Efficient wood pellet burners is goal of research-leading Clarkson University prof
Saturday, November 23, 2013 - 8:18 am

By JIMMY LAWTON

POTSDAM -- Local researchers are working on several projects to help create and test wood pellet burners that run more efficiently and produce less pollution.

Philip K. Hopke, a professor and director of the Institute for a Sustainable Environment at Clarkson University, has been actively studying solid fuel combustion systems with an emphasis on emissions and efficiency.

His expertise earned him a spot as judge in the “Wood Stove Decathlon” that took place last week in Washington, D.C. There he evaluated 12 prototype burners to consider how the designs can improve real-world use.

He said similar work is performed right at Clarkson with the installation of state of the art burners in the Wild Center as well as the Walker Center.

Quality counts

Over the past five years Hopke has studied 132 varieties of wood pellets and many different burners. Among the pellets included in the study were the soft and hardwood varieties made locally in Massena at Curran Renewable Energy. Hopke said those pellets ranked quite high as did many of those made in the northeastern United States. He said Curran pellets don’t contain many pollutants.

“Some bagged pellets had waste wood in them. Old wood painted prior to 1977 had high concentrations of lead paint. We found that in some of the pellets,” he said.

Wood pellets made in the New England states tend to come straight from the forest. While it is not uncommon to hear people talk about a difference in quality between hard and soft wood pellets, Hopke says there is a misconception that soft wood pellets are inferior.

“Both have about the same heat content per unit,” he said.

Although well-made pellets are one component to reducing emissions, Hopke said the pellet-burning device can drastically reduce waste.

Highly efficient

He said wood stoves are a familiar heating option in the North Country but there are many poor-quality designs on the market. Hopke says the inefficient models not only waste energy and money, but also harm air quality.

He said the university is currently performing third party testing on high-efficiency pellet boilers, which use hot water to store heat.

“It’s all very fine for the manufacturer to say this is the greatest thing since sliced bread, but we are testing them to see if they perform as well as they model them to perform.”

He said the use of multi chambered burning devices and thermal storage units, which are generally well insulated water tanks can reduce the amounted of wasted energy.

He said research has shown pellet burners are most efficient when burning at the max load, but this can also produce more heat than is needed, especially this time of year, where temperatures are often above freezing.

“One of the problems with pellet burners is their efficiency goes down when they aren’t burning at the max rate. What we are doing now is putting in thermal storage units,” he said.

In order to conserve that energy and allow the burners to operate at peak efficiency, the units heat up water, which is stored in tanks and then distributed throughout the commercial building or residence.

Wetter is better

Although pellet stoves produce far less emissions than traditional wood burning stoves, Hopke says even the most efficient units create double the emissions released by oil burning furnaces.

Hopke says natural gas continues to be the most efficient fuel, but it has flaws as well. Hopke says natural gas is not a renewable resource and that rural communities, like much of the North Country don’t have access to it.

He said pellet burners are a long way from burning as efficiently as natural gas furnaces, but ongoing research is vastly reducing the amount of waste in the process.

Hoping to reduce emissions is another area Hopke is working on. He says a Clarkson team is currently working installing a “particle control system” at Walker Center. This basically consists of a device that traps the some of the waste debris using water and allows the device to recover additional heat that would otherwise be lost.

Hopke said that in the past many of the more efficient burners were developed and made in Europe, but in recent years highly efficient boilers are manufactured right in New York State, in Schenectady and Troy.

Hopke said efficient burners will likely become more popular as the Environmental Protection Agency looks toward tougher standards for emissions. A proposal he said he supports.