Could You Power Your House With A Bike?
The Question
I recently had Mark P. from Pittsburgh ask me how bicycles work — while he was asking as a joke, I decided I’d write about something related. So, how much power does a bicycle generate? And what could you power off of that energy?
The Answer
If you’re an average, decently fit person who is casually riding your bike across flat terrain, you can generate about 100–150 watts of power. If you’re a hardcore biker (i.e. you compete in the Tour de France), you can generate about 250 watts of power, and if you’re really going hard while biking uphill, you can get up to 400–500 watts of power in.
For the purposes of this post, though, I’m going to assume you’re an average person and not a ripped athletic biker (a fair assumption, I think). So let’s say, biking hard, you can generate 150 watts of power as you bike. So what could you power if you generated 150 watts of power for an hour? Well, for one, you could probably power a light bulb (for instance, incandescent lightbulbs draw about 100 watts of energy) for an hour. Ceiling fans also tend to use between 25–90 watts of power (depending on their size and speed), so you could probably also power a ceiling fan. Laptops require about 45 watts of power to stay on, while a smaller monitor (17" LCD, for instance) requires about 40 watts of power — so you could probably power your laptop and an external monitor (not that that would be any good, as you’d be too busy biking).
Could you power all of the appliances in a house? Clearly not, if you wouldn’t be able to power two lightbulbs (200 watts). Let’s say you were to pedal an hour a day, every day, for thirty days. You’d generate about 100 * 30 watts, or 3000 watts (3 kWh). The typical family uses about 920 kWh per month, so you wouldn’t even come close to generating enough power to keep your house running. Okay, fine. Let’s pretend, though, that you bike 24 hours per day. You’d generate about 100 * 24 * 30 watts, or 72,000 watts (72 kWh). That’s still less than 10% of what you’d need to generate. However, we absolutely don’t want to be biking 24 hours a day, so let’s assume we bike three hours a day (100 * 3 * 30 = 9 kWh for the month). How fast would you have to bike in order to get that 9 kWh up to 920 kWh? Assuming you weigh 160 pounds, and that your bike weighs 20 pounds, generating those 9 kWh would require you to bike at 15 mph every day for three hours. To generate the 920 kWh required to power a house, you would have to bike at a constant 77 mph, for three hours nonstop every. single. day. To put that in perspective, the Earth’s circumference is approximately 24,901 miles. After 111 days of biking at that speed, for three hours each day, you’d have biked enough miles to go around the earth. Fine. For the sake of argument, let’s assume you could bike every day for three hours at 77 mph. How much food would you have to eat to keep biking? Well, biking at 77 mph, you’d burn approximately 105,000 calories after three hours. To put that in perspective, burning a pound of fat requires you to lose 3,500 calories. After biking for three hours, you’d have lost 35 pounds. If you don’t want to lose weight, you’d have to eat 35,000 calories per hour. A McDonald’s regular cheeseburger is approximately 313 calories — so you’d need to eat about 1.85 cheeseburgers per minute so as not to lose weight.
In conclusion: please don’t try to power your house using your bicycle.
