Human power, past and future
We’ll assume you’ve seen The Matrix – it was from 1999, after all. The surprise, in the end, was that humans were being used as human batteries to power a civilization of intelligent machines. But in addition to putting a little heat, the idea has a precedent. After all, humans powered machines like mills, sewing machines and pumps for centuries before there were good alternatives.
Early machines used cranks, running wheels, pedals, and even pedal power to harness the energy of humans. Consider, for example, an old galley ship with many rowers providing an engine. It was not a great use of human power. A rower on a galley used his arms and back but did not use his legs much. The legs, however, have bigger muscles and are often stronger. A pedal boat or racing hull would have been much more efficient, but without the 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 treadles or treadles operated many machines, from sewing machines to lathes. There were even old radios capable of transmitting and receiving without external power thanks to foot pedals as late as the 1940s.
Today, most of what we ride is bicycles, and mostly as a leisure activity. We also use treadmills, but we use them for a different purpose than generating movement through human power. In fact, most treadmills today move using a motor so you can feel like you’re running without going anywhere.
This was almost the case in Victorian England where prisoners sentenced to hard labor had to run on a treadmill as punishment. In 1818, it was decided that prisoners sentenced to hard labor had to work all the time, so they were put on treadmills that did nothing. There were also crank machines which are exactly what they sound like: a machine with a crank that does nothing.
In 1895, 39 treadmills and 29 cranks were in use in England. Some prisons eventually adopted unnecessary labor to grind grain or pump water, but many were just “grinding the wind” with no other purpose than to punish the inmate.
The United States also played with penal treadmills around 1822, but they were never very popular. Typically, these treadmills were configured as wheels configured as endless stairs and had partitions to prevent prisoners from communicating with adjacent prisoners. A fifteen-minute drive was worth a five-minute break, and that lasted up to six hours a day.
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 energy. Worse still, when a modern machine tries to harvest energy manually, it usually does so to generate electricity, which is usually not very efficient.
Of course, sometimes you really need electricity. For example, a hand-cranked flashlight, phone charger, or emergency radio needs electricity. But if you’re trying to, say, pump water, it’s better to use the energy directly to do the job than to generate electricity and then charge an electric motor to do the job.
What tomorrow may bring
However, lately we are seeing a trend towards electronics consuming less and less energy. Even small watch batteries now last almost as long as their lifespan thanks to devices that have great power saving and improved battery management systems. As devices consume less energy, the possibilities of powering them from the human body increase.
Granted, the nPower PEG seems to be gone. The Pavegen system which generates electricity from people walking on special ground does not appear to generate much power and is mainly used for tracking footsteps rather than generating power.
But harvesting energy from humans could provide power for micro-powered devices, especially portable or medical devices. Body heat is an obvious candidate, or – borrowing from Pavegen – a type of generator in your shoe. A few experimental medical devices use blood sugar as fuel. For decades, self-winding wristwatches have captured the movement of your arm to operate the clockwork. Maybe a future smartwatch will increase its battery life using the same method.
To make this practical, you need ultra-low-power electronics. While we know a few tricks, we probably need to scale back at least another order of magnitude to make human-powered wearables more than a novelty.
[Banner image: “Pedal power” by KylaBorg, CC BY 2.0]