If you have been wondering about this “colour code” used to describe the various fuels proposed at the future fuel to decarbonize shipping, here is your answer:
GREEN OR BLUE ENERGY – WHAT IS THE DIFFERENCE?
When discussing carbon-free fuels such as ammonia and hydrogen, different colour codes are often used to describe how they are produced. Green refers to production with surplus renewable energy, such as wind or solar power, without greenhouse gas emissions. Grey and blue both refer to using fossil natural gas as feedstock, but in the latter, the carbon dioxide produced as a by-product is captured, reducing greenhouse gas emissions. The price of green fuel can be as much as four times higher than that of blue fuel.
Presently, producing green hydrogen through electrolysis, powered by wind and solar power, looks to be the most promising alternative for storing renewable energy. While hydrogen can be stored in either pressurized or liquified form and transported in pipelines, it has some drawbacks – such as the fact that it is explosively flammable. One solution is to convert renewable hydrogen into a more stable fuel such as green ammonia through synthesis, or even as green methanol together with captured carbon dioxide.
Source: Aker Arctic