1. Wood Pellets and the Raw Materials
WOOD PELLETS are traditionally manufactured from wood by-products including sawdust, wood shavings, wood chips, etc. Or generally speaking, all wood residues can be processed into pellets and then used for residential and industrial application.
Wood by-products are generated in the process of harvesting wood and converting wood into wood products. Thus raw materials for wood pelleting include the residues from operations within forest and timberland, as well as residues from the process of converting wood into intermediate or final products. More specifically, wood resides from wood processing come from primary mills and secondary mills.
So, we conclude that Wood Residues come from Forestry (generating tree tops & branches, logging residues, etc.), Primary Mills (generating residues such as bark, slabs, edgings, trimmings, veneer clippings & cores, sawdust, pulp screenings, etc.), and Secondary Mills (generating residues like scraps and sawdust from woodworking shops–furniture factories, wood container & pallet mills, and wholesale lumberyards).
2. Residential Heating in the U.S.
2.1 Residential Heating Source
Heating source is indispensable for people, especially for American residents in cold winter. Residents have several choices like coal, natural gas, wood and solar energy. But, are these good choices in overall? There are a lot of factors we need to consider: economy, environment and society. After taking all these factors into consideration, wood pellets (or biomass pellets broadly) came into view.
They were initially used for industrial, commercial and institutional sectors heating and power generating. However, as the pellet stove gained popularity, they began to enter the residential heating market. They have been endorsed by the U.S. Environmental Protection Agency and they are one of the cleanest-burning and most renewable energy sources on Earth. The main benefits of using pellets are shown as below.
1) They are clean.
Different from coals, which generates air pollution, wood pellets can reduce carbon footprint. So they are friendly to environment.
2) They are renewable and sustainable.
They come from wood residues during wood related activity. Pelleting makes them fully utilized and helps us to save energy.
3) They are more independent.
Unlike solar energy which cannot be used in cold days without sun, nor heating oil whose price is unstable, pellets can be stored and used at any time and the price does not fluctuate dramatically.
2.2 America’s Residential Heating Choice
According to the U.S. Energy Information Administration, biomass is likely to surpass the use of petroleum for home heating by 2020; about 20% of total U.S. wood energy consumption in 2015 was shared by the residential sector, and wood accounted for about 3% of total residential energy consumption. This indicates that there will be a fair amount of households choosing biomass, especially wood as their home heating source. Wood pellets is a better choice for them.
The U.S. uses wood pellets mostly for house heating with pellet stoves, unlike China mostly use them for co-firing at coal-fired power plants. Now, in the U.S., they are consumed in nation wide as residential heating fuel, which is not only good for environment, but also economical for residents. So financial incentives need to be offered to encourage more and more families to choose pellets as their home heating source.
3. Pellet Fuel Appliance
PELLET FUEL APPLIANCE can be operated more easily compared to ordinary wood stoves or fireplaces. Besides, they possess much higher combustion and heating efficiency; they generate less pollution to the air. In one word, they are clean home heating appliances.
Now there exists complete set of wood pellets heating system to meet households’ demand for space heating as well as hot water. First, there will be a SILO TANKER which is to delivery pellets to the STORAGE ROOM (the place where household users store their pellets). And then the pellets are carried to the PELLET BOILER by an automatic PELLET FEEDER. Wood pellets are fully burned in the boiler only with less ash left behind (P.S. the ash can be disposed of together with domestic garbage).
It would be better if the boiler is connected with a BUFFER STORAGE, so the emissions can be reduced and efficiency can be increased. Finally, the buffer storage deliveries the energy to your domestic water equipment and space heating equipment. Then you can get hot water and heat. The residential heating system with wood pellets is shown as below.
4. Biomass Residues Available in the U.S.
In the United States, there are plenty biomass materials which can be used to make pellet fuel, since it is of vast territory and abundant resources. Let’s have a look.
4.1 Types
Speaking of biomass residues, farmers have a lot to say. When grains are harvested, there are a lot of AGRICULTURAL RESIDUES left behind, like corn stover (i.e. stalks and leaves), wheat straw, rice straw, rice husks, peanut shells, oil palm wastes, coconut shells, bagasse, etc.
ENERGY CROPS are also a major source. They include tall grasses like alfalfa, miscanthus, switchgrass, etc.
FORESTS offer biomass materials, too. (see Wood Residues in 1.)
Last one, WASTE MATERIALS. Household garbage, manure, and vegetative wastes (including clippings and trimmings as well as demolition debris) can be collected and used as biomass, as well.
4.2 Distribution of Biomass Residues in the U.S.
According to the maps from Nation Renewable Energy Laboratory (NREL), biomass residues are mainly distributed in the Midwest, Northwest, East and Southeast. It is reported by Energy Efficiency and Renewable Energy (EERE), biomass in the Midwest is extensively composed of agricultural residues while the Eastern America owns plenty wood residues. And in the Northwest and the Southeast, both agricultural residues and wood wastes are adequately distributed.
4.3 Make Pellet Fuel from Available Biomass Residues in the U.S.
It is recommended for businessman to establish plants near the original place of biomass residues to produce pellet fuels, and then sell them to plants who need heating source or to power plants used for power generation. In addition, commercial enterprises (such as hotels) and institutions (like hospitals and schools) are also potential users of fuel pellets. For businessman, it is important to establish his pellet plants between the places with abundant biomass residues and larger consumers, which is convenient to transport raw materials and final products.
Of course, individuals can get wood pellets from dealers. But if a person happens to be a farmer who has quantity agricultural residues awaiting for treatment, why doesn’t he choose to get pellet fuel just by himself? He can buy a small pellet press and then make his own pellets for residential heating (sometimes a hammer mill is also needed, according to the types of raw materials; while a dryer is not necessary because the raw materials can be dried by wind and sunlight).
Or small plants like sugar refineries can make pellet fuel as well, since they have a good deal of bagasse, the wastes from sugarcane processing, which is more economic and energy-saving. Another example, sawmills can also purchase complete equipment for pellets making, for they have adequate wood wastes. Likewise, other plants who have plenty biomass residues may also make pellets for themselves or for other plants nearby needing fuel source.
All in all, there is still a lot to do to effectively utilize these residues in the U.S..
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