By next year company founder Avi Brenmiller said he will have a 1.5
megawatt (MW), 15-acre (6-hectare) site in the Negev desert
connected to Israel's national grid, and a number of 10 to 20-MW
pilots abroad are expected to follow, which will produce electricity
at a price which competes with power from fossil-fuelled plants.
"A couple of years from now, not later than that, we will be putting
full-size commercial plants to work. Because the basic technology we
use here is a bankable technology ... I'm sure that banks will not
hesitate to finance such projects," he said.
Many have tried to find ways to keep solar thermal power generators
running after dark, but current solutions have shortcomings and have
not always proven cost-effective.
The direct generation of electricity by photovoltaic (PV) solar
panels is a far more common way to convert solar energy than by
using solar heat to fuel thermal power plants, which take up more
space and are not suitable for small-scale applications such as
But a row of parabolic mirrors now tracks the sun at Brenmiller's
research site in the searing Negev desert, concentrating the rays to
generate the steam needed to drive a turbine for producing
It is a technique that has been used for years but in addition to
immediately generating steam some of the solar heat is also
conducted by a fluid into a novel storage system buried beneath the
mirrors which operates at 550 degrees Celsius.
This store can then be tapped at night or on cloudy days to keep the
steam supply to the turbines flowing night and day, said Avi
Brenmiller, chief executive of Brenmiller Energy.
The innovation is in the cement-like medium that stores the heat, a
technology that Brenmiller says is more efficient than other systems
on the market, such as those using molten salt, which has severe
price and operational drawbacks.
"We will have this technology at conventional fuel prices with the
same availability around the clock. I think that's the major
breakthrough here," he said from the control room of the project,
which he called a working proof of concept.
Brenmiller was a co-founder and chief executive of Solel Solar, a
producer of concentrated solar power fields which was bought by
Siemens in 2009 for $418 million but subsequently closed by the
German group last year.
He has already poured $20 million of his own money into the latest
venture over the past two years.
Energy storage can be a key to bridging the gap between energy
supply and demand across the globe, the International Energy Agency
said in a report earlier this year.
The primary hurdle is reaching "grid parity", or the point at which
electricity generated from renewable energy sources costs the same
as electricity produced by fossil-fuelled power plants. That is
when, experts believe, environmentally friendly energy conversion
can take off.
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Grid parity has been achieved in some places with PV panels but
while direct electrical energy storage is possible with batteries,
they are still relatively expensive, use potentially toxic materials
and cannot be applied on a large scale.
Meanwhile some thermal concentrated solar power (CSP) plants have
introduced molten salt storage facilities that store excess heat for
use in the night, like Torresol Energy's Gemasolar plant in Spain,
but while it works it cannot match the cost of burning fossil fuels
and depends on subsidies.
There are also technical drawbacks to using molten salt. The salt
stores the high temperatures in liquid form, but if the heat drops
below about 220 degrees Celsius, it will freeze, potentially ruining
parts of the system.
This is not an issue for Brenmiller, he said, as he uses a solid
cement-like storage medium in a structure which is buried about two
meters below the mirrors.
He would not give any details on the storage medium's composition
but said the system was similar to storage facilities under
development called thermocline systems, which enable the heat to be
conducted in, stored and conducted out again in a single tank, which
is less costly than having to use two tanks to separate the hot and
cold conducting fluids.
"In my understanding, there is no other technology like it in the
world," said Amit Mor, chief executive of Israel-based consulting
and investment firm Eco Energy and a former energy adviser to the
World Bank. "It can be very useful to developing countries and
developed countries alike."
An hour of sun produces enough energy to sustain three hours of
equivalent electricity generation, Brenmiller said, and with every
24 hours of storage, 5 percent of the heat is lost.
It costs three times more to build than a conventional PV plant
which can achieve grid parity during sunlight hours, but because it
produces three times as much energy, the price of electricity is
also at grid parity, he said.
In the United States and Israel, he expects electricity produced by
the system to cost 12 cents per kilowatt hour, on a par with the
average cost of grid electricity.
(Additional reporting by Christoph Steitz; Editing by Greg Mahlich)
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