(FORTUNE Small Business) – Trucking is a dirty business, says veteran long-hauler Bill Schreiner, 59. "It's not so much the driving," he explains from the cab of his 75-foot Freightliner, parked at a TA Travel Center of America off I-295 in Paulsboro, N.J. "It's all the idling we have to do whenever we're parked." By law, truckers are parked quite a lot. After a typical 11-hour shift, they must rest for at least ten hours. For most of that time, drivers normally idle their diesel engines to power their cabs for warmth in winter or air conditioning in summer. At major truck stops, noise, vibrations, and fumes emanating from dozens of trucks can be overwhelming, says Schreiner. "In those situations, she's no help," he says, pointing to his hula-dancer air freshener.

"That's where we come in," says Tom Badgett, co-founder and CIO of IdleAire, a four-year-old Knoxville firm that's trying to, well, clear the air. IdleAire is the big dog in an emerging pack of companies that provide technology to reduce pollution at truck stops. Badgett's firm installs a system of gray control consoles attached to bright-yellow tubes suspended from an overhead rack. Drivers pull up, turn off their rumbling engines, latch the unit onto a $10 adapter that fits in their passenger window, and open a clamshell-like control console that pipes in climate-controlled air, electricity, broadband Internet access, satellite TV, and long-distance phone service.

Since 2000, IdleAire has retrofitted 23 of the busiest truck stops from California to New Jersey. Agreements with three major truck-stop chains—Pilot, Petro, and TA—mean the company is on track to equip 600 other locations. By IdleAire's own estimates, its system has already saved more than three million hours of idling. That adds up to about three million gallons of fuel conserved and more than 32,000 metric tons of potential diesel emissions that didn't wind up polluting the air. It's a tiny percentage of the one billion gallons consumed by idling, says the EPA's Suzanne Rudzinski. "But it's a very practical and positive step in the right direction."

Environmentalists aren't the only ones enamored with Idle-Aire. "We tell our guys to head over to an IdleAire truck stop whenever they can," says Mike Mundy of National Freight, one of 700 trucking fleets that now have accounts with IdleAire.

Even new trucks burn about one gallon of diesel each hour they idle, costing around $2.25 a gallon. IdleAire's service costs just $1.40 an hour. "Factor in the wear and tear we're saving on our trucks, and it's foolish not to use the system," says Mundy.

Despite IdleAire's loyal fan base, the company hasn't yet turned a penny of profit. While this very green firm won't say exactly how red its books are, IdleAire reports that it needs another $150 million in financing to meet its 2005 rollout target. That's on top of the $100 million in equity investment and an additional $30 million in federal loans and grants that the company has burned through since 2000.

Where has all the money gone? The truck stops have full-time IdleAire staffs of about 12 to oversee an average of 50 parking spaces at each location. One parking spot costs $15,000 to build and is backed up by a customer-support team that's available 24/7 for tech-challenged truckers. "Building the technology from scratch, rolling it out, and supporting it isn't cheap," admits Badgett. "This is an expensive business."

IdleAire expects to be profitable by August. Meanwhile, federal and state agencies seem willing to help foot the bill. Clean-air programs in California and Texas alone are funneling $150 million and $100 million, respectively, into R&D for the so-called truck-stop electrification industry. But IdleAire's biggest benefactor is the federal Congestion Mitigation and Air Quality Improvement Program, which provides $1.8 billion to state departments of transportation, city planning organizations, and transit agencies. In turn, those groups are helping fund new IdleAire installations around the country.

That's fine with big-rig drivers like Schreiner, who planned a recent Northeast haul so he'd have an overnight in Paulsboro, where IdleAire recently set up at a TA Travel Center. Schreiner spends nearly six months a year and up to 70 hours a week on the road. "I go out of my way to find these IdleAire truck stops because they make for a better night's sleep and I know they're better for the environment," says Schreiner, a cigarette pinched between his fingers.