MSU Extension

For most Michiganders, convenience and price will determine which fuel will heat and cool homes and businesses. For most, whatever is currently in a purchased building is what will be continued. For new buildings, the choice is usually whatever the HVAC installers know how to do. Change comes slowly.

Not often on the radar screen is the use of wood. Not so much the throwback technologies of the last century, or some of the lower-end outdoor furnaces available today, but more the advanced “wood-based thermal” technologies that increasingly become available.

These advanced systems are no less convenient than natural gas, propane or fuel oil. Their emissions can barely be detected and are, in fact, cleaner in terms of carbon than fossil fuels. An explanation is needed here, however.

Carbon from burning wood-based fuels came from the atmosphere just a short time ago. It cycles into the atmosphere and then back into the forests. There are plenty of studies showing this, and there are more all the time. This is part of the carbon cycle. Wood can be sustainably burned for centuries with no impact on the carbon cycle.

However, burning wood does, indeed, generate more carbon than fossil fuels. Studies demonstrate this, too. But carbon from fossil fuels is not part of the carbon cycle. That carbon hasn’t been part of the cycle for millions of years. That is a critical difference between burning fossil fuels and wood fuels.

Beyond carbon benefits, using wood-based fuels offers new forest management opportunities and better outcomes for timber, habitat, and environmental services. Management provides higher quality and greater amounts of goods and services than unmanaged forest landscapes. Many of these goods and services are essential to human society. There are many benefits to forest management. And having another market for the lower quality materials is needed.

Wood is the easiest widespread renewable solution to displacing fossil fuels used in heating and cooling. For power generation and transportation fuels, other technologies come into play, such as solar and wind. However, we hear less about heating and cooling, thus we hear less about wood as a fuel source.

While wood is not an inexhaustible resource, large volumes can be sustainably managed at prices more stable than those for fossil fuels. Michigan is a long way from harvesting our annual growth. Wood must be locally sourced due to transportation costs. That means that those dollars are turned back into the community. Wood energy cannot be outsourced.

What are “advanced” wood-based thermal technologies? There are three basic wood fuel types; cordwood, wood chips, and pellets. Each have multiple ways to be used.

Cordwood works only for smaller applications, such as homes, out-buildings, and small businesses. It takes more time and effort than most people are willing to invest. Using modern, high efficiency boilers greatly reduces required cordwood volumes and does not generate smoky emissions. Using dry, well-seasoned wood is also needed to obtain good performance.

Pellet boilers, different than pellet stoves (another technology), are quite clean. When bulk pellet delivery is available (not currently in Michigan), the only thing a homeowner needs to be concerned about is adjusting the thermostat. Pellet systems are often less expensive than propane, fuel oil, and electricity.

Wood chip systems produce the lowest cost thermal energy but buildings need to be larger, arguably at least 50,000 square feet. The best applications are schools, hospitals, large businesses, and district energy systems. Maintenance needs are similar to those for fossil fuel systems. Operating costs can be competitive with natural gas and are usually lower than propane, fuel oil, and electricity.

Common concerns about the larger systems are noise, smell, and increased truck traffic. However, case studies from Michigan and many other regions demonstrate that these systems are quiet, nearly odorless, and truck traffic is minimal. Their use for schools and hospitals are good testimonials.

These advanced wood-based thermal energy systems have many configurations. They are flexible enough to fit many different sites and situations. For more information and case studies, visit the website from the Michigan Statewide Wood Energy Team.