Unbelievably, this is not science fiction. Mr Pal holds up a small beaker of bug excretion that could, theoretically, be poured into the tank of the giant Lexus SUV next to us. Not that Mr Pal is willing to risk it just yet. He gives it a month before the first vehicle is filled up on what he calls “renewable petroleum”. After that, he grins, “it’s a brave new world”.

However, to substitute America’s weekly oil consumption of 143 million barrels, you would need a facility that covered about 205 square miles, an area roughly the size of Chicago.