In a comment on Blown Away, in which I discussed the Scottish Government’s Onshore Wind Policy Statement 2022, Jit asked “Any mention of how swingy the electricity supply is going to be?” The answer to which is, I think, “yes and no”, for the simple reason that although the policy statement does recognise the intermittency problem (in a heavily disguised manner), it doesn’t really address it.

Scotland

The extent to which the problem is recognised at all can be seen at Section 8.4, which discusses “Security of Supply & Storage Potential”. I take the following extraordinarily convoluted paragraph to amount to an admission that wind turbines are unreliable and can lead to power shortages, the gap is currently filled largely by fossil fuels coming to the rescue, and that the new system will have to find a way of dealing with that problem (though naturally the statement doesn’t use clear language to make clear what the problem is):

We believe that onshore wind can play a greater part in helping to address the substantial challenges of maintaining security of supply and network resilience in a decarbonised electricity system. This will mean an increasing ability to provide some of the services and responses that are currently provided by thermal generation, and market / regulatory arrangements which can incentivise and support such outcomes.

Sir Humphrey would be proud of the opaque and confusing choice of language, but we get the gist of it from what follows. First we are treated to a discussion about Black Start. The policy statement explains only briefly what this is, but the National Grid website goes into more detail:

Black Start is the procedure to recover from a total or partial shutdown of the GB Transmission System which has caused an extensive loss of supplies. This entails isolated power stations being started individually and gradually being reconnected to each other in order to form an interconnected system again.

The policy statement tells us that the Scottish government

provided £550,000 to support a demonstration project delivered by [Spanish company] ScottishPower Renewables at its Dersalloch Wind Farm, looking at the potential for delivering Black Start…The project delivered a global first during a test in October 2020 by delivering black start capability from wind power to re-start part of the electricity system.

I may be overplaying my hand here, but I suspect the most likely reason for a total or partial shutdown of the system in a net zero world will be a failure of renewable energy sysyems to supply the required amount of power.

Next we are told that wind power can be co-located with hydrogen electrolysers. We are not told that this policy actually works, but we do learn:

The renewable hydrogen produced from such processes can serve a number of highly valuable purposes; in addition to greatly reducing network constraint payments and costs, the renewable hydrogen produced could help meet demand for zero carbon heat and transport as well as being used to generate electricity and provide vital flexibility at key strategic locations on the network.

It sounds good, but what does it mean? Well, first of all, it amounts to an acknowledgement that constraints payments are substantial and need to be reduced. It also consists of the extraordinary proposition that wind farms should be used to produce electricity, and when they produce too much, it can be used to produced hydrogen which can then be used to produce electricity again. This doesn’t sound terribly efficient or cost-effective to me. And it probably isn’t. So far the Scottish government has committed to throwing loads of money at trying to make this work. Its Hydrogen Action Plan is apparently backed by £100M of taxpayers’ money, and we learn that a report on the assessment of electrolysers was published in October 2022. Tucked away near the end is a SWOT analysis. The “strengths” section smacks of desperation, including things like “The Scottish Government is very supportive of the hydrogen sector and wants to promote growth.” Also, with no apparent sense of irony:

A strong oil and gas and offshore industry, which includes manufacturers, a skilled workforce and established supply chains.

Weaknesses strike me as rather more compelling:

At present there are no commercial-scale electrolyser manufacturers in the Scottish market. The majority of materials required for electrolyser manufacture will likely have to be imported.

The policy statement also talks about the desirability of co-located wind farms with battery storage facilities, but doesn’t talk much more about battery storage. Which is a pity, since battery storage is probably the key to making a net zero, renewable energy-powered economy work. Given that the Scottish government doesn’t talk much (in its onshore wind policy statement, anyway) about how the intermittency problem is to be resolved, where else might we find some information regarding the plan to deal with the intermittency problem? There is a plan, isn’t there?

United Kingdom

As it happens, Westminster Energy Environment and Transport Forum (WEET) is hosting a conference on 26^th April 2023, titled “Next steps for energy storage in the UK – Policy and regulation, support for investment, development and rollout, achieving whole-system change and priorities for innovation”, and the notes accompanying the email invitation make interesting reading.

It talks a lot about LLES. The acronym isn’t explained, so I had to look it up. I was somewhat relieved to learn that it is short for “large-scale long-duration electricity storage”. Since that is exactly what will be needed in a de-carbonised country whose electricity grid is at the mercy of renewable energy, it’s a relief to know that somebody has worked out that this is the critical issue.

Before looking at the notes to the WEET conference, it’s worth checking out a very interesting article that appeared in Current News on 21^st July 2021, headed “BEIS makes call for evidence on enabling long-duration energy storage”. I find it a little alarming that it appears to have taken two years from Theresa May’s slipping the net zero agenda through Parliament before the (then) Department of State tasked with looking after the UK’s energy supply system got around to looking into how the key net zero problem might be addressed. Still, never mind; at least they are looking at it.

Describing electricity storage as an “essential” source of low carbon flexibility that currently faces barriers limiting its deployment, BEIS said its own analysis shows around 30GW of short duration storage and flexible demand alone may be needed in 2050, however this does not include longer duration storage.

It defines LLES projects as being able to store and discharge energy for over 4 hours, and up to days, weeks and months, and deliver power of at least 100MW when required. This definition is one of the elements it is seeking views on.

Worryingly:

It found that challenges associated with financing large-scale storage were particularly prevalent, with stakeholders stating that the high capital costs associated with some LLES developments combined with long lead times and uncertainty over novel technologies can make it difficult to attract investment when combined with a lack of bankable or forecastable revenues.

The call for evidence itself, rather lamely said:

Large-scale and long-duration electricity storage could provide an important role in decarbonising our energy system, for example by storing renewable power and discharging it over periods of low wind. However, there is evidence that it faces market challenges that mean it may struggle to deploy at scale.

This call for evidence seeks to gather information to help us understand in more detail the barriers within the current market, how these might be addressed, and to map out risks that may be associated with potential interventions to support large-scale and long-duration electricity storage to deploy.

Given the critical importance of a mechanism to ensure energy supply when renewable energy sources are failing, such a tepid and lethargic couple of paragraphs don’t exactly fill me with confidence. Still, that was over eighteen months ago, so how have they got on?

The Government response advises that 66 responses were received, 23 from developers, 8 from trade associations, 6 from asset owners, 9 from academics, 3 from investors, one from “technology” and 16 others (unspecified). The UK government has concluded that LLES has an important role to play in achieving net zero, provides flexibility, “diversifies our technology mix”, but, ominously:

faces significant barriers to deployment under the current market framework due to their high upfront costs and a lack of forecastable revenue streams.

Which sounds rather problematic. The ongoing commitment sounds rather vague, too, with little sense of urgency and a tendency to kick the can down the road. The government will carry out further analysis, consider options, and work with Ofgem to deliver an appropriate policy. Further consultation with stakeholders is anticipated.

Worryingly, the questions asked in the call for evidence simply seem to assume that the technology is available at the necessary scale, and that all we have to worry about is bringing it to market, removing obstacles, providing incentives, and ensuring a benign investment environment. Only one of the questions asked what LLES technology might be available in the next five years, and even it didn’t ask whether it would be available at the scale required and at anything other than prohibitive cost. No appropriate technical questions were asked. The questions fell into four areas:

Strategic context: The role and value of LLES in a net zero energy system

Current market: Understanding the storage landscape

Current market: Potential barriers to LLES deployment

Addressing barriers to the deployment of LLES

Twenty one questions were asked in total. Many related to financing issues (notably, whether financing would be available for investors, rather than whether the cost would be prohibitive). Only one addressed the vital technical question, and then rolled a load of sub-questions in, as though this is all of peripheral importance:

Please provide details of specific LLES projects that could begin development in the next 5 years. These details should include technology type (including intended use of fuel generated through sector coupling), MW and MWh, the business model or route to market, efficiency and expected development, capital, operational costs and expected lifetime of projects.

This doesn’t, to me, have the feel of politicians and civil servants being on top of the issues. Let’s not forget that the Labour Party is still talking, ever more earnestly, about “decarbonising” electricity production by 2030 if it forms the government after the next general election.

From the WEET conference notes we learn about various sums bandied about by the government in the seemingly vague hope that they will enable the technical problems to be resolved. For instance, a press release on 23^rd February 2022 announced £6.7M of funding “to develop new energy storage technologies that can utilise stored energy as heat, electricity or as a low-carbon energy carrier like hydrogen. Ranging from the development of thermal batteries to converting energy to hydrogen, they have been selected because of their potential to improve technology performance and reduce the cost of meeting net zero“.

I suppose I should be grateful that there is some recognition that net zero comes at a cost, though I suspect they have no idea just how enormously high that cost is. Three examples of supporting grants were singled out for mention:

Sunamp’s EXTEND project, East Lothian, Scotland – will receive £149,893 for a feasibility study to further develop the storage duration of their thermal batteries. They will look to pair their heat batteries with household energy systems to tackle periods of low renewables generation on the grid

Cheesecake Energy’s FlexiTanker project, Nottingham, England – will receive £139,411 to develop their thermal and compressed air energy storage technology to integrate more renewables into the grid, helping to fast-track the decarbonisation of the UK electricity system

B9 Energy Storage’s Ballylumford Power-to-X project, Larne, Northern Ireland – will receive £986,082 to mobilise an innovative 20MW Power-to-X project at Ballylumford. Green hydrogen produced by electrolysers will be stored in underground salt caverns and used for transport and to displace natural gas in fuel blending trials. This project paves the way for future large-scale deployments connected to offshore windfarms

On 21st October 2022, a press release announced that:

The UK’s world-leading manufacturing industries will be boosted thanks to £211 million in new government funding for battery research and innovation.

Reading on, we learn that to date “[t]he Faraday Battery Challenge has been backed by £541 million since 2017.” Just another cost of net zero.

Another press release on 28^th November 2022 proclaimed that:

Five projects based across the UK will benefit from a share of over £32 million in the second phase of the Longer Duration Energy Storage (LODES) competition, to develop technologies that can store energy as heat, electricity or as a low-carbon energy carrier like hydrogen.

The variable nature of renewables like solar and wind power means that energy can be produced when it is not needed, such as during extended periods of high wind. However, new energy storage technologies can store excess energy to be used at a later point, so the energy can be used rather than wasted – meaning we can rely even more on renewable generation rather than fossil fuels, helping boost the UK’s long-term energy resilience.

That second paragraph seems to me to have things the wrong way round. Yes, of course, if practicable and economic, it makes sense to store surplus energy rather than waste it or pay wind farm owners not to generate power because the National Grid can’t cope with it. But the real issue is not that wind farms produce too much power, rather that they all too often don’t produce enough, and it’s to cover those shortfalls that storage of surpluses is vital. The five projects to receive funding might be innovative, interesting and in due course useful, but I don’t see anything here which is going to solve the large-scale problem of energy shortfalls that will be associated with decarbonising the electricity system:

StorTera Ltd, based in Edinburgh, will receive £5.02 million to build a prototype demonstrator of their sustainable, efficient, and highly energy dense single liquid flow battery (SLIQ) technology. SLIQ will offer flexibility to the grid by storing electricity which can then be released when weather dependent technologies such as wind turbines and solar panels have periods of decreased energy generation.

Sunamp Ltd, based in East Lothian, will receive £9.25 million for a project that will trial their advanced thermal storage system in 100 homes across the UK. They will extend their existing heat battery to provide increased storage duration and capacity and pair it with household energy systems to tackle periods of low renewables generation on the grid.

The University of Sheffield will receive £2.60 million to develop a prototype modular thermal energy storage system, enabling optimised, flexible storage of heat within homes, providing benefits for both the occupant and the grid. The protype energy systems will be manufactured by Loughborough University and deployed at the Creative Energy Homes campus at the University of Nottingham, demonstrating the technology within lived-in homes.

RheEnergise Ltd will receive £8.24 million to build a demonstrator near Plymouth of their ‘High-Density Hydro®’ pumped energy storage system. The system uses an environmentally safe mineral-rich fluid more than two and half times denser than water, to create electricity from gentle slopes, without requiring steep dam walls or high mountains like traditional hydropower. The project will use surplus electricity to pump the fluid uphill, then later when electricity is needed by the grid, the fluid will be released back down the hill through turbines to generate electricity.

EDF UK R&D, in partnership with the University of Bristol, Urenco and the UK Atomic Energy Authority (UKAEA), will receive £7.73 million to develop a hydrogen storage demonstrator utilising depleted uranium at UKAEA’s Culham Science Centre in Abingdon, Oxfordshire. Electricity will be converted to hydrogen via electrolysis and stored for future use – either directly as hydrogen, or converted back to electricity via a fuel cell when required.

It’s all very well, but everything I’ve read so far seems like small beer, and it isn’t as though the government isn’t aware of the massive scale of the problem, arising from net zero, that is facing us. In July 2022 BEIS received a report headed “Benefits of Long Duration Electricity Storage”. It runs to well over 100 pages, and doesn’t shy away from the problems. It notes, inter alia, that increasing reliance on renewable energy combined with increasing demand for electricity arising from planned electrification of the transport and heating sectors brings at least three obvious problems.

First, greater variability in residual demand means that:

Flexibility is needed to maximise the use of renewables when there is an excess, and to fill the supply gaps in periods of shortfall. In this study we have observed that, in addition to increasing the need for flexibility within-day, the system of the future will have greater seasonal volatility, and extended periods of days or weeks where there are prolonged excesses, or shortfalls, of renewable output. There is a need for both sufficient capacity and energy production.

Secondly, “more renewables will increase the need for system services”. Or, to put it another way:

As renewables replace thermal generation the proportion of synchronous generation on the system falls, reducing the levels of inertia readily available for secure operation of the system…In addition, it is also more likely that transmission lines will be more lightly loaded at times, increasing the need for voltage support services.

Thirdly, new generation locating at high renewable resource locations may exacerbate network congestion issues, i.e.:

Wind and solar resources are not evenly distributed across the country and it is likely that much of this generation will be sited further from demand centres, to access the best locations.

Thus, energy will be lost en route to where it is needed. In addition, it is suggested that:

Intermittent renewables, in this example, result both in periods where generation is significantly greater than demand (up to 50GW in a given period) and periods when generation is significantly lower than demand (100GW).

The problem is enormous because, returning to a point mentioned above, but focussing in more detail on it:

[T]he backbone of a low-carbon generation mix will be renewables, predominantly intermittent wind and solar resource, which…could be up to ten times higher in 2050 than today.

Electrification of heating, transport and some industrial processes may result in final electricity consumption being more than double current levels by 2050…

As we move towards a net zero system, the balancing issues become more challenging with both more extreme residual demand positions to manage…and greater volatility across time…by 2050, in addition to weeks with higher residual demand, the system of the future is also likely to feature weeks with high excess renewable output.

From the perspective of system stability, large growth in non-synchronous renewable generation will reduce the levels of inertia of the system and make secure operation of the system at 50Hz more complex. This fall in inertia levels is an existing trend that will continue out to 2030 and beyond.

It is likely that maintaining a stable voltage level will be more challenging. Voltage stability is needed to ensure that power is transferred across the network. With more renewables, power transmission lines are likely to be lightly loaded more frequently, leading to reduced voltage stability. This will drive the need for voltage support (typically reactive power absorption). Provision of the right levels of voltage support, maintaining sufficient inertia and responding to deviations in system frequency will be more challenging in a more weather driven system. Forecasting output from generation will also be harder, due to the inherent uncertainty in weather forecasts. Larger forecast errors from weather-driven renewables are likely to lead to a greater need to manage imbalances at short notice.

For storage technologies, a key consideration is the duration of periods of high demand and low wind output.

An example is then given, using assumed 2050 electricity demands and the January 2010 weather pattern:

The week shown here was from an extended cold spell with the 2010 weather pattern modelled with illustrative 2050 capacities. Peak residual demand is 114GW and the overall energy requirement is 8.7TWh over the week…This analysis is theoretical but illustrates the challenge the very long duration high demand, low wind events and the role of LDS.

Their conclusion:

Considering only capex, it is clear that the most competitive options for maintaining security of supply are the low carbon thermal plant options, rather than power LDS options. Peaking thermal capacity would be even cheaper still purely on a per MW cost basis. In the case of CCGT hydrogen plants, the ability of long duration hydrogen storage to store the volumes of hydrogen is key. Salt cavern storage can make it possible for these plants to generate continuously for extended periods such as this. By contrast, the power LDS options are apparently typically less efficient. The relatively infrequent but critical weeks would theoretically require much of the power LDS to operate at low cycling rates. This is a relatively cost inefficient means of balancing the seasonality of the system.

I take that to conclude that on cost grounds, retaining gas in the system is the best solution. There is a host of technical detail in this document. Those better able than me might like to read it to consider the conclusions reached regarding potential various long-term storage solutions. As well as battery technology we encounter all sorts of propositions such as blue hydrogen, use of salt caverns, compressed air, liquid air, hydrogen fuel cells, etc, etc.

Conclusion

I can’t help feeling that the Government is flailing around with no real understanding of the problems that net zero brings in its wake. All sorts of storage solutions are touted, but nobody seems to be making any firm decisions, nor do those in charge really seem to know what to do next or when or how to do it (possibly because there are currently no plausible solutions to the scale of the storage problem). They are throwing money at some possible solutions, in the style of Mr Micawber, hoping that something will turn up. We seem to be thundering towards the buffers, politicians of all stripes are shouting “faster, faster”, and disaster looms. To repeat a much-used, but highly descriptive and appropriate, analogy – the government has thrown us out of an aeroplane at 30,000′ and is vaguely hoping that someone will invent the parachute before we hit the ground.