Large scale solar thermal innovations, curated(ish)

Concentrated solar power is an old technology making a comeback. Here’s how it works

optimization on heliostats

metalized BoPET instead of glass mirror
single (DC) motor for dual axis tracking
- shape support so that circular rotation turns into elliptical movement (in a plane) with constant offset in the third dimension
13, Monolithic 2 DOF fully compliant space pointing mechanism
same same but different
mylar film mirror roll
- heliostat = streched Mylar between 2 rolls
  - washing = roll enough new film such that clean new area replaces dusty old area
    - periodically replace rolls (tweak periodicity for economics)
    - wash dusty rolls in dedicated plant w/ closed loop water system
- (2011) Novel solar cogeneration trough system based on stretched microstructured Mylar film

robot peeling plastic film

save millions of cubic meters of desalinated water a year
- insert water usage numbers from Ouarzzazzate and others
- closed loop water use
solve PV dust deposition issue on other celestial bodies as well
- links/images to Mars rovers
- and NASA's attempts at circumventing this issue
  - too harsh weigth constraints for blower, broom, film rolls
  - dust devils help
  - larger dust grains help
stack 25 years worth of transparent PET/PMMA/... film stacks on top each PV panel
- so dust off happens through peeling one film
  - save on desalinated water
  - 25 years meaning as many as times PVs are water washed
not this: 13, Automated Removal of Prepreg Backing Paper - A Sticky Problem
no pneumatics, no general problem solving
but instead a 1-servo peelable design. Made especially for this purpose.
at scale replace servos by something a single machine or human can peel off at walking speed
peeling thin transparent film
surface protection tape

alternative concentrators

19, A Review on Solar Concentrators with Multi-surface and Multi-element Combinations

alternative plants ~ fewer moving parts

Cassegrain -type reflector & concentrator systems

https://en.wikipedia.org/wiki/Cassegrain_reflector
- a combination of a primary concave mirror and a secondary convex mirror

from the amazing Why is this Space Telescope so Tiny?

TransAstra Corporation’s Optical Mining Technology

Beam-down solar thermal power plant

The Yumen Xinneng CSP Plant and NREL’s listing.

(2014) Issues with beam-down concepts
- Most beam-down central receiver systems replace the usual central tower, receiver, and heat transfer vertical piping and pump with a hyperbolic reflector located below the aim point of the field. This reflects the impinging light toward the ground. It is shown that this also expands the image which would have been produced at the initial aim point by several fold, to the extent that an array of CPC’s is required to restore some of the concentration. It is suggested that the costs of the towers to support the secondary reflector assembly, the reflector and its strong-back, and the CPC’s may well equal or exceed that of the elements eliminated. The requirement that secondary size and cost be constrained also limits the boundary of the heliostat field to the extent that, for a given aim point height, typically half or less of the optimum power to the tower top receiver can be achieved in the beam-down configuration.
(2015) Modeling of Beam Down Solar Concentrator and Final Optical Element Design
(2015) Preliminary Optical, Thermal and Structural Design of a 100 kWth CSPonD Beam-down On-sun Demonstration Plant
(2016) Validation of an optical model applied to the beam down CSP facility at the Masdar Institute Solar Platform
(2017) An Origami-Inspired Design of a Thermal Mixing Element Within a Concentrated Solar Power System
(2023) A Novel Dual Receiver–Storage Design for Concentrating Solar Thermal Plants Using Beam-Down Optics
(2023) Progress in beam-down solar concentrating systems
(2011) Concentrated solar power on demand
(2022) SUNSON: Concentrated Solar energy storage at Ultra-high temperatures aNd Solid-state cONversion
(2016) Solar energy at high temperatures; researches at the Weizmann Institute of Science, Israel; 25 years of success
(2018) High temperature systems using solid particles as TES and HTF material: A review

Notable authors:

MOSAIC

Spherical cassegrain-schmidt solar concentrator with mobile receiver on a Cable-Driven Parallel Robot

Part of EU’s H2020 Research program.

(2020) Low-Cost Solar Electricity Using Stationary Solar Fields; Technology Potential and Practical Implementation Challenges to Be Overcome. Outcomes from H2020 MOSAIC Project
- At any time of the day, a spherical mirror reflects the rays coming from the sun along a line that points to the sun through the center of the sphere.
A funky paper: 1975, Stationary concentrating reflector cum tracking absorber solar energy collector: optical design characteristics
(2012) Cassegrain Solar Concentrator System for ISRU Material Processing
(2008) Innovative design of cassegrain solar concentrator system for indoor illumination utilizing chromatic aberration to filter out ultraviolet and infrared in sunlight
companies + links

synthese

reduce cost
- minimize moving parts / motor count
- maximize concentration factor (>9000 Suns! .webm)
Beam-down has sub-ideal concentration:
- final image is enlarged by hyperbolic secondary concentrator.
- low aperture = smaller heliostat field (than towers)
- ... but beaming directly to TES (thermal energy storage) skips pumping, pipes and cycling day-night
MOSAIC has
- fixed heliostats (yay)
- pumps, pipes and oven (nay) mounted on a cable-driven parallel robot

I feel there’s something to be found at the intersection of this Venn diagram!

=> given a large static spherical heliostat field, is there a possible secondary concentrator that would focus this linear light?