Why is everybody talking about hydrogen?
Hydrogen is an environment and climate-friendly (zero-emission) energy carrier. Produced from renewable energy sources (RES), e.g. sun and wind energy, hydrogen has significant potential to completely replace fossil-based energy and thereby avoid all the related CO2 emissions.
Green Hydrogen is hydrogen produced through electrolysis from renewble energy sources such as photovoltaic , on-shore and off-shore wind, hydroelectric plants or similar. Since neither the production of renewable energy nor the conversion to hydrogen create any CO2, green hydrogen is emission free and has zero GHG footprint.
Grey Hydrogen is produced from natural gas (=methan, CH4) through an industrial process called Steam Methane Reforming (SMR) . During this process, 10 kg CO2 is created for each 1 kg of hydrogen. When this CO2 is emitted into the air, the resulting hydrogen has a high GHG footprint. When at least 60% of this CO2 are captured and either used or stored (CCU/CCS) the resulting hydrogen is called blue hydrogen. Blue hydrogen has a lower GHG-footprint – 4kg CO2 per kg of hydrogen or less – than grey hydrogen, but it is more costly to produce. The bigger the share of CO2 removed, the higher the value for the climate, but the higher also the cost.
When hydrogen is produced from electricity other than renewables, the electricity entails CO2 emissions and the resulting hydrogen is then not CO2 emission free. The GHG-footprint resulting from using not renewable hydrogen depends on the electricity type. based on the average EU electricity ix, the emissions are 38,4 kgs of CO2 for each kg of hydrogen produced. For the ultimate goal of emission reductions it is important to use RES.
When producing hydrogen from biogas (usually also through SMR) there is no additional GHG-footprint since the CH4/CO2 would have been emitted to the atmosphere anyway.. So the contribution form the source of the input gas to the hydrogen production process is „net-zero“. There is however still emissions stemming from the production process so the resulting GHG footprint is ca. 2 kg of CO2 emissions for 1 kg of hydrogen produced through this method.
The below graph gives a comparison of the resulting GHG emissions The first bar in the chart is 0, it comes from green hydrogen