-Sorry had to get that out of my system-
$4 gas. It sparked a conversation this weekend between the Moose and I. Alternative energy sources was the topic.
A few years back Moose and I kicked around the idea of human powered electricity. It sounded pretty good. What we thought was: "lets get a stationary bike and rig it to generate a current."That shouldn't be too hard to do. We imagined installing this invention in places like homeless shelters- anyone who needs a job can just go in and peddle- and in prisons- you could give the guards masks and whips and transform beatings into electricity.
One problem with the bike concept was that the current generated would vary with however fast the convict/hobo peddled. That type of current would be anything from useless to annoying to fatal for most real applications (imagine pulsing light bulbs, microwaves, radio volumes, life support systems). My solution was to convert the energy generated by the peddler first into a form that could be released uniformly, then convert that to electricity. Some sort of mechanical water pump that the bike drives water to a reservoir on top of your roof say. The water can then be released at a uniform rate to generate a uniform current.
Eventually I took the time to do some research and some simple math/physics on the concept to determine how much electrical power one guy might be able to generate on a bike. Here is what I found out.
Q: What is a Watt?
A: A Watt is a measurement of Power, or in other words, energy used per time. In physics:
1 Watt= 1 Joule per sec
Q: Ok what is a Joule?
A: A Joule is a measurement of energy, specifically 1 Joule= 1 Newton meter. (A Newton is a metric measurement of weight or force,- about .273lbs) (a meter is 3.28 ft,) so:
1Joule = .273lbs x 3.28ft = .895 ftlb
One way to think of this is to remember that 1 Joule is the amount of energy it takes to lift .895 lbs 1 foot off the ground on Earth. (or you could say that 1 Joule is the amount of energy it takes to lift 1 lbs .895 feet off the ground- or any combination of feet and lbs that multiplies out to .895)
Q: Your power bill most likely reads in kWh (kilowatt hours). What is a kilowatt hour?
A: A kilowatt hour is a measurement of watts used in an hour. It is a measurement of energy, like the Joule.
1kWh= 1000watts x 3600 seconds = 3600000 Joules.
Hence 1 kilowatt hour = 3600000 x 0.895 ftlbs.= 3.2 million ftlbs
OK... so lets assume you are going to rig your bicycle-generator up in your living room. Lets say you are going to pump water from your basement to the top of your house- for a potential energy drop of 30ft. that means to generate 1 kWh, you will need to move 107,000 lbs of water from basement to roof. Given that a gallon of water weighs 8.34 lbs, you are looking at 13,000 gallons of water moved from basement to roof to generate 1 Kilowatt hour of power.
That's a lot of gallons.
Q: How much does a Kilowatt hour cost you?
A: Well, it varies from place to place. You can take a look at your power bill and find out what it is for you exactly but chances are its about 8cents.
So. You get on your bike and work up an inhuman sweat to move 13000 gallons of water up 30 ft- (I hope you can imagine this - If you can't, try carrying 13 gallons of water up the stairs 1000 times- it should give you some idea)- thus generating 1 kWh of energy- and how much money have you saved? About 8 cents.
The moral of the story: Alternative power is not as simple as it sounds. One of the main things that gets forgotten in the debate of how to manage our energy needs is the sheer titanic power represented by fossil fuels. We use electricity soo much that we take it for granted. Trying to imagine what it would take to create this type of power using just your body is a good reality check.