Money doesn’t grow on trees, so it should stand to reason that diesel fuel wouldn’t grow on trees either. And yet the Brazilian Copaifera langsdorfii tree has been quietly producing a natural diesel variant in the tropical rainforest, something we’ve known about since the seventeenth century. It’s only now that farmers in Australia have decided to farm the tree on a large scale in the hopes of having 20,000 living, above-ground fuel wells.

One of the technologies being touted as the next great thing for our cars is the hydrogen fuel cell. If you’ve heard anything about them, it’s that there are no harmful emissions, the only by-product is pure water, straight from your tailpipe. Of course, that’s only part of the story. While it is true that your exhaust will be clean, that’s only because hydrogen in a cell is not a source of energy the way gasoline naturally is—it’s a carrier, like a battery. The energy to be stored in the cell has to come from somewhere else. Right now, the sources are the same as they’ve always been, relying heavily on fossil fuels. The emissions are simply moved from your exhaust to a power plant.

But what if the hydrogen could be produced with alternative energy sources?

This rocket car shot along at 90 miles an hour on a different sort of alternative fuel: liquid oxygen. The driver ended up being killed in an explosion at a later trial, but its inventor insisted that the successful first run proved "the scientific possibility of driving vehicles this way."

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