The solar radiation received on the earth exceeds total annual global energy consumption by a factor of more than 5000.1 Effectively harnessing and utilising solar energy at the gigawatt (GW) and terawatt (TW) scale requires bulk energy storage, time-shifting, and location-shifting of solar output, requiring GW-scale energy storage and long-term time-shifting. Other than pumped storage, which is limited by the availability of environmentally and socially acceptable sites, no other viable and scalable solutions exist today.
Hydrogen is emerging as a scalable and more flexible alternative that is based on the ability to convert sunlight (photons) to electricity (electrons) to hydrogen (protons), which can be stored indefinitely. The hydrogen can be converted to other chemicals (molecules), which can be transported in bulk, as is the case for crude oil, natural gas, and refined petroleum products, making it a versatile energy vector for decarbonisation of hard-to-abate sectors. Like fossil fuels - which are formed by a combination of solar, biomass, geothermal energy, and geologic time-hydrogen is an energy carrier. Solar-to hydrogen mimics the natural processes that create fossil fuels, and potential uses of solar hydrogen mimic the existing global hydrocarbons business.
