Performance/Economics Comparison of Sensible and Thermochemical Energy Transport Systems for Solar Thermal Dish Applications

Abstract

A major challenge facing the development of distributed receiver solar systems is the efficient transport of high temperature thermal energy from the collectors to the point of use. As receiver temperatures increase, conventional sensible (SEN) energy transport methods become less attractive because of increased heat losses and insulation costs. A promising alternative that is particularly attractive for the high temperatures characteristic of paraboloidal dishes and the extensive piping associated with large collector fields is the concept of themochemical (TC) energy transport. Estimates of the performance and economics of 4 SEN and 2 TC transport systems for a dish collector field are compared at 4 delivery temperatures ranging from 400 to 815° C. On the basis of levelized energy cost (LEC), there is no clear choice between SEN and TC energy transport at 400°C. At higher output temperatures, TC transport is more cost-effective and is the only viable choice at temperatures above ∼700° C. The TC system based on the carbon-dioxide reforming of methane has the best performance and lowest costs at temperatures >400°C and appears closest to meeting the DOE Solar Thermal Technology (STT) Program long-term IPH goal of 3¢/kWhth (9$/MBtuth ) LEC.