The Solar Highbeams Project will initiate and sustain a forum for a collaborative international effort to conceive, research, and develop a supply chain for next-generation concentrated solar power (CSP) plants, energized by the new possibilities of telescopic heliostats. The Project will leverage the success and toolset of Creative-Commons-based collaboration in open source software projects. Funding is sought for administration of a GitHub project page and sponsorship of token cash prizes for best relevant work presented at a designated solar conference.
Concentrated Solar Power (CSP) power tower demonstrations have shown high efficiency and the ability, when combined with sufficient thermal storage, to operate at capacity factors typical of conventional fossil-fueled plants. However, these technology demonstrations are based on Vant-Hull and Hildebrandt's power tower concept, an idea now forty years old and consigned (by conservation of extendue, an optical statement of the Second Law of Thermodynamics) to poor utilization of land. The land utilization problem of CSP's is starkly evident in a satellite view of any of the CSP demonstrations: most of the available sunlight falls to the ground between heliostats.
Redirecting light from a high sun toward a low target is implicitly an attempt to increase solar flux density—the Second Law of Thermodynamics requires either a compensating loss of energy (sunlight hits the ground) or an increase in beam divergence. An optical instrument that increases beam divergence while keeping the beam as collimated as possible (parallel rays are mapped to parallel rays) is called a telescope. Therefore, we must either resign ourselves to the wasteful land appetite of current CSP demonstrations, or begin investigation of telescopic heliostats and explore what their consequences will be for the rest of the system.
The difficulty in advancing a fundamentally new concept of CSP is that ultimate success depends on an ecology of new ideas and things, ideas and things that will never come into being unless a community of people endorse a common goal and individually see how their own possible contribution would fit. The same problem is faced by open source software projects, and a number of new tools and practices have fostered their successes. GitHub is a website for opensource software projects beginning to be used for open source hardware as well. The site provides a public and permanent record of incremental contributions—encouraging maximum openess from contributors—but also allows hive dispersal through forking, a facility that permits an independent-minded faction of contributors to take things in their own direction if their ideas do not find acceptance in the community as a whole.
Preliminary investigation of telescopic heliostats indicates that they improve mirror/land ratios from 0.21 to 0.70. Central, beam-down optics are unavoidable, but the necessary central optics, which look something like an overturned apple, need only 60% the height of a power tower on the same field. That makes larger heliostat fields practical.
Calculations indicate that a solar generating unit harvesting a quarter-township, a Public Land Survey System unit which is nine square miles (23,000,000 m2,) would need central optics 190 m high—that is just 15% taller than the current generation of power towers (the Crescent Dunes tower is 165 m.) Based on the performance of Ivanpah Unit 1, which is rated 126 MW at 32% capacity factor, with no storage, and harvests a land area of 3,800,000 square meters, the increased field area, and the improved mirror/land ratio (0.70 vs. 0.21,) a quarter-township solar generating unit in the Desert Southwest should be rated about 1 GW at 75% exploiting a half-day of thermal storage.
126 MW * (0.32/0.75) * (0.70/0.21) * (23,000,000 m2 / 3,800,000 m2) = 1.08 GW
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