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Biomass Energy Operations Impacts

Operations activities that may cause environmental impacts include operation of the biomass energy facility, power generation, biofuel production, and associated maintenance activities.

Typical activities during biomass facility operation include power generation or production of biofuels, and associated maintenance activities that would require vehicular access and heavy equipment operation when components are being replaced. Biomass power plants require pollution control devices to reduce emissions from combustion and large cooling systems. Water requirements vary greatly among the various biomass facilities. Potential impacts from these activities are presented below, by the type of affected resource.

The following potential impacts may result from biomass facility operations.

Acoustics (Noise)

Operations of heat recovery systems of a biomass power plant, milling rooms and boilers of a biofuel facility, wood chippers, and steam turbine generators would result in occupational noise that would exceed the Occupational Safety and Health Administration (OSHA) 8-hour noise threshold limit. Personnel working in these areas would be required to wear hearing protection. Insulation of these areas would reduce noise levels so that hearing protection would not be required outside these areas. Noise levels in other parts of the facility would most likely be below the 8-hour threshold limit established by OSHA.

Other noise sources would include exhaust stacks, mechanical-draft cooling systems, switchgear at substations, corona noise from transmission lines, vehicular traffic, and maintenance facilities.

No adverse community reaction would be expected as a result of noise levels below 50 A weighted decibels (dBA) at the nearest sensitive receptor (e.g., closest residence). Noise control equipment could be incorporated to achieve these levels.

Air Quality (including Global Climate Change and Carbon Footprint)

Operation of biomass facilities results in emissions of criteria air pollutants and hazardous air pollutants (HAPs). Criteria air pollutants include particulate matter, carbon monoxide, sulfur oxides, nitrogen oxides, lead, and volatile organic compounds (VOCs). HAPs are 189 toxic chemicals, known or suspected to be carcinogens, which are regulated by the U.S. Environmental Protection Agency as directed by the 1990 Clean Air Act. If the facility is in an area designated as "attainment" for all state and national ambient air quality standards (NAAQS), then emissions from operation, when added to the natural background levels, must not cause or contribute to ambient pollution levels that exceed the ambient air quality standards.

In particular, combustion of municipal solid wastes could result in trace quantities of mercury, other heavy metals, and dioxins in the air emissions. The use of Best Available Control Technology (BACT) would minimize the potential for adverse air quality impacts from biomass facilities. A gas-fired regenerative thermal oxidizer would reduce VOCs by 95%. Baghouses, which are a type of dust collector using fabric filters, control particulate matter. Enclosing the processing equipment in a slight negative pressure envelope in addition to the use of baghouses could minimize fugitive dust emissions from milling operations.

The use of cultivated biomass fuels (i.e., fuel specifically grown for energy production) in place of fossil fuels like coal, oil, and natural gas can result in a reduction in the amount of carbon dioxide that accumulates in the atmosphere only if the carbon released by combustion of biomass fuels is effectively recaptured by the next generation of feedstock plants. If the biomass source is not replaced by growing more plants, the carbon released in biomass combustion is not recaptured; therefore, these forms of biomass energy can only be considered to be carbon-free if the energy production cycle includes replanting of the feedstock. Using perennial or fast-growing biomass plants, such as switchgrass or poplar hybrids, can increase the rate of carbon recapture. While the combustion of biomass fuels under these conditions can be considered to be carbon-free, in practice, any gains in terms of reduced carbon dioxide emissions are offset by carbon dioxide emissions associated with the use of fossil fuels in the cultivation, harvesting, and transportation of the biomass feedstock. Certain agricultural practices (e.g., no-till agriculture and use of perennial feedstock crops) produce fewer carbon dioxide emissions than conventional practices. Biomass energy derived from waste product fuels (e.g., residues from forestry operations, construction wastes, municipal wastes) is not considered to be carbon-free as the energy production cycle does not involve any cultivation of new biomass.

Cultural Resources

Impacts during the operations phase would be limited to unauthorized collection of artifacts and visual impacts. The threat of unauthorized collection would be present once the access roads are constructed in the construction phase, making remote lands accessible to the public. Visual impacts resulting from the presence of a biomass facility and transmission lines could affect some cultural resources, such as sacred landscapes or historic trails.

Ecological Resources

During operation, adverse ecological effects could occur from (1) disturbance of wildlife by equipment noise and human activity, (2) exposure of biota to chemical spills and other contaminants, and (3) mortality of wildlife from increased vehicular traffic and collisions with and/or electrocution by transmission lines. Disturbed wildlife would be expected to acclimatize to facility operations.

Deposition of water and salts from the operation of mechanical-draft cooling towers has the potential to impact vegetation.

Intake structures for withdrawal of water from lakes or rivers would result in impingement and entrainment of aquatic species. Proper design of these structures can minimize these impacts. Discharge of heated cooling water into water bodies could be beneficial or adverse, depending upon the design of the discharge structure and the temperature of the effluent.

Environmental Justice

Possible environmental justice impacts during operation include the alteration of scenic quality in areas of traditional or cultural significance to minority or low-income populations and disruption of access to those areas. Noise impacts, health and safety impacts, and water consumption in arid areas are also possible sources of disproportionate effect.

Hazardous Materials and Waste Management

Nonhazardous solid waste would be transported to a sanitary landfill. Industrial wastes are generated during routine operations (dielectric fluids, cleaning agents, and solvents). These wastes typically would be put in containers, characterized and labeled, possibly stored briefly, and transported by a licensed hauler to an appropriate permitted off-site disposal facility as a standard practice.

Ash produced from combustion could be sold for other uses (e.g., cement additive for road construction), or it could be taken to a landfill for disposal. Ash from combustion of municipal solid waste could contain hazardous constituents (and need to be handled as a hazardous waste) if the municipal waste stream included minor amounts of hazardous materials or hazardous wastes.

Impacts could result if these wastes were not properly handled and were released to the environment.

Human Health and Safety

Possible impacts to health and safety during operation include accidental injury or death to workers. Health impacts could result from exposures to chemicals and products used and produced in biomass facilities, air emissions, and noise. At an ethanol plant, ethanol vapors are highly flammable, and several older ethanol plants have experienced explosions. Other chemicals used in biomass facilities could include anhydrous ammonia, sodium hydroxide, sulfuric acid, hydrochloric acid, phosphoric acid, and sodium methylate. Gasoline or diesel might also be stored on site.

Dry dust produced from handling feedstock, such as soybeans, switchgrass, or wood chips, may be combustible. Explosion hazard can exist when the finest dust forms or settles.

All personnel involved with the operation would utilize appropriate safety equipment and would be properly trained in required OSHA practices.

Land Use

Any land use impacts would occur during construction, and no further impacts would be expected to result from biomass facility operation.

Paleontological Resources

Impacts during the operations phase would be limited to unauthorized collection of fossils. This threat is present once the access roads are constructed in the construction phase, making remote lands accessible to the public.


Direct impacts would include the creation of new jobs for operation and maintenance workers and the associated income and taxes paid. Indirect impacts are those impacts that would occur as a result of the new economic development and would include new jobs at businesses that support the workforce or that provide project materials, and associated income and taxes. The number of project personnel required during the operation and maintenance phase would be fewer than during construction. Therefore, socioeconomic impacts related directly to jobs would be smaller than during construction.

Soils and Geologic Resources (including Seismicity/Geo Hazards)

During operation, the soil and geologic conditions would stabilize with time. Soil erosion and soil compaction are both likely to continue to occur along access roads. Within the project footprint, soil erosion, surface runoff, and sedimentation of nearby water bodies will continue to occur during operation, but to a lesser degree than during the construction phase.


Increases in the use of local roadways and rail lines would occur during operations. Biomass fuels for boilers and power plants would arrive daily by truck or rail. Feedstock for biofuels facilities, such as corn, soybeans, wood products, manure, and sludge, would also arrive by truck or rail, and ethanol and biodiesel produced would most likely be trucked to the end user that would blend or sell the product. Depending upon the size and function of the facility, truck traffic could be on the order of 250 trucks per day. Biogas facilities would either combust the gas at the production plant or send it by pipeline to the user. Landfill gas would either be used to produce electricity near the point of collection or sent by pipeline to the user.

Visual Resources

The magnitude of visual impacts from operation of a biomass facility is dependent upon the distance of the facility from the viewer, the view duration, and the scenic quality of the landscape. Facility lighting would adversely affect the view of the night sky in the immediate vicinity of the facility. Plumes from stacks or cooling towers might be visible, particularly on cold days.

Additional visual impacts would occur from the increase in vehicular traffic.

Water Resources (Surface Water and Groundwater)

Withdrawals of surface water and/or groundwater are expected to continue during the operations phase of both biomass power plants and biofuel production and refinery facilities. The amount of water needed depends upon the type of facility.

In a typical biomass power plant, the primary consumptive use of water will be to support the cooling system used to condense spent steam for reuse. Once-through cooling systems require large quantities of water to be withdrawn from and returned to a surface body of water. Wet recirculating cooling systems recycle cooling water through cooling towers where some portion of water is allowed to evaporate and must be continuously replenished. Wet recirculating cooling systems also periodically discharge small volumes of water as blowdown and replace that amount with fresh water to control chemical and biological contaminants to acceptable levels. A third type of cooling system, the dry cooling system condenses and cools steam using only ambient air and requires no water to operate. However, some dry cooling systems can also be hybridized into wet/dry systems that use minimal amounts of water that is allowed to evaporate to improve performance. Other consumptive uses of water at a biomass power plant include the initial filling and maintenance of the steam cycle, sanitary applications to support the workforce, and a wide variety of incidental maintenance-related industrial applications.

Most uses of water at a biomass power plant will ultimately result in the generation of some wastewater. Blowdown from both the steam cycle and the wet recirculating cooling system will represent the largest wastewater stream and, because water in both the steam cycle and the cooling system undergoes some chemical treatment, the discharge will contain chemical residuals. Its temperature will also be elevated. Water discharged from once-through systems does not undergo chemical treatment, but the temperature of the discharge will be elevated. All wastewater discharges from biomass power plants can be directed to a holding pond for evaporation, cooling, and/or further treatment, but are likely to be eventually discharged to surface waters. The Clean Water Act requires any facility that discharges from a point source into water of the United States to obtain a National Pollutant Discharge Elimination System (NPDES) permit. The NPDES permit assures that the state's water quality standards are being met.

Water is used in a wide variety of applications for biofuel production and refining facilities and can be consumed at rates as high as 400 gallons per minute (gpm). Some water used in production and refining activities can be recovered and recycled to reduce the demand on the water source. Algae production ponds can be large but are very shallow (about 12 inches). Only a small volume of water would need to be added to replace any evaporation. Bioreactors for algae production are closed systems and require very little additional water. As much as 100 gpm of wastewater can be discharged from a biofuel production and refining plant. The effluent discharge temperature would be at or slightly above ambient temperature and would often contain small amounts of chemicals. As with wastewaters from biomass power plants, such discharges can be directed to lined holding ponds for further treatment or discharged directly to a surface water body under the authority of an EPA-issued NPDES permit.