By Kelvin Kemm
At a shopping mall or amusement park one can see vendors selling balloons filled with Helium. Kids love them and dance around trailing their balloons, which float above them. From time to time some kid accidentally lets go and you see the balloon soaring high into the sky, to the delight of many watching, but to the heartbreak of the kid. The balloon soars up into the sky because it is filled with Helium, and Helium is a gas much lighter than the Oxygen and Nitrogen which make up most of the atmosphere.
Atoms are made-up of a nucleus, and electrons which orbit around the nuclei, Each nucleus is composed of neutrons and protons. The mass of each atom is essentially the mass of the total number of neutrons and protons in a nucleus. The scientifically quoted masses are not whole numbers because the atoms of a single element have slight variations in the number of neutrons. These variations are called isotopes. So, the quoted mass of Oxygen, for example, is 15.999 which is not a round number. But for now, I will just use the closest round number, so Oxygen will be 16. These numbers are measured in Atomic Mass Units, so Oxygen is 16 amu. Nitrogen is 14, and Helium is 4. As you can see, the Helium is way lighter than Oxygen or Nitrogen, and that is why a Helium balloon shoots up into the sky so fast when the kid lets go. But there is an additional factor, and that is that in nature the atoms exist as molecules. Both the Oxygen and Nitrogen molecules consist of two atoms each, but the Helium molecule is only one atom. So, the molecular masses in the air are actually; Oxygen 32, Nitrogen 28, and Helium is still 4.
Golf balls in a fishing net
But now a universal disappointment for kids. The kid has fun with the balloon all day, and then usually ties it to a chair so that he can play with it again in the morning. But when he comes to look at it in the morning it is nearly flat and typically lying on the floor. This disappointing sight then generates much discussion as to what went wrong during the night. The answer is quite simple. The Helium atom is not only light in mass, but is also very small in comparison to the Oxygen and Nitrogen atoms. It is like comparing a soccer ball and a golf ball, if you are looking at Oxygen and Helium. In fact, two soccer balls glued together, because the Oxygen has to exist as a 2-atom molecule. Imagine filling a fishing net with pairs of soccer balls glued together. You can easily carry a whole load of double soccer balls in a fishing net with no problem. But you can’t fill the fishing net with a load of golf balls, because they will all fall through the net holes. In the case of a balloon the wall of the balloon is not solid, it is in effect a net. The spaces between the big molecules which make up the balloon are small enough that Oxygen and Nitrogen can’t get through, but Helium can. So what actually happens during the night, is that the Helium just leaks out through the wall of the balloon, much to the disappointment of the child.
These difference in sizes of the molecules also present problems in industry. Pipelines which have joints, valves, and all sorts of steps in a production process will readily contain Oxygen or Nitrogen, but can very easily leak Helium. So, making a Helium pipeline is far more difficult than making an Oxygen pipeline.
Hydrogen heartache
But now let us turn our attention to Hydrogen. The atomic mass of Hydrogen is 1, and yes, in nature, Hydrogen exists as a 2-atom molecule, which means that its molecular mass is 2. So, Hydrogen comes out way smaller even than Helium. So now just imagine the industrial challenges of moving Hydrogen around and trying to store it. If Helium leaks out of a pipeline joint which has not been tightened correctly it is a nuisance because it costs the production company money for lost Helium. But if Hydrogen leaks out, it’s even worse because Hydrogen can explode or burn.
For a while now there has been much hoopla in the media about Hydrogen as a fuel, and how wonderful it is. Hydrogen has been known for centuries, so how come nobody came up with this idea long before this? Think about that. This whole Hydrogen thing came about as a result of the politically induced introduction of solar and wind energy all over the place. The big downside of solar and wind is that they are highly intermittent and therefore unreliable. In the case of solar, you quite likely get excess over lunch time but then nothing as the Sun goes down. This was clearly a serious limitation of solar power. So in Germany, under political inducement, the scientists came up with the idea of taking the surplus solar at lunchtime and storing it so that you could use it as dinner-time approaches.
The one method of storage proposed was to take the surplus solar and put it through a water electrolyzer which breaks the H2O water molecule into Hydrogen and Oxygen. You then store the Hydrogen until later in the day and then burn it to recreate the excess electricity collected at lunchtime. Sounds great, but that’s an incredibly complex route. Firstly, there’s a law of physics that says that every time you change energy from one type to another, you lose some of it. So, each one of those changes loses energy and therefore pushes up the price of the remaining energy.
As we have already found out, storing and transporting Hydrogen is extremely difficult, requiring much higher specifications than storing or moving Oxygen or Nitrogen. The costs of installing a Hydrogen transport and storage system are way higher than for Oxygen or Nitrogen.
But it gets a lot worse.
Ice blocks are hot in comparison
To store even a moderate amount of Hydrogen energy requires a large volume. To make storage practical, Hydrogen must either be compressed to very high pressures, or cooled to extremely low temperatures until it becomes a liquid.
Both methods require expensive equipment. High-pressure tanks must be specially designed to very high specs.
Liquid Hydrogen requires temperatures close to minus 2530 Celsius, and needs advanced insulation. Transporting Hydrogen is also clearly very difficult.
Hydrogen fuel is absolutely not a fantastic new scientific development. It was known a couple of centuries ago. The reason why people didn’t use it in the past was because of all the practical difficulties of industrialising and retailing Hydrogen gas. It has been brought into the popular media now because of the political need to solve the intermittent nature of wind and solar. Hydrogen is not being developed because it’s a good engineering idea but because of desperation to try and make the financial equations of variable excess solar and wind become a bit more palatable to the consumer. The whole problem is compounded manyfold more when one talks of producing vast volumes of Hydrogen in African countries and then transporting it to Europe.
So when you see excited chats about the glories of Hydrogen in the media, bear in mind that Hydrogen as a fuel was created as a political response to the politically induced problem of the huge variability of solar and wind. Solar and wind were thought up as a response to the political reaction to a perceived fear of global warming and climate change. The Hydrogen issue was never developed by scientists and engineers in response to a genuine engineering requirement.
