Hydrogen's Coat of Many Colours

Hydrogen is the most common element in the Universe. It's now being much touted as an AI-encouraged investment and as the 'fuel of the future'. Hydrogen's unique selling point is that, when it burns, only water is produced. So, why the proliferation into blue, grey, brown, pink and green hydrogens? (https://www.theguardian.com/environment/2023/mar/07/hydrogen-clean-fuel-climate-crisis-explainer). Hydrogen, irrespective of its colour code, is hydrogen. The labels are derived from the source materials and energy sources used to extract useable gas. Ninety-six percent of the current hydrogen fuel comes from coal (brown hydrogen), natural gas (grey hydrogen) or nuclear (pink hydrogen). The first two both generate carbon dioxide. Extraction of petrochemicals (including oil and natural gas) risks also releasing methane into the atmosphere. We really don't need higher concentrations of either 'greenhouse gas'. Blue hydrogen is the 'baby' of the fossil fuel companies. The hydrogen is still extracted from gas but its advocates claim that any carbon dioxide produced would be captured for underground storage (in disused oil wells?). There's, however, considerable debate about how efficiently carbon capture could (or would) be done. Green hydrogen is the only form of the gas that unequivocally doesn't add to 'greenhouse gas' emissions. It's obtained by hydrolysis of water, exclusively using renewable sources of electricity. This effectively means using solar power (photovoltaics), as wind turbines are intermittent. What you need is a sunny location, with a plentiful supply of freshwater. Tunisia has been suggested as suitable but that country could only obtain sufficient water by desalinating seawater. Desalination is very energy intensive and generates a sludge whose disposable would be problematic. Transporting even green hydrogen for its use in other locations, would generate 'greenhouse gas' emissions. So, what's the future of 'the fuel of the future'? Most scientists, without fossil fuel links, believe that hydrogen will play an important role in energy-intensive processes, such as the production of steel and pharmaceuticals. They do not think, however, (unlike 'big oil') it can ever be a valid replacement for petrol, diesel and kerosine in transport. This one, as they say, 'will run and run'.