Solar chemical

[1] A promising approach is to use focused sunlight to provide the energy needed to split water into its constituent hydrogen and oxygen in the presence of a metallic catalyst such as zinc.

The benefit of this approach is that there is an established infrastructure for transporting and burning methane for power generation, which is not true for hydrogen.

As early as 1909, the dimerization of anthracene into dianthracene was investigated as a means of storing solar energy, as well as the photodimerization of the naphthalene series.

If the activation energy is too small the fuel will tend to spontaneously move to the more stable state, providing limited usefulness as a storage medium.

Research into both the azobenzene and norbonadiene-quadricyclane systems was abandoned in the 1980s as unpractical due to problems with degradation, instability, low energy density, and cost.

[5] With recent advances in computing power though, there has been renewed interest in finding materials for solar thermal fuels.

The CNT substrates will allow customizable interactions between neighboring molecules which greatly helps in fine tuning the properties of the fuel, for example an increase in the amount of energy stored.

This system provides an energy density comparable to lithium-ion batteries, while simultaneously increasing the stability of the activated fuel from several minutes to more than a year and allowing for large numbers of cycles without significant degradation.

Such units range from portable stoves or small personal heaters that can be charged in the sun to providing medical sanitation in off-grid areas.