Renewable energy’s contribution to the generation mix continues to grow. However, it still faces one major challenge. Producing green electricity is one thing, but storing it is quite another.

The problem? It’s the weather, stupid. Scotland may be the windiest place in Europe, but that wind isn’t consistent. When it blows, the turbines turn, but you don’t always get a breezy force five when and where you need it.

The answer lies in saving the power on blustery days and then using it on calmer ones. That means battery storage. This may sound a profoundly simple solution, but until now, its rollout has been hindered by technical challenges and the cost of the infrastructure.

However, things are changing. Scottish Power has announced plans for a 50 megawatt battery storage facility at its Whitelee wind farm on Eaglesham Moor outside Glasgow – the biggest in the UK. And another company, RES, is managing a 20 megawatt storage centre at Broxburn, West Lothian, the first of its type in Scotland, on behalf of The Renewables Infrastructure Group (TRIG).

We are still catching up with the United States, where some 1.4 gigawatts of batteries have been deployed in the last year alone. But there is plenty of optimism. “Our Broxburn project has been operational since last summer,” says Tim French, RES’s Head of New Technology. “It’s been very successful, operating at high levels of availability. The customer, National Grid, is very happy.”

RES has its own Glasgow-based control system that manages the batteries intelligently and assists with the operation and maintenance.

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The stored power is available 24/7 and feeds into the grid automatically when demand exceeds supply. The energy is stored in thousands of individual but connected lithium-ion battery cells, stacked in arrays within containers. These cells have high capacity and respond quickly when needed.

Deploying power in this way is not just environmentally friendly – it has a positive economic impact, too. National Grid calculates that battery technology will save it some £200 million, which will ultimately feed through in lower costs to the end user. This is because this stored and readily available green energy avoids having to use other, more expensive generating options to keep supply stable.

“Because the batteries can respond in super-quick time, the grid does not have to switch into these other sources,”

Tim French explains. “We use lithium- ion technology because it’s very good at this kind of application. It is able to charge and discharge very quickly and the energy density within each cell is quite high.”

The combination of renewable power and flexible storage is reckoned to provide the most cost-effective low carbon solution for consumers. Another Scottish energy giant, SSE, is also trialling lithium-ion storage including for solar panels, researching if it could be a cheaper solution than building new transmission lines.

“The chemistry has been around for a while, with lithium-ion used in all sorts of applications over the last decade or so, but the main reason battery storage is now revolutionising the market is cost.

The Herald: RES currently have more than 1,000 MW (megawatts) of renewable energy projects constructed, under construction or at advanced planning stages.RES currently have more than 1,000 MW (megawatts) of renewable energy projects constructed, under construction or at advanced planning stages.

“This has come down by as much as 50 per cent in the last three or four years.”

The ultimate aim of this technology is to allow the complete phasing out of fossil fuel generation over time. “We believe that can happen,” says Tim French.

“Obviously, we’re on a journey, but one would hope that we could move quicker than we have until now. By 2030, we’d like to see fossil fuels off the grid.”

One issue which still needs to be fully addressed is not just how much power can be provided, but for how long. Typically, batteries can currently feed into to the supply for one to four hours before they become exhausted. This is enough most of time, but other technologies are still needed in order to prove more longevity.

Different types of energy storage are already available, and some have been around for decades. The venerable Ben Cruachan pump hydro scheme on the shores of Loch Awe near Oban, for instance, has been generating power through water and gravity since 1965.

Other solutions include supercapacitors, solid state and lithium-air.

These can be more suitable for short duration, high power applications. However, lithium-ion is likely to be the lead technology over at least the next five to 10 years, largely because it is seen as a relatively mature solution which gives comfort to investors. Cost is also likely to continue to fall.

Interestingly, lithium-ion is also the same storage solution used for electric vehicles (EVs), the use of which is expected to grow incrementally in coming years, with predictions of 230 million of them on the road across the globe by 2030.

Rachel Ruffle, who is the Managing Director of RES, share Tim French’s vision for the Broxburn facility and the wider industry.

“We believe this project will play an important role. Energy storage can play a large part in supporting the transition to a secure, low carbon, low cost system.”

This article appeared in The Herald on the 14th March as part of The Heralds weekely Climate for Change editorial.

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The Herald’s Climate for Change initiative supports efforts being made by the Scottish Government with key organisations and campaign partners. Throughout the year we will provide a forum in The Herald newspaper, online at and in Business HQ magazine, covering news and significant developments in this increasingly crucial area.

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