The Gemasolar plant near the Spanish city
of Seville, built by Torresol Energy, can store enough heat to operate
for 18 hours at full capacity without any additional power from the Sun. For many months of the year it can run for
24 hours a day.
The plant is small by power station
standards, producing 20 megawatts of electricity – enough for 25,000
homes, reducing carbon dioxide emissions by 30,000 tonnes a year.
It has 2,650 mirrors, known as heliostats,
which cover an area of 185 hectares. These train the Sun’s rays onto a
central tower, where they heat molten salt to more than double the
boiling point of water. More heat is produced than is needed for maximum
power, so the surplus is stored in molten salt tanks until it can be
used during cloudy periods or at night.
The award comes from DESERTEC, an
organization dedicated to providing energy from arid regions, which had
shortlisted four power plants, all able to store power from the Sun and
produce electricity at night. It described the Gemasolar plant as "a
pioneer for future power stations".
The plant has been working for three
years, showing that the technology works effectively summer and winter.
The company and DESERTEC both believe that it, or a series of similar
plants, can be scaled up to provide much larger populations with
There are now 105 similar installations -
known as concentrated solar power plants - across the world. One has
been operating for 30 years in California, and a large number of newer
ones have been built in desert areas of the western United States. Spain
is a world leader in the technology, and a number of Middle Eastern
desert states have built plants of different designs with molten salt
storage capacity. Gemasolar is described as the most successful design
The eventual aim of concentrated solar
power companies is to build large plants in the deserts of the world and
transfer the electricity by super-conducting cables to large centres of
population hundreds of miles away.
The most obvious application is from the
Sahara desert across the Mediterranean to Europe. Germany is
particularly interested in the potential from this source of large-scale
It is quite distinct from photovoltaic
panels, which produce electricity directly from sunlight. Here the
problem of intermittent power remains, particularly where the weather is
very changeable, as in north-west Europe. Despite the difficulties,
engineers are working on ways of balancing the output from various
solar, wind and biogas plants to keep the grid evenly supplied.
The industry is growing at an enormous
pace worldwide, because the cost of solar panels has fallen by half and
now is far cheaper per watt than nuclear power; and in the US it is only
marginally more expensive than coal.
Those keen on preventing climate change
reaching dangerous levels point out that a one-kilowatt solar system can
each month eliminate the burning of approximately 170 pounds of coal,
preventing the release of 300 pounds of CO2 into the atmosphere, and
saving up to 105 gallons of water consumed in cooling towers.
Climate News Network