Hydrogen — a “bomb” or a “temporary plumb”?
In recent climate change-obsessed decades hydrogen got a lot of attention as a clean fuel of the future. But will it really live to the hype? Let’s find out!
In its free form hydrogen is an extremely volatile, odorless and colorless gas. But you won’t find it in its free form on Earth. Why? It is so light that it can easily escape the Earth’s gravity and get blown away by the solar wind. Also, this cutie is very eager to engage in close relationships with other elements, thus it is more likely to be involved in some sort of reaction even before it flies away from the planet.Therefore, all of the hydrogen on Earth is chemically bound and its prevalent form is water, H2O. Water is, to say the the least, so abundant on our planet that we have endless supply of hydrogen.
Also, it is the most abundant element in the Universe, so future space colonies will have it as well. Hydrogen is present in absolute majority of organic compounds, mainly bound to carbon atoms.
The reason why hydrogen is so attractive as a “green” fuel is that burning of hydrogen results in water, just pure water, the one you can safely drink. It has as well some other benefits such as being the most energy-rich fuel per molecule burned. The most potentially powerful chemical engines are the hydrogen ones. Saturn rockets from Apollo Moon missions burned hydrogen, precisely it.
Any hydrogen-eco-fan will point out that hydrogen can be obtained in a super environmentally-friendly way: via the electrolysis of water. Basically, if you pass electric current through water, hydrogen will be released from that water on the cathode. Certainly, electricity for such a noble purpose should come from clean sources.
A lot of interest, effort and most importantly investment to the hydrogen research came from the automobile industry and from the big oil companies. We’ll understand why later on Honda developed Clarity FCX and Clarity FCV hydrogen cars which are sold now in Japan and the US. Honda also offered the customers a Home Energy Station that can produce hydrogen at the owner’s proper home.
Toyota also stepped in with a hydrogen car — Mirai, available from the 2014. The Japanese automaker’s efforts are supported by Shell, which started to develop a network of hydrogen filling stations in the US and the UK. Toyota, Shell, Total SA, Liquide SA and Linde AG created the global hydrogen council with plans to invest about 10,7$ billion into hydrogen over the next 5 years.
Besides from being used as fuel for cars, hydrogen is a promising option for aicraft. Now there is already a small 4-seater plane HY4 running on hydrogen fuel cells.
Sounds good, doesn’t it? But don’t get excited just yet. Hydrogen has some major drawbacks and you probably won’t feel easy with them.
Hydrogen is very light, 22 liters of gaseous hydrogen weighs only 2 grams. This volume gives 286 kilojoules during combustion. For comparison, 22 liters of gasoline gives around 16280 kilojoules, which is 57 times more. That means, in order to store considerable amounts of hydrogen you would either need to compress it (300–700 atmospheres) or cool it to a liquid state (-252 degrees Celsius).
Both processes are incredibly energy-consuming and rather complicated. What is funny is that even liquid hydrogen contains less hydrogen than the exact same volume of gasoline.
More than that, since its molecules are so tiny, they can escape from the steel tank just by passing through the walls of the vessel, like water escapes the mesh. Extreme flammability of hydrogen adds up to the problems of storage and transportation.
The famous catastrophe of Hindenburg airship which has sent this kind of transportation to oblivion is quite illustrative.
Nowadays hydrogen is mostly obtained from natural gas and oil through pyrolysis process. That is why oil companies are interested in it. In fact, the aforementioned Honda’s Home Energy Station works on natural gas.
Why not on water, you would ask?
Water electrolysis is quiet an energy-expensive process itself, moreover ‘demanding’ hydrogen needs only pure water. If there’s any salts or other substances (which is always the case with the natural water), hydrogen simply won’t be released. So prior to electrolysis one needs to purify water thoroughly.
Numbers speak for themselves, as in 2017 the optimistic plan is to sell around 3000 hydrogen cars in US by Honda and Toyota (according to NY Times).
Compare that to 10 000 battery electric cars sold in just first quarter of 2017 solely by Tesla!
Space industry is also not eager to adopt hydrogen fuel due to its low density and storage problems. SpaceX is now testing its new methane/oxygen engines for future Mars missions, reasoning it with the lower cost of fuel, ease of handling and storage, possibility to produce fuel rather easily on Mars and better mass/size/power ratio of the methane rocket compared to that on hydrogen.
Hydrogen perspectives now seem uncertain, especially as a “green” fuel. The process of its extraction is expensive, complicated and not that environmenally-sound, transportation and storage are as well sophisticated and relatively dangerous. Infrastructure of hydrogen fueling stations is limited, as there are now only around 30 of them in the USA. Battery-powered electric cars seem to be more convenient and practical options than hydrogen ones. Space industry is more eager to adopt methane or kerosene.
Speaking of fuels being “green”, both kerosene and methane can be produced via biotechnology, leaving zero carbon footprint.
Still, hydrogen could be a viable option for airplanes and can become really ecological and cost effective if massive and cheap power sources are available (yes, I’m looking at you, nuclear fusion power) for water treatment and electrolysis.
In that case hydrogen from electrolysis will serve as an energy storage between power plant and vehicle.
To sum it up, if you are now looking forward for a hydrogen-powered car to go green you’d better look at some Tesla or Renault Zoe instead.
Nota Bene: Hydrogen is probably most renowned as the main component of hydrogen bomb but don’t be confused: nuclear reactions with hydrogen occur only under temperatures of millions degrees and pressures comparable to those inside the Sun.
Actually, to make hydrogen explode as a nuclear bomb you would need to compress it first with the power of a plutonium nuclear bomb! That is exactly how the hydrogen bomb works.
Author: Ruslan Rodriguez
