Sunday, July 12, 2009

H Is For Humble Hydrogen

The sun consumes about a half billion tons of hydrogen every second, fusing mass into helium and radiating the excess as energy. We just sit back on sunny days and bask in the afterglow of the nuclear holocaust at a very safe distance, thinking nothing of it. Our nonchalance towards any solar dimming is justified by considering that the sun should last another 5 billion years or so.

Hydrogen fuel cells (chemical, not nuclear) are already used in spacecraft, and modern rocket engines burn liquid hydrogen and liquid oxygen. But back on earth, there is talk of using hydrogen as an energy source to replace hydrocarbon fuels. Hydrogen gas burns cleanly, as the very name reminds us: hydrogen = water generating; the catch is that hydrogen gas has to be made because little is found naturally on earth.

By far the cheapest way to make hydrogen gas is from natural gas, CH4, using a process that co-produces CO2 (the carbon atom has to go somewhere). But another little appreciated fact is that a big consumer of hydrogen gas is the fertilizer industry—hydrogen is used to make ammonia from nitrogen—and another big user is the food industry—it is used it to hydrogenate vegetable oils. Any large-scale diversion of existing hydrogen to transportation fuels will ultimately raise the price of food via the costs of ammonia fertilizer and food processing costs. Sound familiar?

What’s really needed is a new and different way to cheaply make hydrogen gas—something like the efficient photolysis of water or the electrolysis of water using electricity from nuclear power plants. Both technologies exist, but they are economic nonstarters. For my money, I’d rather see cars run on methane, rather than going through the additional process hoops of converting the methane to hydrogen gas. A similar argument holds for bio-fuels, which I will discuss when I get to carbon and oxygen.

Hydrogen is the most promiscuous chemical element, pair bonding with nearly every element and even forming special bonding threesomes called hydrogen bonds. Hydrogen bonds are the principle force binding the two strands of DNA together. Arguably, hydrogen bonds are present at the conception of human life: when the two single strands of DNA, one from the mother, one from the father, join for the first time, those strands are united by about 3 billion hydrogen bonds. Each one is worth a small amount, but together, summed over the entire double helix, amounts to a formidable binding glue.

The themes of family and weak and strong chemical forces reminds me of some lines from the David Lynch movie “The Straight Story." Richard Farnsworth says (while demonstrating with sticks):
When my kids were young I played a game with them. I'd give each of them a stick. One for each of 'em, and I'd tell them to break it. They'd do that easy. Then I'd tell them to make one bundle of all the sticks and try to break that. And course they couldn't. I used to say that was family, that bundle.


  1. I remember this 8th grade science experiment. We dissolved shells in HCl and captured the resulting gas. Then we inserted a glowing wooden stick in the gas and it burst into flames. Very good indicator of why zeppelins fly on Helium and not Hydrogen anymore. Oh, the humanity!

    Can you explain why Helium affects voices the way it does?

    Excellent beginning! I never saw the 'generating of water' part, but I'll always remember you for it. 2nd grade son starts chemistry this year at co-op. We're using a new homeschool program: Real Science 4 kids. Mom, a PhD in biochem, didn't like the curricula available, so she wrote her own. Awesome and not dumbed down.

  2. when the two single strands of DNA, one from the mother, one from the father, join for the first time, those strands are united by about 3 billion hydrogen bonds.

    You get many chromosomes from each parent (composed of double strands of DNA), not single stranded DNA. And the two parent's chromosomes don't bind to each other.

  3. @Ruth Anne: I recall that helium voice change experiment from an undergraduate physics class. The simple answer is that the frequency (pitch) of your voice changes simply because of change in gas density. Helium, being much less denser than air, changes the frequency upwards to higher pitch. In theory, you could go the way and lower your voice by breathing and talking with a heavier than air gas such as Xenon. However I wouldn't recommend it because of the suffocation danger of exhaling a heavier-than-air gas.

  4. @Jason: The problem I have with your excellent retort is that the intimate mechanism of chromosomal cross-over--genetic exchange of parental DNA--does involve the two strands unwinding and recombining. See for example here.
    I do apologize for misleading or oversimplify things to the point of absurdity. I’ll give you another example from my post: The sun cannot make helium from hydrogen directly, but rather must go through an intermediate isotope of hydrogen, i.e., deuterium. I thought about including that factoid (because I happen to appreciate deuterium), but decided to leave it out.
    In any case I’m grateful for your comment because it spurred me to think more about what I wrote.

  5. @Jason,

    In retrospect I should have avoided the whole single strand/double strand thing and just noted that the hydrogen bonds in the double helix do an excellent job of protecting genetic information (i.e. family) during the lifetime of the cell. That would have been just as good of an analogy to the Farnsworth quote, which was what I was looking for anyway.

  6. In retrospect I should have avoided the whole single strand/double strand thing

    No, it's a good example! It's the teleology, the narrative (?), you are adding that causes problems.

    I was a biology major and I'll be the first one to say that the terminology around chromosomes is a little crazy.

    A double strand of DNA can be a chromosome, but if you link it with an identical copy, THAT mass can be called a chromosome. And you'll see pictures of a chromosome linked with an identical copy next to a similar, but not identical chromosome (with its own identical copy) all given the same label!

    There's no room for romance in Biology, and we're probably the single field most antagonistic towards it:

    We've had the Creationists after us ever since Darwin; tons of people die by our hand (still do); and theories thrown out because of "bad science" (still happens).