We’ve now used some of the funds from our current share offer to purchase the battery for our microgrid at the new Water Lilies housing development in the Lawrence Weston area of Bristol. The 223 kW /446KWh lithium-ion Tesla battery has now arrived in the city, and will be craned onto site in the coming weeks.

Microgrids combine high-standard energy efficiency with shared on-site renewables, heat pumps for heating and hot water, and battery storage. No gas boilers are required. We’re super-proud that our share offer is helping enable this first-of-a-kind project at Water Lilies, with battery storage being used to help achieve Net Zero carbon emissions through on-site measures.  Our battery will be used to store electricity generated from the residents’ solar panels and provide services to the national electricity grid.

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Balancing the network

Energy storage has a huge part to play as we transition to a net zero world. Thanks to the deployment of over 30 GW of new renewable energy capacity in the UK in the last decade, we now have periods when there’s an excess of capacity on the grid – typically on sunny summer days and windy winter nights.

At these times the National Grid can invoke agreements it has with large energy producers that they pay their consumers to take the excess electricity off their hands. Another solution is to store the excess electricity for the times when less renewable energy is available. Energy storage isn’t a new concept, and you may be aware of the Dinorwig power station in Wales. This uses pumped-storage hydro-electric energy to provide a big surge of electricity to the grid just before advert breaks on prime-time TV.

Once that water has been released though, it takes a long time to pump it back up the mountain during the night. But if we’re going net zero across the UK we need energy storage that can respond to grid demands in real-time, and we need a huge amount of it. This blog detailing Zero West’s research into our regional energy needs gives a flavour of how much energy storage we need in the West of England region alone.

And this is where battery storage can help. It balances the electricity grid by storing energy produced at times of low demand, then releasing it back into the grid at times of high demand. And it has a second crucial role in alleviating system stress. The National Grid has an obligation to keep the grid frequency close to 50Hz. If the frequency moves outside the range of 50.5Hz – 49.5Hz there’s a danger of blackouts, and it must act quickly to correct the imbalance. An over-supply of renewables can take the frequency too high. A gas power plant tripping or one of our inter-connector links with other countries going down can take the frequency too low. A grid-scale battery can react to these events in milli-seconds, charging or discharging as appropriate, to help restore stability in either direction.

This isn’t futuristic wishful thinking. Renewable energy, while intermittent, is highly predictable, and the National Grid has been confident for some time that it can fully operate Great Britain’s electricity system zero carbon by 2025.  And those batteries are busy stabilising the grid right now.

Scale and type

Battery technology has developed at great speed in recent years, accompanied by a huge drop in production costs. Thanks to these advances the UK now has more than 16GW of battery storage capacity either operating, under construction or in planning. An additional 6GW of energy storage from other sources – liquefied and compressed air, pumped hydro, flywheels and gravity-based technologies – is also operating, under construction or in planning. This brings the UK’s total energy storage portfolio capacity to more than 22GW. To put this into context, the much-delayed, hugely-subsidised, Hinkley C nuclear power station will have a capacity of less than 4GW.

There are different types of battery in use on the grid. The vast majority are lithium-ion.  These can react in under a second, and typically discharge over a period of 1-3 hours. Others, such as such as vanadium-flow and iron-flow batteries can’t react as quickly as lithium-ion batteries, but they can discharge over a longer period. They are far less common on the grid at the moment because the business model for them is less well-developed. They are however far more sustainable, and don’t contain cobalt.

Not a silver bullet

We know there are genuine concerns about the ethical sourcing and sustainability of lithium-ion batteries. The sector is working to address these, with Tesla planning to replace them with lithium-iron ones, which don’t use cobalt, and battery recycling facilities beginning to ramp up to scale. But we recognise these aren’t immediate fixes to these issues, and it’s a delicate balance between needing to act rapidly on climate change and avoiding causing other kinds of harm to people and the environment.

Aiming for 100%

We’re delighted that our share offer has now raised over 80% of our £2 million target. If you want to help drive the net zero transformation too, the share offer is open until the end of March 2021. Find out more, including how to invest here.