Vascular Plants as Biofuels

Biofuel crops [Photo: National Renewable Energy Laboratory Image Library]
Biofuel crops [Photo: National Renewable Energy Laboratory Image Library]

The following traits make certain vascular plants good for potential development as biofuels, but it is important to note that they have overlap with traits known to contribute to invasiveness (indicated with a *). The decision to use plants as biofuels should carefully consider the pros and cons of each candidate species and anticipate any potential for the threat it poses as an invasive species.

  • *C4 photosynthesis. This refers to the use of a 4-carbon rather than a 3-carbon compound in photosynthesis. C4 plants are better adapted to arid conditions because they use water more efficiently.
  • *Long canopy duration
  • Perennial
  • *No known pests or diseases
  • *Rapid growth in spring (to outcompete weeds)
  • *Partitions nutrients to below-ground components in the fall
  • Sterility

For more information on biofuels and invasive plants, visit NBII's Invasive Species Information Node.

USGS Microbiology Research

United States Geological Survey logo
[Image: USGS]

The United States Geological Survey (USGS) is developing renewable energy technology along with other public and private agencies and institutions. Scientists in the USGS Microbiology Program are working on several projects that use microorganisms for biofuel technology development, such as bacterial formation of nano-scaled materials, biogenic methane generation from coal and other geopolymers, microbial fuel cells, and production of nanomaterials of Group 15 and 16 elements.

To find out more about these projects, visit the USGS Microbiology Energy Research Activities or Nanotechnology Research Activities web sites.


Grain harvesting for biomass energy. [Photo: US Department of Energy]
Grain harvesting for biomass energy.
[Photo: US Department of Energy]

Biofuels are a form of renewable energy derived from organic material, or biomass. Biofuels are also referred to as biofuel energy, biomass energy, bioenergy, biogas, or biodiesel. There are many sources of biofuels ranging in scale from microbes to traditional crops such as corn (Zea mays) , soybeans (Glycine max) , switchgrass (Panicum virgatum) , giant Miscanthus (Miscanthus x giganteus) , jatropha (Jatropha curcas) , and rapeseed (Brassica napus) , to name a few. Plant crops grown on land as well as in water are primary producers of biomass for the production of biofuel, and in the United States corn ethanol is the most common. Other sources of biofuel energy include agricultural and forestry residues which are the unharvested and traditionally undesirable parts of a field or forest, such as corn stalks or the limbs and tops of trees left on the ground.

Advantages: widespread distribution and diverse use
As a renewable energy resource, biofuels are advantageous because their potential for production is more evenly distributed over the Earth's surface than that of other non-renewable energy sources. Plant or animal matter used as biofuels can be produced most places across the Earth's surface, unlike petroleum, which can only be found in pockets deep within the Earth. Biofuels also have diverse uses such as transportation fuels, electricity generation, and heating, making them flexible energy sources. Like other renewables, biofuels also provide a means toward energy independence because they can be produced within the country's boundaries.

Disadvantages: land competition, energy inputs, and water use
The use and production of biofuel, especially corn ethanol, is controversial. The energy inputs (fertilizers used, harvesting and processing with machinery, greenhouse gases emitted) versus the energy outputs, and the food or fuel debate, are at the forefront of the controversy. The food or fuel debate is centered around the question of whether or not we should be using crops as fuel rather than using them for food purposes. An example of this is corn, which is used not only for human food products, but also feed for livestock. If enough of the corn produced was used for fuel purposes, theoretically the price of food and feed could increase. In addition, biofuel power plants use water resources and may degrade water quality through increased temperature and pollutants.

Microorganisms as Biofuels

Biofuels can be derived from more sources than animal and vascular plant residues or crops. Microorganisms, especially algae, are playing a growing role in the biofuel industry.

Microbial fuel cells (MFCs) use bacteria or cultures of several species of bacteria as catalysts to oxidize matter, which in turn creates an electric current. Many types and combinations of bacteria microorganism catalysts, and electrodes can be used in MFCs. MFCs can range in size and complexity, and new technologies are constantly emerging in this growing field as it gets closer to commercialization.

Algae is another biofuel source currently in the research and development stages. It can be cultivated nearly anywhere, in containers and water bodies, as long as there is a source of sunlight and a source of water for the algae to use in photosynthesis. Algae can be cultivated to produce ethanol, methanol, biodiesel, or hydrogen through different processes.

Logan, B..E. and J.M. Regan. 2006. Electricity-producing bacterial communities in microbial fuel cells. Trends in Microbiology: 14(12): 512-518.
World Intellectual Property Organization

Environmental Impacts of Biofuels

Banner of bioenergy imagery [Image courtesy of U.S. Department of Agriculture]

The U.S. Environmental Protection Agency lists the following as environmental impacts of biomass power:

Air Emissions   Biomass power plants emit nitrogen oxides and a small amount of sulfur dioxide. The amounts emitted depend on the type of biomass that is burned and the type of generator used. Although the burning of biomass also produces carbon dioxide, the primary greenhouse gas, it is considered to be part of the natural carbon cycle of the earth. The plants take up carbon dioxide from the air while they are growing and then return it to the air when they are burned, thereby causing no net increase.

Biomass contains much less sulfur and nitrogen than coal; therefore, when biomass is co-fired with coal, sulfur dioxide and nitrogen oxides emissions are lower than when coal is burned alone. When the role of renewable biomass in the carbon cycle is considered, the carbon dioxide emissions that result from co-firing biomass with coal are lower than those from burning coal alone. 

Water Resource Use   Biomass power plants require the use of water, because the boilers burning the biomass need water for steam production and for cooling. If this water is used over and over again, the amount of water needed is reduced. Whenever any type of power plant removes water from a lake or river, fish and other aquatic life can be killed, which then affects those animals and people that depend on these aquatic resources.

Water Discharges   As is the case with fossil fuel power plants, biomass power plants have pollutant build-up in the water used in the boiler and cooling system. The water used for cooling is much warmer when it is returned to the lake or river than when it was removed. Pollutants in the water and the higher temperature of the water can harm fish and plants in the lake or river where the power plant water is discharged. This discharge usually requires a permit and is monitored. For more information about these regulations, visit EPA's Office of Water Web site. In general, crops grown for biomass fuel require fewer pesticides and fertilizers than crops grown for food, which means that less pesticide and fertilizer runoff will reach local streams and ponds than if food crops are grown. 

Solid Waste Generation   The burning of biomass in boilers creates a solid waste called ash that must be disposed of properly. However, the ash from biomass normally contains extremely low levels of hazardous elements. 

Land Resource Use   Generating electricity from biomass can affect land resources in different ways. Biomass power plants, much like fossil fuel power plants, require large areas of land for equipment and fuel storage. If these biomass plants burn a waste source such as construction wood waste or agricultural waste, they can provide a benefit by freeing areas of land that might otherwise have been used for landfills or waste piles. Biomass grown for fuel purposes requires large areas of land and, over time, can deplete the soil of nutrients. Fuel crops must be managed so that they stabilize the soil, reduce erosion, provide wildlife habitat, and serve recreational purposes.

Resources on Biofuels and Agriculture
Showing 10 of 45 ( Show All )
CollapseAgricultural Research Service (ARS) Home Page
Description: From About ARS: "The Agricultural Research Service (ARS) is the U.S. Department of Agriculture's chief scientific research agency. Our job is finding solutions to agricultural problems that affect Americans every day, from field to table. Here's a few facts about the scope of our organization: 1,200 research projects within 22 National Programs; 2,100 scientists; 6,000 other employees; 100 research locations including a few in other countries; $1.1 billion fiscal year 2005 budget."
Resource Type: Federal Government Agencies (U.S.)
Resource Format: URL
Publisher: United States Deaprtment of Agriculture (USDA) Agricultural Research Service (ARS)
ExpandAvian Response to Harvesting Switchgrass for Biomass in Southern Iowa
ExpandBig Bluestem Biomass Trials in North Dakota, South Dakota, and Minnesota
ExpandBiofuels: Implications for Land Use and Biodiversity (PDF, 15 pp., 1.37 MB)
ExpandCNN Algae as Biofuels page
ExpandCrop Residue Removal for Biomass Energy Production: Effects on Soils and Recommendations
ExpandEnergy Farming With Switchgrass Saves Carbon
ExpandEnvironmental Impacts of Biofuels (PDF, 17 pp., 110 KB)
ExpandEthanol and a Changing Agricultural Landscape (PDF, 64 pp., 2.18 MB)
ExpandEthanol Production: Environmental Effects (PDF, 22 pp., 2.99 MB)
Resources on Biofuels and Wildlife Habitat
Showing 10 Results
CollapseAn Analysis of the Environmental Impacts of Energy Crops in the USA: Methodologies, Conclusions and Recommendations
Description: Various national and regional groups of bioenergy stakeholders have issued consensus recommendations and guidelines for sustainable bioenergy development. As reported in this article, it is a consistent conclusion from these efforts that displacing annual agricultural crops with native perennial biomass crops would very likely help restore natural ecosystem functions in worked landscapes, and help to preserve natural biodiversity. Conversely, if biomass crops displace more natural land cover -- such as forests and wetlands -- there would very likely be a loss of ecosystem functions and reduced biodiversity.
Resource Type: Unpublished Documents
Resource Format: URL
Publisher: National Audubon Society
ExpandBiofuels: Implications for Land Use and Biodiversity (PDF, 15 pp., 1.37 MB)
ExpandBird habitat benefits of using switchgrass for biomass fuel in the U.S. Midwest
ExpandBird habitat benefits of using switchgrass for biomass fuel in the U.S. Midwest
ExpandEvaluating environmental consequences of producing herbaceous crops for bioenergy
ExpandLiquid Transportation Fuels from Coal and Biomass: Technological Status, Costs, and Environmental Impacts
ExpandPlanting and Managing Switchgrass for Forage, Wildlife, and Conservation
ExpandPotential effects on grassland birds of converting marginal cropland to switchgrass biomass production
ExpandPotential Environmental Impacts of Bioenergy Crop Production (PDF, 76 pp., 1.38 MB)
ExpandPotential Impacts of Biomass Production in the United States on Biological Diversity
Biofuel Resources
Showing 10 of 144 ( Show All )
Collapse2003-12-11 Archived Document: Role of Renewable Energy in Reducing Greenhouse Gas Buildup (PDF, 4 pp., 370.16 KB)
Description: The Tennessee Valley Authority is researching how the United States, in particular the Southeast can increase the use of renewable energy in reducing Greenhouse Gas Buildup within the Tennessee Valley. Electricity produced from wind, solar, or geothermal sources, biomass energy conversion systems, and increases resulting from modernization of hydroelectric systems generally are considered renewable energy. Biomass energy systems encompass a wide range of sources, including dedicated energy crops, wood waste, landfill gas, digester gas, animal waste, and municipal solid waste.
Resource Type: Fact Sheets
Resource Format: PDF
Publisher: The Internet Archive
Expand25 x '25
ExpandA Framework to Assess Regional Environmental Impacts of Dedicated Energy Crop Production
ExpandA Geographic Perspective on the Current Biomass Resource Availability in the United States (PDF, 70 pp., 2.5 MB)
ExpandAdding Biofuels to the Invasive Species Fire?
ExpandAdvanced Energy Initiative
ExpandAgricultural Research Service (ARS) Home Page
ExpandAn Analysis of the Environmental Impacts of Energy Crops in the USA: Methodologies, Conclusions and Recommendations
ExpandAn integrated environmental analysis of short rotation forests as a biomass resource
ExpandArundo donax Fact sheet or species profile (Fire Effects Information System, US Forest Service

Arundo donax as a Biofuel

A flower head of Arundo donax. Photo credit: USDA.
A flower head of Arundo donax. Photo credit: USDA.

Giant reed ( Arundo donax ) is a tall perennial cane that grows in damp soils; it is known by many names including Carrizo, Spanish cane, wild cane giant reed and Arundo. It is native to eastern Asia but can grow in California, the Mediterrean and Caribbean. Arundo can grow up to 10 meters, and consumes large amounts of water. Arundo grows in dense groups crowding out other native plants. Arundo is a potential second generation biofuel, because of its fast growth, it is essentially sterile, and can potentially produce more fuel than first generation biofuels.

Arundo donax Fact sheet or species profile (Fire Effects Information System, US Forest Service

Florida Native Plant Society Policy Statement on Arundo donax [pdf]

Production of Giant Reedgrass for Biofuel (Univ. FL, IFAS)

What are Greenhouse Gases?

The Greenhouse Effect [Image: NOAA Paleoclimatology]
The Greenhouse Effect
[Image: NOAA Paleoclimatology]

Gases in the Earth's atmosphere that trap heat are referred to as "greenhouse gases". Some of these greenhouse gases occur naturally in the atmosphere but are augmented by inputs from human activities. Others are unnatural compounds that are only created and emitted into the atmosphere from human activities. The principal greenhouse gases released into the atmosphere from human activities are carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O), and fluorinated gases. The U.S. Environmental Protection Agency inventories greenhouse gas emissions and sinks and provides information about greenhouse gases and climate change.

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