Frequently Asked Questions (FAQs)
(The questions sometimes change, and so do the answers as we learn more about the process)
- Pellet stoves
- Other appliances
- Pellets & Pelleting
- Grass production
- Grass biofuel history
- General questions
- Rarely asked questions
How frequently does the ash pan need to be dumped?
This depends on the stove, the ash pan capacity, and the rate of pellet feeding. With a medium feed setting using grass pellets that are 4-5% ash content, ash would probably need to be removed every couple of days. Some stoves, such as the Country Flame Harvester Corn stove, require ash to be removed daily, regardless of the type of pellet or if corn is the fuel used.
Which pellet stove works best for burning grass pellets?
At the current time, the Harman corn stove appears capable of handling grass pellets at least up to 5.2% ash content, without any modifications to the stove.
Why is low ash content more desirable when burning biomass pellets?
High ash content increases the chances of problems due to chunks of melted ash (“clinkers”) and also increases the chances of buildup on the burn pot surfaces, restricting air flow and influencing the removal of ash from the burn chamber. High ash content also means more frequent dumping of the ash pan.
Who is manufacturing pellet stoves specifically to burn grass?
No company is doing this, but several are attempting to modify their stoves to better manage high ash fuels.
Can I burn grass pellets in my pellet stove?
Most likely not. Average pellet stoves with a standard burn pot are not designed to cope with high ash content. In general, corn stoves will have more potential to handle grass pellets because they are designed to deal with a somewhat messy residue. This is no guarantee that corn stoves will burn grass, corn stoves sometimes have difficulty dealing with corn.
Can I recycle the ash as fertilizer?
Yes. Ash from herbaceous plants, like wood ash, is highly alkaline. It can be used as a liming agent to increase soil pH. It also contains some essential plant nutrients, but would be considered a very weak fertilizer source. It would provide almost no nitrogen.
Does burning cause pollution?
Yes, but.... Burning clean, renewable biomass is better than burning coal. The Dell Point stove, for example, is EPA-certified to have emissions no more than 0.5g/h, this is over 10 times lower than EPA limits on emissions. So new generation pellet stoves can have very low emissions. Since any particulate matter from burning biomass is likely to be very alkaline like the ash residue, this small amount of material should not contribute to acid rain problems, it might help alleviate them.
Who is burning grass pellets in stoves at this time?
We have the only site burning cool-season grass pellets in North America that we know of. REAP-Canada is burning switchgrass pellets in a Dell-Point Industries Europa stove. Switchgrass pellets are also being burned in Iowa in a Country Flame Technologies Harvester stove.
How much routine maintenance is required to burn grass in pellet stoves?
Routine (weekly) maintenance is recommended for burning any type of pelleted material (including wood pellets) in any pellet stove. Aside from dumping ash at necessary intervals, the heat exchanger and burn pot area will need cleaning at least once a week. The flue pipes should be inspected for buildup at regular intervals.
Can pellet boilers burn grass pellets?
Not yet. The major advantage of boilers over stoves is that they provide hot water and central hot water heating. Commercially available pellet boilers are designed to burn wood pellets and possibly corn pellets. They have no means of dealing with high ash content. They can successfully burn grass pellets, but will generate a large clinker that would need to be removed from the burn chamber every 6 hours or so, in order for the boiler to continue functioning. Pellet boilers designed specifically for grass pellets are currently being tested in Europe. Large commercial-scale boilers are capable of burning grass biomass.
What is a gasifier?
Thermal decomposition of organic matter in an oxygen deficient atmosphere at controlled temperatures produces combustible gases. Solids remaining from this process are ignited to provide the heat for driving off moisture and also driving off the volatile gases. Gases can be collected and used to power a turbine or internal combustion engine to generate electricity. Heat can also be used as an energy source from this process.
Is pelleting required for biomass burned in a gasifier?
Some form of densification is probably necessary, loose material may not work effectively. It is possible that cubing would work in lieu of the more expensive pelleting process.
Can large hay or straw bales be burned without any densification (pelleting, cubing, etc.)?
Some large heating units have been tried in North America, using whole bales for fuel, with variable success. Whole bales have been used in Europe to power large boiler operations.
Who is currently pelleting cool-season grass in the USA?
No one. Several groups in New York State are comtemplating a grass pelleting enterprise for the 2005-06 heating season.
Are there other markets for grass pellets, in addition to energy?
Yes. Straw pellets are currently being used for horse bedding in some markets. Not only are they considered higher quality bedding than sawdust or shavings, but they can be less expensive. Any mature grass hay should make pellets suitable for bedding.
What does it cost to start up a pelleting business?
Quite a lot. A gross estimate for the purchase and set up of all the equipment necessary to start up a pelleting business might cost around $150,000 for used equipment. New equipment set up to work with baled hay might be around $400,000. Production costs for pelleting could be as low as $25/ton of hay. It may be possible to lease pelleting equipment with the option to buy. Cooperatively-owned equipment among neighbors is an option, this is done in Europe.
Can I purchase a small-scale pelleting unit for personal use?
Relatively small-scale, used pelleting equipment can be found for sale on the web. It is not clear at this time if it is economically or functionally feasible to set up a small-scale pelleting unit for occasional grass pelleting on an individual farm.
What would be the price of hay sold as biomass for pelleting?
This will be influenced by market supply and demand of biomass vs. fossil fuels, but it is unlikely that hay prices would increase greatly even with a demand for the biomass.
What is the energy value of grass pellets compared to wood or corn?
There is a range in BTU values for different types of wood and grass biomass materials. On average grass might be around 8,000 BTU/lb, premium wood pellets around 8,400 BTU/lb, and corn grain around 10,000 BTU/lb.
How do grass pellets compare economically to fossil fuels?
As of now, we do not have any economic comparisons of cool-season grass pellet systems with fossil fuels. REAP-Canada has made some comparisons of switchgrass with fossil fuels and estimated that switchgrass may be economically superior to all but natural gas. As the price of natural gas continues to climb, grass pellets will ultimately be cheaper than natural gas, if that has not already happened.
Can I mix low quality hay with wood residues and pellet them together?
It may be possible but not a good idea. Pellet dye specifications will be different for grass and wood. It would be much simpler to blend different lots of pellets to achieve any desired ash content, just as multiple feeds for cattle are blended. It would be easy to develop a pricing scheme that valued the ash content and composition of the fuel.
Can I use my lawn clippings for pelleted energy?
No, this is not feasible. Reason No. 1: Even if you have a very large lawn, the number of pounds of grass biomass in clippings is not significant. Reason No. 2: Immature, generally fertilized, grass leaves produce lawn clippings that will be very high in ash content, probably over 10%. Better to minimize lawn fertilization and mulch mow to recycle these nutrients back into your lawn.
What species are acceptable for grass pellet biofuel?
All grass species and mixtures. Legumes may not work quite as well but also may be acceptable. Grass crop selection should match the soil type, for maximum sustainability and productivity.
Do grass stands need to be fertilized for biofuel production?
No. Mixed grass stands cut once a year with regrowth left in the field to provide soil organic matter as well as wildlife cover should persist indefinitely. A shift in species composition or an increase in weed population is not of great consequence; all have similar BTU/lb. Of course, higher yields will be obtained with some form of nitrogen fertilizer application. Animal manures or other such land-applied waste products are well suited for this purpose.
What yield per acre can I expect?
Yield potential is primarily a function of soil type and fertilization (see Species Selector for potential yields in NYS). Soil with the lowest production potential without added fertilizer might only yield 1/2 ton/acre of hay. Good soils with added fertilizer can yield as high as 6 tons/acre. Very little material is lost between baling and pelleting, so one ton of hay will yield slightly less than one ton of pellets (some hay moisture is lost during pelleting).
What changes to the farm operation are required for grass biofuel production?
Almost none. The necessary equipment is generally available on the farm. Planting an improved species is an option, but the current species in a mixed meadow will work. Harvest in mid to late summer can be accomplished at off-peak labor times.
How many acres of grass would it take to heat my home?
Wild guess, with a good yield of grass it might take 2 acres to heat a 2,000 sq. ft. detached home for the winter in NYS. Keep in mind that grass yield can vary by up to 10-fold.
Will grass bioenergy solve the energy crisis and the greenhouse gas crisis?
No, but... Every BTU produced locally is one less that we need to rely on from foreign sources. And each BTU of grass bioenergy comes with at least 90% less production of greenhouse gases compared to fossil fuels. Grass bioenergy can provide some local energy security. Heating 5.5% of residential homes in NYS with biomass could offset 100% of the greenhouse gas production attributed to agriculture in the state.
Why is it recommended to overwinter switchgrass in the field before harvesting?
Ash content and composition of fuel is critical for many pellet appliances. Overwintering switchgrass lowers ash content by leaching of the forage and loss of plant components that are higher in ash (inflorescence and leaves). This produces a fuel with characteristics more like wood, but will also result in yield loss of 20% up to 50%. Warm-season grasses (switchgrass, indiangrass, big bluestem etc.) start growth late in the spring and do not mature until later in the season. There is little opportunity to cut these grasses in the fall, allow them to leach, and then bale in a dry state. There is generally ample opportunity to harvest last year’s growth the following spring before new growth resumes.
Is it reasonable to overwinter cool-season grasses prior to harvest?
Probably not. Reed canarygrass has been successfully overwintered in Sweden. However, overwintered reed canarygrass in NY during the winter of 2003-04 resulted in 100% loss of harvestable yield. Overwintered reed canarygrass in Iowa also was not very successful. Since cool-season grasses mature early in the summer it is possible to cut them and allow for leaching during the summer, with time left to bale a dry product.
How old is the “new” concept of grass heating in the US?
Pioneers who settled in the Midwestern prairies had no wood and could not afford coal. So they burned “Prairie coal” (buffalo chips) until supplies grew scarce. Then they switched to burning grass, twisted up into packets (the earliest form of densification). The packets were known as “cats”. (Fire on the Hearth, by J.H. Peirce, 1951, Pond-Eckberg Co., Publ.).
What ideas came with the immigrants to allow burning hay on the prairies in the 19th century?
Large brick or stone “Russian” furnaces were fed significant quantities of loose grass 3-4 times daily, the structure radiated sufficient heat for up to 6-8 hours. They were usually centrally-located in the house.
Did Yankee ingenuity build a better mousetrap?
Numerous US patents were granted for hay burning iron stoves in the late 19th century. Metal cylinders over a foot in diameter or magazines were stuffed with grass, and tension was provided to feed the hay directly into the firebox. One packed cylinder could keep a good fire for an hour or two. These stoves were very dangerous to operate. Various devices also were invented for twisting grass into sticks that could be cut to length like stove wood.
How far back is the Cornell connection with grass heating?
The following is part of a letter sent by Daniel W. Oaks to his brother on Dec. 13, 1877 in the Sioux Falls Dakota Territory (Courtesy of H. David Thurston, Cornell Emeritus Professor of Plant Pathology; Daniel Oaks was his great grandfather).
“Now D.B. I would like to tell you about how we got along without wood for fuel instead of working my team to death a hauling wood from 6 to 20 miles all winter to get enough to last. All summer I just take my mower and horses and go down to the Sioux bottom and in two days I can cut and put up enough hay to last me one year. And then not having to cut it. That is the worst of all. I do sympathize with you that have to chop wood. Instead of doing that all you have to do is whenever tired you can go and sit down by the side of a stack of hay and twist and rest all the same time. I would not chop the wood if you would give it to me. I have altered my stove so that I can burn hay better than I can wood.”
If you would like to see the full text of this interesting letter click here.
When was pelleting first used commercially in the US to provide heating fuel?
The first municipal installation using pelleted fuel in the US was in Watertown, S.D. which fired the heating plant for the downtown area in the early 1970’s. They pelleted flax straw for this purpose. The installation operated until the flax grower moved out of town. (Courtesy of Bob Massengill, Pellet Systems Consulting).
Are you trying to replace wood pellets with grass pellets?
Absolutely not. If both were available for the same price, wood pellets would be preferred as they will burn with less ash, making for easier cleanup of the stove. If the pellet stove industry continues to expand at its current rate, however, there will not be enough wood pellets to meet the market. This is the situation in parts of Europe and why wood pellets are currently being imported from North America to Europe (only economical due to subsidies).
Why are you bothering with this? Americans will not choose to cope with the relative inconvenience of a pellet heating system.
Some will. Bioenergy from grasses has quite a litany of environmental benefits, sooner or later an ecological response to energy concerns will have concrete value.
Wouldn’t it be more economical and energy efficient to focus on systems capable of utilizing whole bales without any need for densification?
No doubt whole bale systems are more economical and energy efficient. They are large units that require municipal, company or industry support, and are more constrained by the radius of economical transport of bulky biomass feedstocks.
What would be the best way for the USA to become energy independent?
A serious effort at energy conservation in everyday life by citizens would do far more to improve our energy independence than the sum total of all solid biofuel technologies.
What are the disadvantages of grass pellet fuel?
As with coal or wood stoves, and wood pellet stoves, routine maintenance is required. Pellet handling and ash removal make this less convenient than fossil fuels. There are some emissions as is the case with burning anything, but nothing like the wood stoves of the past.
Why do Federal and State governments have little interest in grass pellet biofuel?
Grass has no political lobby. A grass roots effort is not enough. (Washington State has funded a project to burn bluegrass stubble in a downdraft gasifier).
Where in the US does grass pellet biofuel have the most potential?
The Northeast. For many decades the Northeastern US has been officially labeled as the “Hay & Pasture” Region of the country. Like much of Europe, the temperate humid climate is not so hot for corn, but perfect for grass. The most recently published switchgrass study in the northern US by USDA-ARS personnel concluded “Western North Dakota is subject to periodic drought and wide fluctuations in precipitation that would jeopardize the capability of producers to provide a consistent supply of switchgrass biomass for biofuel purposes.” (Agron. J. 97: 549. 2005). So although some northern regions are not as well suited as others, grass bioenergy has good potential all across the northern tier of states that have a high winter heating requirement.
What would it take to get a grass pellet biofuel industry up and running?
Not much. One “Proof of Concept” demonstration of a pelleting unit providing fuel for local clientele with stoves capable of burning grass might be all the jump start required.
Is there any state government with interest in grass biofuel?
Washington State Dept. of Water and Energy is funding a downdraft gasifier to test the feasibility of this system for converting bluegrass stubble/straw into electricity and liquid fuel. After harvest of bluegrass seed in the Northwest, the remaining residue was burned in the field in the past. As it is no longer acceptable to burn fields, removal of residue as a bioenergy source solves the residue problem. Also, the Wisconsin Department of Energy has shown some interest in pelleting switchgrass for use in pellet stoves.