Could the Greenock "Cut" be used for hydropower?

Since the construction boom of hydropower stations in Scotland, including notably in 1950 the Loch Sloy dam and power station (Miller, 2002), hydropower has played a vital role in delivering electricity to Scotland . However, since this great development programme, the scope for more large-scale hydropower schemes has become limited, and hence mini or micro-hydropower schemes are becoming increasingly popular. These small-scale hydropower sites are more efficient than other forms of renewables as the schemes present better power generation efficiencies: small hydro: >50%; solar <10% and wind ~30% (BHA, 2012). As energy demands increase, this highly topical undergraduate dissertation study assesses the potential of the Greenock Cut for the production of renewable energy using small scale hydropower schemes and connecting such schemes to the National Grid. Although the cut is maintained by the local council, the proposal of such a project is in conjunction with Scottish Water, who are responsible for the supply of water from Loch Thom to Greenock. The Greenock Cut (or, “the cut”) and Loch Thom were designed by engineer Robert Thom in 1825 to supply the town of Greenock, Inverclyde (Inverclyde’s population being 81,000 in 2013 (Inverclyde Council)) with clean drinking water. The cut consists of an almost six mile long man-made trapezoidal shaped channel that curves around the topography of the local hills to the town (Cumming, 1980; Paxton & Shipway, 2007). The cut continued to supply water to the town until 1971, when a tunnel was installed to convey water from Loch Thom directly to the Overton Reservoir through Whinhill hill (Paxton & Shipway, 2007). Despite the discontinuation of its original purpose, the channel maintains a flow of water, meaning that the installation of a turbine to produce energy is plausible as a run-of-river type scheme. Of the three main categories of turbine; Impulse, Reaction and Gravity (BHA, 2012) the main deciding factor is the hydraulic head at which the turbine can operate to an optimum efficiency. However, in more recent years there has been a greater interest in new turbine developments, specifically for low head environments. Unlike developments such as the Loch Sloy power station, with steep head differences, the Greenock Cut slopes with the topography of the hills. Thus, with the steepest parts of the cut’s canal being 3.5m, a low head turbine is considered the most viable option.Alongside the original design to supply the town with drinking water, engineer Thom had plans to create “green energy” using the cut (Hamilton, 1965), and so it did, through supplying The Shaws Water Cotton Spinning Factory in the east end of Greenock with the equivalent of 143kW, using a 24m diameter iron turbine (Paxton & Shipway, 2007). Thus, the introduction of modern Hydro power to the scheme would put the cut back to its original use, and could have the potential to supply homes and schools in the surrounding area.Design will examine the potential power generation of the cut using a turbine and power house located at the foot of the Overton Reservoir, where all channels from various reservoirs on the hill as well as the cut itself come together. The dataHydrological data collected from the cut over a period of 5 6 months will be combined with topographical survey data to determine flow rateshelp to produce an average flow rate over a series of chainage points along the channel. These flow rates will determine how much power the cut could produce with a given maximum discharge, and so a particularidentify particular the types of run-of-river turbines will be selectedappropriate to the site,. Design process will then include estimation of power generation potential. This power generation potential will then be assessed for likely benefit to the Inverclyde area. based on the magnitude of the flow rate estimated.It is anticipated this study will indicate potential for re-examination, rehabilitation and reuse of other water engineering legacy site across Scotland and the UK with potential to provide localised sources of power and thus reduce current challenges for energy-supply. The initial thoughts for the design of such a scheme is to locate the turbine and power house at the foot of the Overton Reservoir, where all channels from various reservoirs on the hill as well as the cut come together. ReferencesBritish Hydropower Association (BHA) (2012) British Hydropower Association: A Guide to UK Mini-Hydro developments. The British Hydropower Association. Pdf available at: http://www.british-hydro.org/Useful_Information/A%20Guide%20to%20UK%20mini-hydro%20development%20v3.pdf (Accessed 18th October 2014) Cumming, J.W. (1980) The Greenock Cut: Story of Greenock’s water supply. Strathclyde department of leisure and recreation, Strathclyde Regional CouncilHamilton, S.B. (1965) Robert Thom and the Greenock Waterworks. Article from The Engineer magazine on 22nd January 1965.Inverclyde Council (2013) GRO Reveal Higher Inverclyde Population. Available at: http://www.inverclyde.gov.uk/news/2013/jan/gro-reveal-higher-inverclyde-population/ (Accessed 18th January 2014) Miller, J (2002) The dam builders: Power from the Glens. Edinburgh: Birlinn.Paxton, R., Shipway, J. (2007) Civil Engineering Heritage: Scotland Lowlands and Borders. Pages 252-257. London: Thomas Telford Ltd.