Hydrogen storage, page-5

Some definitions from https://utilityanalytics.com/2020/10/the-colors-of-hydrogen-brown-grey-blue-and-green-think-about-it/

"Hydrogen, in itself, is a clean fuel. Manufacturing hydrogen fuel, however, is energy-intensive and has carbon byproducts. What is now called brown hydrogen is created through coal gasification. The process for producing grey hydrogen from natural gas throws off carbon waste. Blue hydrogen uses carbon capture and storage for the greenhouse gases produced in the creation of grey hydrogen.2 Green hydrogen production – the ultimate clean hydrogen resource – uses renewable energy to create hydrogen fuel. For example, water electrolysis used to produce long-duration hydrogen energy storage requires a lot of energy. That energy could come from renewables.

Wood MacKenzie has predicted that green or low-carbon hydrogen will become cost-competitive by 2040, given increased scale and lower costs of renewables, along with higher costs for producing brown, grey and blue hydrogen. That seems like a long way off. Still, utilities are no strangers to long-term planning."