Today, hydrogen is mainly produced from natural gas, but can also be produced from electrolysis.
Depending on if the CO2 from this production is captured, the hydrogen is often called blue or gray, whereas blue hydrogen is where the C02 is captured and stored. Hydrogen from natural gas is made by steam methane reformating (SMR). Water electrolysis is a well-known technology that has been used in Norway on an industrial scale since the start of Norsk Hydro production from facilities at Rjukan in 1940 and Glomfjord from 1953. Hydrogen produced from electrolysis with renewable energy is called green hydrogen.
The electrolysis process needs electrical power.
Water is applied an electric charge, and water molecules are split into hydrogen and oxygen, as seen in the figure. If the applied electricity is from hydropower, solar, or wind turbines, the hydrogen is completely C02-free and called green hydrogen. Producing hydrogen from surplus power, such as wind or small unregulated power, is, therefore, a smart way to store energy that would otherwise be lost.
Hydrogen is a colorless and odorless gas.
Hydrogen is a gas that is lighter than air and rises. It is not dangerous in itself, but there is a risk similar to other energy-rich gases when pressurized. In Norway, we have almost 100-years of experience in handling hydrogen on a large scale. Hydrogen is a safe gas to produce, store, and use with solid risk evaluation studies.
The efficiency of electrolyzers is increased.
New electrolyzer technology is being developed, and the energy consumption is expected to reach 50kWh/kg H2 at the plant level within a few years. For the production of 1 kg H2, around 10 L of water is needed. Around 8 kg of oxygen (O2) is produced per kg hydrogen produced, and around 10kWh of potential heat per kg hydrogen.