Thermal energy storage
(November 3, 2015) Engineers
at Oregon State University have identified a new approach for the storage of
concentrated solar thermal energy, to reduce its cost and make it more
practical for wider use.
The advance is based on a new innovation with thermochemical
storage, in which chemical transformation is used in repeated cycles to hold
heat, use it to drive turbines, and then be re-heated to continue the cycle.
Most commonly this might be done over a 24-hour period, with variable levels of
solar-powered electricity available at any time of day, as dictated by demand.
The findings have been published in ChemSusChem, a
professional journal covering sustainable chemistry. The work was supported by
the SunShot Initiative of the U.S. Department of Energy, and done in
collaboration with researchers at the University of Florida.
Conceptually, all of the energy produced could be stored
indefinitely and used later when the electricity is most needed. Alternatively,
some energy could be used immediately and the rest stored for later use.
Storage of this type helps to solve one of the key factors
limiting the wider use of solar energy – by eliminating the need to use the
electricity immediately. The underlying power source is based on production
that varies enormously, not just night and day, but some days, or times of day,
that solar intensity is more or less powerful. Many alternative energy systems
are constrained by this lack of dependability and consistent energy flow.
Solar thermal electricity has been of considerable interest
because of its potential to lower costs. In contrast to conventional solar
photovoltaic cells that produce electricity directly from sunlight, solar
thermal generation of energy is developed as a large power plant in which acres
of mirrors precisely reflect sunlight onto a solar receiver. That energy has
been used to heat a fluid that in turn drives a turbine to produce electricity.