More than a dozen Northwest schools and hospitals have replaced old diesel heating systems with boilers that burn wood pellets. Advocates say that this wood fuel -- called forest biomass -- is an affordable local source of energy. And it can help rural communities cut back on their fossil fuel use.
But the push to develop markets for forest biofuels has sparked a debate among scientists. Some say burning more wood could increase greenhouse gas emissions. Amelia Templeton of EarthFix reports.
Illinois Valley High School is on the outskirts of Cave Junction, a Southern Oregon timber town about an hour from the redwoods.
Behind the noisy cafeteria where 300 students line up for lunch, there’s a large silver silo, the kind that normally holds grain.
Twice a month, a truck fills it with wood pellets. This school is heated almost entirely by wood. And Jim Bunge knows that sounds a little old fashioned.
Bunge: “It’s not backward at all. It’s pretty high tech, with the computer system and everything.”
Bunge is responsible for maintenance and energy savings at the Three Rivers School district.
A few years ago, the district decided to replace this school’s diesel heating system with a high efficiency wood pellet boiler.
Bunge: “It’s just switching from a fossil fuel to a renewable energy source.”
Every few seconds, a computer program sends pellets through a tube and into a black metal firebox.
Bunge: "It almost sounds like rice crispies popping as they go through the tube."
The new boiler cost about half a million dollars. The district paid for it with the help of stimulus funding and a renewable energy tax credit. Bunge says its going to pay off in the long run. Pellets are a cheaper fuel source than diesel. The district is saving about $30,000 a year by heating this school with wood.
Bunge: "We’re locked into one price on pellets. We’re not at the mercy of the changing of oil prices, up and down.”
And the Northwest has plenty of wood to burn.
Kauffman: "Tops, limbs, branches. That’s the part that we need to find markets for."
That’s Marcus Kauffman, a biomass specialist with the Oregon Department of Forestry. He says loggers often remove tree trunks but leave behind piles of smaller stuff called slash. All that slash could be turned into pellets and used to heat more schools.
And selling that biomass could create a little extra revenue to help keep Oregon’s struggling mills open.
Kaufmann: "That’s the concept here, that we can be taking the byproducts of forest management and turning it into a sustainable homegrown fuel, which competes really well with imported fossil fuels."
But not everyone is convinced that burning pellets or wood chips is better than burning fossil fuels.
Law: "Well, wait a minute -- did you do the math on this yet?"
That’s Beverly Law, a forestry professor at Oregon State University.
Law: “You need to be thinking about it from an atmopsheric perspective.”
You might remember from middle school science class wood is 50 percent carbon.
Burning it releases carbon dioxide into the atmosphere, just like burning coal or gasoline does.
Law is co-author of a study, published in Nature Climate Change, that found that harvesting more forest biomass in the Northwest could increase the region’s carbon dioxide emissions.
Law: "Biomass burning from, say wood pellets releases a large amount of carbon dioxide into the atmosphere that can create a carbon debt that lasts for decades."
Carbon debt. That idea probably wasn’t covered in your middle school science class, so here’s a crash course.
Unlike the carbon in fossil fuels, the carbon in trees is part of a living cycle. Trees breathe in carbon dioxide and use it to build branches and needles. Every tree rots or burns eventually, and releases its store of carbon into the atmosphere. That carbon is recaptured by new trees as they inhale and grow.
The problem, Law says, is that you can burn a wood pellet in a few seconds. And it takes the growing forest decades or longer to soak that carbon dioxide back up.
Law: "It’s neither sustainable nor greenhouse gas neutral."
A Canadian study found that burning wood pellets instead of coal increased carbon emissions for the next 16 to 38 years.
After that time lag, biomass helped cut emissions compared to coal.
But advocates of biomass energy say there’s one more factor we need to think about.
Many forests East of the Cascades are crowded with too many small trees, and at very high risk of wildfire.
Kaufmann: "Isn’t it better to remove some of those trees, turn them into pellets, and use them to heat a school?" Again, Marcus Kauffman with the Oregon Department of Forestry.
Kauffman: “We have a carbon benefit when we displace a fossil fuel, and we protect a forest from emitting that carbon back into the atmosphere in the form of a wildfire.”
Jeremy Fried is a research scientist with the Forest Service. He says thinning trees is an effective strategy for preventing really large fires. And in forests where the risk of fire is high it’s also a good way to reduce carbon dioxide emissions.
Fried: "If you do it on the Olympic Peninsula where fires happen every 200 years, it would be pretty difficult to justify the carbon benefit. If you do it on the east side of Oregon, where fires happen every 20 to 50 years, it does seem to make sense."
So here’s the takeaway: The biomass pellets in that boiler back at Illinois Valley High School might be carbon neutral. It all depends on where they came from.
source: Northwest Public Radio