Power in The Desert: Solar Towers Will Harness Sunshine of Southern Spain

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The Guardian/UK

Power in The Desert: Solar Towers Will Harness Sunshine of Southern Spain

Andalucia project will power 11,000 homes • Technology exported to Morocco, Algeria and US

Alok Jha

This PS10 solar tower plant near Seville can generate 10MW of electricity. (Photograph: Denis Doyle/Getty)

SEVILLE, Spain - In the desert of southern Spain, 20 miles outside Seville, more than
1,000 mirrors are being carefully positioned. Each is about half the
size of a tennis court, so the adjustments will take time. But when
they are complete in a few weeks, it will mark a major moment in the
quest for renewable energy.

The mirrors are part of the world's
biggest solar tower plant, a technology that reflects sunlight to
superheat water at a central tower. Once this €80m (£67m) plant is
inaugurated in January, it will generate 20MW of electricity, enough to
power 11,000 Spanish homes.

Concentrated solar power (CSP)
technology, as it is known, is seen by many as a simpler, cheaper and
more efficient way to harness the sun's energy than other methods such
as photovoltaic (PV) panels. But CSP only works in places with clear
skies and strong sunshine.

The Andalucian deserts are an ideal
location, and Spain hopes the PS20 plant will enable it to take
advantage of its huge solar resource and lead the field in CSP

"The radiation hitting the earth is 10,000 times
the consumption of energy," said José Domíngues Abascal, chief
technology officer at Abengoa, the Spanish energy company behind the
plant. "There is great potential in solar energy."

Abengoa has
already built a smaller version of the tower technology to test that
the idea works. The 11MW PS10 system has been generating electricity
for almost two years. Its new design uses an area larger than 100
football pitches, with 1,255 mirrors, called heliostats, each with a
collecting area of 120 sq m. These track the sun as it moves through
the day and reflect the energy to the top of a 160-metre tower at the
centre of the field. Here, the concentrated light is used to heat water
to more than 1000C, producing steam that can turn an electricity
generating turbine.

When switched on, the new plant will be the
world's largest commercial CSP plant feeding electricity into a
national grid. It will be also be a significant step for tower
technology, seen as a candidate for the large-scale solar plants of the

Spanish firms are charging ahead with CSP: more than 50
solar projects around Spain have been approved for construction by the
government and, by 2015, the country will generate more than 2GW of
power from CSP, comfortably exceeding current national targets. The
companies are also exporting their technology to Morocco, Algeria and
the US.

"CSP is at the very beginning of a big boom," said José
Luis García, at Greenpeace in Spain. "Spain is in a good position to
develop and implement the technology. We have the sun so we are in the
best position to lead in this field."

The country's clean energy
targets are in line with the EU's plan to source 20% of primary energy
from renewables by 2020, which means that 30% of electricity would have
to come from carbon-free sources. A new EU renewables directive would
increase that electricity target to 40%, but García said Spain could
easily reach for more, up to 50%.

John Loughhead, executive
director of the UK Energy Research Council, said that Abenoga's tower
approach at the new plant was relatively efficient "because what you're
doing is concentrating a very large area of sunlight on top of a very
small area so you can get very high temperatures".

He added
that, given the right environment, solar towers were a credible way to
make clean power. "But can you make them cheap enough, will they be
reliable enough, will they have the right lifetime?"

difficulty for potential developers is cost. In Spain, the generation
costs of electricity from CSP are double those from more traditional
methods. But Abascal said the price was falling as solar projects got
bigger and it would match that of fossil fuel power within a decade.

now, CSP projects across Spain are built with the promise that the
government will pay a premium, known as a feed-in tariff, for any CSP
electricity sent into the grid. The PS20 is part of a €1.2bn series of
solar power plants based on CSP technologies including tower plants and
trough-style collectors - where water is passed in tubes directly in
front of parabolic mirrors that collect sunlight - and a few PV panels
planned by Abengoa. The solar farm will eventually generate up to 300MW
of power, enough for the 700,000 people of Seville, by 2013.

20MW solar tower is also a forerunner for an even more ambitious idea,
one that Abascal hopes will become a standard for CSP plants in future
- a 50MW version that could generate electricity around the clock.
"During the day, you'd use 50% of your electricity to produce
electricity and 50% to heat molten salt. During the night you use the
molten salt to produce electricity."

Molten salt technology is in
its early stages but Abengoa is testing the idea at a power plant in
Granada. So far the company has demonstrated that it is possible to
store up to eight hours of solar energy by heating tanks containing
28,000 tonnes of salt to more than 220C. "This will make it possible to
have almost constant production or at least it will be able to produce
energy for most of the day," said Abascal.

The European
commission has identified CSP as part of its future clean energy
technology plan. Earlier this year a representative from its joint
research centre argued that CSP could even form a major part of a
proposed EU supergrid that would transport electricity, generated in
solar plants in southern Europe and northern Africa, across Europe.

supergrid has received political support from Gordon Brown and France's
president, Nicolas Sarkozy, who has commissioned a feasibility study on
the project.

Graveyard generation

The Spanish town of
Santa Coloma de Gramenet has placed more than 450 solar panels on top
of mausoleums at its cemetery to generate power, it emerged yesterday.
The crowded, working-class town outside Barcelona decided that flat,
open, sun-drenched land was so scarce that the graveyard was the only
viable spot to site the panels, which provide enough electricity to
power 60 homes. They rest on mausoleums holding five layers of coffins.
The idea was a tough sell, said Antoni Fogue, a city council member.
But town hall and cemetery officials waged a campaign to explain the
project and the panels were erected at a low angle, to be as
unobtrusive as possible."This installation is compatible with respect
for the deceased and for the families of the deceased," Fogue said.

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