Mapping Scotland’s hydropower resource
Duncan, Niall James
Increased renewable electricity generation is key to the reduction of carbon emissions and has the added benefit of reducing reliance on imported gas and coal while increasing diversity of the generation mix. To encourage development of renewable generation the Scottish Government has adopted an ambitious 100% renewable electricity generation target to be met by 2020. Although hydropower has generally been considered insignificant in a UK context, when forming part of a Scottish target the resource becomes much more significant as the majority of the UK’s existing capacity and potential for new capacity is located within Scotland. Scotland has a long history of hydropower development with the majority of current operational capacity installed during the mid 20th century. Recent studies have produced a range of estimates for the remaining resource from 286 to 1000 MW. The studies undertaken have tended to rely upon catchment analogue methods or the use of regression equations to produce estimates of flow at sites of interest, with simple assumptions of installation costs and energy yield. This work uses a novel method combining time series flow data produced from a distributed hydrological model with GIS techniques and a detailed parametric cost model to enable a state-of-the-art hydropower resource model to be developed. The use of time series flow data allowed investigation of the spatial and temporal characteristics of the resource to be made, both run-of-river and impoundment schemes to be investigated and a preliminary assessment of the impact of climate change to be performed. Three financial scenarios have been considered using 5%, 10% and 15% discount rates as this is the most sensitive variable when assessing the feasibility of hydropower projects, reflecting the cost of finance available and investors’ attitude to risk. The spread of discount rates will account for changes in available subsidies, electricity prices and ongoing costs. Clearly availability of low cost finance and a low risk subsidy environment will have the largest impact on hydropower development. A major limiting factor was found to be the cost of grid connection; if this were reduced the potential figure could be higher. The results of this work show that at a 10% discount rate, 440 MW of new run-of river hydropower potential capable of producing 1.7 TWh per year is available. Exploitation of this would represent an additional 4% contribution towards the Scottish Government’s 100% renewable electricity target.