* Electrolysis of water for hydrogen production combined with solar photovoltaics using alkaline, PEM, and SOEC electrolyzers; This basic use of solar light generated electric power to separate water into hydrogen and oxygen has proven a little bit more efficient than for example hydrogen capture by steam reforming. The alkaline production technology of hydrogen has low costs and is considered mature. This has a consequence that the yield per unit of time is significantly higher than when using PEM technology. However, PEM technology has no corrosion issues and is more efficient, whereas alkaline production technology has the disadvantage of corrosion and worse efficiency. In addition to that, PEM technology has a fast start-up and simple maintenance. Though, in bulk production the alkaline hydrogen production technology is superior.
* Heliogen claims success in the use of solar heliostats used to direct sunlight to a tower, to reach temperatures over 1000°C in the production of hydrogen. Temperatures above 2500°C can thermochemically split water into hydrogen and oxygen without the use of electricity. This can be done using the heat of nuclear power plants or by adaptive solar mirror fields to redirect the sunlight to reach high temperatures needed for these thermochemical processes. However, this way of producing hydrogen is in its infancy and it has not yet been proven that this production hydrogen is profitable and efficient, because it has to compete with other, mature technologies.