Fresnel Lenses for CSP

Large, Low-Cost Fresnel Lenses in Glass for CSP

Abstract

The industrial revolution moved society organization from farming communities distributed on the land, self-sufficient in energy and food provided by the sun, to concentrated sources as oil and natural gas. Now there is a reversal of this trend due to the return to the use of solar energy. We produce electricity with PV panels, but we need also heat, and we do not have any way to do so in a distributed way. We propose a model of collecting, storing, and using the energy locally. The first step, collecting, we discuss in this paper. We propose the use of a large Fresnel lens in glass. To mold the lens in glass we use a modified groove design where the vertical step directs the light to the focal point through reflection by a mirror. The angle between facets is large enough to let the glass fill the grooves. We solve the problem of cost by producing the lens in a cylindrical configuration, extruding and calendaring the glass in a commercial plant for textured glass at a cost of $10/m². The basic unit size can be realized as an assembly of eight 4x8 feet glass panes, collecting what we expect to be 10kW per unit, at a cost of few hundred dollars per unit for the collecting optic. We will capitalize on the know-how on making the receivers for the Parabolic Reflector geometry. This proposal allows solar heating to be affordable by a homeowner, lowers CO₂ emissions.