PLANS for a renewables storage scheme on the Isle of Lewis which could power 200,000 homes will be unveiled today.

The proposals from Eishken Limited would see a battery-style installation built next to a windfarm on the island which would be capable of generating 300 megawatts (MW) of electricity.

The large pumped storage hydro (PSH) scheme will store electricity, principally generated by windfarms on Lewis. It will also double the use of the Western Isles Link, the cable being installed by the National Grid to export and import electricity generated from renewable energy sources on the islands.

The island community will also share in any financial surplus from the sale of electricity to the Grid.

Eishken estimate that more than 150 jobs will be created during the three to five-year construction period.

Pumped storage facilities are relatively rare in the UK compared to continental Europe, the United States and Asia - particularly Japan - but essentially act like huge batteries storing electricity.

The operate by pumping water uphill from a lower reservoir to a second reservoir at a higher level. When demand for electricity is high, the stored water is released through generators situated at the foot of the hill into the lower reservoir.

The technology is proven and has been in use for nearly a century although none have been built in the UK for the last 30 years. At present, such facilities operate commercially without government financial assistance schemes.

However, the Eishken scheme with use the sea as the "second reservoir" in its design, with water extracted from and returned to the waters off the coast of Lewis.

This means the design has a much lower environmental impact because it eliminates the need to construct a reservoir and also makes the installation easier, cheaper and quicker to build.

Nick Oppenheim, chief executive of Eishken Limited, said: “Although using the sea as the lower reservoir is new to the UK, the technology is proven in Asia.”

He added: “There are very few PSH schemes throughout the UK and what we are proposing is particularly innovative given the use of the sea as the lower reservoir.

"This scheme will not only materially enhance the benefits to be derived from the Western Isles link but will make a material difference in the supply of energy to the mainland. It will also be a key element in the Scotland’s renewable energy armoury.”

The Lewis development will be located next to and incorporated into the already consented 162MW Muaitheabhal Wind Farm.

It will allow some of the electricity generated by the windfarm to be stored up until required, helping to balance out the unpredictable nature of wind energy.

Eishken Ltd is expected to seek consent for the scheme later this year.

Aecom, the international infrastructure design and engineering consultancy, is advising Eishken on the technical aspects of this project.

The project is in line with a Scottish Government target to generate the equivalent of 100 per cent of Scotland's gross annual electricity consumption from renewable sources by 2020.

Similarly, a target has been set for renewables sources to provide the equivalent of 11 per cent of Scotland's heat demand by 2020.

Renewables overtook nuclear in volume of electricity output in the first half of 2014, and matched the output from fossil fuel generation a year earlier.