Lithium could soon see increased use in the solar energy
industry as a working fluid component in concentrated solar
By replacing traditionally-used organic heavily oil
fractions or solar salts, a lithium-based molten salt could
increase lithium carbonate equivalent (LCE) demand by about 1m
tpa, according to Jon Hykawy, president of Stormcrow Capital
Speaking on the side-lines of the IM Lithium Supply &
Markets conference, held in Montreal, Canada, last week, Hykawy
told IM that traditional working fluids have
comprised organic heavy oil fractions or solar salts, both of
which come with positive and negative attributes.
Organic oil fractions are heavy, expensive and break
down at about 400°C. If you spill
them on the desert floor they basically turn into oily soil
that you have to truck somewhere to dispose of, Hykawy
The high break-down temperature means that the system is
efficient, but it is still limited to 400°C and, if a spillage occurs, it can be
an expensive problem.
Solar salts, which are cheap, have a much lower
melting point at around 130°C
but they break down at around 150°C. If you
spill [molten salt] you can pick it up and reuse it. But if it
freezes, youve got a problem, as trying to melt all of
the salt in all of those pipes is going to take a long
time, he told IM.
As a result, many researchers have been looking at
alternative salts that melt well below the boiling point of
water and have a property called eutecticity, which means all
of those individual salts melt at the same temperature, even
though each of them has a different melting temperature.
A couple of formulas have been found, which typically
contain four or five different types of salt. One of them is
always lithium nitrate (LiNO3), Hykawy
What lithium does for you is it lowers the melting
point, but also lowers the viscosity of the salt, meaning you
dont have to use as much energy to pump it through the
system. They also have exceptionally high operating
temperatures well above 500°C, typically, he added.
Lithium therefore offers several advantages over traditional
working fluids as the electricity produced is cheaper, the
system is no longer in danger of freeze-up and if there is a
spillage, the salt turns hard and is able to be reused.
|SolarReserve's Crescent Dunes 110MW CSP project
located near Tonopah, Nevada, US.
If the best salt used contains 25% LiNO3, then
32,000 tonnes of salt contain 8,000 tonnes of LiNO3,
or about 4,300 tonnes of LCE.
This would create a 10-fold increase in lithium
demand, just for that application, equating to 24.6m tones LCE,
or about 1m tpa, Hykawy told IM.
It would be nice if the lithium industry could
actually deliver this in the chemical form needed, rather than
asking them to buy lithium carbonate and then getting them to
convert it to lithium nitrate. I think this would boost the
lithium industry over time, he added.
How CSP systems work
CSP systems use optics such as lenses or curved mirrors to
concentrate a large amount of sunlight onto a central solar
tower or collector, which uses this energy to heat a working
fluid to drive a heat engine usually a steam
This heat engine is connected to an electrical power
generator or powers a thermochemical reaction.
While space restrictions are as relevant for CSP systems as
they are for any other large-scale renewable energy
alternative, the fact that CSP can be used anywhere there is
sunlight not necessarily sunshine means they are
a viable option worldwide.
Hykawy explained that in the reflecting tower applications
are relatively compact and a user can get a factor of 10,000
increase in solar insolation on that tower, while for a
parabolic reflector the best that can be expected is a factor
of a few hundred augmentation of the suns energy.
The biggest impediment is that the sun only shines for
half the day, so youre really looking to build the heat
load and then spread that out over the entire 24-hour
period, he told IM.
This means that, unlike solar photovoltaics systems, which
require battery power when the sun goes down, CSP systems can
continue to generate energy at night. This is because the
system has built up heat throughout the day.
Over time I think youre going to see [CSP] take
off. It is inexpensive, it is base-load, and its not
solar PV, where if the sun goes behind a cloud youve lost
half the output from the field. As long as the sun shines, they
can continue to produce power and even when the sun goes down,
they can continue to produce power, Hykawy told
For more information on the use of industrial
minerals, like lithium, in renewable energy applications, pick
up your copy of IMs Critical Materials for Green Energy
supplement magazine, out this August.