Burning biomass

🕔Dec 07, 2010

The Duerichens’ home is a simple log design with wood paneling and locally sourced materials. Colourful wool rugs, lots of light, creeping plants and a 1989 RSF woodstove as the home’s centerpiece combine to create a cozy atmosphere.

But it’s not just the wood, the espresso and biscotti, and the hospitality that makes their house feel so warm.

Hans Duerichen recently designed a biomass boiler he says is the first of its kind in North America. Capable of burning a variety of combustible materials, priced for the average homeowner, and small enough to fit into a moderately sized shed, his MBB-100—the first to operate in Canada—burns quietly out back, heating their home with discarded sawdust from a local mill.

“You’re not tied to a specific fuel,” Duerichen says about the boiler, which heats water and sends it into the home for use in their sinks, showers and in-floor heating system. It can burn a variety of fuels, from wood chips to small twigs. “It gives you an assurance for the future that you won’t be saddled with expensive fuel.”

It was the future that inspired Duerichen, a mechanical engineer, to design the home-heating system he hopes will create a shift away from fossil fuels and toward locally sourced resources.

“Nobody can tell me in what situation my children’s children are going to be at in terms of energy,” he says. “I feel we’re being very wasteful with limited resources.”

Duerichen grew up in the Bulkley Valley, living on the same Kitseguecla Lake Road property with his parents where his new log home now stands. In 1978 he started the RSF wood stove company, which he sold 19 years later to a company in Eastern Canada.

While working with wood stoves, he became interested in the Stirling engine, which produces electricity without using gas or diesel. He thought there must be a way to generate electrical power with a wood stove.

He stumbled upon Wood-Mizer, a company in Ohio that was developing that idea with a cogeneration, or combined heat and power (CHP), engine. In 2001 he moved to the U.S. to work with Wood-Mizer, designing a wood-waste burner that would create both heat and electricity. After two years, the company discovered the product was just too expensive.

“There’s tons of technology out there,” he says, “but people can’t afford it.”

Eventually, Wood-Mizer shut down the division, letting everyone go but Duerichen. He was asked to design a sawdust burner, since Wood-Mizer had 40,000 customers needing to get rid of the waste material. Then, almost three years ago, Duerichen was one of three Wood-Mizer employees that left the company to form Laskow Enterprises Inc. The company set about designing a biomass burner that was suitable for the average family home.

“There’s enough dead beetle-killed pine in BC to heat every home and every business for the next 15 years,” he says. “We have a tremendous source of green fuel that we’re not using, really. I feel it’s something important we should pursue.”

Smithers thinking green
It’s exactly this availability of green fuel that the Town of Smithers is hoping to capitalize on. Mark Allen, director of development services, says the town is currently considering a biomass burner to replace the natural-gas boilers at the arena, which is the town’s largest consumer of natural gas.

“Wood is carbon-neutral, and that helps our carbon emissions targets,” says Allen, adding that the primary fuel source would be the Wetzin’Kwa Community Forest, in which the town is a one-third partner. The boiler would run on pine needles and branches that have dried two years and been put through a wood chipper.

Costs for the biomass fuel would largely revolve around trucking, Allen says, which he expects would cost in the neighbourhood of $10,000 per year. Currently, heating the arena with natural gas costs more than $20,000 annually. Although the biomass boiler would cost much less than that to run, there’s a significant capital investment to be considered.

The cost would include building a large holding area for the boilers and holding wood waste. The town is currently looking into the system’s feasibility and will include it in the upcoming budget discussions, starting in December.

“At this point I’m just guessing that it’s a $250,000 project,” Allen says, noting that it would take many years to recoup the initial costs, but that there is an intangible benefit to reducing the town’s carbon footprint. The town would also benefit from carbon tax credits.

Heating the arena would likely require more than one 500,000-BTU burner, the largest boiler Duerichen will produce. He plans to make the boilers in three sizes: the home-sized 100,000-BTU, medium-sized 250,000-BTU and industrial 500,000-BTU burner.

Creating a single, larger boiler to heat the arena is not cost effective, he says. When boilers get bigger, the costs increase exponentially, up to one dollar per BTU for a million-BTU boiler. By comparison, his 100,000-BTU boiler costs just $10,000.

Warmth from waste
Duerichen’s boiler hums softly in a 12-by-24-foot shed behind his home and has the faint smell of sawdust and wood smoke. He calls his MBB-100, which was recently CSA-certified for safety and emissions, “one of the cleanest biomass boilers you can buy.”

The shed is divided in two, with one half housing the boiler and the other designed to store sawdust. Planks can be stacked horizontally in the doorway between the two sections, to the height of the sawdust, allowing for easy transfer into the boiler. Duerichen estimates the room filled with sawdust would last a year. He currently uses about two 20-kg bags of sawdust, which he got from the Seaton Sawmill, each day.

A large canister next to the boiler can hold enough fuel to last their home about 10 days in winter, Duerichen says, with an automatic feed that supplies enough sawdust to keep the boiler burning.
The boiler itself is a non-descript black box about five feet high and similar width with a screen showing the flue, water and combustion chamber temperatures, along with fan and fuel speed. Inside, a cyclonic burner rotates the flame, throwing heavier particles outward to create cleaner burning.

The auto-feed is an improvement over wood boilers, which need to be fed several times a day in winter, but Duerichen says the ultimate goal is to create a system that feeds directly from the fuel storeroom and never needs refilling.

The boiler heats water that is sent into the home through existing infrastructure, such as baseboard or in-floor radiant heat systems or forced-air heat exchangers.

“It’s ideal for several reasons,” Duerichen says about the system. “It heats your water and your house. The unique features are that it burns a wide variety of fuels, so you can take your pick of what’s the easiest to get.”

Although Duerichen’s biomass boiler is the only one operating in Canada, he currently has orders for four more—three in Smithers and one in Dawson City—along with 10 additional units currently in production.

“I personally feel that part of our problem is things not being local enough,” he says. “To me, it just doesn’t make sense. We have local fuel, why don’t we use it?”