So, I’ve been using the rowing machine (some call the ergometer) at the gym lately.
How does the wattage measured by that relate to the wattage of a lightbulb?
Say that I average 150W for 30 minutes. If they had a good way to store my energy (as I drive & recover), is that just the same as powering a 150W light-bulb for 20 minutes?
That seems like a lot of damn energy expended for just one lightbulb.
If they could store my energy, could my work power a 75 watt for 40 minutes?
If your ergometer is measuring the mechanical power correctly, that would be in fact the case (assuming a lossless electrical generator).
You’d need a specially built rowing machine, though, as to my knowledge ergometers don’t brake the flywheel via a generator with regulated electrical load, but by a (mechanical or eddy current) brake.
if you average 150W for 30 minutes, you will power a 150W lightbulb for 30 minutes, and a 75W bulb for 60 minutes. Of course, if you used an energy efficient compact flouro, you would run it for 7 hours (for the same light output), and a LED bulb could run for even longer. Incandescents are really inefficient, as they emit a lot of IR along with the visible spectra.
In general, we have no idea how much energy things use and how much effort it would take to do things manually. An average PC requires 200W - you could not power that sucker for long by human effort. A real gamers PC may draw up to 500 W - only an elite athlete (Tour de France cyclist, say) would be able to power that for long. It would take a team of people to power your microwave, and forget about using your oven.
BTW: your 75Wh is the energy equivalent of 17g pure sugar or 7ml (just over a teaspoon) of gasoline - if I’ve done my maths right.
Si
I’m assuming that you meant “20 minutes” rather than “30 minutes” the first time you mention it in the OP; otherwise, you’re completely correct.
A ridiculous amount of energy that goes into an incandescent light bulb (something like 90%) is converted to heat instead of light. You could light a compact fluorescent bulb for a lot longer using the energy expended in your exercise routine.