Fuel from Heat: Plants grow by using energy from the Sun to convert carbon dioxide into sugar-based polymers and aromatics. These compounds in turn can be stripped of their oxygen, either through millennia of underground degradation to yield fossil fuels, or through a rather more rapid process of dissolution, fermentation, and hydrogenation to yield biofuels. Can we use sunlight to turn CO ₂ into hydrocarbon fuel without relying on the intervening steps of plant growth and breakdown? Chueh et al. (p. 1797 ) demonstrate one possible approach, in which concentrated sunlight heats cerium oxide to a sufficiently high temperature (∼1500°C) to liberate some oxygen from its lattice. The material then readily strips O atoms from either water or CO ₂ , yielding hydrogen or CO, which can then be combined to form fuels.

Concentrated solar energy provides a virtually unlimited source of clean, non-polluting, high-temperature heat. This article reviews the underlying principles of concentrating solar radiation and describes the latest technological advances and future prospects of solar thermal power and thermochemical fuel production.

Solar reactor technology for splitting CO₂via a 2-step thermochemical redox cycle using concentrated solar radiation.