ABSTRACT
Solar energy has a high exergetic value since it originates from processes occurring at the sun’s surface at a blackbody equivalent temperature of approximately 5777 K. Because of this, more than 93% of the energy may be theoretically converted to mechanical work by thermodynamic cycles (Winter et al., 1991) or to Gibbs free energy of chemicals by solarized chemical reactions (Kodama, 2003), including promising hydrogen production processes (Romero and Steinfeld, 2012). According to thermodynamics and Planck’s equation, the conversion of solar heat to mechanical work or Gibbs free energy is limited by the Carnot efficiency, and therefore to achieve maximum conversion rates, the energy should be transferred to a thermal fluid, or reactants, at temperatures close to that of the sun.
