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Stones of Stenness on Orkney

The Future of Energy Storage Rozie Apps explores hydrogen cell technology – a fast-emerging alternative to lithium batteries – in an ancient landscape

© Tim Harland

One of the downfalls of renewable energy is storing the excess. When the electricity grid reaches capacity, this excess energy is simply wasted. In the Orkney Islands, this is a common problem. Through tidal, wave and wind, they are able to generate more electricity than the population uses, regularly exporting to the UK National Grid. At times the power cables reach full capacity, and electricity production is capped. Wind turbines can be turned off, meaning clean energy is going unharnessed, curtailed.

One solution to energy storage has been the rise of hydrogen technology, and the Orkney Islands are paving the way.

Hydrogen is an abundant chemical element. It is not freely available as it’s often tied up to make another element. To access the hydrogen, water is split using an electric current (electrolysis) which breaks it into its component parts, hydrogen and oxygen. The hydrogen can then be used as a storage medium, and can be used at a later date for heat, power and fuel. One big benefit of hydrogen, is that it can be used close to where it is generated, which means it has a place within community renewable energy production.

Surf ‘n’ Turf is an Orkney community project already using surplus renewable energy to split water and create hydrogen gas for fuel and energy storage. On the island of Eday, with around 150 people, the project utilises a community owned 900kW wind turbine and tidal power to convert and store excess energy as hydrogen. They are also working towards a training facility in Kirkwall, Orkney’s capital, to establish local skills and encourage future hydrogen uptake.

Surf ‘n’ Turf use an electrolyser owned by the European Marine Energy Centre (EMEC), which is where the tidal energy is collected. The electrolyser is a proton exchange membrane (PEM) system, which can handle variable energy inputs better than other systems. It can handle 500kW, which means it can take over half the output of the island’s 900kW turbine when it is curtailed, keeping the turbine moving when it would otherwise have to stop due to overload.

The hydrogen produced is com­pressed and stored at EMEC’s site, until the Surf ‘n’ Turf project needs to transport fuel to Kirkwall.

In 2009 the community in Orkney published the Sustainable Orkney Energy Strategy, which was updated in issue 104  summer 2020

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