Plastics, oil, petrol– the modern world is entirely dependent on hydrocarbons. The good sources are slowly running low and supply is increasingly complicated by geopolitical factors we really don’t want to get into, but hey! It’s just hydrogen and carbon, right like it says in the name. How hard could it be to roll your own at home. Well, if you’ve got a lab like [Marb]’s Lab on YouTube, it might just be doable, as he demonstrates in his latest video.
The Fischer-Tropsch reaction was discovered back in 1925 in Germany by a couple of gents named Fischer and Tropsch. In the unpleasantness that followed later, Germany made good use of their process on an industrial scale, since they had ample coal and no oil on hand. Coal-rich South Africa has also made us of it, particularly during the Apartheid-era trade restrictions. Every so often the idea of industrializing the process comes up in the USA, but there’s still enough oil there it doesn’t make sense economically.
Those nations all have something in common: they’re all coal-rich countries, and that makes sense because coal is easily converted to carbon monoxide and hydrogen– a combo known as syngas– and it just so happens that those are the feedstock for this reaction. The actual chemistry going on inside is quite complex, but conceptually it is pretty simple: hydrogen and carbon monoxide mix over a hot metal catalyst, and combine to form various hydrocarbons.
In [Marb]’s glassware-based demonstration, the catalyst is Cobalt (III) Oxide on silica gel– a lovely, cancer-causing substance that must be prepared for each use, as it lasts but 24 hours before further oxidization ruins it. That’s in spite of purging the system with argon– a necessary step if one does not wish to explode. The yield isn’t amazing, and [Marb] isn’t sure exactly what mix of hydrocarbons he has created– although they smell like gasoline and burn like the dickens, so mission accomplished.
This might seem like the furthest thing from green, but if you use solar power to run the process and something like woodgas– which is syngas by any other name– as a feed-stock, then you’ve got a carbon neutral energy storage medium.
Thanks to [Markus Bindhammer] for the tip!
And you don’t necessarily need coal feedstock. I mean, it’s super convenient: South Africa’s SASOL plants burned it for the energy and used it for feedstock to produce motor fuel. Because the coal is so cheap, the resulting liquid fuel is not outrageously expensive.
But, in principle, you can make liquid fuels from nothing but thin air and sunshine: The water vapor and carbon dioxide in air provide all the hydrogen and carbon you need, and sunshine provides the thermal and electrical energy.
Yep, not efficient, and very capital intensive, but it’s FREE ENERGY!
It’s not “free energy” because it consumes hydrogen stored in the sun. Once it runs over and our star enters red giant phase its joever for humans unless we relocate to Mars.
To paraphrase, free energy is only free if your time has no value.