Annual Report 2006 - Plataforma Solar de Almería

PLATAFORMA SOLAR DE ALMERÍA
Motivation: Desalination is an intensive energy consumer; in reverse osmosis
seawater desalination systems, this consumption is around 3.5 kWh/m 3 . Taking
into account that 2 10 6 m 3 /day are distilled in Spain, the need for developing
sustainable and economically feasible desalination technologies is unquestionable.
The solar reverse osmosis plants in operation to date are based
on photovoltaic technology. The use of solar thermal energy for this process
would enable better use to be made of the solar resource and less environmental
impact once the problems of waste involved in the use of batteries
required for photovoltaics is eliminated.
Purposes: The main goal of the OSMOSOL project is the development of an
innovative technology based on solar thermal energy applied to the reverse
osmosis desalination process which complies at the same time with the principles
of environmental sustainability and economic feasibility. To do this it is
intended to use thermal energy collected and concentrated in a solar device to
feed a thermodynamic cycle based on a fluid that evaporates at a relatively
low temperature and which, hooked up to a turbo-compressor system, allows
direct transformation of the thermal energy into mechanical energy required
by the osmosis process.
Figure 4.16 Generic reverse osmosis system hooked up to a solar driver
Objectives met in 2006: During the first year of the project, low and mediumtemperature
solar thermal collectors were thoroughly reviewed from the point
of view of their application to desalination processes.
Once certain solar organic Rankine cycles had been selected, we proceeded
to choose from among the solar collectors compiled in the previous activity,
those which best adapted to the conditions delimited by the thermodynamic
cycle mentioned above. Four stationary solar collectors and two parabolictrough
collectors meeting the technical and functional specifications were preselected
for analysis of the solar power cycle, which was done employing up
to 22 different working fluids.
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