Lord Redwood: I would like to ask a question that bridges into the next group of questions, but arises directly out of the fascinating testimony by Professor Bell, who told us that when there are these problems of windless and sunless days and weeks, the first thing would be dearer electricity. If that did not shake enough demand off, you would need to go to rationing. He reminded us of the 1970s model. As a very young man I experienced that—it was called the three-day week. It was the first time that I had a very profound disagreement with the so-called Conservative Prime Minister who imposed this on the country and discovered that it was not popular and he promptly lost a general election caused by the issue. I would like to explore with Professor Bell how practical this idea is, that in order to deal with windless and sunless periods you either make sure that only the rich can carry on buying power at crucial times or you ration us all.
Professor Keith Bell: In the end, this is a policy decision about how much risk we are willing to take, and policymakers making that decision on behalf of the whole of society. The particular economic model for how you recover the cost of that is something for policymakers to decide. Whether it is a progressive policy or a regressive one, that is a decision to be made. The key point of course is that energy is a crucial part of modern society and reliable supplies of it are therefore important. It is also worth noting the importance of energy supplies for various aspects of critical national infrastructure, things like health services, transport, water treatment and so on. Of course this has to be taken very seriously, regardless of where you get your energy from, and there are risks associated with all forms of energy supply. What is notable about the 1970s is that it was a fossil fuel-based energy system.
The Chair: And nuclear.
Professor Keith Bell: It had some nuclear power, yes, and nuclear power has a value. I know that Energy Systems Catapult has been an advocate of nuclear power for a very long time. It has its advantages, although the costs are stubbornly refusing to come down. It is all part of that decision and risk-taking or risk-judgment context.
Q11 The Chair: Absolutely, and we will certainly be asking Government about that when they are before us. Before we move on to Lord Krebs’s question on technologies that could fill the gap, I want to go back to how we quantify and measure the problem and whether it is important for parliamentarians in terms of accountability for the system. We need to be able to grab hold of some data, some baseline and so on, to say, “This is not right. What did you do to meet this foreseeable problem?” From publicly available information, it is not clear what parameters NESO has chosen to assess the risk of Dunkelflaute events. We have heard of some of the difficulties in looking at these parameters, but nevertheless it behoves experts to be able to define some of those parameters and give us some indication of the guidelines to which they should be working. What parameters, in your view, should NESO use to assess the risk of Dunkelflaute events? I know that that is a tough question, but it is something that we need to try to get to the bottom of. Professor Bell, would you like to start us off?
Professor Keith Bell: I would suggest something that I mentioned earlier, which is an assessment of the risk in terms of that energy gap, that residual demand over different periods of time, given the long-term variability of weather. It is something that has to be done using modelling, and that is a thing that has to be looked at carefully, what the credibility of your model is, where you are getting the data from and so on.
The Chair: Whose job is it to do that, Professor Bell?
Professor Keith Bell: NESO has this responsibility, being a strategic energy planning adviser to Government, so NESO would be the first party that I would look to. However, there is no harm in others having a separate assessment so that we can compare that with what NESO is saying. Perhaps we can get things out more quickly than NESO seems to be doing. We can be open about the modelling methods and be happy to have those methods critiqued, to understand where we can improve the methodology or where it seems to be all pushing in the same direction and we can be confident in the results. Energy Systems Catapult, as Jon has already talked about, has done some of its modelling. My group at the University of Strathclyde has done some as well. Various consultancies have done some. The Climate Change Committee commissioned work from a consultancy called A3. All of this is helping to inform us, but it needs to be done sufficiently, robustly and transparently, giving the full picture of information. I am not sure that the full picture is always there. For example, in my group a lot of our funding is a bit piecemeal. We do bits and pieces and improve the model, but to properly inform all of this debate there is more that can be done.
Jon Saltmarsh: I just add that from a modelling perspective, a model is just that. It is not a perfect representation of the real world and you have to make compromises to make the models run and be meaningful. People make different compromises and they end up with a different set of assumptions. The only way that you can test this for real is to compare results of different models and have, as Keith says, full transparency of what assumptions and what modelling approaches are being taken. It is more than simply defining what a Dunkelflaute is and everyone will be happy. It is much more about how you are using that information.
Q12 Earl Russell: I want to pick up on a couple of points that Professor Bell made. It is an important point that that transparency is there, not just in relation to Dunkelflaute but across the whole of the energy sector, and that different forms of energy have different risks and different profiles associated with them. Do you think that there is more to be done in terms of the whole of the energy mix and some of the rationale and risk profiles associated in making that more publicly available so that there is opportunity for greater parliamentary scrutiny on the energy mix that is being created and the risk profiles associated with the different sectors?
Professor Keith Bell: Yes, I think that there is more that could be done. Some of these models are difficult to set up and time-consuming, especially in management of the data. They are sometimes also very long to run. That means that people can take a while to get around to publishing their results. I will confess that my group is a bit the same. We have some stuff that we could get out there, but for academics we are pushed towards doing, quite rightly, peer-reviewed journal publications, which take forever, frankly. I think that there is value in quicker, dirtier analyses that illustrate the nature of the problem and the dimensions of the problem and can help inform that debate, with the slight caveat, as Jon said, that there are always approximations or assumptions that are made. The quick, dirty models will have some things that are a bit rough around the edges, but they can help, as you say, as an assessment of the various options.
I do get a bit frustrated sometimes that NESO is so cautious in what it puts out and that everything seems to be very slow. It has delivered just a week or two ago six different possible pathways for its strategic spatial energy plan, delivered to the Secretary of State. However, it has not told anyone else what they are and what the dimensions are. I am not sure that that is okay. The Secretary of State wants to be able to make a judgment. He has a role in Government and the Secretary of State has that degree of authority, but the public debate about what the right options are and understanding the different risks is important.
The Chair: To quickly summarise that, there are of strands of very useful information lying with various stakeholders. The body currently responsible for bringing those strands together is NESO, but we do not know what NESO is doing, and its work and workings are not in the public domain and you would like them to be. Is that a good summary?
Professor Keith Bell: Some of what it does and some of its working is in the public domain—it tries to be transparent—but in other aspects of the work it seems to be not at that position. Maybe I am putting words in its mouth. Maybe it is not yet completely confident about the methods that it has developed and wants to wait before it puts it out in the public domain. In respect of the strategic spatial energy plan, the way of proceeding with these six scenarios and presenting it first to the Secretary of State is something that it agreed with Government, in my understanding.
Q13 Lord Krebs: I would like to move on to the potential technologies or approaches for addressing periods of intermittency in renewable supply, as illustrated when there is a Dunkelflaute. I would like to distinguish between long term in days to weeks rather than short term, which would be hours or within a day. Could each of you say what potential technologies you think are in the running for both long and short-term energy storage, what the timescales for their deployment are and what scale is feasible for them?
Jon Saltmarsh: I am very happy to start off on that. You are absolutely right to look at what we can do in less than a day, within-day balancing, and how we deal with the much longer term. There are two ends to that, and within a day your primary solution will be batteries and moving demand around, which in a lot of cases is batteries. When you choose to charge your car, for example, that is still making use of a battery. That is the within-day bit. However, at the end of that day all those batteries and forms of energy, for example, if you are overheating your house and letting it cool down a bit, will only last for a short period of time and you need to return those batteries or the house temperature to what it was at the beginning of the last day by the beginning of the next day. Those are the ones that are about flexibility and moving stuff around short term.
At the other end, you need technologies that are very long term. From an Energy Systems Catapult perspective, we believe that that will almost certainly be molecular storage in some sense, so broadly storing gas, whether that gas is biomethane, whether that gas is methane or whether that gas is hydrogen, but you need the storage to be able to run your generators for periods of days or weeks. The interesting bit comes in the perhaps two days, up to five or 10 days. That is a place that hydro is operating to a degree at the moment and there are a lot of other technologies being developed there, such as compressed air storage, some forms of thermal storage and so on. The debate is whether they have a role in their own right or whether you will see batteries that will become increasingly less expensive and starting to encroach into the one day, two day. Batteries are always talked about as one hour. Suddenly we are now talking about batteries as four hours, eight hours or even 10 hours and that can continue to expand.
From the other end, your molecular storage, be that hydrogen or whatever, will that start encroaching from the top and do you end up with a squeezed middle? Is there a role for some of these technologies in the middle? I do not think that anyone has a clear answer to that at the moment. It very much depends on the price of those technologies and their round-trip efficiency. There are two prices there, the price of the entity that is storing it and the price of volume of storage. If you are talking about hydrogen, you have a very cheap price for the volume of storage, but it is quite expensive to generate it and produce power. Batteries, on the other hand, cost a huge amount to store energy but they can put it out very cheaply and have a very high round-trip efficiency. There are horses for courses. What I cannot tell you is who the winners in the middle will be.
Lord Krebs: Before I move to Emily and Keith, can you say a few words about the timescales to deployment—you mentioned various technologies like molecular storage, compressed air and so on—and the potential scale at which they could be deployed? For instance, Chris Llewellyn Smith concluded in his report that we needed north of 100 terawatt hours of long-duration energy storage. When I was on the S&T Committee and we looked into it, we thought that was pretty extreme and more like 10 to 20 terawatt hours would be a no-regrets level. Can you comment on scale and magnitude and timescale?
Jon Saltmarsh: That is very important. In terms of technology readiness, which is in many ways your timescales, batteries are here today. They have a technology readiness of nine and we are seeing them deployed at scale. That is not the case for hydrogen, which is probably at a technology readiness of eight. It is not being deployed at scale for a number of reasons. We are probably talking about five years before we would see a significant amount of it, even if we were to start today and move forward with some of the projects that seem to be stalled at the moment. In terms of scale, at the moment we have something like 18 gigawatt hours of batteries and we have something like 12 gigawatt hours of pumped hydro storage, hydropower. To put that into context, if we move to 30 million electric vehicles, that would increase the total amount of battery storage to 2 terawatt hours. That is still not getting anywhere close to the 10 or 20 terawatt hours that people are saying is probably the likely amount of long-duration storage.
On the gaseous storage at the moment, if you look at Rough, which is the main gas storage plant—it is a disused oil field in the North Sea—that stores something like 16 to 18 terawatt hours of energy today. Therefore there is a three orders of magnitude difference between what we are likely to see with batteries and what we are likely to see with molecular storage. Even if you were to convert Rough into hydrogen storage—there are some big challenges with doing that, not least that we have not done that before—that would reduce the amount of storage, perhaps 8 terawatt hours of hydrogen, but it is still massive compared with what we are getting from batteries. Does that answer the question?
Lord Krebs: It does, thank you very much. Emily, is there anything you would like to add?
Dr Emily Wallace: No, I think you are better off with Keith and Jon for the technology questions. What I would add is the importance of thinking about—as well as the average conditions that storage is operating in—what other potential compounding hazards might need to be considered at the same time. Water resources would be an obvious one, where there is a signal amount of rainfall we are expecting to see in future and where that is relevant to storage, for example. It would be worth thinking about that sort of compound picture of what else is going on as well as us charging and discharging storage.
Lord Krebs: Climate resilience.
Dr Emily Wallace: Climate resilience. There are other hazards as well, but clearly I am here with a climate resilience hat on.
Lord Krebs: Keith, do you want to add anything to what Jon has talked about, on scale and time to deployment and alternative technologies?
Professor Keith Bell: I think Jon has summed it up very well. With that kind of importance, at that scale of tens of terawatt hours, molecular-based storage seems to be the way to go. Another important point that Jon made was about the cost: the cost of converting and the rate of converting energy from one form to another, so the cost per megawatt compared with the cost in terms of the total volume over a period of time, the cost per megawatt hour. That is a trade-off, depending on what you want to do with the storage. At the moment lithium-ion batteries are playing very well in giving a rapid response to things to smooth out variations on the electricity system, but the cost per megawatt hour of those batteries might not be competitive with other options.
In terms of moving the things along and how quickly, Lord Krebs, you will recall in the Science and Technology Committee hearing evidence from some of the people involved on the geological storage side that there is work to be done to evaluate the different options, to establish that a particular geological resource that you think is suitable really is suitable and then to get it available. Then it is the conversion to and from hydrogen. We keep being told by the big gas turbine manufacturers that “Yes, we are ready. We can do it”. Then there are the buyers. It is like a standoff, saying, “Well, we will buy one when you have proven the price and the performance” and the manufacturers say, “Well, we will prove the price and performance when you place an order”. We have to somehow break that logjam.
The Chair: Thank you. I have a series of supplementaries from Baroness Whitaker, Earl Russell, Baroness McIntosh, and Lord Redwood. Baroness Whitaker.
Q14 Baroness Whitaker: Thank you for your evidence. You have explored various things that are very expensive, particularly battery storage. I do not know whether it is in your particular areas of expertise, but there are other technologies outside. As far as households are concerned, there is thermal energy. You cannot dig it out of the ground everywhere, but you could do it much more than it is done. It is already in use. Also, as far as the grid is concerned, there is at least marine energy. Tidal is already almost there. There is tidal stream and there is wave energy. These are obviously long term, they are a few years away, but they would cope with intermittency extremely well because—I do not need to say it—the tide is every day, twice a day, and the waves are all the time.
Jon Saltmarsh: Two separate points there. I am glad you mentioned thermal because it is something I forgot about in my list. Thermal storage is a cheap way of storing energy for short-ish periods of time. There are a number of companies in the UK, some very innovative, that are producing heat batteries, for example, which can provide the energy to your house for a period of a day. You can charge it up overnight and then use that heat during the day. Thermal storage is a great way of looking at it.
In terms of your firming up generation, which is what you are proposing to do with tidal, wave and some of these other technologies, yes, you can do that and they are good approaches. In most of our modelling at the moment—and this is perhaps Energy System Catapult—the way we price these technologies compared to nuclear, we tend to firm up our renewables with nuclear and that proves to be the most cost-effective solution. We build into our modelling prices for tidal, prices for wave technology, but at the moment the data we are seeing says that those prices need to come down a long way before they are attractive.
Baroness Whitaker: They do.
Jon Saltmarsh: Absolutely they are a good solution, but only if we can make them at an affordable price.
Professor Keith Bell: If I could briefly add to that, yes, a great point about thermal energy storage over short periods of time is that it is really cheap. People have been exploring using, for example, disused mines to store heat down there. You could store for a longer period of time and then extract the heat later on—maybe you are using a heat pump or something—so it is not always very cheap by the time you get the heat in and out, but it has potential.
In respect of marine energy sources, idle stream, the turbines are quite similar. I suppose it is on a different scale to the sort of thing we see quite commonly as the design of wind turbines, but of course you have this different environment under the water and the different stresses on the machinery, so that is still to be proven in terms of the reliability of it. Tidal barrage is expensive, very high capital and has environmental impacts, but you can store a lot of energy and access a lot of energy. As Jon said, it depends what assumptions you make about these relative costs as to how some kind of optimal design would come out from your big energy system model. I am not an expert on this stuff at all, so I would have to defer to the experts, but wave energy comes from the wind as well, so the best way of harnessing the wind energy—I think we already have technologies that are well proven in doing that.
Q15 Baroness McIntosh of Pickering: I am slightly baffled as to why all the evidence you have given us is focused on storage. My understanding is that renewables in any event rely a lot on household subsidies and other subsidies. Baroness Whitaker has given a number of variations. I am quite taken by energy from waste, and of course Drax used to take quick-growing willow coppice trees from local farmers across Yorkshire, so it had a double effect. Are these not proper alternatives? Why are we so obsessed with very costly storage?
Jon Saltmarsh: Because we have always had storage.
Baroness McIntosh of Pickering: It has not been a success, carbon capture and storage.
Jon Saltmarsh: If we go back to the coal age, when most of our power stations were coal-powered, we had huge amounts of energy stored in piles of coal beside power stations. We now have huge amounts of energy stored first in the North Sea in the fossil fuels, the gas reserves, and in the gas network itself and in our storage. This storage has been intrinsically part of our system in the past and by moving to a world where we are using more renewables, that does not come with this sort of inbuilt storage. It is something that we have taken for granted up to now and when we move to renewables, it is not there to be taken for granted. We need to address the fact of the gap there.
Baroness McIntosh of Pickering: Just humour me for a moment. If we relied on energy from waste, which serves two purposes—it is getting rid of residual household waste and it is creating an energy stream, which is working very successfully in north Yorkshire, but it is going into the national grid—it could be used locally, which is a whole separate question, but you seem to discount it.
Jon Saltmarsh: I am not discounting it, but it is a matter of scale. If you burned all the waste that we have, it would not come anywhere near enough. I could write to you with the exact numbers; I do not have them off the top of my head.
Baroness McIntosh of Pickering: Please do.
Jon Saltmarsh: It would come to a very small percentage of the overall demand for electricity or the overall demand for energy that we have. We are not discounting any of these other technologies and saying that they do not have a role, but let us look at the big numbers. We will write to you on that one.
Professor Keith Bell: Very quickly, bioenergy does have a role to play. To the extent that you can store the wood pellets or whatever, it is a storable source and it is replenishable because you can grow more biomass. However, we need to be careful about the provenance of the biomass and whether it is genuinely sustainable and what impact it has relative to other potential uses of land. Energy from waste has carbon emissions. I think 40%-ish of waste is biogenic, so it counts as biomass, if you like. The rest of it—a lot of that tends to be fossil-based—has emissions, so energy from waste is not zero carbon. I think that is the thing to be to be cautious about.
The Chair: Lord Redwood and Earl Russell, and we do need to speed up a bit, colleagues.
Lord Redwood: I would like an update on the Swansea tidal barrage scheme, because my understanding was the public sector scheme did not have numbers that added up and that part of the problem was the design life of the barrier. I thought the private sector had now extended the life to 125 years and had found potential industrial interest in co-development and in co-contracts and they thought that was now economically viable. Do our experts have an update on that?
Jon Saltmarsh: I do not.
Professor Keith Bell: I do not either, I am afraid. I am sorry. I am not on top of the latest numbers.
The Chair: I think in two weeks we will have the relevant experts in place to be able to answer that. Hopefully they are hearing this session as we speak and will write in to us with their suggestions.
Q16 Earl Russell: Very briefly, Jon Saltmarsh, I want to go back to the fascinating comments you made earlier about this times-three order of magnitude of lack of long-duration energy storage. As you rightly said, every energy system has had its need for storage. Whatever type of energy you are using, you need a store of it. My basic question to you, just for brief comment, is that we have this huge gap and we are not managing to fill it. Do you think technology will develop to fill it in time? Why do we continue to transition our energy system and continue to have this gap in long-duration energy storage? And a comment: obviously energy from waste is the most polluting form of energy we generate.
Jon Saltmarsh: At the moment we do not need it because we have lots of gas-generating plants and we can use those when the wind is not blowing. We put them in in the 1980s and 1990s in the dash for gas. The problem comes in over the 2030s, when a lot of those reach the end of their life and get taken out of commission. It is not a burning issue today. As it stands at the moment, the technologies to burn hydrogen or to create hydrogen in the first place and then burn it, or to use carbon capture and storage and store the carbon dioxide you produce, will be more expensive than simply burning and pumping the carbon dioxide into the atmosphere as we do today. There is not an economic business case for anyone to develop one as it stands at the moment. If you want to generate it, that requires government policy to recognise the difference in costs and pay for that.
Earl Russell: As a kind of interregnum.
The Chair: We need to move on. This is something we can explore further in another session. Lord Rooker, your question.
Q17 Lord Rooker: Good morning. Do not laugh, but I am a non-paid director of the Ludlow Hydro, which is a small Archimedes screw on the River Teme. I have to say that because there are some nit-pickers out there. It supplies 4,000 houses when the river is running, but we need rain in Wales to run the river.
I want to ask about gas and using retained gas power. Dr Wallace, you said this, and it was on the first three questions, but it overloads all of what we have been talking about. At the time of the conditions of no wind and no sun, I am assuming the interconnectors are out because you made it clear it is across northern Europe, so we have to take into account that the interconnectors are not available. That is the way I have looked at the conversation so far.
I want to ask you about the Government’s clean power 2030 target, the 5% coming from retained gas. What do you see are the trade-offs between retaining gas beyond the early 2030s and investing in alternative technologies, some of which of course are completely unproved, such as carbon capture and storage?
Dr Emily Wallace: I will make a comment on the scale of the high pressure just to start off the conversation and then I will probably pass it on. The worst situations might be where the high pressure sits over northern Europe as well and because of the scale of it, that is something that will happen from time to time. Often the high pressure will be offset, so we will have renewable generation from the continent. It is also true to say that that would not be the only source of electricity generation on the continent, so whether or not the interconnectors are flowing would be a much more complex question than whether or not the wind was blowing. However, there is a relationship there, and thinking about a large-scale lack of wind is certainly a scenario that we should be considering, yes. Now I will pass to my colleagues.
Jon Saltmarsh: It is an interesting question that you should ask some of the other people that come to give evidence: do their models assume that interconnectors will be flowing at the times when we have peak stress? It does make a huge difference to the overall cost of the system and the overall amount that you need. You are probably always going to end up with some unabated gas being burned for short periods because it is your cheapest fallback. If you are dealing with something that happens once every 10 or 20 years, do you want to put a huge carbon capture and storage plant on the end of that or is it just better to accept that every 10 or 20 years we will have to burn a bit of gas and we will absorb it in some other way? I think it is not unabated gas or carbon capture and storage. There is a spectrum between those. As time goes on, the less you are using these plants and having them for backup, the less important the carbon emissions become and it is much more important that you do your backup in the cheapest way possible.
Professor Keith Bell: Adding to what my esteemed colleagues have said, I think Emily is quite right. There are nuances and subtleties around what is happening on a continent scale. It is not always that it will still be absolutely everywhere. As it happens, the model of the electricity system that we have in my group does model the whole of Europe, so we do try to do that. On nuclear power or hydropower, some of it is available, but there might be a lot of demand for it. Our interconnector that we already have between Britain and Norway offers a very nice complementing of resources. When it is windy here, we can export electricity to Norway. They can leave more water in the reservoir while still meeting demand in Norway. When it is less windy here, we can make use of the water that they have saved in the meantime. There is a spatial dimension to it; there is a choice about where they need to be if you have the ability to move energy across space.
On Jon’s point about what the volumes are, with a small amount of unabated gas, the emissions associated with that are small, but we have to understand how small and how much we need to capture. If we do have some of those emissions, that is part of our carbon budget. If we have more emissions in one sector, we maybe have to reduce emissions in another sector, but it is important to get that sense of scale, of quite how much and how often we would end up using any backup unabated gas capacity.
Lord Rooker: I have one final question. I know we will have other witnesses, but I could not help but recall, Dr Wallace, that you were involved with NESO. You are here talking for the Met Office, but were you involved with NESO when the clean power 2030 report was published?
Dr Emily Wallace: I joined the organisation and started my secondment about a year ago. No, that was before I was in the organisation.
Lord Rooker: You are not responsible for this rubbish—that is what it is been described as by some other people: the list of items to get to clean power 2030. There are about 10 items, all of which have to be delivered at maximum capacity simultaneously. There does not seem to be a shred of evidence that that will happen. I obviously cannot ask you about that because you are not responsible, but I warn NESO that it will be asked about it. Thank you very much.
Dr Emily Wallace: Yes, I cannot comment on that one.
Professor Keith Bell: To be slightly fair to NESO, I think the question it was given was: what would need to happen in order to meet this target? I think there are caveats in the report about this that are highly challenging. Certainly when I have spoken privately to the people involved in some of that work, they have been very keen to highlight how challenging a lot of these things are to deliver in the timescales outlined.
Q18 Lord Jay of Ewelme: Just one question following from what Professor Bell was saying when we talked about the interconnector. You talked about how the interconnector between Britain and Norway is fine when there is wind in Britain and no wind in Norway and vice versa. What happens if there is no wind in either? Does the interconnector work there?
Professor Keith Bell: The interconnector still works and they still have water in Norway, provided they have not already used it.
Lord Jay of Ewelme: That is not a problem then.
Professor Keith Bell: It is the water resource in Norway that is so fantastic. Also, as we were discussing earlier, they still have to manage the risk associated with that, the possibility of having a relatively dry winter so there is not as much snow. They depend on the snow melting in spring to fill up their reservoirs. They have to size their reservoirs appropriately to manage the same kind of weather variability in the end that we have been talking about. It is a choice about how much money we need to spend on making the reservoirs bigger, given what we think the variability is, both of the water inflow and of the demand for electricity.
Q19 Lord Trees: My question to some extent you have answered. What challenges exist for gas power with carbon capture and storage? Is there anything more you want to add to what you have said so far? Particularly though, what chance is there of a realistic, scalable, commercially viable system being in place in the timeframe we need?
Jon Saltmarsh: It depends what timeframe you are looking at. By 2050 almost certainly, yes. There is always the question about what you mean by “commercially viable”, because it will always be cheaper to use the atmosphere as a sewer than to store the carbon dioxide, so you will have to have some mechanism as far as that is concerned.
Lord Trees: Environmentally acceptable, then.
Jon Saltmarsh: Fine. From a technology perspective, we will have to do some carbon capture and storage at some point because we will almost certainly overshoot our carbon targets and have to do some sort of amelioration. Carbon capture and storage is one way of doing that. I think it needs to work. We have proven that you can pump carbon dioxide into the ground. It is been used for decades for enhanced oil recovery. It is pumping it into the ground and keeping it there with a commercial business model that makes sense that appears to be the biggest problem.
Professor Keith Bell: I fully support what Jon has just said. There has been an ongoing debate about how you get the business model right to get some of this deployment of carbon capture and storage at scale. My understanding is that the Teesside industrial cluster has a dispatchable power agreement that is supposed to be delivering some decent-sized scale plant by around 2028, but that is something you may want to follow up with other witnesses who are closer to the detail.
The Chair: Thank you. Before we move on to Baroness Whittaker’s questions, just a quick follow-up from what Lord Trees was asking about. Many gas plants will be approaching retirement by the early 2030s. Alternatives will take many years to deliver. With hydrogen storage, for example, it says here “seven to 10 years”. Jon, I think you mentioned five years at the moment, but you also said it was stalled, the development of hydrogen storage. Can you say a little bit about why it has stalled? Given that what we are looking at is how we deliver decarbonised electricity and fill it with low-carbon options, hydrogen seems to be a good contender. Professor Bell was talking about molecular storage being a possible way forward for the longer periods when we needed to fill the gap. What is the problem with hydrogen storage?
Jon Saltmarsh: Technically, there is no problem. We have had hydrogen salt caverns in the past in the UK. Most of them have been converted to methane now. You can convert one back again; you can produce new salt caverns. Technically, that is doable. The reason that it appears to be stalled is because of the cost of doing it. We have been very good at funding innovation. You can do an awful lot of innovation for £10 million. When you come to, “We want an end-to-end plant that will electrolyse power, produce hydrogen, store it in the ground and then put a gas turbine on the end of it at a scale that is useful for grid generation” then you are talking £500 million upwards, £1 billion that needs to come from somewhere. The simple answer is that I do not think the Government have had the money to do that and that is predominantly why it has stalled. It is very difficult to do that without putting money into it, because at the moment it is cheaper to do that with a simple unabated gas turbine. It broadly comes down to money.
The Chair: I will park that there and move on to Baroness Whitaker. Lord Redwood, if we have time to come back for your supplementary, I will do so.
Q20 Baroness Whitaker: Thank you. We return to intermittency. The majority of the new capacity set out in the Government’s Clean Power 2030 Action Plan and the Clean Flexibility Roadmap is set to be delivered between 2030 and 2050. Do you think that that level of progress is right? If not, in what areas ought there to be further progress particularly?
Jon Saltmarsh: Are you talking about the whole programme here or the storage bit?
Baroness Whitaker: I think we are talking about anything that is relevant to addressing Dunkelflaute intermittency.
Jon Saltmarsh: I am not sure how to answer this one. The starting point is that the more variable renewables you add on to the system, the more you are going to make this a problem that you need to be solving. Clearly, we have a plan at the moment that is moving to significant amounts of wind for the future, so that problem becomes increasingly an issue. It is driven as much as anything at the moment by when the gas plants are going to go offline. As we have discussed on the previous point, we are not moving fast enough with replacements for those gas turbines. Even if you were to replace them like for like, there is a huge waiting list for gas turbines at the moment. It is not as if you can turn around and say, “Right, we will just do more gas” and expect that to appear within two years or some such. It will be longer than that, so there is a looming problem as far as this is concerned. We will almost certainly solve it by running these gas plants on for longer, but running something on beyond its lifetime ends up with the costs going up because you end up with more maintenance et cetera. I do not feel I got to the heart of your question.
Baroness Whitaker: There are other things. NESO said in July 2025 that this will require investment in new low-carbon generation, but I would also like to turn your attention to the market mechanisms at the moment for getting all these new technologies on to the market. It seems to me that you could say there is a market failure at the moment from the lack of investment in scaling up new technologies. We do have the contracts for difference system and tidal energy has got a little way with that, but, as you pointed out, the other marine things are very expensive. That is because they are still at the prototype stage—but, you know, private sector, come in on this!
Jon Saltmarsh: This has always been the way. You need the first of a kind funding et cetera to come from somewhere other than the private sector. The private sector does not like taking those first risks. The cost of borrowing associated with first of a kind is absolutely enormous compared to what the Government can borrow at, so it makes a lot of sense for the Government to be funding things like this. It then comes down to priorities. The other point to note with how we prepare for Dunkelflaute and events that happen very rarely is whether it is ever going to be sensible to have contracts for difference that will pay you once every 20 years.
I think there will be an argument in the future about this. Should Governments be saying that this is a strategic asset we need to buy and that we should not put the risk of when it will be used on the private sector, because we will pay through the nose for that risk when actually it is the Government who are ensuring against that risk? Contracts for difference has been very successful for what it has done to enable wind. It should not be the only tool in the toolbox.
Baroness Whitaker: There are other reasons for addressing intermittency apart from Dunkelflaute. It is not our concern, but could Dunkelflaute be an incidental gain from the general approach to dealing with intermittency?
Jon Saltmarsh: Absolutely, but as we discussed earlier, you have these two solutions, one for the short-term problems, within day, and one for the longer ones. If you solve the short ones and you solve the long ones, you probably deal with the bit in the middle. If you just go for the bit in the middle, you will leave the extremes to fend for themselves and that will not necessarily work.
Baroness Whitaker: Thank you. Anything to add?
Dr Emily Wallace: Just a comment on how the processes in place at NESO are already taking account of this intermittency problem. I have already described the short term. Checking the resilience against Dunkelflaute and other intermittency in the winter ahead is taken care of in the winter outlook, where they use the 10,000 simulations. The resampling of weather years is making its way into calculations around the capacity market and also resource adequacy out to 2040. The simulations to understand the problem are making it into those assessments. But the policy questions are not for me.
Professor Keith Bell: I know we are running out of time, have run out of time almost—
The Chair: Indeed, so before you say anything, we realise we are a little bit over time. Is it okay if we overrun by a couple of minutes? Excellent, thank you. Professor Bell.
Professor Keith Bell: Yes, so I will chip in a couple of quick things. For the short-term variability, the market mechanisms do seem to be working. On battery deployment, grid-scale batteries are being installed and used. There is a new mechanism, the cap-and-floor mechanism, which is trying to encourage further investment, in particular pumped hydro storage, to help manage the investment risk. It is a kind of sharing of risk between consumers and the investors.
We have talked about the scale of this long-duration, longer-term storage, and we are maybe being a bit scary—I am a bit scared—by the scale of tens of terawatt hours. On the other hand, however, we have to start somewhere. It cannot all be delivered overnight so we have to start doing things. It inevitably gets developed in stages, so there are opportunities for learning by doing when we get going. But, as noted, these things are of expensive.
There are a few things and we have to see how effective they are: the dispatchable power agreement and the hydrogen transport business model that the Government have put forward. Are they going to deliver? We can maybe also say something about the choices on the storage of energy. Jon has already noted that we have made use of the storability of fossil fuels for ever. Of course it is a one-way store; we will not turn it back into fossil fuel. The point about wind and solar and its variability is that, although there are periods when this residual demand is large and has to be filled from somewhere else, there will be periods when that is negative and there is a surplus that can be used. That represents an opportunity to make a form of energy that can be stored for a long duration and then extracted from the store when needed.
The Chair: Excellent, thank you very much. Before we finish, I will come to Lord Redwood and then Lord Jay.
Q21 Lord Redwood: Briefly, I think it would be very helpful to the committee if we could have in evidence what the current gas dispatchable capacity is that we rely on to keep the lights on. Also, what is the current view in the system about how much dispatchable gas we will still need in 2030, when there will be even more unreliable renewables on the system?
Professor Keith Bell: I think NESO’s publications do give some information on that.
Lord Redwood: I know where to find it, but I thought it would be helpful for somebody to put it into the record.
The Chair: Yes, of course it would, but this is in the absence of any further action that the Government or NESO and the energy generators take to fill the gap. Is that right?
Lord Redwood: Yes, but my main concern is keeping the lights on.
The Chair: Indeed, we all want to make sure that that happens. That is one of the reasons for carrying out this inquiry. We want to make sure that the Government are thinking ahead as to how we are going to plug that gap. Lord Jay.
Lord Jay of Ewelme: Just one interest that I should have declared. I used to be a member of the main board of EDF in Paris.
The Chair: Excellent, thank you very much. Colleagues, thank you all very much and thanks to our panel of expert witnesses for being with us today. We look forward to receiving the bits of supplementary evidence that you have undertaken to send to us. With that, I call an end to the public part of this session. Thank you.
