Three huge wind turbines at heart of plan for Gremista thermal store

Plans for a so-called smart grid in Shetland will pave the way for more small windfarms like Burradale to start up and generate money without having to wait for an interconnector cable to mainland Scotland.

Central to the innovative joint venture between the local community and Scottish and Southern Energy will be a 6.9 MegaWatt windfarm north of Gremista consisting of three big wind turbines nearly as tall as Viking Energy intends using and a huge tank of hot water next to Lerwick Power Station.

The thermal store would be built by Shetland Heat and Power (SHEaP), the Shetland Charitable Trust subsidiary which runs the district heating scheme in Lerwick. Heating the tank and using the water for new district heating would help SSE juggle an unpredictable power load, providing a kind of buffer system to help stabilise the peaks and troughs in demand along with the fluc­tuating power levels generated by wind.

According to SSE, the local grid is currently unable to cope with more wind power, which is denying local people the chance to build turbines and earn an income from selling surplus energy to SSE. Without some other solution Shetland’s would-be windpower barons have to hope a connection is made to the National Grid via an inter­connector cable in at least five years’ time if Viking Energy windfarm gets the go-ahead.

The Shetland Times understands that the 2.3 MegaWatt turbines at Luggies Knowe, between the dump and the Dales Voe base, could be turning within two years. Standing at 125 metres to their blade tips, they would be just 8.5 metres shorter than the models favoured by Viking, providing an early experience of what is to come if the giant windfarm gets the go-ahead. They would dwarf the five at Burradale which only reach up to 71 metres.

The windfarm on Lerwick Port Authority land is more imposing than was proposed previously before SSE became involved. Three years ago the idea revealed publicly was for two or three small turbines generating up to a total of 1.6MW to heat water, charge batteries and possibly produce hydrogen to run council vehicles on.

SSE has said that as well as helping the district heating scheme expand, the turbines would contribute towards Scotland’s 2020 target of generating 50 per cent of its electricity from renewables.

There is another incentive for SSE to make it a success because, as it said earlier this year, it could mean it only has to build a smaller, cheaper new power station for Shetland than previously thought to replace the dirty old diesel-burning station in town.

If the smart grid project goes ahead, helped by storage systems like the thermal tank, it could allow the likes of the long-planned windfarms in North Yell and between Quarff and Cunningsburgh to proceed as well as other smaller-scale schemes and single turbines.

The concept of storing the power for later use, which has been a key weakness for renewables, could be extended from the Lerwick turbine and storage tank concept to include similar units in compact communities outwith the town, providing hot water heating, and also perhaps using the hydrogen storage system pioneered by PURE in Unst.

The council’s head of environment and building services Stephen Cooper said: “The only way we can bring more renewables into the grid is to find ways to store that energy. The thermal store is one project which will help store energy, which will allow the Gremista windfarm to happen.”

Details of other possible energy storage schemes are currently under wraps, Mr Cooper said, until funding is sorted out.

The project is currently being pursued by SSE and SHEaP. However, it has not yet been decided whether the trust and/or the council will commit to a partnership venture. A report is to be considered in private session at Tuesday’s meeting of the council’s infrastructure committee but Mr Cooper said a decision was not likely until early in the new year.

Next week there are to be three public exhibitions about the investigations that have been taking place. They are in Bressay, Tingwall and Lerwick.

SSE announced in July that its power distribution arm in the north of Scotland, Scottish Hydro Electric Power Distribution (SHEPD) was seeking £51 million from the energy regulator Ofgem towards smart grid systems for Orkney and Shetland costing £81 million. Funds are available under the Low Carbon Networks Fund to help power providers get away from power generation which causes pollution and accelerates climate change. SSE said a decision was due next month.

SHEaP already has a planning application in for its big tank. Manager Neville Martin said it and the Gremista turbines would provide hot water to allow at least another 300 homes and businesses to be connected to the Lerwick district heating scheme, which has 1,000 homes and 100 non-domestic customers plus a long waiting list.

His company’s proposed water tank would be about 10 times the size of its existing blue-painted water tank and would be similar to one of the biggest 3,800 tonne capacity fuel tanks that sit next to the power station. It would store the equivalent of 135 MW/hours of energy which he said is enough to run the heating scheme for about five days without further heat.

Currently the scheme cannot expand to more homes and businesses because it is already exploiting all the available heat from the municipal incinerator.

Mr Martin said: “I think most people are quite excited by it, if it goes ahead. I think it has a lot of implications elsewhere long term, not only here. In Shetland it could open up the ability to do other things in some of the areas, either district heating or with new storage heater systems.”