Late in the process of writing The Human-Powered Home I learned about Mike Taggett. Mike created the Human Dynamo and Team Dynamo exercise machines that generate electricity at the Green Microgym in Portland. Unfortunately, by the time someone slipped me his name my manuscript deadline was looming (okay, had passed) and it was too late to interview him. Still, I wanted to know more about Mike and his creations. He and I finally talked this weekend.
Mike is a jack-of-all trades—entrepreneur, tinkerer, and an alternative energy enthusiast since the late 1980s. At that time he began working with small-scale steam engines, those capable of about 100 kilowatts or 120 hp, which, he said, no one really makes anymore. His research with steam engines led him to consider other unorthodox ways of generating electricity. A few years ago he began experimenting with human power. And that’s been the primary focus of his company Henryworks ever since.
Mike’s human-powered generators differ from those featured in my book in a few significant ways. They’re high-quality exercise machines first, designed to provide a full lower- and upper-body workout. He consulted with industrial designers and trainers to fine-tune their ergonomics. Users may rely leg power or arm power alone, or try both together.
Most fit exercisers are able to generate an average of 75 watts for at least a half hour on the Human Dynamo. (As detailed in Chapter 2 of The Human-Powered Home, output depends on many factors, including duration, age, gender, and fitness level, but 75 watts is a good approximation.) In the case of the interconnected machines that make up the Team Dynamo, a quartet of riders could generate 300 to 400 watts. At the Henryworks office and a few gyms around Mike’s home town of El Paso, the machines are operating stereos and lights.
Mike’s design is also unique in that it relies on a high-quality automotive alternator to generate power. True, alternators are 10-15% less efficient than permanent magnet generators, Mike told me. On the other hand, they allow easier, less expensive control over the output, are quieter, and will probably last longer under heavy use.
And where other human-power generators might max out at 300 watts due to the permanent magnet generator’s limits, Mike’s machine allows higher output. If you are a Tour de France contender, for example, you might generate 500 to 600 watts on the Human Dynamo—though probably only for a few seconds.
Henryworks is now producing version 4 of the Human Dynamo, which is available without an electrical generator for $1450 or with an electrical generator for $1950. So far the company has built 50 of the machines on spec. Gyms and universities have expressed interest in using the machines as green power generators and teaching tools.
And how do gym-goers like the human-power generators far? Mike regretted that they’re not as popular as the elliptical machines and treadmills. He guessed that was because they provide a little harder workout. Or maybe they’re intimidating. But once people found out how much you could burn on one of the Human Dynamos compared to an elliptical machine, he thought, they’d be convinced to try it.
In addition to the Human Dynamo, Henryworks makes the FireWheel, a grid intertie mechanism for the human-power generator. The FireWheel can be plugged into a standard wall socket to feed electricity back to the grid. A sophisticated control mechanism stops the flow of electricity if the grid goes down, so no one would get hurt if they were working on the wires. According to Mike, the same control mechanism—which is used for elevators and factory conveyors—makes it possible to tie the human-powered generator into the grid without having to get a permit from your electricity provider.
What’s next for Henryworks? Mike is exploring the option of making a more affordable, home version of the Human Dynamo, a small machine that anyone could set up in the living room or office and use to power a TV or laptop. He’s also searching for the ideal partner to license and market his machines. And he’d like to make a version that’s practical for use in the developing world.
He admitted that the numbers for individual human power output are humbling. However, it’s also an inexpensive way to generate electricity. In a gym with many people exercising over the course of 6 or 7 hours, he said, human power turns out to be less expensive than a solar-power system.
Like many enthusiasts I interviewed for The Human-Powered Home, Mike mentioned that generating watts with your muscles gives you a real sense of power, what it takes to create it. Then, he said, you have a metric to compare everything else to. Now, when he assesses any new appliance or gadget—a 200-watt TV, a 25-watt printer—his first question is, how much muscle power would this require?