POWER June 2011 - 12

subsidies from €4 billion annually to €1.5 billion because they
are unaffordable. The country, a major proponent of renewable
energy development, has also become Europe's first country to
ditch the European Union target to procure 20% of its domestic
power from renewable sources by 2020.
Czech Republic. Cuts to a feed-in tariff program that reportedly
spurred the increase of solar energy plants in the Czech Republic
from nine in 2005 to 2,230 by 2010 were approved by the government
last year. The cuts target solar plants that provide a return on
investment in less than 11 years and that will be built after January
2011. The government has said it supports the move because it
would increase grid stability and level electricity prices.
Slovakia. Slovakia, following the Czech Republic's lead, had
also considered subsidy cuts, but this January, the Ministry of
Economy decided that it would retain price incentives for solar
and biomass. The ministry earmarked €18 million until the end
of 2013 for subsidies, and it will this May try to get parliament's
approval for its decision.
Italy. Italy's government will cut generous support for renewables
to ease the burden on consumers, who pay for renewable incentives
in power bills. It will cap subsidies for solar developers at €6 billion
to €7 billion per year by the end of 2016. The government plans to
slightly cut incentives until the end of a transition period ending in
2012. Current incentives were due to expire in June, but in April, the
country approved a three-month extension (until Aug. 31) to allow
some investors to complete their projects.
France. France in December suspended the registration of solar
power projects of more than 3 kW for feed-in tariffs to study
how cuts in the program would limit growth in the industry. In
February, the country's Environment Ministry announced that solar
capacity in the country would be much higher than the 5,400 MW
target for 2020, even though subsidies would be cut. The country
has since slashed solar subsidies by 24%, from €0.55 to €0.42/kWh
and is instead focusing on increasing wind power capacity.
Australia. In March, Australia's states called on Prime Minister
Julia Gillard to roll back generous subsidies for rooftop solar
plants after forecasts suggested that costs would add as much as
A$90 per year to household power bills. Last October, New South
Wales slashed by two-thirds the revenue that homeowners who
had installed solar panels would receive.
Spain. In Spain, where the government has made the controversial
decision to slash subsidies by up to €3 billion over the
next three years-and possibly retroactively, on plants built before
2008-regulators are also suspending subsidy payments to
power producers who do not meet regulatory requirements. The
country recently suspended payments to 304 solar power installations
after requesting proof from more than 9,000 rooftop and
plant operators that they qualify to receive incentives. Spanish
news reports have suggested that hundreds of subsidy recipients
were illegally collecting the extra payments. (For more on Spain's
situation see " Spain: A Renewable Kingdom " in this issue.)
China. As of April, almost all the 10 billion yuan ($1.54 billion)
of China's Golden Sun solar subsidy program to support solar
photovoltaic businesses has been allocated, but an investigation
has shown that a relatively high percentage of recipients may have
declared material costs to be higher than they were, fraud that
increased the cost of the whole system, reported China Dialogue.
Battery That Extracts Energy from Water
Salinity Difference
A rechargeable battery developed by researchers from Stanford
University employs the difference in salinity between freshwater
12
5. Worth one's salt. A rechargeable battery developed by Stanford
University researchers employs the difference in salinity between
freshwater and saltwater to generate power. In the first step, a small
electric current is applied to charge the battery, pulling ions out of the
electrodes and into the water. In the second step, the freshwater is
purged and replaced with seawater. In the third step, electricity is
drawn from the battery for use, draining the battery of its stored energy,
and in the final step, seawater is discharged and replaced with
river water, for the cycle to begin anew. Courtesy: Yi Cui
Step 1
Charge
River water
Discharge
Sea water
Step 3
and saltwater to generate a current. The technology could make
it possible to harness power from anywhere freshwater enters the
sea, such as river mouths or estuaries, Yi Cui, associate professor
of materials science and engineering, who led the research
team, said.
As the researchers explained in the March issue of the journal
Nano Letters, the battery essentially uses two electrodes-one
positive, one negative-immersed in a liquid containing electrically
charged particles or ions. In water, the ions are sodium
and chlorine, the components of ordinary table salt. The positive
electrode is made from nanorods of manganese dioxide, which increases
the surface area available for interaction with the sodium
ions by roughly 100 times compared with other materials, Cui
said. The researchers continue to search for a better material for
the negative electrode than the silver used for the experiments,
which is too expensive to be practical.
Initially, the battery is filled with freshwater and a small electric
current is applied to charge it up. The freshwater is then
drained and replaced with seawater. Because seawater is salty,
containing 60 to 100 times more ions than freshwater, it increases
the electrical potential, or voltage, between the two
electrodes. That makes it possible to reap far more electricity
than the amount used to charge the battery. " The voltage really
depends on the concentration of the sodium and chlorine ions
you have, " Cui said. " If you charge at low voltage in freshwater,
then discharge at high voltage in sea water, that means you gain
energy. You get more energy than you put in. "
Once the discharge is complete, the seawater is drained and
replaced with freshwater and the cycle can begin again. " The
key thing here is that you need to exchange the electrolyte, the
liquid in the battery, " Cui said.
In their lab experiments, Cui's team used seawater they collected
from the Pacific Ocean off the California coast and freshwater
from Donner Lake, high in the Sierra Nevada. They achieved
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POWER June 2011

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