Gov. Brian Schweitzer envisions a day when New Yorkers will be driving cars powered by the wind that howls across the Montana prairie. The Democrat recently called on the federal government to spend $15 billion to build a next-generation transmission grid to link such far-flung regions.

"You start delivering wind to cars and the [oil-nation] dictators, they get sad fast," says Mr. Schweitzer in his Helena office-cum-classroom, where he keeps vials of biofuel feed stock and model windmills to show visitors. He has a lump of coal, too - a reminder that Montana not only has lots of wind to harness, but tons of coal to shovel.

The interior West's abundance of both green-energy resources and traditional fossil fuels make some watchdogs nervous about a rush to build what has been called an Interstate highway system for electrons. The idea of expanding transmission lines is commonly pitched by politicians as a way to put people to work while removing a crucial obstacle to renewable power.

But it's not going to be just wind and sun on those wires. "[S]ome proponents of expanding coal-fired electricity production are using windfarms as a rationalization for greatly expanding transmission lines through the region.

They talk a lot about wind power, but their real interest is vastly expanded use of coal in generating electricity," says Larry Swanson, a regional economist at the O'Connor Center for the Rocky Mountain West at the University of Montana in Missoula.

Schweitzer does not deny that federally funded transmission lines would also help his state's coal industry. He says he is a strong advocate not just for renewables but for so-called clean coal technologies.

"We're going to hook some coal into it," he says. "Fifty percent of the electricity in America comes from coal. I'm all for change, but unless you are willing to live naked in a tree and eat nuts for the next 30 years, coal's going to be part of the portfolio."

Environmental groups have made transmission a priority: Al Gore's "We Campaign," for example, is calling for a Unified National Smart Grid, which the group sees as part of a 10-year plan to get the nation using "100 percent clean electricity."

But they still have some reservations.

"[T]he whole environment community remains concerned about transmission because there is no clear idea of what's going to be on it," says Rachel Shimshak, head of the Renewable Northwest Project, a regional advocacy group for renewable energy. "There is nervousness with Montana."

Nevertheless, her group has been collaborating with power generators, utilities, and regulators on decisions about how and where to upgrade the grid.

Harnessing the prairie wind

In the center of Montana, tucked on rolling prairie land, the population of Judith Gap barely outnumbers the 90 wind turbines cranking out power there. The wind comes roaring from the Crazy Mountains and the Little Belt Range, smooths out as it passes over the grassland, and provides enough force to generate 7 percent of the regional utility's needs.

Invenergy, the company that owns the Judith Gap wind farm, plans to build more turbines here and in other parts of the state. Other companies are scouting around, too.

The man who chose Judith Gap as the place to plant Montana's first wind farm warns that transmission is becoming a real limitation.

"There still is quite a lot of wind where there are transmission lines, but most of those transmission lines are full," says Bob Quinn, an organic farmer who took up harvesting wind with the help of a cousin. "We could light Los Angeles if we had the power lines."

Plans for new transmission lines are cropping up across the West. Such projects tend to be initiated by a utility, then coordinated through regional planning groups and potentially expanded to include multiple utilities.

In recent years, the private sector has also started building and running transmission lines. This spring, construction will start on the Montana Alberta Tie Line that connects the Canadian and US grids from Great Falls, Mont.

"All of our capacity has been awarded to companies that plan to develop new wind farms in north central Montana," says Bob Williams, the vice president of regulatory affairs for the Montana Alberta Tie Ltd (MATL), the company building the line.

There's already skepticism, however, about whether this line will be entirely green. If the wind farms don't get up and running, short-term power contracts have been signed with six global energy shippers to lease the space, according to a 2007 report in the Missoula Independent newspaper.

Mr. Williams denies that any such short-term contracts have been signed. But "certain potential customers have registered with MATL and they may or may not be awarded short-term capacity in the future," he says. It depends on whether the wind-power companies want to offer any of their unused capacity back to the market, he says.

An environmental trade off?

"That line is in fact going to carry dirty power," says Ken Toole, Montana's Public Service Commissioner. The economics of a power line mean that it has to be full all the time, he explains. And that's a huge challenge moving forward with just wind and solar power, since their output varies over the course of a day and a season.

"I've talked with [MATL] about the concept of ‘greenwashing' these projects. Talking about them as facilitating wind, giving the public the impression that they are all about clean, renewable power - that's a little misleading," says Mr. Toole.

One of the obvious ways to get more green electrons flowing on any new transmission wires is to put pressure on the buyers of the power, says Ms. Shimshak with the Renewable Northwest Project. Many states like California already have emission performance standards that prevent utilities from purchasing power that spews too much carbon.

The federal government could also take away some of the economic imperatives for maximizing the load on the line. Traditionally, transmission lines are built to the size they are needed in the near term. The current discussion of federal dollars is not about financing the entire cost of new lines, but about funding the supersizing of them for future growth, says Doug Larson, executive director of the Western Interstate Energy Board.

"It's clear if you don't build the wires, you'll never tap the wind. From an environmental perspective, there's this trade off - you could oppose this transmission, but you are cutting off renewables," says Mr. Larson.