Painting a picture of a UK energy future that incorporates greater integration of renewable energy sources and maximises efficiency of operation with smart grid technology is an easy thing to do – a solar farm here, a tidal lagoon there, and a vast collection of electronic vehicle charging points there.
Actually making it a reality on the other hand, is a far more painstaking and uncertain undertaking. That is the challenge that UK Power Networks, with the support of energy regulator Ofgem and a number of industrial partners, has taken on with the Smarter Network Storage Facility.
With ‘Europe’s biggest battery’ at its core, the £18.7m project – with £13.2m from Ofgem’s Low Carbon Network Fund, £4.3m from UK Power Networks and £1.2m from other parties – is aiming to serve as proof of concept that battery storage is both technologically and economically favourable when applied at network scale.
Providing the potential to absorb excess power when demand outstrips supply, and inject it when the see-saw tilts the other way, the technology is tailor made for an energy eco-system growing ever more reliant on renewables and therefore ever more at risk of intermittency. But in order for that potential to begin to be assessed, first must come a very big battery.
Bringing the battery to life
When building a facility the size of three tennis courts that must house two massive rooms where electricity is converted from AC to DC in one room, via a vast array transformers and inverter units, and stored in another in battery racks and modules, the first challenge is choosing where to put it. Having assessed multiple different locations across its existing network infrastructure, UK Power Networks settled on one of its main substations in the Bedfordshire town of Leighton Buzzard.
Combining the critical criteria of existing infrastructure in need of rejuvenation (due to thermal capacity constraints of two overhead lines), a track record of exceeding peak demand (between nine and 37 days in each of the past five years) and ample already owned land on which to build it, the site was well-suited.
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Contained within a built site, raised off the ground to avoid the risk of disruption from flooding, the ‘battery’, or to be more precise the collection of multiple Lithium-Ion batteries, itself is a Russian Doll like configuration of 16 individual 3.5KWh cells inside each of the 24 trays that make up the 132 racks. Altogether, it offers 6MW of battery storage capacity, with the in-built availability to scale it up to 8MW.
Combining that storage capability with sophisticated software systems that forecast, optimise and schedule distribution of the power to where its needed, the system should offer an alternative and effective method to balance usage across the network. Unlike demand response, where peaks are eased by incentivising heavy users to reduce demand, the Leighton Buzzard facility would be able to fill any void directly with stored electricity.
What’s in store for UK Power Networks?
To resolve the capacity challenge at Leighton Buzzard, the standard approach for UK Power Networks would have been to refurbish the existing infrastructure, such as the faulty overhead power lines. In order to solve the issue temporarily, the operator transferred capacity from a neighbouring section of the network, however, with demand expected to continue to grow, an extra circuit from the feeding site at Sundon Grid would have been required in order to provide an additional 35.4MVA of capacity.
Instead, the storage facility will provide a maximum peak power output of 6MW and energy capacity of 12MVAh, providing the minimum bounds of power and energy to make storage an effective peak shaving solution. But while storage offers a favourable long term solution in many ways on operational terms, there is a cost.
Were the company to have opted for the conventional reinforcement route, achieving the required extra capacity would have required an investment of £5.1m. The storage option requires more than double the capital, with an overall cost of £11.4m. While much of the excess results from the projects scale and novelty, which would come down if storage is more widely adopted by the company and across the sector, it is of critical importance to the exercise that a strong business case can be proven.
How to make it pay
For Nick Heyward, project director at UK Power Networks, that is where the real challenge lies. "The benefits or the applications that it can typically be deployed for are not on the whole sufficiently beneficial to justify the cost and in a nutshell that’s why it’s more difficult for storage to be deployed with a valid business case," he says. "That forces you down a route of having to look at multiple applications and stack them up so you can get as many benefits as possible. The consequence is that it’s commercially quite challenging to do that."
Fortunately, UK Power Networks believes that over the life of the project, up to £8m of the initial forecast investment can be recouped. Of that, the highest return is likely to come simply from a 30% drop in battery prices since the budget was first announced, with the discount currently standing at £2.9m. More interesting though, it believes new revenue streams made possible by the technology could recoup the rest.
It has already estimated that it could generate an £400,000 in revenue by offering a range of load balancing services to transmission system operators and the National Grid. The range of envisaged services include providing reserve power in when unforeseen demand is encountered, reactive power, and short term operating reserve power (STOR) to transmission systems operators.
In its business case, the operator highlighted the value of the facility in an environment where renewable generation plays a more dominant role. Backing this up, it outlined the opportunity for it sell stored electricity to TSOs in periods of intermittency, while in periods of excess renewable generation, it could offer generators a service to store the excess until it is required.
One area where it sees particular potential is in its ability to provide societal benefits. The company has highlighted that its facility, and the greater use of large scale energy storage, would significantly reduce the need for additional peak generation capacity and would be a helpful means to reduce carbon emissions. On this side, the company has estimated that the value would be around £2.5m. The issue though is that current regulatory schemes do not recognise these and therefore rarely result in revenues.
Over the course of the development of the Smarter Network Storage Facility so far, planning and design obstacles took time but were overcome. While establishing the technology to get it into operation, save for a small number of stumbling blocks such as a supply of faulty circuit boards and electromagnetic interference, ran rather smoothly. But even though it can work on those fronts, it must still overcome the regulatory and economic challenges in order for its role to be significant. Europe’s largest battery is charged, but it remains to be seen whether the market is ready for it.