• Tables listed for riding a bicycle on level ground at 10 mph varies for your weight, but assuming you weigh maybe 150 lbs, then you would burn 188 calories. Since the bike, generator, and thermal calories are all hard to accurately convert due to a lot of factors, including ineffeciency, the best numbers one could come up with are perfect numbers if everything was ideal circumstances. 1 Calorie can be roughly equivalent to 0.00000116 KwH, so 188 Calories would be 0.00021808 KwH. My electric bill charges about \$.061 per KwH, so .061 X .00021808 = 0.00001330288 \$\$\$ You would have to ride for 75 thousand hours to make about \$1.
• A slight mistake here in order of magnitude. When we usually talk about "calories" with food or exercise, it's really kCal, so you're off by a factor of 1000 in your calories to kwh conversion. So instead, it's 75 hours.
• A VERY rough estimate: a well-trained person may have an output of a few ten to maximum 100Watt ( I did a cardio once where I had to cycle at 60Watt for some time). Let's assume 100W and 100% efficiency. So that would be 1kWh for ten hours cycling. You see, even the most menial task is paid much better!
• The realities of your situation make no difference at all. Doing your part to postpone global warming is a moral issue. So hook up that bike and pedal for all you are worth. It is the thought that counts!
• You probably won't be able to make enough money that it's worth hooking up to the grid. However, you can produce enough that it might be worth it to you personally. The average rider can generate around 75-150 Watts while riding at a moderate pace. Connected to batteries and pedaling for an hour a day or so you could get quite a bit of use out of it. You can read more including exact formulas that will show you how much energy will be produced here: http://renewable-energy-future.com/do-it-yourself/bike-generator.php
• It would not make much of a difference. Maybe invest in some solar panels?