Lerwick Power Station

Originally the facility had six 6 MWe Mirrlees diesel generator K Major sets (some of which have been decommissioned); two 8 MWe French Pielstick engines were added in 1983 and a further Finnish 12 MWe Wärtsilä (originally a Stork Werkspoor design) engine was 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).[1]

The growth of output from wind turbines in Shetland has increased instability in the local grid (which is not connected to the national grid on mainland Scotland). SSE installed a 1 MW sodium–sulfur battery in a nearby building to ameliorate the peak loads.[1] however due to safety concerns, the sodium-sulfur battery was removed prior to commissioning and the energy storage building was reconfigured to accommodate 3MWh of advanced lead-acid batteries.[2]

There are proposals to replace the power station at a new greenfield site north of the existing one. Planning permission has been granted for the development however the decision to proceed has been delayed by the proposed Shetland HVDC Connection, which depending on how it is implemented may make such a station redundant, or only required as standby, which would affect the type of plant chosen.

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.