Energy storage: making 100% renewable power a reality

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Whirring away beneath Arsenal’s Emirates Stadium are several rows of large white boxes. At a glance they’re a little unassuming, but in actual fact, they’re gamechangers: massive batteries with enough energy to power the entire stadium for a full ninety minutes. Installed in 2018 by Octopus Energy and Downing LLP, the groundbreaking Arsenal battery can stop as much carbon going into the atmosphere as would be emitted by 2,700 homes over the course of a match.

This is the future of energy, and the only way society could one day be powered by 100% renewables, 100% of the time.

An image of the arsenal batteries

Energy storage is a hot topic. From big batteries like the one at the Emirates Stadium to the smaller smart batteries popping up in homes across the UK, the ability to store energy is a vital part of a plan to make renewables work on a massive scale, and it’s all because they bring flexibility to the grid: creating a smarter, more complex, dynamic system not unlike the internet.

Right this very moment, teams of ‘flex-perts’ are hard at work putting batteries at the service of the green energy revolution; bringing the benefits to ordinary people up and down the country.

What exactly is energy flexibility?

To give a bit of background, our electrical grid must always be ‘well balanced.’ If there isn’t enough energy being pumped in to meet demand there can be power cuts, and if more energy is pumped in than is being used up it can damage grid infrastructure.

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When it was first built over 100 years ago, our energy grid revolved around huge coal power plants where tonnes of dirty fossil fuels were burnt to meet the nation’s energy demand.

Any ‘flexibility’ in the system came from being able to adjust the energy supply - if the country began to use more energy, you could just turn on more coal plants to keep up.

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In recent years, we’ve come to understand the threat that burning fossil fuels poses to people and ecosystems all over the world, and have begun to pivot to cleaner, greener sources like wind and solar energy. Wind turbines and solar farms are quite simply wonderful; not only are they green, but they don’t require any fuel to run - so the electrons they generate are remarkably cheap. In fact, renewable generation is already the cheapest way to produce energy globally.

Yet wind and solar energy is also ‘intermittent.’ We can’t say for sure when the wind will blow or the sun will shine; we can’t just ‘turn on’ renewables whenever we want.

On some especially windy days we already have far more wind power than we need, and we actually have to pay wind generators to ‘turn off’ in order to protect the electrical grid. It’s an utter waste of low-carbon power, especially given that when energy demand peaks (usually between 4-7pm in the evening, when the sun is low) the grid often has to ask generators to burn more fossil fuels to keep up.

So there’s the central challenge of the energy transition: if we can no longer rely on turning large, dirty generators on and off to match our ever-changing energy demand, then flexibility is going to have to come from somewhere else. Only then can we smooth the sun and wind's spiky, erratic power into a stable, controllable, 24/7 supply.

If we can no longer rely on turning large, dirty generators on and off to match our ever-changing energy demand, then flexibility is going to have to come from somewhere else.

Is energy storage the answer we've been waiting for?

An image of the Arsenal Stadium

This is where solutions like the Arsenal battery come in. Energy storage devices like those at the Emirates Stadium can charge up when renewables are abundant (and so energy is at its very cheapest and greenest). Arsenal can then choose to run a full ninety minute game off their battery and avoid using the grid whenever energy is dirtier, and more expensive.

But that’s not all. Given that games at Arsenal happen relatively infrequently, the Arsenal battery can fill up on green energy, and then send it back to the grid to give neighbouring homes cleaner energy whenever the UK is in danger of being ‘short’ of energy.

Here then, we’ve managed to find another way to unlock ‘flexibility.’ By storing renewably generated electrons when they’re available for use later on, we now have a way to ‘call on’ green energy when we need it. In other words, energy storage devices like the one Octopus helped install at Arsenal allow owners to get paid to help make renewables work on a huge scale.

Writing in Utility Week, Lucy Yu, who heads up Octopus' Centre for Net Zero, explains that flexible energy projects like the Arsenal battery are 'indicative of what a future energy system may look like', showing the 'potential to harness existing infrastructure, especially in urban areas.' One option would be set up a 'direct wire', with assets like these operating as virtual power plants for local housing and communities. Still, Lucy argues that projects like these are put to better used serving 'the wider local energy system', as the Arsenal Battery does currently.

In the near future, we might well see other ways of storing energy come to the fore -Octopus and RES have recently pledged to invest £3bn in developing ‘green hydrogen’ over the next decade, some of which will be used to explore ‘green hydrogen storage’.

Here then, we’ve managed to find another way to unlock ‘flexibility.’ By storing renewably generated electrons when they’re available for use later on, we now have a way to ‘call on’ green energy when we need it.

Unlocking unparalleled flexibility

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Bathed in the greenish glow that radiates from several complex-looking wall-mounted arrays, a team of mysterious flexibility vanguards are busy running a series of crucial experiments. Octopus’ Kraken team uses cutting-edge machine learning technology and unparalleled energy expertise to help batteries unlock as much flexibility as possible, and make sure as little of the UK’s wind power as possible goes to waste.

Kraken currently controls hundreds of batteries across the UK - enough to store 1.2GWh of power: that’s as much storage space as in half the UK’s total 350,000 Electric Vehicles. To give a concrete example of what they do, at half-time during the momentous Euro semi-finals, the Kraken team anticipated a massive nationwide tea-break and so unleashed their batteries, sending enough stored power to the grid to address half of that extra demand.

As it stands, smart energy schemes like those enabled by Kraken could save the UK £8bn a year by making the most of cheaper, greener renewable energy and reducing the need for expensive infrastructure updates, according to the National Infrastructure Commission.

As it stands, smart energy schemes like those enabled by Kraken could save the UK £8bn a year

How can I get involved?

It’s not all huge companies and big batteries doing this stuff. Right now, people like you and me are mucking in, using in-home flexibility to support renewables and saving huge cash to boot. Kraken's team are working to make this a part of everyday life, so that in the near future, your home and car can make you money without you needing to do anything at all!

In fact, thousands of Octopus Energy customers are already living in futuristic flexible homes thanks to home batteries and EVs, storing and discharging energy in much the same way that Arsenal are. In doing so, they’re laying the blueprint for a second massive, decentralised network of smaller, smarter in-home batteries.

An image of a powervault battery

A trial run by Octopus Energy and Powervault in 2020 showed that even without having solar panels on the roof, the average UK customer could save up to £270-580 per year by using a ‘Powervault’ battery alongside a smart tariff like Octopus Energy’s AgileOctopus (which allows you to take advantage of cheaper ‘off-peak’ energy, which you can then store when demand is low and the electrical grid is chock full of cheap, green electrons).

What other groundbreaking gadgets have massive storage potential? Electric cars – they’re basically giant batteries on wheels, and more and more of them are being built with the ability to export power rather than just taking it in. Octopus’ Powerloop project transforms the UK’s electric vehicles into another huge network of decentralised batteries.

Powerloop is an example of something called Vehicle-2-Grid charging. You charge up on cheap, green energy overnight, drive around in the day, and then rather than plugging your vehicles in to charge when you get home, you ‘discharge’ any leftover energy, powering your home, or sending those stored green electrons back into the grid to help address consumer demand at a point when renewables are generally scarce.

Early analysis suggests that if the UK’s EV’s were all plugged in at the right times, they could store renewables with enough capacity to meet a whopping half of the UK’s energy needs.

In the near future, the boffins at Kraken expect that they could even group the batteries in people’s homes (and electric vehicles) together, which would allow these customers to get paid even more for providing a coordinated, local, data-driven flexibility service.

What’s next for flexibility?

So there we have it. Energy storage, renewable electrons and flexibility go together like three peas in a very green pod. Early pioneers are already saving hundreds by using energy and batteries flexibly at home and flexperts like the team at Kraken are working to make energy storage and flexibility a part of everyday life in the near future. By allowing us to store green electrons (that might otherwise go to waste) for use later on, batteries are unlocking the flexibility we so desperately need, paving the way for a world that can finally be powered entirely by zero-carbon solar and wind energy.

an image of a powervault battery
Groundbreaking battery trials? Check out our work with PowerVault!
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Want to contribute to a greener grid? With AgileOctopus, you can help unlock flexibility at home...
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Gunning for Green Find out more about our partnership with Arsenal FC

Published on 25th January 2022 by:

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Jackson Howarth

Senior Writer

Hey I'm Constantine, welcome to Octopus Energy!