Human Power, Past and Future [Hackaday]

View Article on Hackaday

We will assume you’ve seen The Matrix — it was from 1999, after all. The surprise, at the end, was that humans were being used as human batteries to power a civilization of intelligent machines. But aside from just putting out some heat, the idea does have some precedent. After all, humans powered machines like mills, sewing machines, and pumps for centuries before there were good alternatives.

History

Early machines used hand cranks, treadwheels, treadles, and even pedal power to harness energy from humans. Consider, for example, an ancient galley ship with many oarsmen providing an engine. This wasn’t a great use of human power. An oarsman on a galley used his arms and back but didn’t much use his legs. The legs, though, have larger muscles and are often stronger. A pedal boat or racing shell would have been much more efficient, but without mass production of strong metal parts, it would have been difficult to build and maintain such machines in ancient times.

There was a time when pedals or treadles operated lots of machines from sewing machines to lathes. There were even old radios able to transmit and receive with no external power thanks to pedals as late as the 1940s.

Today most of what we pedal are bicycles, and most often as a leisure activity. We also use treadmills, but we use them for a different purpose than generating motion through human power. In fact, most treadmills today move using a motor so you can feel like you are running without going anywhere.

Prisons

That was almost the case back in Victorian England where prisoners sentenced to hard labor were made to run on a treadmill as a form of punishment. In 1818 it was decided that prisoners sentenced to hard labor should have to labor all the time, so they were put on treadmills that did nothing. There were also crank machines that are just what they sound like: a machine with a crank that does nothing.

By 1895 there were 39 treadmills and 29 cranks in use around England. Some prisons eventually adopted the wasted labor to mill grain or pump water, but many were just “grinding the wind” serving no purpose but to punish the inmate.

The United States also toyed with penal treadmills around 1822, but they were never very popular. Typically, these treadmills were set up as wheels configured as endless staircases and had partitions to prevent prisoners from communicating with adjacent prisoners. A fifteen-minute stint on the wheel earned a five-minute break and this went on for up to six hours a day.
<h2 style=”clear:none;”>Modern Times

Since the rise of electric motors — not to mention changing conditions in prisons — there hasn’t been much interest in using humans to power machines. Pedaling or using a treadmill today is likely to be for exercise or pleasure and not to provide power. What’s worse is that when a modern machine does try to harvest manual energy, it usually does so to generate electricity which is typically not a very efficient thing to do.

Of course, sometimes you really need electricity. For example, a crank flashlight, phone charger, or emergency radio needs electricity. But if you are trying to, say, pump water, you are better off using the energy directly to do the work than generating electricity and then tasking an electric motor to get the job done.

What Tomorrow May Bring

However, we are seeing a trend lately of electronics that use less and less power. Even tiny watch batteries now last nearly as long as their shelf life thanks to devices that have great power economy and improved battery management systems. As devices sip less power, opportunities to power them from the human body increase.

Granted, the nPower PEG seems to have vanished. The Pavegen system that generates electricity from people walking on a special floor doesn’t seem to generate very much power and is mostly used for tracking footsteps more than producing energy.

But harvesting energy from humans could provide energy for micropowered devices, especially wearable or medical devices. Body heat is an obvious candidate, or — borrowing from Pavegen — some type of generator in your shoe. A few experimental medical devices use blood sugar as fuel. For decades, self-winding wristwatches captured your arm’s motion to keep the clockwork running. Maybe a future smartwatch will boost its battery life using the same method.

To make that practical, you need ultra low power electronics. While we know a few tricks, we probably need to get at least another order of magnitude lower to make human-powered wearable devices more than a novelty.

[Banner image: “Pedal power” by KylaBorg, CC BY 2.0]