From: Climate News Network
Dec 8, 2013
Giant ‘battery’ ensures renewable supply
By Paul Brown
Energy from surplus wind power can be used to pump water uphill and will provide
“battery” power to even out energy supply and demand, researchers say.
LONDON, 8 December – Norwegian hydropower schemes linked to Europe’s large wind
farm projects could successfully act as a backup when wind power fails to
deliver enough energy, according to SINTEF, the largest independent Scandinavian
With both on- and off-shore wind power being seen as key to reducing the EU’s
carbon emissions by 80-95% by 2050, a big hurdle for the technology is solving
the problem of intermittent power production. Sometimes there will be too much
power on offer, and at others too little.
A northern European offshore power grid is being developed to link wind farms
and carry the electricity to population centres where it is needed in Sweden,
Denmark and Germany. But the key problem remains how to maintain a regular
supply of energy.
If the existing Norwegian hydropower schemes were refurbished and updated and
connected to the same grid they could act as a giant “blue-green battery” for
the system and provide all the necessary backup power, according to SINTEF.
The potential for wind power in northern Europe is huge. There are already 3.8
gigawatts of installed wind power, replacing four coal-fired power plants.
According to the European Union this is expected to rise to 150 gigawatts
between 2030 and 2050, the equivalent of 150 medium-sized coal-fired power
Although there are always variations in wind speed, clever use of the grid
system, linking to other renewables like biogas and other back-up gas stations,
evens up supply. One way of dealing with electricity surpluses, for example from
nuclear power stations that have to run 24 hours a day and produce power at
night that no-one needs, is to use the electricity to pump water uphill into
reservoirs. This water can be released and used for hydropower during daytime
peaks. This system is called pumped storage.
This is exactly SINTEF’s idea, but on a larger scale. Norwegian reservoirs could
be constantly recharged with water delivered by electricity generated by surplus
wind power, with the water power used as a “green” battery in times of shortage.
“If this large wind project is to succeed, we must secure stable electricity
supplies”, says Daniel Huertas-Hernando at SINTEF. “Today, forecasts of wind
velocities provide the only information which gives us any indication of power
generation levels from wind farms for the next 24 hours.
“If these prognoses turn out to be wrong, or if bad weather makes generation
from the turbines impossible, we will need an effective stand-by source which
can fill the energy supply gap at short notice.
“This is exactly what Norwegian hydropower can do, because it makes it possible
to store energy which can then be released on tap as and when it is needed”, he
By refurbishing existing plants and installing pump storage, the research shows,
the potential of Norwegian hydropower plants could be increased by between 11
and 18 gigawatts, enough to provide adequate backup.
The next question the researchers are looking at is how to integrate all this
into the European grid so that the system is cost-effective. An EU project
called Twenties is looking at large-scale stable renewable energy for the EU.
Peaks and troughs
Some renewables like solar, which are also intermittent, pose less of a problem
because peak production is around mid-day when energy use is at its highest.
This has already led to peak wholesale prices being reduced in countries like
Germany and Italy where there are large-scale solar installations.
Wind is less predictable. The problem is to work out how best to use the output
to even out production peaks and troughs before final decisions on a
distribution network are taken.
There are already grid connections between countries, for example to export
surplus nuclear power from France to Germany, Italy and the UK. Surplus wind
power from Denmark is exported, and Norway can sometimes offer spare hydropower.
“So far the only power cables we have extending directly between different
countries are the so-called ‘cross-border trading cables'”, says
Huertas-Hernando. He says what is needed is a grid development strategy across
Europe to even out supply and demand.
“Since grid construction takes such a long time, it’s important to find the
answer to this question now, so that we can plan in time”, he said. – Climate