Hydrogen is a secondary source of energy. It stores and transports energy produced from other resources (fossil fuels, water and biomass). It is a clean-burning fuel, and when combined with oxygen in a fuel cell, hydrogen produces heat and electricity with only water vapor as a by-product. Hydrogen can be made directly from fossil fuels or biomass.

It is the simplest element. Each atom of hydrogen has only one proton. Hydrogen is also the most abundant element in the universe. Hydrogen occurs naturally on earth only in compound form with other elements in liquids, gases or solids. 
Natural gas is currently the primary source of hydrogen production, accounting for around 75% of the annual global dedicated hydrogen production of around 70 million tonnes. This accounts for about 6% of global natural gas use. 

Hydrogen can enable renewables to provide an even greater contribution. It has the potential to help with variable output from renewables, like solar photovoltaics (PV) and wind, whose availability is not always well matched with demand. Hydrogen is one of the leading options for storing energy from renewables and looks promising to be a lowest-cost option for storing electricity over days, weeks or even months. Hydrogen and hydrogen-based fuels can transport energy from renewables over long distances – from regions with abundant solar and wind resources, such as Australia or Latin America, to energy-hungry cities thousands of kilometres away.

Hydrogen 101. Student Energy, www.studentenergy.org