When you think of ethanol, you might think of it as a type of alcohol, not alcohol itself. However, in reality, it is the primary ingredient in adult beverages. Which means humans have gotten quite good at making it, as we’ve been doing for a long time. With this in mind, [Sam Barker] decided to make ethanol out of apples to power a small engine to charge his phone.
The steps for making pure ethanol is quite similar to making alcoholic cider. A friend of [Sam’s] had an orchard and a surplus of apples, so [Sam] boiled them down and stored the mush in jugs. He added activated dry yeast to start the fermentation process. A dry lock allowed the CO2 gas that was being created to escape. Over a few weeks, the yeast converted all the sugar into ethanol and gas. In the meantime, [Sam] sourced a chainsaw and adapted the engine to run on ethanol, as ethanol needs to run richer than gasoline. The video below the break tells the story.
With his solution at just 15% ethanol, he needed to distill it to get pure ethanol for the engine to run. With a little bit of handwaving due to UK laws, [Sam] soon had a 94% ethanol solution. The next step was to use a molecular sieve, which absorbed the water but not ethanol. He secured the engine and generator to an old cutting board, and [Sam] was ready for the first test. Fine-tuning the right throttle and choke took a while, but [Sam] had it going consistently when he ran into a snag; the phone wasn’t charging. He revved the engine up, and his little charge regulator exploded. His multimeter probes were backward when he had measured the generator, and it was outputting a negative voltage. With the board swapped, the phone was charged. But [Sam] saw over 50 volts coming off the motor at times. So like most of here at Hackaday, he wanted to see how fast/high/far it could go. This ultimately fried the motor.