"It's also a great Axe grinder!"
Here's my idea. Some kind of huge pedal-powered flywheel. I mean huge. 6 feet in diameter, one foot in width, made of stone or metal. I'm not a physicist, so I don't know if this is the most efficient way to translate pedal power into electricity, but I think we need to be able to SEE what our work is doing, or we'll get discouraged and give up.
If one were to pedal to charge up a set of batteries, you wouldn't get visceral feedback about what your work is getting you. If you hook up your pedal generator to a TV so that the TV works only while you're pedaling, you can see what it takes to power a TV, but...so much for being a couch potato.
And usually people want to exercise for half an hour in the morning and then get on with their day. If by pedaling you set this giant flywheel in motion you GET it, in a wonderful big way. The flywheel's energy can then be stored in a battery. For use throughout the day or night. There would be gears just like on a bicycle so that when you first start pedaling the gear ratio gets the flywheel going without too much struggle, and as you get faster and faster you can change gears and really get that flywheel moving.
I got this idea while biking around town. When I bicycle up the hill, I'm very aware of how much energy it takes to get my body and the weight of the bicycle up the hill. It's a lot a work. All these cars fly by me, most with just one person at the wheel and no passengers, and our cars are so powerful that the driver really has no sense of how much energy is being expended to lift all that steel and plastic up the hill. As such, my invention is not just about creating or harnessing the energy from an exercise regimen and turn it into electricity, but also about helping people to realize how much energy it takes to run a light bulb or a washing machine or a television set.
While walking the other day, I passed a woman who was blowing leaves with an electric blower. Now, leaf blowers are pretty ridiculous any way you look at. Are they really that much easier to use than a rake? The simplest way of reducing the energy used by leaf blowers is just to stop using them. But this woman's house had a huge solar array on the roof. So, ostensibly, she was just harnessing the power of the sun to blow her leaves around. Much better than using a gas powered leaf blower or electricity from a coal-fired power plant. Still, harnessing the sun's energy is not without its costs (the manufacture of all those silicon solar panels, the chemicals involved, et cetera). I believe that she, and all of us, need to understand how much energy it takes to blow those leaves around. If someone had to pedal a generator like mad so that she could blow leaves around the yard, we'd be back to using rakes in no time.
So I look around my house and I think about the things that I really depend on, or like to use, and the things that are not so important. I really love using the computer, I love having a music studio (which is mostly run by electricity), and it's great to have lights in the evening and the early morning. Whoa yeah, and the dishwasher and the clothes washer - those are really handy. I would love having a huge flywheel that I could spend 30 minutes on each morning and know that it would power my computer for four for five hours. I'd get exercise and I'd feel really good about the energy I was using. I'm pretty sure that even if each member of my family was peddling for two hours a day, we probably still wouldn't make enough energy to totally supply our daily household energy usage. But it would make a dent. And it would show us how precious the energy that we do have really is.