Integrated solar thermochemical cycles for energy storage and fuel production

Abstract

Integrated solar thermochemical cycles comprise a range of promising novel process technologies that use concentrated solar energy to drive endothermic chemical reactions at elevated temperatures. The most promising application is the production of carbon-neutral fuels, particularly via single or multistep water and CO 2 splitting or via the solar thermochemical upgrading of carbonaceous fuels such as biomass, waste, or oil residues. Furthermore, intermediate storage of solar energy in reversible reactions, the so-called solar thermochemical heat pipes, shows great promise to replace latent heat storage for concentrating solar power generation. Potential niche applications are material processing and material testing. Widespread deployment of solar thermochemical cycles hinges on the development of several key technologies: (i) reaction systems and catalysts able to endure tens of thousands of conversion cycles without significant degradation, (ii) reactors and heat recuperation systems that fully exploit the theoretical potential of solar thermochemical cycles, (iii) industrial-scale reactor technologies, and (iv) process control technologies that address the inherently transient nature of solar power. C 2012 John Wiley & Sons, Ltd.

Syngas and Synfuels from H2O and CO2: Current Status

“…Fuel production is the central objective of most solar thermochemistry research 142. The single‐step thermal dissociation of H 2 O or CO 2 , known as solar thermolysis, has been impeded by the need to operate at very high temperatures (above 2500 K) for achieving a reasonable degree of dissociation, and by the need of effective techniques for separating H 2 and O 2 or CO and O 2 at high temperatures to avoid ending up with an explosive mixture 143, 144.…”

“…Status reviews on multi‐step cycles are given by Serpone et al 154, Funk 155 and Petrasch 142. All of these cycles are complex; most suffer from unfavorable thermodynamics or kinetics.…”

Multiphase ultra-low grade thermal energy storage for organic Rankine cycle

“…Most require storage of gases at dangerously high pressures and temperatures, some require potentially dangerous, flammable, or corrosive chemicals, and most require very high temperatures and the facilitation complex chemical reaction pathways . Using high temperatures to produce fuels creates a TES media that is very portable, stable, and does not require significant insulation but suffers the same disadvantages as other thermochemical storage options and has the added disadvantage of low net energy efficiencies, sometimes in the low single digits . All forms of thermochemical TES are in the early stages of research and are far from commercialization.…”

Modeling of Ceria Reduction in a Solar Thermochemical Reactor via DEM Method

“…Non-stoichiometric CeO2 (CeO2-δ) was proposed to solve the issue of melting at high temperature. Based on the two-step thermochemical process, the reactions can be represented by [21,22]. At 1500 and 0.1 mbar O2 partial pressure, the enthalpy change of ceria reduction is around 475 kJ per half mole of O2 [21].…”

“…Based on the two-step thermochemical process, the reactions can be represented by [21,22]. At 1500 and 0.1 mbar O2 partial pressure, the enthalpy change of ceria reduction is around 475 kJ per half mole of O2 [21]. Therefore, the reaction enthalpies to generate one mole of CO and H2 are estimated -192 kJ/mol and -233 kJ/mol.…”