In Europe the utilization of air as heat transfer medium was favored since then. The main
disadvantages of air, its low heat capacity and bad heat transfer characteristics, are
compensated using a new receiver design: instead of a closed tube receiver a porous structure
with large specific surface is used. In the PHOEBUS-program the structure consisted of wire
mesh, ambient air sucked through this structure was heated up to 700 °C. This concept (figure
6) was tested on the CESA-1 test facility, a 1 MWe experimental power plant built by
CIEMAT on the PSA beside the SSPS-field. A 10 MWe power tower (PS10) is currently under
construction near Sevilla, Spain, with support from the European Union.