The boilers in Marvin Windows and Andersen Windows factories have been fueled by sawdust from the plant floor for years.

"The boiler system's run exclusively with waste material," said Susan Marvin, president of Warroad, Minn.-based Marvin. "And more and more companies are doing it. That is really cool. It's environmentally responsible and should be applauded."

Indeed, other Minnesota manufacturers are catching the "green" bug and bringing earth-friendly processes into their factories in a move that spares landfills and racks up millions in savings. Some use recycled ingredients instead of virgin. Others grow and burn their own heating fuel or use technology to slash hot water use; still others have perfected VOC (volatile organic compound)-free formulas that don't pollute the air.

State officials say the number of entrants into this green game swells each month and includes United Taconite, Northshore Mining, Bituminous Roadway in Inver Grove Heights, Midwest Asphalt, Hirshfield's Paints and Ecolab, among others.

Their approaches vary, but they all have an impact on wallets and the environment.

According to just-released state figures, Minnesota homes and businesses generated 6.2 million tons of municipal trash last year. They recycled 2.5 million tons of it (2 percent more than in 2005), which let businesses save $539 million in electricity costs and cut 6.4 million metric tons of carbon dioxide emissions.

"We still have 1.3 million tons of recyclable material that remains in the waste stream and it's worth $312 million," said Wayne Gjerde, recycling market development coordinator for the Minnesota Pollution Control Agency.

Companies such as Andersen and Marvin also save money that isn't tracked by the state because their sawdust waste never makes it into their cities' trash. That can cut back on hauling, landfill fees or material spending, Gjerde said.

Bill Grant, Midwest director of the conservation group Izaak Walton League, applauds the steps from an environmental standpoint, but also notes: "All of these things are not only being driven by the desire or need to be greener, but by simple economics.

"For example, with the price of natural gas going so high, it just makes every bit of common sense to find ways to reduce the amount of water use ... not because of the cost of the water, but because of the cost of the gas to heat up the water," he said. "Most of the things being done [by manufacturers] should be good for their bottom line as well as making them greener."

Both small and large companies are involved.

Consider Wipers Recycling in Maplewood. The owner of the tiny company, Patty Gearin, bought a giant shoe grinder this summer that converts trashed leather wing tips and other shoes into kits that can soak up oil spills. The shoes won't end up in landfills and Gearin saves money on raw materials, she said.

In February, Hank Specialties, a New Brighton tool supplier, began collecting old nylon carpet from installers and shipping it to St. Paul-based Bro-Tex. That company chops and sells the nylon fabric to Shaw Carpet in Georgia and other firms that turn it into new carpet, padding, cement mix or sewer pipes.

"Now carpet [collection] is approaching 1 million pounds a month," Gjerde said. "That is such a success. And they need more carpet."

Jeff Hanson, Bro-Tex operations vice president, said Shaw eventually wants to get 100 million pounds of Nylon-6 fibers a year. Hank's and Bro-Tex hope to eventually provide 15 million pounds of it, enough to generate roughly $750,000 in sales and turn a slim profit, officials said.

In Hopkins, Midwest Asphalt has begun using old roofing shingles to make asphalt. Last year, the company chopped up about 50-plus tons of them and mixed them into hot virgin asphalt to pave the Lower Afton trail in Maplewood over the summer.

Midwest Asphalt is the third company to join Minnesota's pilot shingle recycling program, state officials said. Bituminous Roadways Inc. was the first three years ago, when it hired St. Martin-based Rotochopper Inc. to make shingle-chopping machines.

Ohmann Brothers Inc. in Albertville was the second last year, when it paved a 900-foot stretch of road in Hassan Township with various blends of virgin asphalt, asphalt from "tear-off" roof tiles and factory-fresh tiles.

The goal was to see whether the mixed asphalt would crack. It didn't, said James Ohmann, who added that paving contractors like the idea of recycling old shingles because they are 33 percent petroleum asphalt and save big money when reused. About 400 tons of tear-off shingles come off homes and get dumped in Minnesota landfills each year. "That's a lot of barrels of oil," Ohmann said.

In 1996 virgin asphalt cost about $90 a ton. Now it's around $400 a ton. Recycled shingles slash that cost considerably, Ohmann said.

The MPCA hopes to dramatically widen the pilot program in 2008 and 2009.

Renewing, not just recycling

Other manufacturing firms are opting for renewable ingredients and energy, not just recycling.

Cleveland-Cliffs Inc., which owns United Taconite in Eveleth and Northshore Mining in Silver Bay, Minn., announced last week that it bought a controlling interest in Rosemount-based Renewafuel, a company that makes biofuel cubes out of cornstalks, switch grass, soybeans and oat husks. As a result, United Taconite and Northshore Mining will soon blend their coal with an undisclosed amount of "fuel cubes" inside their taconite pellet furnace and power plant.

The move will cut carbon and sulfur dioxide emissions and reduce Cleveland-Cliffs' fuel costs, Cliffs spokeswoman Dana Byrne said.

But Grant said other operations do best when they can grow their grasses, husks and stalks close to the furnaces that will burn them. That cuts transportation emissions and costs. He added that most ventures like this still rely strongly on coal.

Turnabout at Marvin

Marvin, who runs her family-owned window and door firm, said the company also believes in renewable ingredients. Marvin buys lumber only from companies that replant four trees for every felled tree, she said.

While the company was fined a hefty $2 million for hazardous waste violations in 1990, it has since won numerous environmental awards from the state. It's been praised for its tree policy and for ditching various toxic substances in favor of non-hazardous products. The revised policies saved money, reduced chemicals and cut disposal needs by some 80 percent.

"There is always a strong desire to do what is right in terms of the environment," Marvin said. "There were definitely practices that we had in place [in 1990] that were out of compliance and it was very clearly a violation. But then there was a real aggressive [push to say], 'OK. We didn't get this right. We've got to get this better and make a commitment to do that.' We brought in people who were a lot more savvy than we were. And today, we have world-class commitments in both" safety and the environment, Marvin said.

Other manufacturers are adopting computers and new products and taking them into customer operations to reduce water usage.

Ecolab Inc. of St. Paul recently introduced an enzyme-based cleanser for greasy floors that requires no water. And this summer Ecolab installed 2,000 water-saving monitors for dishwashers in restaurant chains across the country. The effort is expected to save Ecolab customer T.G.I. Friday's restaurant chain about 13 million gallons a year.

Dee DePass • 612-673-7725