There's nothing like a roaring fire to stave off winter's chill, or—as some consumers are finding—to cut their heating bills.
Nationwide, about 2.5 million households are expected to use wood as their primary fuel source this winter, according to the Energy Information Administration's Short-Term Energy Outlook. Granted that's just 2 percent of all households, but a 39 percent increase since 2004.
Another 8.8 million, use wood as a secondary heating source—such as an occasionally used fireplace, said Chip Berry, residential energy consumption survey manager for the EIA.
"It's by far the most inexpensive fuel source," said Bill Cook, a forester with the Michigan State University Extension. Cook estimates he spends about $500 over the course of a northern Michigan winter to heat his home. "And that's purchasing the wood," he said. "If you go out and cut and haul your own, it's close to free."
(Read more: Affording a $2,000 winter heating bill)
In comparison, the EIA expects that the average consumer in the Midwest will spend $713 to heat using natural gas from October 2013 to March 2014. Using electricity to heat, the average bill will be $974, and using propane, $1,584. The agency does not track average wood expenditures. (See chart below for more average bills by region and fuel type.)