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GRASS-BASED FUEL INFORMATION:

If you are familiar with grass fuel or pelleting and briquetting you have probably heard that grass pellets do not burn as well as wood pellets because of any one of a number of common reasons.  The two most common explanations are that they have a very high ash content and that they are corrosive to the combustion equipment.  It is also common to hear that they cause pollution and that they have less energy content per pound than wood pellets.  All of these statements are misleading and the purpose of this page is to shed light on the subject of grass pellets.

ASH CONTENT & COMPOSITION:
Much research has been done on the use of grass pellets and how they compare to wood pellets by various groups.  BHS Energy has done a significant amount of research and the materials reviewed indicate that grass pellets have only about 3-4% ash as compared to the 0.5-3% ash allowed of premium wood pellets.  The actual issue is not so much the quantity of ash but the composition of the ash.  Switchgrass, when harvested, contains more calcium and phosphorus than wood and therefore the ash that is left over after combustion has a lower melting point.  Because of this it can form "clinkers" during combustion in stoves that are not designed to deal with such ash. This is the same issue encountered when burning corn and therefore at this time it is believed that many corn stoves should work well for burning grass pellets as they are designed with more aggressive ash removal systems. Many newer pellet stoves are also designed to handle multiple fuel types, and more and more manufacturers of combustion equipment are beginning to advertise that their stoves & boilers can handle grass pellets. Also note that 3-4% ash is still insignificant as compared to the ~30% ash contained in coal.  In most cases, with modern combustion equipment, ash should only need to be emptied a few times per week at most.

In addition to "clinkers", another issue encountered due to grass pellet composition is the corrosion of the combustion equipment.  This may be partially true and more research needs to be done on the subject.  However, this problem is not unique to grass pellets as combusting all biomass including wood causes corrosion in combustion equipment to one degree or another.  Because of this many stoves and boilers are already built with corrosion resistant features such as stainless steel burn pots and smoke pipes.  Also there is experimentation with adding a base chemical such as lime to grass prior to pelleting to help prevent corrosion.

BURN EFFICIENCY AND POLLUTION:
Sometimes we will hear that grass pellets pollute the environment more than other sources of bio-heating and this is untrue.  The fact is that the pollution created by the combustion of any biomass depends entirely on the efficiency of the combustion equipment.  In most cases grass pellets, just like wood pellets, burn very efficiently with the only significant pollutant released being carbon dioxide.  When combusting fossil fuels, the carbon is removed from the ground and put into the atmosphere during combustion.  With biomass, the carbon dioxide put into the atmosphere during combustion is reabsorbed by the plants as they grow ultimately making the entire cycle from growth to combustion carbon neutral.  This is possible because the native grasses involved have an extensive root system and they sequester carbon in the soil permanently as they grow which offsets pollution created during the harvesting and densificaiton of the raw biomass materials.  Another large benefit of this carbon sequestration is that it improves soil quality dramatically over time.  There is research available and still being done on the specifics but BHS Energy is confident that the combustion of easily renewable biomass, such as switchgrass and other native prairie grasses, is among the most environmentally friendly and benign sources of energy currently available.

ENERGY (BTU) CONTENT:
Another very commonly asked question is "How much energy per ton is contained in grass pellets compared to wood pellets?"  The answer is that all biomass contains essentially the same energy content minus the particular ash content.  Therefore if you are comparing one ton of wood pellets with 2% ash and one ton of grass pellets with 3% ash, the difference in energy is about 1%.  So if the 2% ash wood pellets contain 16,000,000 BTU's (which is true, approximately), then the 3% ash grass pellets contain 15,840,000 BTU's.  This is an insignificant difference.  In other words, the short answer is that grass pellets and wood pellets contain approximately the same amount of energy per any given weight.