(Kudos to Anick-Marie who helped me with and motivated me for this post.)
A place a lot of us people in the western world use every day and that traditionally consumes lots of energy is your favorite gym around the corner.
Usually there is lots of light (light helps to keep you active even when you are a little tired), a large music system, lots of heating/air conditioning and warm water and often even a solarium or a sauna. And while doing sports is good for your health, leaving this large footprint on our planet is a substantial side-effect.
Doing sports outside seems to be the solution but might not be suitable in every live situation in large cities or rougher climates. Also, as a quote from LEARN1 states "Don't fight culture". You have to take people from where they are instead of lecturing them about what to do.
Forms of Energy
You sweating in the gym obviously takes a lot of your energy, obtained from the food you consume and transformed into physical energy. The work this energy carries out is visible in the form of moving weights and spinning wheels.
We have two general cla**** of workouts, those which use machines or weights to primarily increase your strength and those where you get your pulse high for a longer period to increase your stamina. During strength workouts you usually lift weights producing primarily potential energy (energy that is conserved in the position of a mass) while during cardio workouts like riding a bike, rowing or running you create motion / kinetic energy that is a lot easier to use. Just think of the dynamo systems used for bikes.
Amount of Energy
So how much energy are we talking about for your usual cardio workout? Well just look for yourself, most of the modern machines already give you that kind of information. I produce somewhere between 100-200 Watts depending on the intensity of the workout.
This number is roughly what you can find searching on the internet. There is a nice short howstuffworks article that states that you can easily run a laptop (15 Watts) for 4 hours using the energy of one chocolate-chip (60 kcal) cookie. Running a full-fletched PC is already very exhausting, but possible (>200 Watts).
Energy producing bikes
There are free plans available on the internet explaining how to build your own bike for energy generation. Many people did exactly this, you can even find video showcasing prototypes.
There are social innovators out there who already help with the supply of bikes and knowledge to create energy with bikes. One example is the Maya Pedal project in Guatemala or PEDAL in Vancouver, Canada.
Current Innovators in the Gym world
There is a human-powered gym in Hongkong that is run by California Fitness. The green microgym in Portland, OR goes further by making a small energy footprint central to the wh*** design of the studio, combining reduction of energy consumption wherever possible with producing energy during your workout. But see for yourself.
Let's make it a game!
Now lets take this idea to the next level by making it a (social) game (Jane Mcgonigal says games can change the world and I guess we all agree ;) ).
The gym I go to already has a big projector which usually shows a sports channel. This could be the place to put up a leader-board for the new "green gym" game we are creating. Who is producing the most energy right now / today / this week / overall? You would register online and have an online social community for the gym. In your profile you can gain different skills like strength, vitality, energy production and energy awareness (sounds familiar?).
All the necessary data would be collected automatically for all agreeing participants. This could be done using a combination of RFID technology to identify people and connecting the little computers any cardio machine contains even now (of course there would have to be some changes, e.g. a clean network interface to all machines).
In addition there could be a vote system just like on urgentevoke to add another social component and award people who could convince their peers that they improved a lot or done something especially useful.
By designing the right incentives, we can motivate people to work out and produce energy. Such incentives could be recognition, a reduced gym fee or even collaborations with energy providers and health insurance companies. You could setup certain quests and select a winner regularly. Every participating person can win 10$ of free energy by producing a goal amount or gets a payback from health insurance when she reaches her healthy training goals.
Designing a green gym, we could improve health, raise energy awareness and have fun doing it all at the same time.