Down and Dirty: 5 Ways to Go Seriously Green Environmentalists talk of composting toilets, power from poop.

July 1, 2009  -- There may be something of an "ick" factor to this story -- but some environmental advocates say that's just fine with them. Maybe, they say, it will make people think twice about wasteful ways they never thought about at all.

The waste at issue is human waste. Some environmentalists ask why we go to so much trouble to get rid of it -- when, they say, it's full of microbes and nutrients that can be put to good use in farmers' fields as fertilizer.

What's more they say, why are people driving to gyms, working up a sweat on treadmills or exercise bikes -- and letting all that effort go to waste?

So here are five ideas they offer, some new and some old, that may strike you either as whacky -- or very clever in the way they conserve resources.

The Composting Toilet

In Austin, Tex., a group called the Rhizome Collective has built a commode that uses no water. Instead, when you're finished, you pour sawdust down the toilet.

"This is a great system for environmentally conscious individuals and families," said Jennifer Melia, a member of the collective. She and her cohorts try to live a sustainable, off-the-electric-grid lifestyle -- though the powers that be took four years to give their approval for the system.

"It was just a new thing," said Jill Mayfield of the Austin Water Utility, which finally gave Rhizome the go-ahead. "It takes a while to make sure it's something that would be safe."

The members of the collective say they may not have a solution that pleases everyone, but they're doing their part for the environment. A flush from a conventional toilet, they said, takes 3-5 gallons of water -- clean water that could be used for drinking or cooking, and is in short supply in many parts of the world.

Meanwhile, people who checked out the sawdust-powered outhouse said it smelled mostly of sawdust, and not much else. There are commercially made indoor versions as well.

"They save immense amounts of water, they create healthy soil, and they save energy," said Melia. "These are far beyond the latrines of olden times."

Power from Poop

Sanford, Fla., and MaxWest Environmental Systems Inc. of Texas have teamed up to convert the city's stream of wastewater sludge into renewable energy.

The logic, they say: Why flush stuff down the toilet when it can cut the city's natural gas bill?

Top 5: Going Seriously Green

The city dries 30 tons of sludge daily with a natural gas-powered dryer and then hauls it to a landfill. But under a new $3.5 million gasification system, the sludge will be allowed to sit. When it does the gases released create heat, which can replace the natural gas to power the dryer.

The new system is not only greener, it could also save the city $9 to $14 million over 20 years, according to MaxWest.

Pedal Power

The Green Microgym in Portland, Ore., puts its patrons to work, not just through workouts.

This "human-powered" gym is one of the few fitness centers in the world that uses electricity generated by the people working out there, said Adam Boesel, the owner.

As members pedal on stationary bicycles, they turn a small generator, charging batteries that power the gym's television and stereo system.

Boesel said the output is relatively small. But this is just the beginning, he said.

"It's a little humbling -- a person can make about a penny's worth of electricity an hour." said Michael Tagget, president of Henry Works, a firm that makes people-powered generators. "But if 20, 30, 40 people are doing that in a gym, they can do all the electricity for entertainment systems."

Anaerobic Digesters Turn Waste Into Energy

Don't stand in the way of an anaerobic digester.

This process uses organisms to break down biodegradable material in the absence of oxygen to produce biogas. That biogas is then used to power electric-generation equipment, like fuel cells or micro turbines.

Of about 16,000 public wastewater plants in the country, 544 use anaerobic digesters. Of those, 106 use the biogas for heating processes or electricity, said Phil Zahreddine, a branch chief with the Environmental Protection Agency.

"What is interesting is that as more projects are coming online and the technology is becoming more efficient, these options are becoming more attractive to facilities," he said.

Waste 'Electrifies' Los Angeles

The city of Los Angeles has a giant TIRE.

The city's Terminal Island Renewable Energy (or TIRE) project involves injecting sludge into a well a mile deep.

At that depth, Earth's high temperature breaks down the organic compounds in the waste to create methane gas. The process also traps greenhouse gases and prevents them from damaging the atmosphere.

By 2012, the project is expected to produce about 3,500 kilowatts of renewable power, which could power thousands of homes.

"This renewable energy project is absolutely electrifying," Los Angeles Mayor Antonio Villaraigosa told the Los Angeles Times. "It will save money and make money."