A busload of foresters, policy makers, scientists and graduate students headed to the Dorothea Dix state psychiatric hospital on Tuesday, expecting to see a model wood-fired boiler combusting truckloads of woodchips to heat steam and hot water for the 335-acre hospital campus.

Instead, they saw a broken conveyor belt and a few glowing embers, residual woodchips coaxed to life especially for the wood-based alternative energy conference field trip.

Just a few weeks before the conference tour the system’s original woodchip conveyor, installed in the late 1970s, shuddered to a halt, suspending the entire wood-burning operation.

“You have a lot of extra maintenance costs with this wood-fired system,” Rick Stogner, maintenance director at the Dix Hospital, said. “You can find people who can deal with this thing, but you don’t find them around every corner. And there’s a rule that it always breaks on a Sunday night, when it’s 20 degrees out.”

Dennis Hazel, assistant professor of forestry and director of the conference, added a second rule.

“It always breaks when you’re planning a conference,” he said.

Usually, steam plant supervisor Dalton Jenkins can handle the repairs.

“I have 12 years of experience operating boilers,” he said. “This is my first time operating a woodchip boiler; but hey, I’m not too old to learn something new. Sometimes I have to replace a motor, or I leave for the day and something goes wrong and I have to come back, and nine times out of 10 I have to fix it.”

The conveyor, however, is a bigger problem than Jenkins can face himself, and he’s having trouble finding anybody who’s up to dealing with it.

So for now, the Dix Hospital campus is running its fossil fuel boilers, but Stogner wishes the wood system were up and running.

“Wood fuel has much more attractive commodity costs,” he said. “It makes our fuel budgets go a whole lot deeper into the year when we can burn wood instead of oil or gas.”

Wood costs only $2.30 per million British thermal units, while fuel oil costs $5.25 per MBTU and natural gas about $13, Stogner said. For comparison, an average Midwestern home uses about 60 to 80 MBTU per winter.

The boiler was custom engineered in the late 1970s when Dix Hospital planners were facing similar concerns about energy prices.

“It was installed in response to the oil embargoes and the high oil prices at that time,” Stogner said. “Then, like now, people were looking for alternative energy sources.”

When all is working well, the Dix boiler goes through about two truckloads of woodchips per winter day — or about 8,500 tons of chips per year.

The facility buys its chips from a contractor who harvests the trees specifically for fuel, chips them and delivers them to the hospital on 18-wheelers. Each truck dumps 25 to 30 tons of woodchips into a giant metal hopper, and a pair of spiked rotating cylinders sort through the chips. Properly sized chips land on the now-problematic conveyor, which normally carries them to the chip storage area, a pavilion that holds 18 truckloads of chips.

Employees then load the chips onto another conveyor that takes them to the boiler — a contraption reminiscent of a room-sized pizza oven. Jenkins lit a few leftover chips so the tour could get a feel for how the boiler looks when it’s really working.

“We just fill it up with chips, pour a pan of diesel fuel over it, light it up and it’s good to go,” he said.

Every Wednesday and Sunday, employees have to shovel the soot out of the boiler, a job that takes two people about 90 minutes. At the end of the season, a landfill uses the accumulated soot as cover.

The Dix Hospital has historically been on the crest of the energy wave. In 1850, it boasted Raleigh’s first steam-heated and gas-lit public building. Then, in the 1970s, it got the wood boiler.

But some conference-goers observed that this Dix facility is past its prime. Norm Etkind, as director of the school energy management program of Vermont, gave a talk at the conference on Vermont’s state-of-the-art wood burning boilers.

“We save half a million dollars a year by burning wood instead of oil in 25 public schools,” Etkind said. “Our boilers are automated and low-maintenance, they run all weekend without any attention. [The Dix facility] really needs to enter the next level, or scrap it.”

Despite its high maintenance costs, Hazel touts the Dix facility as an alternative energy success story.

“We’ve all seen that this boiler can be a real pain in certain body parts for Dalton and Rick,” he said. “But, over 25 to 30 years, this facility has burned 200 to 250 thousand tons of wood. Think about what that means in terms of fossil fuel displacement, in terms of renewable resource usage. Unfortunately, that doesn’t make it any easier for these two guys.”