Glossary of Terms

Anaerobic digestion

Anaerobic digestion is the breakdown of organic material by bacteria without the use of oxygen. The result is biogas, which consists of methane, carbon dioxide, and other trace gases. The biogas can then be used to generate heat and electricity.

Atmosphere

Atmosphere is the layer of gases surrounding the planet that is retained by the Earth's gravity. It contains roughly 78.08% nitrogen, 20.95% oxygen, 0.93% argon, 0.038% carbon dioxide, trace amounts of other gases, and a variable amount (average around 1%) of water vapor. The atmosphere protects life on Earth by absorbing ultraviolet solar radiation and reducing temperature extremes between day and night. There is no definite boundary between the atmosphere and outer space—it slowly becomes thinner and fades into space—although an altitude of approximately 75 miles, or 400,000 feet, marks the area at which Earth’s atmospheric effects become noticed upon reentry from space.

Biodiesel

Biodiesel is a type of fuel made by combining organic matter such as animal fat or vegetable oil (e.g., soybean oil or recycled restaurant grease) with alcohol and can be blended with or directly substituted for petroleum diesel for use in internal combustion engines. As with ethanol, the blend is named for its percentage of biodiesel content, B100 for 100%, B20, for 20% biodiesel. Biodiesel can be used in vehicles (newer diesel vehicles, usually 1994 or later, are required for B100) and is beginning to be used in on-site electricity generation and heating applications. (Interesting historical note: Rudolf Diesel's original engine was designed to use vegetable oils as fuel in order to help agrarian culture.)

Bio-oil

Solid biomass can be converted into a carbon-rich liquid which can be used to produce chemicals and fuels. Bio-oil is produced through a process called pyrolysis.

Biosphere

Biosphere is the part of the Earth, including air, land, surface rocks, and water, which breeds life, and which living processes in turn alter or transform. It is the global ecological system that integrates all organic matter and their relationships, including their interaction with the elements of the lithosphere, hydrosphere, and atmosphere.

Carbon cycle

Carbon cycle describes the movement or exchange of carbon gases between the four major reservoirs of carbon: (1) the atmosphere; (2) the terrestrial biosphere, which is usually defined to include fresh water systems and non-living organic material, such as soil carbon; (3) the oceans, including dissolved inorganic carbon and living and non-living marine biota; and (4) the sediments including fossil fuels.

The carbon exchanges between reservoirs occur because of various chemical, physical, geological, and biological processes. The ocean contains the largest active pool of carbon near the surface of the Earth, but the deep ocean part of this pool does not rapidly exchange with the atmosphere.

Cellulosic ethanol

Cellulosic ethanol is an advanced transport fuel with a unique combination of attributes including low life-cycle greenhouse gas (GHG) emissions, a high level of sustainability, and seamless integration into the existing transportation and heating systems. It is a cost-efficient way of replacing gasoline in vehicles while reducing carbon load from transportation.

Climate change

"Climate change" refers to a significant variation over a period of time in average temperature and weather patterns, some indicators include changes in annual rain and snow fall, wind and storm frequency and intensity. Climate change is how we at the Earth's surface experience global warming.

Co-firing

Co-firing is process of burning biomass material with coal in eletric power plants. Full-scale experiments have shown that power plants can easily burn mixtures of up to 10% biomass with coal. Because burning biomass is a closed-carbon cycle, co-firing disproportionately reduces emission of some pollutants from such power plants. 49 states are currently co-firing some amount between 2% and 15% of biomass to produce their electricity.

Combustion

Combustion refers to biomass that is burned to provide process and/or space heating. The combustion of biomass can also be used to raise steam to drive engines & turbines which are coupled to generators producing electricity.

Ethanol

Ethanol is an alcohol that is made from biological matter (at this time, mostly grains such as corn and barley) and blended with or burned in place of gasoline as a transportation fuel. Today, gas and ethanol are commonly blended together and the gas you find at the average pump is at least 10% ethanol. The blend is named by the amount of ethanol contain, e.g., E*% is 85% ethanol, E24 is 24% ethanol, and E10 is 10% ethanol.

Feedstocks

Biomass feedstocks are those sources which can be burned to create electricity or refined to create fuel in biomass energy production. Feedstocks include, but are not limited to:

Algae Barley & residues Black grease Brewery waste Brown grease Canola Construction & demolition waste Corn & residues Cotton waste Dairy & cattle manure Food waste Forest slash Hardwood Horse manure Hybrid poplar

Industrial hemp Landfill gas Lawn clippings Leaves Lumber waste Mill residues Muncipal sludge Municipal wood waste Orchard & vineyard waste Paper & cardboard Peanuts & residues Poultry litter Pulpwood Renderings Restaurant waste

Rye & residues Secondary wood waste Short rotation woody crops Softwood Sorghum Soybeans Storm waste Stump grindings Sweet potato Swine waste Textile waste Warm season grasses Wheat & residues Yellow grease

Gasification

If the pyrolosis process is carried out more slowly at higher temperatures, more gases and less bio-oil are produced. Biomass can be gasified with air to make "producer gas" or it can be gasified with oxygen to make synthesis gas, which can be used to create methanol, ammonia, and diesel fuel with known commercial catalytic processes.

Global Warming

Global warming is the increase in the average temperature of the Earth's surface due to an increase of greenhouse gases in the atmosphere. An average surface increase of 1° F can reflect as much as a 12° rise at extreme locations, such as the North Pole.

Greenhouse gases

Greenhouse gases are gases which allow sunlight to enter the atmosphere but absorb the infrared radiation when it is reflected, thus trapping the sunlight's heat. Many natural and man-made gases exhibit these properties; natural gases include water vapor, carbon dioxide, methane, and nitrous oxide, while man-made ones come from industrial practices and use of synthetic compounds. Over time, if atmospheric concentrations of greenhouse gases remain relatively stable, the amount of energy sent from the sun to the Earth’s surface should be about the same as the amount of energy radiated back into space, leaving the temperature of the Earth's surface roughly constant. Too many greenhouse gases of either the natural or man-made variety in the atmosphere can tip the balance and cause global warming. This process by which the atmosphere behaves like greenhouse glass panes is called the greenhouse effect.

Iogen

Iogen is a Canadian company that has been doing pioneering research on ethanol from cellulosic plant material (ethanol has typically been produced using sugar from corn and soybeans). They are currently producing cellulosic ethanol.

Inorganic compounds - Inorganic carbon

Inorganic compounds are of mineral, not biological, origin. Inorganic carbons include carbon dioxide, carbonic acid, bicarbonate anion, and carbonate anion. Inorganic carbon compounds include carbon monoxide, carbon dioxide, carbonates, cyanides, cyanates, carbides, and thyocyanates. Complementarily, organic compounds are those carbons which originate from a biological source.

Landfill gas

Landfill gas is created when the organic waste in a landfill decomposes under anaerobic conditions. Landfill gas is approximately 50% methane and 50% carbon dioxide, with traces of nitrogen, oxygen, water vapor, and sulfur. The CO2 tends to leach out because it is water soluble and landfills tend to be moist. The landfill methane, being lighter, is released as a gas which can be captured and used as a source of energy similar to natural gas (90% methane). Since landfill gas is generated continuously, it provides a reliable, renewable source of fuel for a range of energy applications.

Peak Oil

"Peak oil" is the simplest label for the problem of energy resource depletion, specifically the peak in global oil production. The rate of oil production—meaning extraction and refining—follows a bell curve process, whereby the oil closest to the surface is processed quickly and easily, and, therefore, cheaply. After this initial phase, the process of extraction becomes more costly and time-consuming, and the product recovered is not as easily refined, therefore it brings an increasingly lesser return on the investment of effort. Once the halfway mark of this bell curve has been reached, production is likely to decline, hence "peak." Peak oil does not mean "running out of oil," but "running out of cheap oil."

Oil is a finite, non-renewable resource that has powered phonomenal economic and population growth over the last 150 years. For economies leveraged on the ever increasing amount of cheap oil available in the first 100 years of oil production, the consequences may be dire. When more than half the world's oil has been extracted, prices will soar because the remaining oil will be much more difficult to remove and refine. Many experts predict that this will happen in the first decade of the 21st century, and even the most conservative estimates predict it will happen before 2025.

Photovoltaics (PVs)

Simply explained, photovoltaic cells work like semiconductors by using photodiodes to directly convert sunlight into energy (either current or voltage). In a photodiode, the photons from sunlight knock electrons into a higher state of energy, creating the electricity. A photovoltaic cell is the most basic element of a solar panel, array or system. It creates no pollution, noise, or other impacts on the environment.

Pyrolysis

When biomass is heated to a high temperature (500° C), usually without oxygen, molecular bonds are broken and three products result: gas, bio-oil, and char. The primary goal is to substitute the bio-oil for petroleum products. The char (mainly carbon) can be burned for process heat. The gas can be flared.

One current version of this technology is called "fast pyrolosis," in which hot sand is mixed with the biomass in a rotating conical chamber with the goal of maximizing bio-oil production.

Sediment

Sediment is any particulate matter that can be carried by fluid flow and which eventually is deposited as a layer of solid particles on the bed or bottom of a body of water or other liquid. Sediments can be carried by water, wind, or glaciers. Sedimentation is the deposition by settling of a suspended material.

Warm season grasses

Warm season grasses are native perennial grasses that grow during the summer months (their high time is June through September), slow through the fall and go dormant at the first killing frost. (Compare to cool-season grasses, which have their active growth cycles in both spring and fall.) Because they are natives, they are fast growing and have deep root structures. They require less water, are easier to grow on poorer soils, produce more tonnage than cool-season grasses, use nitrogen more efficiently, and make great riparian buffers as well as excellent crops for ethanol. They also provide a natural habitat for hundreds of wildlife species. Farm efficiency and income can be greatly increased with warm season grasses, which can provide a second, fuel crop to supplement other produce as well as grazing pasture during mid-summer.

Some warm season grass varietals are big bluestem, broomsedge bluestem, eastern grama, indianagrass, little bluestem, sideoats grama, and switchgrass.

Subsections of This Issue

• Biofuels
• Biomass Power
• Our Bioenergy Future
• Virginia Biomass Energy Group
• Resources Online