Lerwick Power Station

Lerwick Power Station
Location of Lerwick Power Station in Scotland
Country	Scotland, United Kingdom
Location	Gremista, Lerwick, Shetland
Coordinates
Status	Operational
Commission date	27 May 1953
Operator(s)	Scottish and Southern Energy
Thermal power station
Primary fuel	Diesel fuel
Power generation
Units operational	6 x 6 MW 2 x 8 MW 1 x 12 MW 2.1 MW
Make and model	Mirrlees, Bickerton & Day diesel generators Pielstick engines Wärtsilä engine
Nameplate capacity	66 MW

The main power supply for Shetland is provided by Lerwick Power Station, located in Gremista, 2 kilometres (1.2 mi) northwest of Lerwick town centre. This is the principal source of electrical energy for Shetland, however currently about 20 MWe is provided by the Sullom Voe Terminal power station which comprises 4 x 23 MWe Gas Turbines, the future of which is uncertain. Opened on 27 May 1953 the station is diesel-fuelled and generates a total of 66 MW of power.

Equipment

It has originally six by 6 MWe Mirrlees diesel generator K Major sets (some of which have been decommissioned), two 8 MWe French Pielstick engines added in 1983 and a further Finnish 12 MWe Wärtsilä ( originally a Stork Werkspoor design) engine commissioned in 1994. A waste-heat recovery system applied to the exhaust of the Wartsila only produces super-heated steam which runs a 2.1 MW WH Allen turbine, thus making this set a combined cycle. Two standby gas turbine generator units, each with a capacity of 5 MW, were installed in containers outside the existing buildings to augment peak output. The plant is operated by Scottish and Southern Energy (SSE).

Load balancing

The growth of output from wind turbines on Shetland has increased instability in the local grid (which is not connected to the national grid on mainland Scotland) and SSE have installed a 1 MW sodium-sulphur battery in a nearby building to ameliorate the peak loads.

Due to safety concerns, the sodium-sulfur battery was removed from the site prior to commissioning. The energy storage building was reconfigured to accommodate 3MWh of advanced lead-acid batteries.

Replacement plan

There are proposals to replace the power station at a new site north of the existing one on a green field site for which planning permission has already been granted. This decision has been endlessly delayed by the proposed Shetland HVDC Connection which depending on how it were implemented may make such a station redundant, or only required as standby which would affect the type of plant chosen.

Lerwick District Heating

There is an adjacent but district heating network see Lerwick District Heating and Energy Recovery Plant. However for a variety of reasons the rejected heat has never been used as a heat source for the network. This is unlikely to happen with the existing power station as it will be closed soon.