"We asked the previous owners how much their highest power bill was, and it was like $210," Jill Amidon said. "The price of heating is going up, so we decided to get a wood-burning stove."

Since then, the Amidons' power bill has topped out at just over $80 in the new house. And since they have access to free wood, so their heating bills are nearly nonexistent.

With energy prices soaring in recent years, some people are turning to wood stoves to take the sting out of their heating bills. Thanks to new technology, wood stoves can heat an entire house with less wood, burn more consistently throughout the night and are less likely to create chimney fires than their earlier counterparts.

"You get more BTUs out of the wood," said Ralph James, a salesman at Bare's Stove and Spa in Bozeman. "Stoves today will burn anywhere from one-third to a half less wood and still heat the same area."

But just as dramatic, modern wood stoves burn far cleaner, putting a fraction of the particles in the air as the stoves of even 15 years ago.

CLEANING UP

Wood stoves took off in popularity during the energy crisis of the late 1970s, said Don Johnson, a market researcher with the Hearth Products and Barbecue Association, an industry trade group. As energy prices skyrocketed during the Mideast oil embargo, more people turned to wood.

But the wood stoves of that era spewed black smoke into the air. In populated areas where wood burning was popular, a visible haze would develop.

In response, the federal Environmental Protection Agency stepped in and set strict guidelines for new stoves. The agency ordered stove manufacturers to build better stoves that would put out only 7.5 grams of particulate per hour.

It was a drastic drop compared to what the older stoves generated.

"In 1985, we had 300 grams of particulate matter going up the chimney," James said.

States and cities also began clamping down on wood stoves. Some cities, particularly in the West, instituted "no-burn" days during cold-air inversions. Other cities, such as Missoula, banned wood burning outright, except for grandfathering in homes where a wood stove was the only heat source.

All stoves sold in the United States had to meet the standard by 1990. The industry achieved that goal by engineering stoves that incinerate the smoke, releasing just a light, gray smoke.

"Today the dirtiest stove has about 5 grams" of particulate per hour, James said.

INGENIOUS DESIGNS

Stoves use one of two ways to burn up the smoke. Some models circulate air into the top of the fire box, where the smoke gathers, through baffles.

The oxygen burns up the particles in the smoke, which not only gets rid of particles, but also produces more heat.

"We're actually controlling the combustion," said J.D. Engle, owner of Burning Stoves and Stuff, Inc. in Belgrade. "It's the right combination of gas and oxygen."

The smoke visibly bursts into flames in a model of Quadra-Fire stove that Engle shows off. The stove is one of the cleanest burning stoves on the market, producing just over 3 grams of particles per hour.

The efficiency of modern stoves also allows them to be damped down overnight for a slow burn that lasts all night. Older stoves could also have the oxygen choked off to burn slowly, but they produced a lot of thick smoke because the fire was essentially being suffocated.

Older stoves could spew up to 900 grams of particulate an hour when damped down.

The other method by which modern stoves burn cleaner is use of a catalytic "honeycomb" insert in the top of the hearth. The insert gets incredibly hot to burn up the smoke.

Cleaner air isn't the only advantage of modern wood stoves. They also produce far more heat for every log they burn by maximizing efficiency, meaning stove owners don't need to use as much wood as in past to heat the same amount of space.

"We had one guy who said he used to use a cart of wood every night with his old stove," Engle said. "Now a cart of wood lasts him four nights."

Another advantage is the lack of creosote build up in the chimney produced by modern stoves. Because they burn so cleanly, the chmneys attached to modern stoves don't have to be cleaned as often, and the risk of a chimney fire is reduced considerably.

MONEY SAVER?

Modern stoves are nice, but they're not cheap.

They cost anywhere from $700 to $2,000 or more. Add to that the cost of materials for a safe chimney, a hearth pad and other accessories and the labor to install it and the total can easily top $3,500.

It would take many years for a stove to pay for itself even while if a homeowner is saving hundreds of dollars every year.

Then of course, there's the need for wood, which is selling for anywhere from $100 to $150 a cord.

Engle said if a person has to buy wood, they're probably not saving much money, if any. But people who cut their own wood can save hundreds of dollars every winter.

Wood stoves make up about 15 percent of Engle's sales, he said. A few people buy pellet stoves, while the vast majority - more than 80 percent - are opting for gas stoves even though gas prices have risen in recent years.

But wood has an ambiance factor that gives it an advantage over gas and pellet stoves, Engle said. Some people enjoy the work of chopping wood, and like the crackling fire and the smell of pine.

Jill Amidon fits into that category. She said although the wood stove saves money, she's just likes having a stove in the living room.

"If you just want quiet time, the lights are off, the TV's, off and you see this nice little fire," she said. "You feel like you want to camp out."