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 The conclusion is a sobering one for proponents of sun and wind
energy because as more of it comes on tap, better storage will be
needed to keep the power produced when it is sunny and windy so it
can be used at other times.
The 30 million euro "Nice Grid" pilot is one of the biggest in a
European Union-backed "Grid4EU" scheme in which France's EDF,
Italy's Enel, Spain's Iberdrola Czech Republic's CEZ, Sweden's
Vattenfall and Germany's RWE are testing the power grids of
tomorrow.
In the Mediterranean village of Carros on the outskirts of Nice,
EDF's power grid unit ERDF has connected compact batteries to solar
panels on rooftops and utility-size batteries to its local power
distribution network.
The technology works perfectly but the pilot has shown it is still
too expensive for wider rollout.
"The economic model of the batteries is not mature yet," Philippe
Monloubou, chief executive of French grid operator ERDF utility told
Reuters.
A quarter of Europe's power already comes from renewables. This may
rise to 50 percent by 2030. But the intermittent nature of solar and
wind power requires flexible grids, the ability to respond to the
ups and downs of demand and, crucially, cheaper power storage.
French company Saft, which sold the batteries for the Nice pilot,
has already installed 80 MW of battery storage around the world,
mainly in remote areas in Canada, South America and Africa, or on
islands where they compete with expensive diesel generators as a
back-up source of power.
But in Europe, they come up against cheaper back-up power from
gas-fired power plants and large, efficient grids.
ACHILLES HEEL
In Carros, which has total solar capacity of 2.5 megawatt/hour, ERDF
has connected 20 lithium-ion batteries to rooftop solar panels.
Residents themselves have no control over the 4 KWh batteries -
which are similar to Tesla's 7 KWh Powerwall batteries - which are
run by ERDF.
ERDF has also hooked up two 100 KWh batteries to soak up solar power
of several dozen residences, two 600 KWh batteries linked to the
low-voltage grid and one linked to the high-voltage grid, for a
total cost of under 2 million euros.
Software developed by France's Alstom regulates the flow of power on
the Carros network, and is already widely used in other cities and
countries.
But the cost of batteries is the project's Achilles Heel.
From the Nice pilot, ERDF has learned that battery storage in Europe
costs 500 to 1,000 euros per kilowatt/hour (KWh), with an extra 30
percent for installation and the inverters that turn direct current
solar power into the alternate current used on the grid, an ERDF
official said.
At that level, battery storage would already be economically viable
in certain parts of Germany and Denmark, where renewable energy use
is most advanced and where retail power rates, at around 30
eurocents per kilowatt/hour (KWh), are among the highest in Europe,
according to Eurostat data.
But that is not the case for France, where residential power rates
are around 17 cents per KWh, and most of Europe, where power
averages about 21 cents.
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"Economical feasibility is usually not a given in most of mainland
Europe's grids," acknowledged Michael Lippert, head of Saft's new
energy storage unit.
Some analysts expect the tipping point for batteries in Europe could
come around 2020. The ERDF official said it is hard to forecast by
how much more the cost of batteries would have to fall to become
viable for grid storage. "That is one thing we will have to evaluate
at the end of the Nice pilot," he said.
Compared to the cost of solar panels, the cost of batteries has been
slow to fall, but as renewables become a greater part of Europe's
energy mix, the need for technologies to overcome the intermittency
problem will also increase, which is why Saft has set up a division
for utility-scale power storage.
MIDDAY WASHING
The Nice Grid pilot has also experimented with "demand response"
systems to use discounted tariffs to encourage citizens to use more
electricity when sunshine is abundant and less during winter evening
demand peaks.
Some 200 households signed up to let ERDF temporarily switch off
their heaters or hot water boilers during winter evening peak
consumption using the new "Linky" smart meters which France plans to
roll out nationwide in coming years.
Another 70 customers signed up to receive an SMS warning the day
before an expected sunny day so that they can benefit from midday
power prices that are 33 percent lower.
"I switch on my washing machine when the sun shines," Carros
resident Lara Muzzarelli told reporters in her red-stone villa.
Around Europe, distribution system operators are running several
pilots as part of the Grid4EU scheme, including Czech Republic's CEZ
Distribuce, which tests Combined Heat and Power (CHP) generation and
Spain's Iberdrola which is testing the integration of electric
vehicles into the grid.
ERDF has several pilots in France, testing the integration of
different kinds of renewable energy in rural and urban areas and
with different storage technologies. The French government will
decide in the coming year on a wider roll-out of some of these
technologies in larger cities.
(Editing by Mark John and Anna Willard)
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