Re: “four times more voluminous"
> On a long enough timescale the cost of hydrogen goes down, cost of petroleum goes up.
Errrm.....no. 100% opposite. That’s a complete misunderstanding of both chemistry and economics.
Hydrogen is produced by electrolysis of water, and “in future” will use “renewable” electricity of some sort. The *amount of effort required to produce a given amount of hydrogen* goes down, as we invent better ways to produce electricity. Yes. Spot on.
But, once we’ve mastered that, light alkane fraction (or petroleum as you insist on calling it) can be produced synthetically too from “renewable” electricity, water and scrubbing CO2 from air. Petrol is a great *chemical storage medium* of energy, not a magical boogeyman of fossil fuel.
Petrol is more energy dense than hydrogen. It is also more easily handleable, and more easily converted at point of use to usable energy. It is therefore intrinsically more valuable, per joule of energy embodied.
In fact, making hydrogen is a monstrous waste of lovely clean renewable energy. Using electricity to make hydrogen is an eco-crime of the first water (pun fully intended).
Finally - economics. “Cost” relative to dollars is a misnomer. The deeper truth is to count everything in terms of our primary energy source. Today, that is fossil fuel, which means *by definition* the cost of a barrel of oil is one barrel of oil. The true cost of a barrel oil was exactly the same in 1950 as 1974 as 2000 as 2020. It costs a barrel of oil. What has changed is that the dollar has become worth less.
And for example, one barrel of oils worth of energy produced as wind power, *used* to cost 100 barrels of oil, and currently only costs 1.3 barrels of oil.
In the near future, something miraculous happens. One of those renewables crosses over that Cost parity point. Suddenly, that becomes the economic primary energy source, and it becomes the new denominator of true value.
At that point, a litre of petroleum is still worth....a litre of petroleum, because it’s a really great means of running engines. How you produce it, that’s another matter. But *hydrogen*......that becomes ever more expensive. Because as we are able to produce more and more green electricity, and plentiful supply of the good energy transfer medium of petroleum, hydrogen becomes relatively ever more costly relative to that synthetic petroleum.
So, no, you got it absolutely wrong. “The hydrogen economy” is neither green nor cheap, it’s vicious environmental vandalism.