Issuu on Google+

THERMAL¦ he says. “My staff then cuts the wood into 28inch sections, splits it, and stacks it in a big firewood barn. Once it’s dry, and it takes about six to eight months, it’s moved down to the two residences that burn that cordwood.” Culpepper has been using both pellets and chips in the ACT boiler since it came online, but has been experimenting with increasing chip usage, which is mainly hinged on the method of preparing them for the system, and their availability without interruption. Through trial and error, he’s adopted an unconventional method that, at least for now, is penciling out nicely. “The past couple of years, I’ve hired a local guy to cut small-diameter trees, with 3- to 6-inch diameter stems, and cut them 12 feet long,” he explains. “He then piles them into large windrows, and in 6 to 8 months they are dry enough so we can run them through a chipper and burn them that way. It’s relatively unique, and I don’t know of anyone else doing this.” Though it remains experimental, Culpepper has invested in a large chip storage facility—12 feet wide, by 11 feet high, by about 40 feet long—that has been completely filled with chips, an accompaniment to the existing 20-ton silo that sits outside of the ACT plant. This winter, the plan is to increase the use of chips in the ACT boiler. Right now, the ratio is at about 50-50. “The big plant is down right now [Nov. 21], as we’re replacing the burn rings in the plant, but when it comes back online, I hope to be using 100 percent chips. If you can maintain temperature with chips, we’ll continue doing that, unless we get to a point where we’re not able to, or we can’t load it fast enough.” Culpepper says he initially predicted it wouldn’t be economically viable to cut and prepare these small-diameter stems, but he’s happy to admit that, so far, he was wrong. “There’s a lot of work involved, but we’re able to do it with small-scale equipment—just one person with a small tractor and a log loader, so the investment up front is not a lot. So far, based on the limited data that I have, it is [economically viable].” Besides the 220 acres of land the school owns and manages, it manages another 130 acres nearby, land owned by a neighbor who took an interest in what the school was doing. “They asked us to thin their land, create trails, and do a lot of thinning for the past few years,” Culpepper says, adding that the reach-in rate is such that no replanting is needed. “We have done lots of baseline studies to determine what sustainable harvest is, here on this campus,” he says. “We have good information, and we’ve been doing this long enough so that we’re confident that we’re not taking more stems than what are naturally regenerating. In

PITCHING IN: Students play an active role in helping collect and prepare the school's wood fuel, including moving and stacking poles. PHOTO: NORTH COUNTRY SCHOOL

fact, what we’re seeing in the areas where we first started doing this, is an overall improvement in the health of the forest—better spacing, better stem quality, and a higher level of diversity.” The school’s land is American Tree Farm certified, which Culpepper says has proved to be the best fit for the institution. “We have a robust forest management plan, written by a professional forester who knows our campus very well, and he is giving us really good guidance,” he says. All fuel is drawn from less than a mile from where the chip plant is, and Culpepper estimates that when and if the school is able to transition to all wood chips, it will increase its usage from around 9,000 poles per year to 11,000 to 13,000 poles, depending on the species and diameter. “It sounds like a ridiculous amount of work, but it seems to be viable,” he reiterates. Another unique aspect of the school and its fuel scenario is that many students are involved and have the opportunity to help cut and process small-diameter trees, and are frequently involved in moving cordwood from the storage barn to the residences. “They’re involved in a lot of different ways,” Culpepper says. Despite all of the benefits, there are some challenges, especially when focusing in wood chip usage. “The cordwood boilers run very, very well—never any problems with them,” Culpepper says. “Chips are more problematic—they take work, thought and real estate.” In this case, the biggest hurdle is getting the chips from the chip facility to the ACT

plant, which is about 300 meters away. “When it’s heavy snow, or raining, it’s a challenge to get dry chips from one location to another,” Culpepper says. “I’m still working that piece out, but I have thought of lots of different possible ways of doing that, from building a vault in front of the facility, where we could take our truck, dump it into the vault, and auger them into the fuel storage bin that contains a flexible auger. Currently, we’re moving chips from the barn into the facility with a Bobcat Toolcat, a skid-steer, all-wheel-drive utility vehicle with an 80-inch snow bucket on it. It can pick up quite a bit of chips, but it’s a bit of a chore, getting chips from storage into the plant. I’m working on a simpler, easier system for that.” But no matter the relatively minor challenge, it’s all well worth the effort, Culpepper says, again highlighting the ability to be able to accurately predict annual fuel expenditures and figure it into an annual budget. “Fuel oil goes up and down, all over the place. At $3 per gallon, we’re saving over $50,000 a year. At $5 per gallon, over $80,000.” And, if the school is able to use 100 percent chips, Culpepper adds, the savings and return will be even better. “We’re still collecting data, but we’ve been able to stabilize our fuel costs, we’re able to pretty closely predict what our average expenditure is going to be year to year. The savings is great, but the ability to be able to forecast is a bonus.” Author: Anna Simet Managing Editor, Biomass Magazine 701-738-4961


2017 January Biomass Magazine