To make hydroelectric power, you need altitude, and you need rainfall. Let’s estimate the total energy of all the rain as it runs down to sea-level.
For this hydroelectric forecast, I’ll divide Britain into two: the lower, dryer bits, which I’ll call “the lowlands;” and the higher, wetter bits, which I’ll call “the highlands.” I’ll choose Bedford and Kinlochewe as my representatives of these two regions.
Figure 8.1: Nant-y-Moch dam, part of a 55 MW hydroelectric scheme in Wales. Photo by Dave Newbould, www.origins-photography.co.uk.
Figure 8.2: Altitudes of land in Britain. The rectangles show how much land area there is at each height.
Figure 8.3: Hydroelectricity.
What should we estimate is the plausible practical limit? Let’s guess 20% of this – 1.4 kWh per day, and round it up a little to allow for production in the lowlands: 1.5 kWh per day.
The actual power from hydroelectricity in the UK today is 0.2 kWh/d per person, so this 1.5 kWh/d per person would require a seven-fold increase in hydroelectric power.
Figure 8.4: A 60 kW waterwheel.
Notes and further reading
Rainfall statistics are from the BBC weather centre.
The actual power from hydroelectricity in the UK today is 0.2 kWh per day per person. Source: MacLeay et al. (2007). In 2006, large-scale hydro produced 3515 GWh (from plant with a capacity of 1.37 GW); small-scale hydro, 212 GWh (0.01 kWh/d/p) (from a capacity of 153 MW).
In 1943, when the growth of hydroelectricity was in full swing, the North of Scotland Hydroelectricity Board’s engineers estimated that the Highlands of Scotland could produce 6.3 TWh per year in 102 facilities – that would correspond to 0.3 kWh/d per person in the UK (Ross, 2008).