Second Post From Catskill Grass Energy Project: Stove and Furnace Challenges

Quadrafire Mt.Vernon

We had on interesting experience this fall. EnviroEnergy experimented with some over wintered grass. They did this to see if the mineral content would be reduced. For reasons we do not fully understand, the ash content was at 9%. The usual ash content from this facility is consistently in the 4% range. I think that raking into windrows might have added earth to the grass. We used these pellets in several appliances with interesting results.  A Quardafire Mt Vernon had trouble burning these pellets even with a grass table that was programed to dump ash at a rather high rate. The tables we are using have no problem handling 4% ash. On a related note I had a call from a man referred to us because we have been successful burning grass. During the conversation I concluded that he had a Quadrafire Mt.Vernon, but it was an earlier version that has only a manual control for the feed rate. It was concluded that this unit was not suited to burn grass. He even has trouble with certain wood pellets that must have higher ash content. The lesson from this experiance is that appliances need to be designed so that they can handle varying ash levels. We have had good luck with several Harmon pellet stoves. The fact that the controls on these units make it possible to control the  feed rate so that ash levels are not so much a problem.

The heating season is in full swing. All of our installations, save one, are operational. The exceptional one came back for the season on October 14. A week later they experienced a power outage lasting six hours. As the outage was very localized no one realized the outage and responded to start auxiliary power. This caused a burn-back that  destroyed critical electrical components on the unit. As this was our hardest pushed unit, we are looking to replace it with a bigger unit with a newer design. It is notable that this defect is not related to grass as they started the season using up a small supply of wood pellets that we had burned last season as a comparison to grass output.

The Catskill Grass Bioenergy Project, as you can see on our website,  is utilizing three Woodmaster pellet furnaces,two Central Boiler pellet furnaces, two Quadrifire Mt. Vernon stoves and five Harmon stoves. We have burned grass pellets successfully in in all the units however each appliance has presented different challenges.  The Quadrafire units will not handle the ash content of grass with any of the pre-installed operation tables. Tables for grass have been developed by the manufacturer but the dealer network does not have access to them. All other units, both furnaces and stoves, can be adjusted to handle grass pellets. One issue that we have experienced is that Grass pellets not only have higher ash content but seem to produce more fly ash which accumulates in all the heat exchangers. Units thus have to be cleaned more often than with wood pellets. If this is not done most units begin to burn poorly and some have even ceased operating. Another interesting observation is that grass pellets seem to ignite faster than wood. This characteristic requires feed rates set at the upper levels to keep the fire in the manufactures recommended location in the fire box. A local resident burning an older Woodmaster has had good luck mixing shell corn with grass pellets to control the fast ignition.

More next month.

Read Full Post »

Grass pellets and stove compatibility

Second Post from Hudson Valley:

In addition to operating our mobile pellet mill, it is of great interest that HVGE assists in fostering a viable market for grass pellets. Combustion unit compatibility is likely the biggest hurdle facing large-scale use of grass pellets. Higher ash and clinker formation are associated with grass pellets, whereas all premium wood pellets are guaranteed to have less than 1% ash. Therefore, HVGE is involved with analyzing pellet and burn quality and in the future supplying pellets to manufacturers for testing. In Europe we are already seeing innovative stove technologies help to bridge the gap between grass pellets and consumers.

Fortunately, we are already seeing manufacturers incorporating grass pellets into their system designs and warranties. Variable feed rate, automated ash removal and an active burn pot are key features to look for in choosing a stove to combust grass pellets. You can find these features in a variety of stoves ranging from $1,200 to $5,000. Some of the manufacturers that are reported to have stoves to better handle grass pellets include Harman, Enviro, Magnum, Bixby and Quadrafire.

One partner Mighty Maples Farm has been burning grass pellets for home heating since fall 2009. They have reported great success with both their USS stove and modified Englander. Owner Jim Wiest reports: “My most significant finding is blends of as little as 10% commercial hardwood pellets and any generic grass pellets can be effectively burned in most low end stoves designed specifically for wood pellets only…  Ash storage and its removal are the limiting factors.”

Finally, I would like to mention the current federal incentive for purchasing higher efficiency stoves called EPA Burn Wise. The tax credit covers 30% of installed costs up to $1,500 and automatically qualifies all pellet stoves because of their inherently high efficiency ratings. This program was initiated in response to emission concerns with burning cordwood and other less efficient resources. Due to poor air quality, many cities are even outlawing certain types of wood burning during the winter months. Burn Wise is due to run out at the end of December, but we hope they continue the program in 2011.

Read Full Post »