Biomass+as+an+Alternative+Energy+Source

= An Introduction to Biomass: an article from the database Science Online =

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=Energy from Solid Biomass=
 * From:** Renewable Energy//, Green Technology.//

Liquid biofuels and solid biomass originate from matter that contains organic compounds. These substances are often referred to collectively as bioenergy sources. Most of the biofuel and biomass that have been envisioned as major future energy sources come from crops and crop residues left over after harvesting. Biofuels consist of mainly ethanol, an alcohol made from plant material (also called grain alcohol); the plant material from which ethanol is produced makes up biomass. Ethanol and biodiesel are the two main biofuels in use today. A gallon (3.78 l) of ethanol contains about 67 percent of the energy supplied by a gallon of gasoline. Biodiesel comes from the processing of vegetable oils from various plants such as corn or soybeans or from vegetable fats. Biodiesel contains a different mixture of hydrocarbons than ethanol, so has a different quantity of energy: A gallon of biodiesel contains about 86 percent of the energy supplied by a gallon of gasoline.

Biofuels became the primary focus of the burgeoning alternative-fuel industry in the 1990s. As interest in new fuels and renewable energy sources bloomed, the worldwide investment in biofuels increased from $5 billion in 1995 to $38 billion on 2005, and it will top $100 billion by 2010. But the clamor for biofuels created unintended effects across the globe with an increase in corn prices—the main source of ethanol fuel—bigger than any increase farmers had seen since World War II. U.S. growers and farmers in other countries jumped at the chance to earn more by growing corn for the biofuel industry than stay with lower paying crops. From 2003 to 2008, the amount of U.S. corn planted has doubled. High grain prices have meant increased prices of the items that use grains, such as beef, poultry, and breakfast cereal, among hundreds of other products. World food prices have begun to rise, and this rise has led to environmental harm. The scenario described by //Time// magazine in 2008 explained the effect of biofuels on the economy and in turn on the environment, as follows: Forests that disappear in the name of biofuels equate to a loss of habitat for endangered species. The fallen trees additionally add large amounts of carbon dioxide (CO2) to air that is already polluted as the ranchers burn whatever timber they cannot sell. Impoverished regions that cannot grow plentiful harvests of any kind fall victim to skyrocketing food prices. Growing corn for ethanol production furthermore consumes fuel for trucks and harvesters and for running ethanol refineries (called biorefineries). Cornell University's David Pemental said bluntly in 2007, "Biofuels are a total waste and misleading us from getting at what we really need to do: conservation. This [biofuels] is a threat, not a service." Global environmental organizations and economists like Nathaneal Greene of the National Resources Defense Council have now acknowledged, "We're all looking at the numbers in an entirely new way." A renewable energy source cannot have a future if it ultimately worsens poverty and devastates the environment. Studies on the worth of biofuels have continued. While environmentalists and some economists have identified the cautionary outcome to biofuel production, biofuel organizations and members of the federal government still support biofuel research. Biomass as an energy source has meanwhile developed in biofuel's shadow. The United States currently gets about 45 billion kilowatt-hours from biomass yearly, accounting for less than 2 percent of total electricity production. Energy from biomass may soon increase, however, because biomass does not interfere with current agricultural production, and it recycles the world's organic waste. Biomass as an energy source has already been shown to work, as this entry discusses. This entry follows the growing importance of biomass as renewable energy. It defines biomass and compares it with other renewable energy sources. The entry also describes the processes used in converting solid wastes to energy and finishes with a discussion on the future of biomass as a crucial energy source in sustainable communities. Finally, the discussion presented here offers ideas on how biomass may be optimized as a cheap, useful, and ecologically sound choice in energy production.
 * 1) One-fifth of the U.S. corn crop diverts to ethanol refineries rather than food production.
 * 2) The increased demand for corn raises world corn prices.
 * 3) Extra land planted with corn makes the supply of other crops, such as soybeans, decline.
 * 4) Soybean prices rise.
 * 5) Farmers already growing soybeans in developing countries decide to increase their crop to take advantage of soy's rising value.
 * 6) The farmers turn pastureland into cultivation, displacing ranchers.
 * 7) Ranchers remove forests for more pastureland.

The Earth's Biomass
Biologists think of biomass as the dry weight of all of the organic matter produced on Earth by plants and photosynthetic microbes. In environmental science, biomass is total plant materials but also animal wastes that can be burned as fuel. Biomass is the energy-storage form for all living things in food chains. The chemical energy held in biomass serves each member of a food chain. For example, plant biomass in the form of carbohydrates provides energy to grazing animals; the biomass in these animals in the form of fats, proteins, and carbohydrates acts as the energy source for predators higher on the food chain. When animals produce waste or when they die, the biomass furnishes energy for microbes and for scavenger animals such as condors. Biomass therefore plays a central role in the Earth's nutrient recycling. 

All of the Sun's energy stored on Earth in the compounds that make up plants and animals equals an ecosystem's gross primary productivity (GPP). When a plant or animal taps into this energy supply to live, grow, and reproduce, it must use some of the gross primary productivity for its own needs. Once those needs have been met, the energy left over is called net primary productivity (NPP), which is available for other organisms to use. NPP = GPP – R, where R is the energy needed for an organism's systems A portion of the energy in biomass disappears as heat whenever energy changes from one form to another. For example, a salmon in an Alaskan river consumes aquatic grasses for energy, but the fish cannot convert 100 percent of the plant energy into animal energy; some of the grass's energy dissipates as heat. Similarly, a grizzly bear feeding on the salmon can convert only a portion of the energy stored in the salmon's flesh. The rest of the energy also dissipates as heat. Such a stepwise scheme in food chain energy transfer is called an ecological pyramid. A large quantity of energy and organisms inhabit the bottom of the pyramid, but with each step to a higher level, the predators become less numerous and the energy available to them declines. Activities on Earth convert biomass into energy in three different biological methods and one chemical method. In biology, microbes degrade biomass into simpler compounds with the release of heat and gases. The first microbial method is fermentation, which converts biomass to alcohols and other end products such as CO2. The second microbial method entails anaerobic reactions, which are reactions that occur in the absence of oxygen. Anaerobic reactions produce mainly methane gas. The third biological method, respiration, is used by animals and some microbes. In respiration, an organism consumes oxygen as it converts sugars to energy and then releases CO2 with other end products. The chemical method that occurs on Earth for releasing biomass's energy is combustion. A lightning strike may ignite a forest and cause the burning of dead leaves and branches as well as living trees. This burning converts the compounds making up biomass into different compounds with the release of heat energy. Making use of the energy that can be liberated from biomass through combustion is the basis of biomass energy production.

Types of Biomass
Different types of biomass can be used for making energy in biomass power plants. When used in this manner for commercial or home energy production, the biomass materials are called feedstock. Feedstock originates from the following sources: agricultural crop waste (called bagasse), horticulture waste, wood and charcoal, pulp processing sludge, municipal solid waste (MSW), wastewater treatment solids, animal waste, and landfill waste. Sometimes used vegetable oils and animal fats also fit into the category of energy-producing biomass. Biomass energy offers an advantage because it can be almost any solid material that when burned releases a usable form of energy. The main types of biomass used throughout the world differ in source so they contain various constituents, which make them more or less efficient as energy sources. Some of the variations in biomass are listed in the following table. Civilization has used wood as its main biomass energy source for hundreds of centuries. In the United States in the 1800s, wood provided about 90 percent of energy use, but new energy sources replaced wood as new mechanized innovations came forward. Today, wood provides little more than 3 percent of the energy used in the United States. In developing countries, however, wood dominates all other energy sources, particularly in small rural communities. The Food and Agriculture Organization of the United Nations (FAO) estimates that more than 2 billion people worldwide fulfill their energy needs with wood.
 * Types of Solid Biomass with Variable Composition**||~ Solid Biomass
 * ~ Possible Constituents ||
 * agricultural waste || stalks, straw, cuttings, leaves, hulls, shells, vines, fruit and vegetable skins, seeds, animal manure ||
 * landfill waste and MSW || paper, cardboard, household garbage, restaurant waste, clothes and fabric, furniture ||
 * wood || pellets, chips and shavings, logging waste, branches, treetops, demolition waste, construction waste, cut timber, charcoal ||

Plant-derived biomass, such as wood, crop wastes, and paper, contains fibrous compounds that serve as the main storage form of the energy released in combustion. The three main fibers in plant biomass are lignin, cellulose, and hemicellulose, and materials high in these fibers are called lignocellulosic biomass. These three fibers vary quite a bit as evidenced by a woody log compared with a supple leaf from a grapevine. In general plant materials contain the following range of fibers: lignin 15–25 percent; cellulose 38–50 percent; and hemicellulose 23–32 percent. Lignin provides strength to plant stalks and occurs at higher concentrations in woody materials. Burning biomass high in these fibers benefits humans because they cannot digest these fibers as well as they digest carbohydrates such as starch and sugar. Since plants high in fiber do not serve well as food for humans, they make a good choice as an energy source for combustion. For this reason biomass is more attractive as an energy source than biofuels because, as discussed earlier, biofuels take land away from food production. Biomass stores energy as chemical energy that is held mainly in the bonds between carbon and hydrogen. Combustion releases this energy in the form of heat by the following process: biomass fuel + oxygen + heat to start the reaction → exhaust + heat The first law of thermodynamics states that energy is neither created nor destroyed. In combustion of biomass, the energy created by the reaction equals the energy held by the constituents going into the reaction. The first law of thermodynamics therefore explains biomass energy production. Biomass power plants, sometimes called waste-to-energy (WTE) plants, convert the unusable form of energy held in biomass to a usable form. These usable forms may be heat, electricity, fuels for powering vehicles, or fuels for heating or powering buildings.

Conversion to Energy and Fuels
Biomass is a renewable energy because of its unlimited supply. Trees and plants regrow, animals give birth to young animals, and people continue to produce wastes. Biomass also offers several options as to how it can be used and the end products of its use. For example, the European Biomass Industry Association lists seven different processing methods for turning biomass into a usable end product, and the various end products can be biofuels, heat, electricity, chemicals, or another type of biofuel, such as the conversion of wood to charcoal. In the United States, industry uses the greatest amount of biomass energy, almost 80 percent of total biomass energy production. About 20 percent of biomass energy goes to residential use and only 1 percent currently serves as feedstock for electric utility companies. Electric utilities would be wise to increase their dependence on biomass because biomass combustion is an uncomplicated process and similar to coal combustion that now produces most of the world's electricity. As mentioned, biomass also can be processed in a variety of ways so that a new power plant might choose a technology for biomass energy that works best in its circumstance. The following table describes predominant technologies for converting biomass into energy.

Biomass energy production includes two technologies that will increase the overall efficiency of energy production. The first technology is called co-combustion or co-firing. In this process, biomass substitutes for a portion of coal being burned at a coal-fired power plant. Co-combustion might offer the following benefits: reduction of CO2 emissions from coal; possible reductions in sulfur dioxides and nitrogen oxides, depending on the biomass composition; easy to modify existing coal plants; and abundant availability of biomass. Cogeneration represents a second technology that biomass energy production may soon perfect. Cogeneration involves the simultaneous production of more than one fuel type, such as heat and electricity. According to the National Climate Change Committee of Singapore's National Environment Agency, newly built cogeneration plants afford an energy savings of 15 to 40 percent compared with conventional electric power plants in their power production operations. Most cogeneration plants in operation produce heat and electricity.
 * Solid Biomass Technologies**||~ Technology
 * ~ Process ||~ Description ||~ Feedstocks ||~ Product ||
 * aerobic digestion || biochemical || microbial digestion of sugars, followed by distillation || * crops
 * straw
 * wood
 * pulp || ethanol ||
 * anaerobic digestion || biochemical || microbial digestion of organic matter in a sealed oxygen-free tank || * manure
 * wastewater sludge
 * MSW || methane ||
 * biodiesel production || chemical || conversion to new hydrocarbons || * seeds
 * animal fat</li? || biodiesel ||
 * direct combustion || thermochemical || burning || * agricultural waste
 * wood
 * MSW || * heat
 * steam
 * electricity ||
 * alcohol fermentation || biochemical || microbial digestion of organic matter || * agricultural waste
 * wood
 * paper || * ethanol
 * methanol ||
 * gasification || thermochemical || heating or anaerobic digestion || * agricultural waste
 * wood
 * MSW || * heating gas ||
 * pyrolysis || thermochemical || high-temperature treatment in absence of oxygen || * agricultural waste
 * wood
 * MSW || * synthetic oil
 * charcoal ||

The Energy Value of Garbage
MSW that settles underneath new loads of waste in landfills has an energy value that should not be overlooked. Garbage—a familiar name for MSW—serves as an available form of solid biomass for making energy or fuels. Landfills contain very high numbers of microbes in the deepest layers where they decompose the organic materials. The decomposition that takes place in layers that hold little oxygen—anaerobic decomposition—leads to the formation of methane. Many landfills collect this methane and route it to energy utilities to be used the same as natural gas for heating and cooking. Biomass recycling complements the natural paths of Earth's carbon recycling. Plants absorb from the air CO2 exhaled by animals and convert the carbon to sugars that animals then use for food, and thus energy. When plant or animal life dies and decomposes, some of its carbon goes to CO2 but some becomes trapped in sediments that sink into the Earth's mantle under tremendous pressure. After millions of years, the carbon turns into solid coal or it becomes liquefied due to the intense pressure and forms crude oil. Biomass is therefore part of an ancient process that has defined life and energy storage on Earth. The average American produces at least 4.5 pounds (2.0 kg) of biomass daily—about 1,600 pounds (726 kg) per year—in the form of simple garbage. The biomass naturally accumulates very rapidly, so burning it for energy seems to be an excellent option for both energy production and waste control. Today, the United States burns 14 percent of its solid waste in almost 100 WTE plants. About 1 ton (0.9 metric ton) of this garbage gives the same heat energy as 500 pounds (227 kg) of coal. Many landfills install pipes that reach into the waste pile and collect the methane that anaerobic microbes produce. This methane has also been called biogas or landfill gas. The collection of methane produces a second energy-valuable use for solid biomass. The United States contains about 400 landfills that convert methane to energy for use by local communities. Depending on the size of the landfill, these operations generate enough power to furnish electricity to several hundred to a few thousand homes each year. Wastewater treatment plants follow similar steps to capture the methane produced by microbes in the plant's anaerobic digester. The digestion step reduces the volume of excess sludge at a treatment plant and also produces energy-valuable biogas. Rod Bryden, executive at Plasco WTE facility in Ottawa, Canada, said at the opening of the plant in 2007, "The share of the waste that can be converted to power [by incineration] is not more than 18 to 22 percent. In ours we get about 44 percent to about 50 percent, a little more than twice as much power." WTE technology from landfills or wastewater treatment plants does not possess the glamour of new technologies in thin solar films or nanotechnology, but it contributes an important part of renewable resource energy use. The following table summarizes the main advantages and disadvantages of today's biomass WTE technology.


 * Energy Production from Biomass**||~ Advantages
 * ~ Disadvantages ||
 * * removes accumulation of solid waste
 * large supply
 * makes use of otherwise unused timber, pulp and paper, and agricultural wastes
 * moderate to low costs
 * reduced CO2 emissions
 * spares crops that can be used for food || * possible environmental damage from cutting forests
 * some emissions depending on composition and burning method
 * burning emits smoke and particles into the air ||

A Biomass Economy
The burning of biomass for energy production helps remove excess wastes from the following industries: agriculture, horticulture, forestry, and construction. It also helps destroy wastewater treatment plant solids and landfill contents, two materials that would otherwise have little value. By these activities, biomass energy production plays a role in the world's biomass economy. Biomass economy refers to an accounting method for keeping track of the Earth's carbon compounds. This involves estimating where carbon compounds are increasing and where they are decreasing. Before the industrial revolution, the atmosphere contained about 280 parts per million (ppm) of CO2. As industrialization grew, machinery burned coal, natural gas, and oil, and the emissions from combustion drifted into the air. By the 1950s, CO2 levels had reached 315 ppm; in March 2009 the atmosphere held 388.79 ppm. The CO2 level increases about 2 ppm per year. CO2 increases indicate that other greenhouse gases are also on the rise. Because greenhouses gases hold warmth in the atmosphere, the Earth's atmosphere is warming. In the IPCC report //Climate Change 2007,// scientists estimated that by the end of the 21st century global temperature will have increased 7.2°F (4°C). More than 2 trillion tons of ice in Greenland, Alaska, and Antarctica have melted since 2003. The amount of water from only Greenland's melting ice in the last five years could fill 11 Chesapeake Bays. The rise in sea levels we face in the future is alarming. Thus, biomass energy production must be managed so that it helps remove CO2 from the atmosphere rather than adds to greenhouse levels. Burning biomass produces CO2. But if new plants grow faster than biomass is burned, the plant life can remove more CO2 from the atmosphere than biomass burning puts into it. Predicting where CO2 levels are headed and how the elevated levels will hurt the environment is not easy. The world pours 8.8 million tons (8 million metric tons) of carbon emissions into the atmosphere a year. These emissions have altered ecosystems in some known ways and have undoubtedly caused hundreds or perhaps thousands of additional unknown alterations. Even with today's best technologies for reducing CO2 in the atmosphere, humanity cannot save the environment from all the harm that comes from a growing population and expanding industry. The climate researcher Susan Solomon warned in 2009, "People have imagined that if we stopped emitting CO2, the climate would go back to normal in 100 years, 200 years; that's not true." Environmental scientists must depend on new technologies that have not yet been invented to slow the rate of carbon buildup.

Conclusion
Biomass energy production serves as a simple technology for energy production when compared with advances in solar satellites, large tidal energy collectors, and other plans for the future of renewable energy. Biomass energy at its most basic is the collection and burning of organic wastes—not much different from what society has done for centuries. The new biomass energy industry will optimize this process by taking the best of conventional power methods and the best of alternative methods. Biomass energy production helps reduce the world's tremendous buildup of wastes as well as lessen the need for burning fossil fuels. In other words, biomass energy accomplishes the objectives that society must meet to lower its ecological footprint. To make a difference in cleaning up the environment, biomass energy must avoid the mistakes made by earlier forms of energy, even biofuels. Biomass plants cannot rely on smoke-belching power plants that look like any coal-burning plant. Biomass planners must also lay out a scheme that allows agriculture to fulfill its main responsibility: food production. If the majority of farmers grow biomass crops instead of food crops, biomass will develop the same problems that biofuels have experienced. The future of biomass requires that the biomass energy industry corrects the few drawbacks of this renewable energy form. First, biomass burning has the potential of producing air pollution. Biomass power plants will be expected to install scrubbers and other devices that remove gases and particles from emissions. Second, governments in several countries must assure that people do not begin cutting down forests for their biomass value. Destroying forestland removes critical habitat for endangered species, and the killing of trees releases huge amounts of additional CO2 to the high levels already in the atmosphere. Finally, biomass energy production will conserve energy sources and natural resources in the most effective manner if it complements other forms of renewable energy. ==Citation Information==

Maczulak, Anne. Energy from Solid Biomass." //Science Online//. Facts On File, Inc. Web. 24 Sept. 2011. .