192Table 26.8, Alternative sites for pumped storage facilities. The proposed upper
reservoir for Bowydd was Llyn Newydd, grid reference SH 722 470; for
Croesor: Llyn Cwm-y-Foel, SH 653 466.

193If ten Scottish pumped storage facilities had the same potential as Loch Sloy,
then we could store 400 GWh.
This rough estimate is backed up by a study
by Strathclyde University [5o2xgu] which lists 14 sites having an estimated
storage capacity of 514 GWh.

196Fridges can be modified to nudge their internal thermostats up and down
. . . in response to the mains frequency.
[2n3pmb] Further links: Dynamic De-
mand www.dynamicdemand.co.uk; www.rltec.com; www.responsiveload.com.

197In South Africa... demand-management systems are being installed.
Source: [2k8h4o]

Almost all of Denmark’s wind power is exported to its European neighbours.
Source: Sharman (2005).

198For over 25 years (since 1982), Fair Isle has had two electricity networks.
Wind speeds are between 3 m/s and 16 m/s most of the time; 7 m/s is the
most probable speed.

199Figure 26.13. Storage efficiencies. Lithium-ion batteries: 88% efficient.
Source: www.national.com/appinfo/power/files/swcap eet.pdf
Lead-acid batteries: 85–95%.
Source: www.windsun.com/Batteries/Battery FAQ.htm
Compressed air storage: 18% efficient. Source: Lemofouet-Gatsi and Rufer
(2005); Lemofouet-Gatsi (2006). See also Denholm et al. (2005).

Air/oil: hydraulic accumulators, as used for regenerative braking in trucks, are compressed-air storage devices that
can be 90%-efficient round-trip and allow 70% of kinetic energy to be captured. Sources: Lemofouet-Gatsi (2006),

Table 26.14. Sources: Xtronics xtronics.com/reference/energy density.htm; Battery University [2sxlyj]; flywheel
information from Ruddell (2003).
The latest batteries with highest energy density are lithium-sulphur and lithium-sulphide batteries, which have an
energy density of 300 Wh/kg.
Some disillusioned hydrogen-enthusiasts seem to be making their way up the periodic table and becoming boron-
enthusiasts. Boron (assuming you will burn it to B2O3) has an energy density of 15 000Wh per kg, which is nice and
high. But I imagine that my main concern about hydrogen will apply to boron too: that the production of the fuel
(here, boron from boron oxide) will be inefficient in energy terms, and so will the combustion process.

200Vanadium flow batteries. Sources: www.vrbpower.com; Ireland wind farm [ktd7a]; charging rate [627ced]; worldwide

201... summer heat from roads is stored in aquifers... [2wmuw7].

Figure 26.18. A possible site for another 7 GWh pumped storage facility. Croesor valley is in the centre-left, between the sharp peak (Cnicht) on the left and the broader peaks (the Moelwyns) on the right.