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Energy / Power station to remain on standby when interconnector links isles to national grid

Lerwick power station is set to produce electricity well into the next decade.
Lerwick power station is due to cease full operations by 2025.

LERWICK Power Station will be transitioned into standby operation mode when Shetland is connected to the mainland electricity system in November 2024.

The station, which currently undertakes full duty operations in meeting Shetland’s electricity demand needs, will provide standby operation until 2035 at the latest.

It will operate in line with Scottish and Southern Electricity Networks (SSEN) Distribution’s other back-up stations on Scotland’s islands, with similar staff levels as currently in place.

The network operator has been reviewing options for a reliable, innovative and cost-effective backup solution to support the security of supply to Shetland once the islands are connected to the national grid via the 600MW HVDC transmission link.

Following extensive technical and commercial analysis of options available, SSEN Distribution said it submitted its proposal on back-up arrangements to Ofgem in December 2020.

Following subsequent engagement with the regulator, SSEN will now include its proposals as part of its upcoming business plan for the RIIO-ED2 price control period, which incorporate:

  • The use of Lerwick Power Station in standby operation mode from November 2024 until 2035 following successful commissioning of the transmission link and the new Grid Supply Point (GSP) connecting the transmission and distribution systems at Gremista.
  • The installation of” innovative interruption avoidance equipment” by November 2024 to provide continued security of supply to homes and businesses on the islands in the event of planned or unplanned outages on the transmission link.

By transitioning the operation of Lerwick Power Station to standby-only mode, SSEN Distribution estimates a 97 per cent reduction in carbon emissions compared to running the station on a 24/7 basis.

That figure is based on a normal outage year of the HVDC system, which is a planned outage of four days during the summer period for maintenance. The 97 per cent reduction also includes test running the station on a monthly basis.

The station has been subject to ongoing investment including a replacement 6MW engine, installed earlier this year, which is said to utilise enhanced efficiency and emissions abatement technology.

An 8MW battery solution will also be in place later this year, providing wider flexibility and carbon reduction benefits.

The interruption avoidance equipment will ensure continued security of supply for the 30 minutes to one hour period as the back-up power station is started in accordance with all relevant codes and standards.

The technology to be used will be determined by a procurement exercise later this year and is anticipated to comprise of fast response and energy storage in addition to network stability equipment.

SSEN Distribution director of operations Mark Rough said: “By transitioning Lerwick Power Station to operate as a standby station, we’re implementing the most economic and reliable solution available, using an existing and trusted asset.

“The combination of the backup power station alongside innovative interruption avoidance equipment will ensure we continue to provide a safe, secure and reliable supply of electricity to the homes and businesses that rely on us to keep the power flowing across the islands.

“This solution will result in a substantial reduction in carbon emissions, and as net zero strategies and pathways crystallise at a national and local level, the continued use of the power station provides the flexibility to transition to a longer-term sustainable solution if reliable and cost-effective technology emerges before 2035.”