Biomass
Biomass refers to organic material derived from plants and animals, which can be utilized as a renewable energy source known as biofuel. Historically, wood has been the most commonly used biofuel, but today, a diverse range of biomass sources has emerged, including agricultural residues, algae, and even some types of waste. The process of converting biomass into energy can occur through burning or decomposition, both of which release carbon back into the atmosphere, illustrating an ongoing carbon cycle. This cycle is crucial for balancing carbon dioxide levels, as biomass can contribute positively to the environment if managed properly. However, there are concerns regarding the environmental impact of biomass harvesting, particularly when it comes to competing for agricultural land with food crops. Despite these challenges, advancements in biomass energy production are evident, with over 600 biomass power plants operating in the U.S. by 2022. Moreover, sustainable practices, such as coppicing and utilizing non-food plant materials, are being explored to enhance biomass energy production while mitigating negative effects. Overall, biomass holds potential as a renewable energy source that can play a role in addressing climate change, provided that sustainable practices are implemented.
Subject Terms
Biomass
Biomass is plant or animal material that is often used for fuel. Biomass is a carbon-based, renewable resource. Biomass used for fuel is called biofuel. People have used wood, a common biofuel, for more than a million years. Today, many other types of biofuel are available.
Overview
Biofuel may be used to produce heat, power, or both. It may be used without processing or improved by drying, grinding, or pressing to make it more energy dense. While wood is the most commonly used biofuel, other types of biofuel include algae, food, plants, agricultural and forest residue, and some municipal and industrial wastes such as methane, which is a fume from the decomposition of matter in landfills.
Biomass is plant or animal material that includes oxygen as well as other elements, such as nitrogen and heavy metals. The carbon in biomass comes from carbon dioxide absorbed by plants when they use the sun's energy. This carbon becomes part of animal biomass when it is ingested by plant-eating animals.
Plant matter may be burned or may decompose, which means it is broken down by microorganisms. When biomass is burned, the trapped carbon is released as carbon dioxide and returns to the atmosphere. When biomass is broken down, the carbon also returns to the atmosphere, generally as carbon dioxide or methane. This illustrates the carbon cycle, in which carbon passes through stages and is reused again and again.
The carbon cycle also encompasses fossil fuels. These materials—coal, gas, and oil—contain carbon that was absorbed as carbon dioxide millions of years ago. Fossil fuels, however, are not biofuel, because the carbon within them has been kept out of the carbon cycle for so long. For example, much of the coal used as fuel today originated as plant material 360 to 290 million years ago. Burning this coal releases this ancient carbon into the atmosphere.
Because of this, the atmosphere contains too much carbon dioxide.
With a correctly managed closed carbon cycle, the amount of carbon dioxide in the atmosphere does not increase. Plants remove carbon from the atmosphere. This carbon is released when fuel is burned. The carbon cycle moves at a steady rate of development, use, and replenishment. Biomass can be an important part of this process. It may even help slow global climate change caused by greenhouse gases.
Biomass Concerns
Biomass can be part of a closed carbon cycle and benefit the environment if it is managed correctly; if it is not, however, it can actually be harmful.
Harvesting biomass may damage the environment and use a great deal of water. Biomass production could be detrimental if energy crops—crops grown to be used as fuel—displace food crops where arable land is scarce or in high demand.
However, even in these areas, it is possible to use the same crops for both food and biofuel. Plant matter that is not used for food, such as the corn stalks that remain after harvest or the straw from wheat and other grains, may be used to make biofuel. This is also true of wood that is harvested to make paper. Wood byproducts such as bark, wood shavings, and sawdust may be used as biofuel.
Biofuel Growth and Development
Until 2007, the US Census Bureau lumped biomass in with other renewable energy sources and reported a combined revenue of $6.6 billion. By 2022, more than 600 biomass power plants were operating in the United States, generating $934.6 million. Biomass was the nation's largest source of renewable energy until 2010. After this, other types of renewable energy began to grow, such as wind and solar power. By 2024, wind had become the largest source of renewable energy in the United States.
Experts see many opportunities to create biofuel from existing operations. Some timber companies thin out groups of trees—they remove small-diameter trees to allow other trees to grow larger. These harvested trees may be used as biofuel, while those trees left to grow become more valuable crops. In other cases, trees that mature quickly may be planted and harvested or coppiced quickly. Coppicing is cutting a tree close to the ground to encourage new growth. Trees such as ash, chestnut, hazel, maple, oak, and willow readily send up new shoots from their established root systems. Coppiced trees may be harvested dozens of times before they must be replaced and may live hundreds of years under this management.
The prairies of the Great Plains were oceans of thin-stemmed perennial grasses before they were plowed for agricultural use. These grasses grow quickly once they are cut and may be harvested for up to a decade before they must be planted again. Many are drought-resistant crops that need little or no fertilizer. These grasses are harvested to feed livestock but have the potential to become important biofuels.
Manure from livestock and poultry may be developed as biofuel using anaerobic digesters. These microorganisms chemically alter biomass, creating biogas such as methane. Such biogas may be burned to replace natural gas or propane or used to generate steam power.
Bibliography
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