Whilst energy generation from renewable technologies has grown significantly, with over 100% of Orkney’s electricity demand being met by green energy, its intermittent nature means we still must rely on other energy resources such as oil, gas, or nuclear power (e.g. when the wind isn’t blowing) to keep the lights on.[Text Wrapping Break]

Today when too much renewable energy is produced, a number of Orkney’s wind turbines are forced to switch off to maintain balance in the grid. Storing energy is considered essential to help balance the variabilities in energy supply with the predictable energy demands, and to aid the transition from fossil fuel to low-carbon infrastructures.

Increasing grid capacity

Technologies being trialled today to maximise the local use of renewable energy include domestic scale batteries, green hydrogen, and creating flexibility in our demand for electricity.

The interaction of these various systems and approaches are complex. The following seeks to highlight some of the efforts underway.

Hydrogen

Hydrogen

In 2016, EMEC installed a 0.5 MW electrolyser to produce green hydrogen from excess renewable energy produced by tidal energy converters on the island of Eday. By 2017, EMEC produced the world’s first tidal-generated hydrogen.

The hydrogen is used to power a 75 kW fuel cell housed at Kirkwall Pier, which converts hydrogen back to electricity to power local ferries while docked overnight at the pier. As the interest in hydrogen has increased, other projects have been deployed including a hydrogen-fueled combined heat and power (CHP) generator at Kirkwall airport and a hydrogen refuelling station for vehicles as part of the BIG HIT project

Domestic batteries

Domestic batteries

In 2019, the ReFLEX project sought to organise the systematic installations of batteries in houses across Orkney using an innovative financing model. Unfortunately, this was not delivered due to complex regulatory and commercial challenges detailed in the 2023 case study.

However, the project did stimulate interest in the community and it is believed that there are close to 100 domestic battery installations now in the county tied to existing solar and wind installations.

A success of the ReFLEX project was the uptake of electric vehicles (EV), as a result of their offer to test drive, lease, or buy a used electric car. EVs effectively work as battery storage and indirectly allow for more renewable energy generation.

Heat batteries

Heat batteries

As the majority of energy used in Orkney is used in heating, the opportunity to store energy as heat has also been investigated. The SMILE Orkney project was set up by Community Energy Scotland and sought to reduce the curtailment of community turbines, by interacting with assorted heat stores in buildings across the county. This led to the successful installation of some ‘phase change’ heat storage batteries by SunAmp.

This energy can be provided from a variety of sources including electrical energy from a solar array, wind turbine, cheap electricity at times of low demand and an electric battery as well as heat energy from a heat pump or central heating boiler The stored energy in the heat battery can be released at a later time to produce hot water or to run your heating system.

Electrical energy storage

Electrical energy storage

In 2013, Scottish Hydro Electric Power Distribution (SHEPD) connected the UK’s first large-scale battery to the electricity distribution network in Orkney as part of a trial. The 2 MW lithium-ion battery was installed at Kirkwall Power Station and built on the work already carried out in delivering the ANM scheme. The 2MW lithium-ion battery was provided by Mitsubishi and was integrated into the existing energy storage system within Orkney’s Active Network Management network.

The installation was later decommissioned at the end of the trial and lessons have been learnt from its trial. After this early testing in Orkney, such batteries are now being used commercially across the UK grid.

Opportunities

Looking forward, it is essential to reduce restrictions and overhaul regulations around renewable energy generation, particularly as local decarbonisation plans seek to increase the production and usage of renewable electricity.

Jerry Gibson, EMEC operations technician, overview of EMEC hydrogen mobile storage unit (Credit Colin Keldie)

Developments in green hydrogen 

Developments in hydrogen technologies are continuing to shape the way we use and store electricity. EMEC’s hydrogen production plant is still very much in the testing stages and visions for the future include moving towards the generation of ammonia and synthetic fuels from green hydrogen.

Electric Tesla charging

Battery storage in transport 

Trials have shown that timely charging of vehicle batteries can be undertaken as a means to reduce stress on the overall network and to actively support the grid. The use of ‘Vehicle to Grid’ (V2G) technology is in its early stages with limited deployments to date. There is an opportunity for this to become a reality in Orkney in the near future

Shapinsay ferry Orkney

Finally, is it inevitable that electric ferries will serve the islands, with additional opportunities to encourage visiting cruise liners to also take shoreside power and possibly e-fuels. It is possible that a combination of improved electrical supply from renewables in the county will be combined with a large-scale battery near the port to serve these developing needs.