HomeDecentralized EnergyEquipment & TechnologyPushing energy storage up the agenda

Pushing energy storage up the agenda

The UK is exploring several types of energy storage. Below: Dr Jill Cainey.

Credit: National Grid

Dr Jill Cainey of the UK’s Energy Storage Network tells Diarmaid Williams of the challenges of integrating energy storage into the British power portfolio

Energy storage has been identified by the main authorities for energy in the UK as a key solution for improving grid resilience and the development of a low carbon electricity grid.

Indeed, it has been estimated that proper facilitation of storage technology could save the country billions of pounds.

Some distance has been travelled in terms of recognition for the industry, but according to Dr Jill Cainey of the Electricity Storage Network, much work needs to be done in the areas of regulation and financing before its financial, environmental and energy security potential is realized.

The Electricity Storage Network works closely with government, regulators and developers to advance the deployment of energy storage in the UK.

To draw attention to the potential storage offers, Dr Cainey cites a paper written in 2012 for the Carbon Trust, delivered by Imperial College London Professor of Engineering, Goran Strbac.

In the paper, entitled Strategic Assessment Of The Role And Value Of Energy Storage Systems In The UK Low Carbon Energy Future, Strbac looked at what he called “the benign dictator”.

“He said if there were 10 GW in storage, you would put that storage where it was technically best to go without any reference to National Grid or distribution network operators or anything like that. You simply put it where you needed it,” Dr Cainey told Power Engineering International. “If you incorporated 10 GW of storage into the system [the UK has 3 GW at the moment]), by 2050 that would save the country à‚£10 billion ($15 billion).”

The newly initiated National Infrastructure Commission, a body set up by Chancellor George Osborne to provide more heft and vision in Britain’s infrastructure strategies, may give the technology the impetus it needs to secure that mammoth saving.

Dr Cainey says: “Within the NIC’s strategic brief they are keen to see large-scale storage fulfilled, and storage has a specific place in their activities although the exact detail hasn’t yet emerged. It was part of their recent announcement.”

Storage solutions can provide a host of applications to improve the flexibility of the grid, help meet peak demand during the winter months, and defer non-essential grid upgrades. These applications can potentially support the grid throughout the year without being susceptible to price fluctuations.

For the UK, electricity storage projects in all categories are of interest, including compressed air, batteries, liquid air, pumped hydro and future technologies that will enter the equation.

The ESN has been busy in recent years looking at resolving the legal and regulatory issues that could scupper real progress.

Dr Cainey says: “When the various energy system acts were written, storage wasn’t included. So we have supply, distribution, transmission and generation but no storage. We now have interconnectors which have subsequently been added.

“Because our electricity industry has been highly regulated,” she continued, “if you are already a regulated entity it becomes tricky to own and operate electricity storage because, although charging storage is not a problem, when storage discharges it is either going to look like supply or it is going to look like generation. Specific entities can’t do that under their current license conditions. That makes it complicated.”

By way of example, she points to the battery currently deployed by UK Power Networks at Leighton Buzzard.

“In order to get their battery on, and they have done it very by-the-book, one side of the battery is connected as a demand customer, and had to go through its connection process, charges and connection agreement and distribution of use charges.

“On the other side of the same device, which is at a distance of, say, 50 metres, it has to be treated as generation connectee, connected on that methodology, with generation connection charges along with distribution use and system charges. It is very complicated as you essentially treat your single asset as two different things”

Helpfully, UK Power Networks has released a report on the regulatory framework necessary for their Leighton Buzzard project and subsequent projects, not only for DNOs but also for third parties. It talks about all the issues – the various low-carbon incentive regimes, how a storage device is often charged twice, and, as Dr Cainey puts it, “all the little niggly things that happen because storage isn’t defined.”

Other recent developments include the National Grid’s call for expressions of interest in enhanced frequency response, the Department of Energy and Climate Change’s (DECC) storage stakeholder steering group and the Smart Grid Forum, including power market regulator OFGEM, which is about to produce a report on what exactly is required to move storage forward in the country.

Types of storage

The types of storage technology that make it to the front of the queue will vary.

“It’s difficult to say, with so many different technologies with different features and scales,” says Dr Cainey. “For instance, National Grid, with their enhanced frequency response service, is looking for something that responds really rapidly but of a short duration of about nine seconds.

“They will be prepared to value any device that can do more than nine seconds and still respond quickly with a higher value, and then for the evening peak issue you need something that’s got a reasonable duration – it could be a battery, be that liquefied air energy storage or perhaps compressed air energy storage – you need a more robust technology and there are resolutions that are tried and tested now.”

So what are the implications for the growing share of renewables in the system? Dr Cainey says that, at the moment, it is difficult to connect renewable generation because the network is constrained, and also sometimes because its variable nature causes particular technical issues on the network.

Storage can improve grid flexibility

Credit: National Grid

“When the sun then goes down in the afternoon everything starts coming back on the system, and that ramp-up in demand causes problems. So if you put storage in the system you can help manage your connections. If solar generation at noon is causing overvoltage, then storage can help you manage your technical issues with your wire and equipment, and then you can release that out into the system later during evening peak.

“Also, if you have limited export connection, more than you get out onto the system, you can store it on your device. Then if you don’t have enough it’s under your cap and you can top it up with your storage device. So you are always maximizing what you can put on to the system, and in certain situations it can even make you dispatchable.”

Up-front investment

The overriding concern for the future of a promising technology remains tied up in the extent of financing required to make it a true contender.

Dr Cainey says that, even if storage does come down in price through innovations such as what it is being done with lithium ion batteries, any new technology must compete with large incumbent providers who have already been on the system for a long time.

“So the standard services that storage could also provide, like short-term operating reserve and standard frequency response, other incumbents can already do that – so it’s very hard for a technology with high up-front investment costs to compete. So it’s about dealing with that up-front investment cost by providing an investment scheme or tax break or Green Investment Bank input to get these on the system.”

Considering where it was even a decade ago, the technology has made progress, and there is a sense that, with the NIC also expressing interest, momentum may continue.

The UK has “gone from Electricity Market Reform and capacity market and Contracts for Difference, none of which helped with storage, to a very broad recognition that we are going to need it, and there are going to be things that have to be done in order to facilitate getting that storage on the system.”

Ownership, pricing & Regulation

DNV.GL chief executive David Walker talks PEi through the fundamental questions facing energy storage

“When I look at storage I tend to look at it on three different levels. One is the very macro level – the pumped hydro level, where you have large, fairly quick-response storage that helps support the grid if there are difficulties.

The opposite end of that is the Tesla power wall level, if you like: whether it’s in homes or businesses, you will have storage that’s behind the meter, and it is therefore up to the consumer how they use that to offset their energy bills, or tie it to their rooftop solar, or use it in any way that they choose.

And then the third level is the more interesting one: a middle level that we can call grid or industrial level, that sits probably before the meter. At the moment that probably looks like large-scale batteries, although there are several competing technologies. This storage can be used for several things: it can provide ancillary services to the grid, and then it can back up or support variable renewables. That is an interesting area that I think we are going to see a lot more of.

That is where we [at DNV.GL] believe that battery storage will probably be the winner in that particular field. The question mark is which set of batteries it will be – probably lithium ion.

But it becomes a big question then as to who actually owns that storage. Is it owned by the grid operator? Is it owned by the generating utility, because it’s part of the power supply? Is it owned by IPPs? Or is it actually owned by independent storage providers, a new group that could enter into this bit of the market?

And how is it going to be priced? Is it going to be priced the same as generation, or is it going to be priced differently?

And the final part of the equation is how is it going to be regulated?

So there are still a lot of questions around energy storage – but it will be a really important part of the future.”