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One reason that the declared Paris goals exceeded some
expectations is the rapidly falling cost of electricity generated
by wind and solar photovoltaic (PV). Over the last six years,
the cost of wind-powered electricity has fallen by 60 per cent, while
the cost of solar-PV electricity has fallen by more than 80 per cent.
Wind and solar PV, however, are known as the ‘variable
renewables’ – the wind doesn’t always blow, and the sun doesn’t
always shine. As wind and solar generate more and more
electricity, eventually they must be partnered with some form of
There have been recent reports describing exciting breakthroughs
with chemical batteries, including the Tesla ‘Powerwall’, the CSIRO
‘Ultrabattery’, and many others; however, when compared with
pumped hydro, battery technologies have shortcomings, such
as limited life span, and they remain quite costly. Consequently,
pumped hydro retains its world-leading position, comprising
around 99 per cent of the world’s existing energy storage capacity.
Pumped hydro’s global popularity continues, with a further $5
billion to be invested in 2016.
The first pumped hydro facilities were built in Europe in the 1890s.
Today, modern facilities range in size from 11 to 3000 megawatts.
Starting in the 1960s in the United States, Europe and Japan,
pumped hydro construction surged. Back then, a new form of
energy generation had appeared on the scene that needed an
energy storage partner. That new form of energy was nuclear. The
first nuclear plants were true ‘base load’ devices that ran at a fixed
production rate, with little in the way of variation up and down. On
the other hand, electricity demand is highly variable, moving up
and down from day to night, from weekday to weekend, and from
season to season. Enormous pumped hydro facilities were built
around the world to store nuclear-generated electricity during
periods of low demand, so that the stored electricity could be used
later in the day or week.
Turning to coal-fired electricity generators, their stability and
performance was found to also improve when pumped hydro
added to the electricity grid. That is why, from 1973 to 1984 in
New South Wales and Queensland, three large-scale pumped
hydro plants, ranging in size from 240 to 600 megawatts, were
integrated with existing conventional hydro-electricity plants.
Since then, however, the topic of pumped hydro has been dormant
in Australia. This has allowed some myths to creep in, such as:
‘the Australian continent is too dry and flat for pumped hydro’, or
‘pumped hydro is environmentally damaging, and large dams will
never be approved’, and ‘if pumped hydro made any commercial
sense, companies would be looking at it already’. At the University
of Melbourne Energy Institute, we have dusted off pumped hydro
and can dispel those myths.
Our research has found that unlike conventional hydro-electricity,
where enormous reservoirs are used (such as the 27,000-hectare
Gordon River system in Tasmania), a useful amount of energy can
be stored, using upper and lower reservoirs of no more than five to
50 hectares each, with pumped hydro. Good pumped hydro sites
are where upper and lower reservoirs can be built, or where they
already exist, at elevations differing by at least 100 metres, and
where those two reservoirs would be separated by no more than a
Because a pumped hydro facility circulates water in a closed loop,
sites away from rivers and streams can be considered. Water make-
up requirements are limited to evaporation and leakage losses.
Finally, pumped hydro sites near existing electricity-transmission
infrastructure will have economic advantages.
With those site selection considerations in mind, recent and
separate studies done by the Australian Energy Market Operator,
the University of Melbourne and the Australian National University
have found that there are thousands of potentially useful pumped
hydro sites in Australia, including coastal seawater-based sites.
These studies have shown that it can actually be more difficult
to narrow down potential pumped hydro sites than it is to simply
identify good candidates.
One way to zero in on an economical pumped hydro location is to
consider where there may be one, or even two, suitable bodies of
water or large holes in the ground already in place. That is what
the company Genex did in identifying the disused Kidston Gold
Mine in Queensland, and securing study funding of $4 million from
the Australian Renewable Energy Agency (ARENA). That study will
investigate the feasibility of a 300-megawatt pumped hydro facility
at that disused mine site using the existing surface pits. Looking
to Victoria, at the University of Melbourne Energy Institute, we
are intrigued about whether existing brown coal mines, with their
advantageous proximity to existing powerlines, may some day also
be converted to pumped hydro.
In addition to disused mine sites, Australia’s existing water
storages are clear candidates for incorporating pumped hydro. We
BECAUSE A PUMPED
CIRCULATES WATER IN
A CLOSED LOOP, SITES
AWAY FROM RIVERS
AND STREAMS CAN BE
ARE LIMITED TO
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