A new generation of workout machines that generate electricity as you work up a sweat are poised to invade fitness centers and help you keep your New Year's resolution to trim down your waistline.

The electricity generated by the machines is fed back into the grid, helping the gym save on its utility bills.

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The so-called Green System from Woodinville, Wash.,-based SportsArt Fitness, represents a novel way to harness "human power," Ken Carpenter, director of sales for the company, told me.

It joins a growing list of similar concepts, including PaveGen's pavers that generate electricity as people walk (and boogie) on them and devices such as shoes and a backpack that charge batteries as you go for a jog or hike in the woods.

Sweaty watts
The Green System consists of recumbent and upright bikes as well as elliptical trainers, each with a box that captures 75 percent of the watts you generate during a workout. 

Boxes in several machines are hooked together and routed through an inverter that can handle up to 2,000 watts. Assuming an average of 133 watts per person, a pod might have 15 machines on it, Carpenter said.

"Most facilities are going to be drawing so many watts and amperage, you'd have to have a lot of inverters to really reverse that meter, because of light bulbs, air conditioning, and all the other things being powered," he said.

Nevertheless, 2,000 watt hours are enough to power a clothes washer for 6 hours, a microwave oven for 2.5 hours, or a 27-inch flat screen TV for 17 hours, according to SportsArt Fitness.

This is enough electricity that the system will pay for itself in about three years, according to Carpenter. The company has an online calculator where you can figure out your potential savings.

The system includes an inverter and the exercise machines. The inverter runs about $3,000, while the the machines could cost about $3,500 to $7,000.

Generating award points
The system is also hooked up with Victoria, Canada,-based EcoFit, which produces digital technology to calculate the number of watts an individual generates during a workout, put it on a graphical display and keep track of watts over time on a card.

In the future, the companies hope to turn these "eco-points" generated at the gym into currency accepted at coffee shops and other retail outlets. 

Back at the gym, the display technology also allows individuals to compete. For example, if you see your buddy is generating 115 watts, you might ramp it up so you can generate 130 watts.

Right now, most people measure their performance at the gym in terms of workout time, or distance biked, or calories burned, but Carpenter said he thinks this paradigm will shift to watts "the more eco-conscious people get."

So, eat, drink, and be merry this weekend. But come the New Year, hit the gym and generate some watts.

More on harnessing human power:

• Shoes redefine 'power walking'
• Backpack generates its own electricity
• Pavers generate electricity from steps
• Device produces electricity from a swinging knee

 

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John Roach is a contributing writer for msnbc.com. To learn more about him, check out his website. For more of our Future of Technology series, watch the featured video below.