Solar photoproduction of hydrogen. IEA technical report of the IEA Agreement of the Production and Utilization of Hydrogen.

摘要

The report was prepared for the International Energy Agency (IEA) Hydrogen Program and represents the result of subtask C, Annex 10 - Photoproduction of Hydrogen. The concept of using solar energy to drive the conversion of water into hydrogen and oxygen has been examined, from the standpoints of potential and ideal efficiencies, measurement of (and how to calculate) solar hydrogen production efficiencies, a survey of the state-of-the-art, and a technological assessment of various solar hydrogen options. The analysis demonstrates that the ideal limit of the conversion efficiency for 1 sun irradiance is (approximately)31% for a single photosystem scheme and (approximately)42% for a dual photosystem scheme. However, practical considerations indicate that real efficiencies will not likely exceed (approximately)10% and (approximately)16% for single and dual photosystem schemes, respectively. Four types of solar photochemical hydrogen systems have been identified: photochemical systems, semiconductor systems, photobiological systems, and hybrid and other systems. A survey of the state-of-the-art of these four types is presented. The four types (and their subtypes) have also been examined in a technological assessment, where each has been examined as to efficiency, potential for improvement, and long-term functionality. Four solar hydrogen systems have been selected as showing sufficient promise for further research and development: (1) Photovoltaic cells plus an electrolyzer; (2) Photoelectrochemical cells with one or more semiconductor electrodes; (3) Photobiological systems; and (4) Photodegradation systems. The following recommendations were presented for consideration of the IEA: (1) Define and measure solar hydrogen conversion efficiencies as the ratio of the rate of generation of Gibbs energy of dry hydrogen gas (with appropriate corrections for any bias power) to the incident solar power (solar irradiance times the irradiated area); (2) Expand support for pilot-plant studies of the PV cells plus electrolyzer option with a view to improving the overall efficiency and long-term stability of the system. Consideration should be given, at an appropriate time, to a full-scale installation as part of a solar hydrogen-based model community; (3) Accelerate support, at a more fundamental level for the development of photoelectrochemical cells, with a view to improving efficiency, long-term performance and multi-cell systems for non-biased solar water splitting; (4) Maintain and increase support for fundamental photobiological research with the aim of improving long-term stability, increasing efficiencies and engineering genetic changes to allow operation at normal solar irradiances; and (5) Initiate a research program to examine the feasibility of coupling hydrogen evolution to the photodegradation of waste or polluting organic substances.