Saccharide: A simple sugar or a more complex compound that can be hydrolyzed to simple sugar units.

Saccharification: A conversion process using acids, bases, or enzymes in which long-chain carbohydrates are broken down into their component fermentable sugars.

Salvable dead tree: A downed or standing dead tree that is considered currently or potentially merchantable by regional standards.

Salvage Cutting: Removal of trees that have dead, damaged, or are expected to die, generally as a result of natural disaster, pest infestation, or disease infestation.

Sandstone: A sedimentary rock formed by compaction and cementation of sand grains; can be classified according to the mineral composition of the sand and cement.

Sanitation Cut: Removal of dead and weaker trees in an overstocked stand to reduce the danger of natural disasters.

Saplings: Live trees 1.0 inch through 4.9 inches d.b.h.

Saturated steam: Steam at boiling temperature for a given pressure.

Sawtimber/Sawlog : Refers to trees that meet specific provisions that allow them to be harvested for commercial use. Standards dictate that trees be at least 9 inches dbh in order to be commercially harvested. Sawlogs are the logs created from whole sawtimber trees.

Screen analysis: Method for measuring a proportion of variously sized particles in solid fuels. The sample is passed through a series of screens of known size openings. Biomass fuel screen sizes usually range from 5 to 100 openings per inch.

Scrubber: An air pollution control device that uses a liquid or solid to remove pollutants from a gas stream by adsorption or chemical reaction. Traditionally, the term "scrubber" has referred to pollution control devices that use liquid to wash unwanted pollutants from a gas stream. Recently, the term is also used to describe systems that inject a dry reagent or slurry into a dirty exhaust stream to "wash out" acid gases. Scrubbers are one of the primary devices that control gaseous emissions, especially acid gases. Scrubbers can also be used for heat recovery from hot gases by flue-gas condensation.

Seasonal efficiency: The efficiency of a heating system averaged over an entire heating season.

Secondary oil recovery: Application of energy (e.g., water flooding) to recovery of crude oil from a reservoir after the yield of crude oil from primary recovery diminishes.

Secondary wood processing mills: A mill that uses primary wood products in the manufacture of finished wood products, such as cabinets, moldings, and furniture.

Seed-tree Harvest: A silvicultural system in which all trees are harvested except for a small number of selected trees are retained for seed production for natural regeneration.

Sensitivity analysis: A part of economic analysis used to determine how sensitive the results of the analysis are to changes in the input variables.

Setting: A base on which a boiler or combustor sits, used to elevate a boiler. Houses the grates and primary combustion zone in a direct-burn system. Can form the connecting chamber in a multi-chamber system.

Shaft horsepower: A measure of the actual mechanical energy per unit time delivered to a turning shaft. See also horsepower.

Shared savings: A form of energy project financing in which the party supplying the financing and/or installation gets a share of the dollar savings resulting from the reduction in energy consumption.

Shelterwood Harvest: A silvicultural system in which trees are removed in a series of two or more cuts, leaving those needed to produce sufficient shade to produce a new forest in a moderated microenvironment. This method produces an even-aged forest.

Short Rotation Intensive Culture (SRIC): - the growing of tree crops for bioenergy or fiber, characterized by detailed site preparation, usually less than 10 years between harvests, usually fast-growing hybrid trees and intensive management (some fertilization, weed and pest control, and possibly irrigation).

Shredder: A machine that tears material apart by shearing.

Simple payback: A method of economic analysis in which cost effectiveness is based on installed cost and first-year savings. Also refers to the number of years it takes an improvement to pay back the investment, computed by dividing the installed cost by the first-year energy savings.

Site Productivity: Combination of soil and climatic factors contributing to plant growth and development; may be measured as biomass accumulation per unit of time.

Sizing: The process of specifying the size (measured in MMBtu/hour or MMBH) of a heating plant.

Skidder: Machinery used to pull logs from their stump to a landing. Logs are pulled with a grapple, cable-winch, or clam-bunk.

Slash: Woody residues, such as tree tops and limbs, which are generated in the forest from harvesting activities. After harvesting, slash is typically piled and burned onsite.

Small round wood (SRW): Small trunk or branch wood of diameter 7-14cm.

Snag: Refers to a standing, dead tree often missing its top and most of its branches and needles.

Softwood: Generally, one of the botanical groups of trees that in most cases have needle-like or scale-like leaves; the conifers; also the wood produced by such trees. The term has no reference to the actual hardness of the wood. The botanical name for softwoods is gymnosperms.

Soil Fertility: The total availability, concentration, and amount of essential plant nutrients.

Soil Function: The role that soils play in the environment and managed landscapes.

Soil Productivity: The capacity of a soil to contribute to the production of a crop, whether it is agricultural crops or forest biomass.

SOx: Oxides of sulfur. Air pollutants implicated in acid rain caused by combustion of fossil fuels. Modern wood systems have 1/6 the sulfur dioxide emissions of fuel oil.

Specific gravity: The mass (or weight) of a unit volume of any substance at a specified temperature compared to the mass of an equal volume of pure water at a standard temperature.

Stack emissions: The components of the hot combustion gases (including particulates) exiting from the stack.

Stack temperature: The temperature of the combustion exhaust gases passing into the chimney. One indicator of appliance efficiency.

Standard chip van: The most common method of transporting processed biomass from the forest to a sawmill or biomass energy facility. A standard chip van can carry 25 green tons of biomass or 12.5 bdt of biomass.

Stand Density: The number or mass of trees occupying a site. Usually measured in basal area or square feet per acre.

Stand (of trees): A tree community that processes sufficient uniformity in composition, constitution, age, spatial arrangement, or condition to be distinguishable from adjacent communities.

Starch: A molecule composed of long chains of a-glucose molecules linked together (repeating unit C12H16O5 ). These linkages occur in chains of a-1,4 linkages with branches formed as a result of a-1,6 linkages (see below). This polysaccharide is widely distributed in the vegetable kingdom and is stored in all grains and tubers. A not-so-obvious consequence of the a-linkages in starch is that this polymer is highly amorphous, making it more readily attacked by human and animal enzyme systems and broken down into glucose. Gross heat of combustion: Qv(gross)=7560 Btu/lb (4200 cal/g,17570 J/g). (Source: Domalski, E.S.; Milne T.A., ed. Thermodynamic Data for Biomass Materials and Waste Components. The ASME Research Committee on Industrial and Municipal Wastes, New York: The American Society of Mechanical Engineers, 1987)
Diagram of the structure of glucoseThe polymeric structure of glucose in starch tends to be amorphous.

Steady state efficiency: See appliance efficiency.

Stem: The main trunk of a tree, exclusive of branches and top.

Steam turbine: A device for converting energy of high-pressure steam (produced in a boiler) into mechanical power which can then be used to generate electricity.

Stinger-steer: A stinger-steer is another type of vehicle that can be used to transport biomass. Stinger-steers are able to navigate roads that standard chip vans cannot because of an advanced hydraulic system that allows them to maneuver around sharper turns.

Stocking: A description of the number of trees, basal area, or volume per acre in a forest stand compared with a desired level for balanced health and growth. Most often used in comparative expressions, such as well-stocked, poorly stocked, or overstocked.

Stoker: An auger or other device for feeding solid fuel into the combustion zone.

Streamside Management Zones: Buffer zones in which cover is retained in riparian areas adjacent to surface water and aquatic habitat.

Stumpage: The value or volume of a tree or group of trees as they stand uncut in the woods (on the stump).

Silviculture: Theory and practice of controlling the establishment, composition, structure and growth of forests and woodlands.

Slagging: The coating of internal surfaces of fireboxes and in boilers from deposition of ash particles.

Slow pyrolysis: Thermal conversion of biomass to fuel by slow heating to less that 842 degrees Fahrenheit (450 degrees Celsius) in the absence of oxygen.

Slurry: A slurry is a thin sloppy mud or cement or, in extended use, any fluid mixture of a pulverized solid with a liquid (usually water), often used as a convenient way of handling solids in bulk.

Sound dead: The net volume in salvable dead trees.

Stover: The dried stalks and leaves of a crop remaining after the grain has been harvested.

Straight vegetable oil (SVO): Any vegetable oil that has not been optimized through the process of transesterification.

Structural chemical analysis: The composition of biomass reported by the proportions of the major structural components; cellulose, hemicellulose, and lignin.

Substrate: The base on which an organism lives or a substance acts upon (as by an enzyme).

Sucrose: is the organic compound commonly known as table sugar and sometimes called saccharose. A white, odorless, crystalline powder with a sweet taste, it is best known for its nutritional role.

Sugarcane (or Sugar cane): is any of six to 37 species (depending on which taxonomic system is used) of tall perennial true grasses of the genus Saccharum, tribe Andropogoneae, native to the warm temperate to tropical regions of South Asia.

Superheat steam: Steam which is hotter than boiling temperature for a given pressure.

Sulfur Dioxide (SO2): Formed by combustion of fuels containing sulfur, primarily coal and oil. Major health effects associated with SO2 include asthma, respiratory illness, and aggravation of existing cardiovascular disease. SO2 combines with water and oxygen in the atmosphere to form acid rain, which raises the acid levels of lakes and streams, affecting the ability of fish and some amphibians to survive. It also damages sensitive forests and ecosystems, particularly in the eastern part of the US. It also accelerates the decay of buildings. Making electricity is responsible for two-thirds of all Sulfur Dioxide.

Summer boiler: A small boiler sized to meet the summer or off-season heating load.

Surplus electricity: Electricity produced by cogeneration equipment in excess of the needs of an associated factory or business.

Suspension burning: A type of combustion in which fuel is blown into the combustion chamber, with some or all of the solid fuel particles burning in the air (in suspension).

Sustainable: An ecosystem condition in which biodiversity, renewability, and resource productivity are maintained over time.

Sustained Yield: A forest management strategy in which the net growth and yield are balanced.

Switchgrass: Switchgrass is native to the US and known for its hardiness and rapid growth. It is often cited as a potentially abundant second generation feedstock for ethanol.

Syngas (synthesis gas): is the name given to a gas mixture that contains varying amounts of carbon monoxide and hydrogen. see Bio-syngas, Fuel gas, Natural gas, Landfill gas,Producer gas.

Synthetic crude oil (syncrude): A hydrocarbon product produced by the conversion of coal, oil shale, or tar sand bitumen that resembles conventional crude oil; can be refined in a petroleum refinery.

Synthetic ethanol: Ethanol produced from ethylene, a petroleum by-product.

Syringyl: A component of lignin, normally only found in hardwood lignins. It has a six-carbon aromatic ring with two methoxyl groups attached.

Systems benefit charge: A small surcharge collected through consumer electric bills that are designated to fund certain "public benefits" that are placed at risk in a more competitive industry. Systems benefit charges typically help to fund renewable energy, research and development, and energy efficiency.

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