mopani
4 days ago edited

Hydrogen molecules are the smallest in the universe, making it very difficult to make effective seals. First strike.

Hydrogen has an extremely wide flammability range, 4% to 76% of air. Strike two.

While the molar energy density (per molecule) and energy density by weight of hydrogen are exceptional, its volumetric energy density is extremely low, even in liquid form. Compare the size of hydrogen tank to the size of the oxygen tank in the space shuttle. That's one of the primary reasons the SpaceX Super Heavy and Starship rockets use methane instead of hydrogen, because the volumetric energy density is orders of magnitude greater. Strike three.

The Hydrogen energy economy is just another government boondoggle like Solyndra. Attractive on the surface, and sounds intelligent, but ultimately impractical and wasteful.

It's funny actually, if not ironic, that the volumetric energy density of hydrogen is so poor, but as soon as you combine it with some other element, say carbon, its volumetric energy density and practical usability go off the charts! I'm sure some commercial enterprise will discover this and exploit it real soon, and I'm willing to wager that it won't take any government money to build an absolutely booming economy out of it either!!

Just skip the hydrogen! If you're not going to exploit the most efficient energy store in the universe by using a hydrogen compound (hydrocarbons), why do you want to use only half of it, the hydrogen alone?

One should not too quickly dismiss what several generations of the most brilliant minds have already developed and streamlined into an efficient system with sophomoric thinking that somehow believes is an overlooked insight into the fundamentals of the universe.

What is being overlooked is the fantastic energy available from fissioning atoms. The most powerful chemical reaction generates 9 electron volts of energy per molecule. The energy from the fission of one atom (of which there are at minimum three in any chemical reaction) is almost 2 million electron volts. We know how to safely harness an energy source that is six orders of magnitude more powerful than any other, and yet it is rejected. You have to ask why.

"What about the nuclear waste?" It's not waste, it is used fuel, and it can be reused, except that Jimmy Carter, who calls himself a "nuclear engineer" although he never completed the Navy nuclear school, decreed that reusing spent fuel was too dangerous.

Consider too, that nuclear power plants are the only source of energy that completely contain all of their waste/byproducts. The used fuel from all of the nuclear power plants in 70 years of operation in the United States would not fill one single Walmart store.

Annual fuel use for one reactor is 35 tons of uranium fuel -- one semi truck load, although it would only fill a couple of milk crates. The same size coal power plant requires 100 coal cars per day.

Much Hoon, Very Flerp -> mopani
3 days ago

Mo, if you don’t mind my asking, what is it you do for a living? That’s probably the best short form explanation of the issue I’ve ever heard or read. Thank you.

mopani -> Much Hoon, Very Flerp
a day ago edited

Thank you for the compliment. I'm a missionary radio engineer that manages diesel generators and some solar plants because of poor energy supply in Africa.

I've been reading about and studying "renewables" and energy most of my life; I've come to the conclusion that most of the world's leaders are at the energy sophomore phase I was at in high school. Will they ever grow up? Doubtful, to be honest.

If you want a really well-rounded perspective on the whole energy and environment picture and not just the hot takes, read Michael Shellenberger's Apocalypse Never. Fantastic book, and hard to put down! His website is http://environmentalprogres... and is the only thing I've ever seen come out of Berserkely that I could whole-heartedly support. =)

[Edit: I should also give a shout-out to David MacKay's Sustainable Energy -- Without the Hot Air, available on Amazon and online at http://www.withouthotair.com. There is not a better "whole picture" view of energy use out there. ]

One of the best nuclear reactor designs was the Molten Salt Reactor, built and tested at Oak Ridge National Labs from 1965-1969. Thorcon Power wants to mass produce this proven design on a ship-yard assembly line. If CO2 emissions are an existential threat, then we need to be building one hundred 1GW nuclear power plants per year.

A molten salt reactor doesn't need to exchange fuel when the fission product isotopes start to poison the reaction, because the worst poisons ("neutron eaters") are noble gases, and if your fuel is liquid, they can easily be removed instead of being trapped in a solid fuel pellet. So instead of 35 tons of fuel per year, it would only need 1 ton of nuclear fuel per year, and it would extract at least 30% of the potential energy instead of 1%, like the typical Pressurized Water Reactors (Boiling Water Reactors are similar efficiency).

Besides Thorcon's website, visit http://www.daretothink.org to learn more about Molten Salt Reactors; I recommend starting with the "Numbers" page. //

mopani > C. S. P. Schofield
2 days ago
"Hydrogen has its own problems"

Yes, yes it does. It may have the highest energy per molecule, but it is also the smallest molecule, making it very difficult to seal. It also has the worst volumetric energy because of its low density. It's funny how combining it with a couple of carbon atoms fixes that! I wrote a long comment about this the other day on Ward Clark's article about hydrogen.

What would really be interesting, and I think is being ignored for obvious reasons, is hydrocarbon fuel cells, combining the simplicity of the electric drive train with the efficient energy storage of hydrocarbons. It also makes it very easy to make it a hybrid, and if we're wanting to improve efficiency and lower emissions, every vehicle should be a hybrid to recover braking and downhill energy. But hybrids with internal combustion engines add significant complexity.