GH2 Facts: CO2 emissions per kg of hydrogen depending on the method of production

The CO2 emissions per kg of hydrogen produced can vary greatly depending on the method of production used.

• Steam Methane Reforming (SMR) is the most common method of hydrogen production, and it typically results in CO2 emissions of around 8-10 kg CO2 per kg of hydrogen produced. This is because the process involves reacting methane (natural gas) with steam to produce hydrogen and CO2. The emissions from this process are directly proportional to the carbon content of the natural gas used.
• Coal Gasification is another method of hydrogen production, it typically results in CO2 emissions of around 14-15 kg CO2 per kg of hydrogen produced. This is because the process involves reacting coal with steam to produce hydrogen and CO2. This method is considered to be highly polluting and energy-intensive.
• Biomass Gasification is a method of hydrogen production that typically results in CO2 emissions of around 2-3 kg CO2 per kg of hydrogen produced. This is because the process involves reacting biomass (such as wood, agricultural waste, or sewage) with steam to produce hydrogen and CO2. The emissions from this process are considered to be low, as the CO2 produced is considered to be "carbon neutral" since it comes from a renewable source.
• Electrolysis of water is a method of hydrogen production that typically results in CO2 emissions of around 1-2 kg CO2 per kg of hydrogen produced. The emissions from this process are directly proportional to the carbon content of the electricity used.
• Photolysis is a method of hydrogen production that typically results in CO2 emissions of around 0 kg CO2 per kg of hydrogen produced. This is because the process involves using solar energy to split water into hydrogen and oxygen, and does not produce any CO2 emissions.

Overall, the most "clean" hydrogen production methods in terms of CO2 emissions per kg of hydrogen are electrolysis of water using renewable energy or photolysis.