Page 10 - European Energy Innovation magazine - spring 2023 edition

Spring 2023 European Energy Innovation
10 COMMUNICATION

REVEAL – Revolutionary

energy storage cycle with

carbon-free aluminium

By Zuzana Taťáková FENIX TNT, Páll Árnason Taeknisetur, Michel Haller OST

Insight photovoltaics is cheap, it only comes hydrogen has an interesting energy
Renewable electricity and heat can during the day, and it comes less in density, but it is a gas, per volume
be produced cheaply today and winter. While balancing from day to the energy density is extremely low.
short-term storage solutions for night is not that difficult, technologies Therefore, hydrogen would have to be
evening out mismatches between for shifting from summer to winter put under enormous pressure of 300
production and demand are available and storing renewables for longer or 600 bar, liquefied, or converted
at low cost. Essentially, there would time spans of months or seasons are to hydrocarbons at considerable
be enough energy if the sun could be scarce and costly - thus not widely expense in order to store it. That
used as a virtually unlimited source. used yet. would lead to the additional effort,
However, most of the sun's energy higher costs, and a loss of efficiency.
comes in the summer but is needed Power-to-gas solutions are being
in the winter. propagated: Water is split into oxygen The REVEAL project develops
and hydrogen by electrolysis, i.e. a game-changing and unique
In the cold season, the demand for with electricity, and the hydrogen solution to this challenge, using the
heat is highest because the sun is is stored. But hydrogen has a very conversion of aluminium oxide into
not shining and while electricity from low energy density. Per kilogram, aluminium metal (Power-to-Al) in
an environmentally friendly way to
store renewable energy and produce
a "renewable fuel" in the form of
aluminium.
Aluminium does not have a very good
reputation ecologically - because
it needs a lot of energy in order to
first produce aluminium oxide from
the raw material bauxite and then
aluminium.

However, if the energy put into it
is firstly renewable or 'clean' and
secondly stored in the material and
not lost, then that is exactly the
outcome desired: A material into
which a lot of energy can be put per
kilogram or per cubic metre and from
which this energy can be obtained
back later.

If aluminium is produced with today's
technology, then about half of the
energy used in production is stored
chemically in the aluminium. If the

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