Hydrogen can be made by a number of processes:

• Electrolysis: using electricity from renewable resources such as wind power, hydro-power and solar photo-voltaic cells to separate water into Hydrogen and Oxygen
• The direct splitting of water using light. This method produces no carbon dioxide
• Biomass conversion: using micro-organisms to convert sewage into Hydrogen. This method does produce carbon dioxide, but it is all recycled through the growth of more biomass
• Reformation: converting natural gas into hydrogen