New dimensions in trough technology

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Sezione collettore

 

  • Concrete frame
  • Multi-arc pneumatic mirror
  • Pneumatic enclosure
  • High-temperature (> 600 °C) air receiver
  • Packed-bed thermal energy storage

Concrete frame

The use of concrete provides a rigid frame that can be easily manufactured on-site, all leading to a very low collector cost per primary aperture area.

structure
Advantages

  • Long lifetime (60 years)
  • On site manufacturing, extensive use of local workforce and resources
  • Low cost per aperture area
  • Increased stiffness enabling larger trough apertures
  • Anti-seismic mechanism able to withstand extreme seismic events

Multi-arc pneumatic mirror

The pneumatic system allows to achieve the focusing characteristics of a parabolic trough with high optical efficiency. The mirror foils are highly reflective (silvered polyester – 95% reflectance). They are kept in shape by differential pressures with a linear parabolic configuration.


Advantages

  • Large aperture (9,7 m with 2 mirrors)
  • High optical efficiency
  • High concentration (60 suns average without secondary)
  • Simple manufacturing
  • Low cost per aperture area
  • No production bottlenecks

Pneumatic enclosure

The mirrors and receiver are protected inside a pneumatic enclosure with a controlled atmosphere, the external film is made of highly transparent ETFE (92% transmittance on the solar spectrum).


Advantages

  • Excellent self-cleaning properties of ETFE film and greater resistance than glass against scratching
  • No dust and low humidity inside the enclosure
  • Easy to wash and total recovery of washing water

High temperature (> 600 °C) air receiver

Air as heat transfer fluid (over 600 °C operation temperature) is used in a specifically developed receiver with secondary optics for re-concentration and spillage minimization, coiled cavity heat exchangers and low thermal inertia radiative shields insulation. The receiver implements a cross-flow design and has inlet and outlet on the same side, which minimizes piping. This solution, besides being inexpensive and environmentally friendly, is optimally suited for high temperature operation, above 600 °C.


Advantages

  • High operating temperatures, up to 600 °C
  • Use of conventional materials and no need for high-tech coatings or vacuum insulation
  • Easy to manufacture
  • Inexpensive and non-polluting thermal fluid, easy to integrate in existing processes

Packed-bed thermal energy storage

Air as a heat transfer fluid makes it possible to create a simple storage that uses a closed container filled with stone gravel.


Advantages

  • Continuous operation (24h/day) as well as power production on demand
  • Field output modulation
  • Simple, proven and effective technology (patented in 1929)
  • Similar thermal losses to molten salt solutions (thermal losses in the range of 1%/24h)
  • Highly competitive, robust, fail-safe technology
  • Filler material locally available, non-polluting, non-corrosive requirements competitive production costs
  • Simple manufacturing, on-site resource usage
  • No maintenance required

Process flow

Here a schematic view of the storage operation principle: during on-sun operation the process air flows and charges the storage system; while during sun-less operations the storage discharges by giving back the air stored before.

CSP_plant operation_generic-03-01-01