by SolarDave » Sat 17 Feb 2007, 02:56:26
$this->bbcode_second_pass_quote('nth', '.').. of course, this makes no sense from a EROIE stand point.
Being alive makes no sense from an EROEI stand point.
But back to the point....
A rowing machine would generate power that was not directly usable (two seconds on, two seconds off). I used to row crew. Without the boat's momentum you would just stop on the back stroke. No rowing machine I have ever seen manages that well.
Rushing the slide creates a small fraction the energy created on the actual power stroke. I could hold you back on the return stroke with two fingers. There is no power there.
But if you cranked up a spring, pressurized a storage tank, or pulse-charged a battery or LARGE capacitor, it would be possible to get a smooth power flow back out. Inefficient, but possible.
There are not examples of "rowing generators" I suspect because it is mechanically difficult to capture the energy (you would have to capture each arm separately), difficult to change very slow, high-torque motions into what generators need (fast, low-torque motion) and as I discovered in crew, there are not a lot of "speeds" available when rowing. I don't just mean gears, like on a bicycle. If you have ever rowed to generate power, you know what I mean. The "comfortable" pace has a very narrow range of body velocities. THAT is hard to convert to usable power as well. Everything has to be "just right."
Rowing does spread work out over more muscles - but it puts a lot of strain on weak ones - your fingers and hands. That's what gave out on me first in racing conditions. You can generate half a horsepower through your legs and feet - because they were made for it. Your arms and hands are not.
Finally, rowing pretty much ties up your hands. No page turning, mousing, or even dialing phone numbers (and panting tends to confuse voice dialing - I have tried with amusing results). Sure, store the power and use it later, for at least a 15% efficiency penalty.
Could such a machine be built? Of course. Would it work "well?" I doubt it.
Disclaimer: Everything I say is 100% biased by the pedal generator experience I have.