Energy Handbook 2011 - GBR

P o w e r S u m m i t - T h e E n e r g y H a n d b o o k 2 0 1 1
F o c u s : H y d r o a n d M a r i n e P o w e r
Hydro & Marine Power
From the water mills of Imperial Rome and Han Dynasty China
to the hydraulic mining systems of the California gold rush,
the harnessing of energy from water has been one of the most
enduring and universal means of generating energy throughout
human history.
Article by:
Joseph Hincks
Above:
Hydro power
electric dam on
Colorado River,
Arizona
Today, hydropower provides onethird
of the world’s nations with
more than half of their electricity,
according to the World Commission on
Dams, while in Norway, the Democratic
Republic of Congo, Paraguay and Brazil
the proportion of hydropower is over
85 percent. And in the international arena
of climate change discussion, in the minds
of the world’s decision-makers, this most
ancient of resources is again rising in
prominence.
the world. Labour costs for operation
are usually low, as plants are automated
and require few personnel on site; and
hydroelectric facilities have a longer
economic lifespan than conventional
thermal power plants: many plants built
50–100 years ago are still in operation
today. Hydroelectricity is a proven and
efficient technology and the most modern
plants have energy conversion efficiencies
of 90 percent and above.
Dinorwig (1.7 GW) in Wales. Most of these
installations are pumped-storage plants
whose job is to support the operation
of the grid rather than to generate net
power.
Despite the global prevalence of
hydropower, large schemes are not
without their drawbacks. “Large dams
have significant environmental impact,”
explains Ashwani Kumar, Head of
Business Development at Reliance Power,
an Indian generator with around 5 GW
of hydro projects in its portfolio. “Our
projects are ‘run-of-the-river’ schemes.
This mitigates the erosion associated
with hydro projects.” Up to 48,000 large
dams now obstruct 60 percent percent
of the world’s 227 largest rivers, most
of which were built in the past 50 years.
The world’s largest impoundment, the
8,500 km2 Volta Reservoir behind Ghana’s
Akasombo Dam, flooded 4 percent of the
country’s land mass. Dam construction
can damage ecosystems and has displaced
an estimated 40–80m people from their
homes, according to figures published by
the WWF.
A 1990 World Bank internal survey of
hydroelectric dam projects showed that
58 percent were planned and built without
any consideration of downstream impacts,
even when they could be predicted to
cause massive coastal erosion, pollution
and other problems. Twenty years later,
legislation has toughened and more
care is exercised in the construction of
large dams. While numerous projects are
currently under construction – the vast
majority in China, which already had
an installed hydro capacity of 197 GW
in 2009 – greater awareness of the
potentially detrimental implications of
large dams, political will, and the limited
number of remaining viable sites means
that the scope for new hydro builds is
severely restricted.
which could generate enough electricity
to power 850,000 homes and cater for
1.5 percent of the UK’s electricity needs.
The agency identified almost 26,000
energy hotspots in English and Welsh
rivers where turbines could be installed.
Limited access to local electricity grids
and the potential to harm migratory fish
or cause other damage to river ecology
limits the number of these sites that can
actually be developed. However, more
than 4,000 sites could provide a “winwin”
situation, generating electricity and
benefiting the local environment, the
Agency says.
The limited new build sites and the
problems associated with hydropower
have meant that – in the UK at least –
the focus has shifted away from rivers,
dams and reservoirs and out toward the
oceans surrounding the country. The UK
has some of the world’s most ambitious
plans for carbon reduction, and also the
best wave and tidal resources in Europe.
While new wind energy is expected to
make the greatest contribution to meeting
the 2020 targets, marine energy – from
waves, tidal streams and ocean currents
– will not be far behind.
According to RenewableUK, the UK’s
largest renewables association, marine
renewable technologies are at the same
stage wind was at 10–15 years ago. While
the UK may lead in terms of technological
development, breakthroughs in the marine
sector will have global implications – in
principle, marine energy is ideally suited
for distributed generation and the majority
of the world’s population live near
reasonably energetic seas. The worldwide
wave power resource potential is massive.
Future Energy Solutions, a unit of UK
consultancy AEA Technology, indicates
that the global ocean power potential has
been estimated at 8,000–80,000 TWh/
y (1–10 TW), which is the same order
of magnitude as world electrical energy
consumption. Tidal energy is very sitespecific,
however. The World Offshore
Renewable Energy Report 2002–2007,
released by the DTI, suggests that while
3 TW of tidal energy is estimated to be
available, less than 3 percent of this
(90 GW) is located in areas suitable for
Hydropower forms only a small part of
In addition to reducing CO2 emissions, the UK’s current energy generation mix.
Smaller run-of-the-river schemes abound
hydropower has a number of advantages According to figures published by the
throughout the UK. While providing
over fossil fuel-fired generation. Water National Archives, the UK generated
much less power than large dams, runof
is exempt from the cost fluctuations about 0.8 percent of its electricity from
the river schemes cause significantly
that oil, gas and coal are subject to, and hydro schemes in 2009. UK hydro plants
less ecological disruption. In April 2010
hydroelectricity requires no imports – a include Ben Cruachan, Foyers, Lochaber,
an Environment Agency study identified
key factor as energy security concerns Mossford and Sloy (all 400 MW and
the potential for thousands of new smallscale
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become increasingly prevalent around below) in the Scottish Highlands and
hydroelectric schemes in the UK, power generation.
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