Gigha Battery Project
The Isle of Gigha is situated approximately 60 miles to the West-South-West of Glasgow and off the Kintyre peninsula.
The Isle is host to the first community-owned grid-connected wind farm in Scotland, the ‘Dancing Ladies’, consisting of three turbines with a combined capacity of 675 kW. Profits from energy generation support the Isle of Gigha Heritage Trust. A fourth wind turbine of 330 kW has now been installed, although the turbine is constrained to 225kW, and operating at an extreme 0.85 power factor to overcome voltage rise. The voltage constraint means a loss of 3 GWh in a 25-year turbine asset life– a value of around £300k and 1.5 ktCO2 at today’s rates.
Being supplied off one of the longest 11 kV overhead-lines in Scotland, the electricity supply on Gigha is subject to the effects of distant faults occurring over a wide area. During March 2013 Gigha was the recipient of an interruption of some 5-days in duration that caused significant disruption to the community. The Isle is populated by circa 150 and the main industries are tourism, farming and the shore-based fish-farm. The fish-farm must continuously draw fresh seawater and pump it through the ponds. The operators maintain diesel generators to start and run these pumps if there is a problem with the electricity supply.
Under the present passive network-operating arrangements, the voltage constraint also dictates that no further generation capacity can be connected. This prevents the realisation of potential additional renewable generation capacity that could be added on the Isle, which could in future be additional wind turbines, photo-voltaic panels and tidal-stream generators. Network constraints are therefore a problem that must be surmounted, if the Isle is to make a full contribution to the future national renewable energy portfolio.
Energy Storage is the only technology that can be deployed at the site of the generation itself and does not add complexity to the electricity network, with all the planning studies, systems and processes entailed. Thus it can feasibly be deployed quickly with little effort from the point-of-view of the network operating company- but it must demonstrate its ability to protect the expensive assets of the electricity network by limiting net export from the site to the allowed power and power factor under all circumstances.
Considering the three competing technologies, DSM, ANM and Energy Storage, the system with the greatest potential to benefit the Gigha community appears to be an Energy Storage solution. Of course, if the aim were to maximise the long-term capacity of renewable generation in the area, with no regard for the implementation timescale, then one would deploy an optimal system that used the capabilities of all three technologies in concert. While time may prove this to be the best approach to meeting our 2050 goals, the precedence of the individual ANM, DSM and Energy Storage elements does not preclude a later, more-optimal solution offering increased renewable energy capacity. Indeed even if an application of ANM, DSM or a network upgrade was to entirely remove the constraint at a later date, the plethora of other ESS benefits would remain and there is no risk of the asset being stranded.
To this end this DECC project looks to install a 1.26mWh Vanadium Redox Flow battery on the island linked to the constrained Enercon E33 to relieve the otherwise constrained 105kW of the 4th wind turbine. Being positioned 'behind the meter' the battery can store power and release at times when there is capacity on the grid. This not only enables the community of Gigha to access the additional power and thereby income, but allows this technology to be prototyped in a real world environment. This purpose designed and built battery could show the way for other rural comunities to harness the full potential of their renewable power.