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Energy / No decision yet on future energy back-up system

Lerwick power station is expected to cease operations no later than 2025. Photo: Shetland News

OPTIONS are still being worked through for a cost-effective back-up solution to support security of supply once Shetland is connected to the national grid by a subsea interconnector cable.

A spokesperson for SSE said the company is engaging with regulator Ofgem before “further stakeholder and market engagement later this year”.

However, a new 8MW battery due to be installed at Lerwick Power Station could form part of a standby provision.

“We will assess the suitability of the battery for use as part of the standby solution as preparation for those arrangements progresses,” the SSE spokesperson said.

“If at that time the battery is technically capable of playing a role, it may help to reduce overall standby costs.”

Shetland is due to be linked to Caithness via a 600MW interconnector cable from 2024 onwards, allowing both the export and import of power, with the Viking Energy wind farm set to come on stream then too.

The ageing diesel-powered Lerwick Power Station is due to move out of full duty operations around 2025.

When asked why SSE is investing in the new battery storage system at the power station, as well as a new engine, ahead of the power station closing the spokesperson said:

“To guarantee security of supply to the homes and businesses in Shetland that depend on us, we need to invest in Lerwick Power Station to support full duty operations of the station until Shetland is connected to the GB system.

“The battery, which was included as part of our plans to manage Shetland arrangements agreed with Ofgem in 2018, will reduce some of the constraint on existing connected renewable generators and, as a responsible network operator, will enable us to reduce our carbon footprint in the coming years.”

The new battery, meanwhile, will only support increased access to renewable generators already in operation.

“The existing renewable generators connected to the grid are currently operating under constraints associated with the level of demand on the system,” the SSE spokesperson said, “and generation and network operational arrangements in place to manage network stability.

“The new battery will support increased access to the grid for these existing renewables only.

“We are reviewing the arrangements for distributed generation (which includes renewable generators) when Shetland is connected to the mainland GB system.”

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