Entry 2230, on 2022-08-09 at 15:48:17 (Rating 2, Science)
A friend recently asked me to write a blog post about hydrogen. That may seem like an odd subject, but why not? It's the first element in the periodic table, and the most widely distributed in the universe. Actually, the subject isn't really hydrogen in general; it is more about the use of hydrogen as an energy source.
Hydrogen has three times the energy density of petrol (by weight), so it would seem like an ideal fuel to use in internal combustion engines. More importantly, the only end product of burning hydrogen is water. Burning petrol, which is an very complex combination of different molecules, produces many products, many of which are dangerous (for example, carbon monoxide) and others which contribute to global warming (mainly carbon dioxide).
Note that hydrogen is just hydrogen, an element, and it cannot produce any carbon products because they're just not there to begin with. I understand that contaminants in the hydrogen or the air used to support combustion can cause small amounts of pollutants, but these are so trivial that we can ignore them.
In addition, hydrogen can be easily used in fuel cells which chemically "burn" the hydrogen to produce electricity which can then be used to power electric engines in cars and for other applications. Basically, the hydrogen tank is used instead of batteries.
There are other situations too, where battery electrical systems are not ideal. For example, electric aircraft have not been conspicuously successful, but hydrogen powered jets are a genuine option.
Finally, hydrogen is by far the most common element in the universe. Because it reacts so violently (which is what we want to produce energy) and because it is so light that it tends to escape the Earth's atmosphere, we rarely see it in its pure form, but there is plenty around, because water is H2O, two hydrogens bonded to one oxygen. In fact, water is the product we get when we burn hydrogen in oxygen.
But there's one problem: the energy we get when burning hydrogen to produce water is exactly what we need to separate those two atoms (three is you count the two hydrogens and one oxygen) again. And because of unavoidable inefficiencies in that process (don't you just hate entropy) we actually need to put more power in to the process to separate the oxygen and hydrogen than we get when we recombine them by burning the hydrogen.
So that makes hydrogen a way to store energy. You use a certain amount of energy to produce the hydrogen, store it until you need it, then release that energy again in an engine. Inefficiencies in the process mean you get nowhere close to 100% of the energy back again, but that is the case with every storage system.
There are other sources of hydrogen though. It can be produced through a reaction involving natural gas. But hydrocarbons use is exactly the problem that hydrogen fuel is supposed to solve, so that seems counter-productive.
Another problem is that hydrogen is a gas and fossil fuels are mostly liquids. It is much easier to store a liquid than a gas, which to get a reasonable amount in a small volume, must be compressed to very high pressures, making it both difficult and potentially dangerous.
I don't think any of these problems are insurmountable, but those who are fans of hydrogen often don't have good answers.
Despite all of the issues I have mentioned, I think hydrogen is worth considering as a fuel in the future, as long as one other technology becomes available and acceptable: nuclear power, preferably fusion.
Nuclear fusion is the ultimate energy source. We can have a basically unlimited amount of power with few dangerous waste products produced. We will never run out of fuel, because fusion utilises our old friend hydrogen. I know there are other forms of fusion too, using different elements, but I'm sticking to hydrogen for this discussion.
Nuclear power has got a bad reputation because of accidents like Three Mile Island, Chernobyl, and Fukushima, but looking at the history of power generation, nuclear is actually the safest and has caused the least number of deaths. More people have died falling off roofs installing solar power than have died from radiation after a nuclear accident. And more people die from radiation poison from trace elements escaping coal plant chimneys than from nuclear stations.
Really, the objection to nuclear is based on ignorance, especially amongst environmentalists. If we accepted nuclear power, many environmental issues could be solved, but the greenies are more interested in ideology than truth.
We should also note that modern nuclear power plants are far safer and more efficient than anything we have had in the past, especially the older, poorly run plants at Chernobyl and Fukishima.
And I am advocating for fusion (a process not commercially available yet) which has three advantages over fission (the existing nuclear energy process we use). First, it is safer. Fusion only occurs at huge temperatures and pressures. Any problem tends to break the reactor, reducing the temperature, and stopping the process, because it isn't a chain reaction. You can't have a meltdown. Secondly, hydrogen is incredibly common where uranium is quite rare, so the fuel source for fusion will last forever. Third, the amount of energy produced by fusion is incredible; millions of times more than chemical reactions like burning coal. However fission is almost as good in this regard (about 4 time less).
So we could have nuclear plants generating hydrogen by electrolysis of sea water, and the hydrogen could be burned or used in fuel cells for most energy needs. Of course, the nuclear plants could produce electricity directly too, to power battery powered cars, especially if battery technology improves significantly.
In summary, hydrogen is worth considering as one possible energy source, but we need nuclear to make it work. Actually, we need nuclear to make anything work in the future, in my opinion.
Finally, I did this post from memory of my reading on this topic. If you notice any errors, or want to disagree for some other reason, please let me know in the comments.
Comment 1 by Allan on 2022-08-10 at 10:36:46:
A most interesting analysis Owen
Comment 2 by OJB on 2022-08-10 at 11:57:14:
Thank you. Some of it might even be true! :)
Comment 3 by Anonymous on 2022-08-10 at 16:03:49:
Now you have me worried. I had always thought that with the research you do that I could accept the statements in your Blog with complete confidence.
Comment 4 by OJB on 2022-08-10 at 16:09:13:
Never accept anything with complete confidence, especially in a blog. I see this as a place for opinions, which I hope are based on facts and sound reasoning, but who really knows. That’s why I allow all comments: just for the unlikely case I am wrong!
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