Lynn L. Wright

Biomass as Feedstock for A Bioenergy and Bioproducts Industry: The Technical Feasibility of a Billion-Ton Annual Supply

The U.S. Department of Energy (DOE) and the U.S. Department of Agriculture (USDA) are both strongly committed to expanding the role of biomass as an energy source. In particular, they support biomass fuels and products as a way to reduce the need for oil and gas imports; to support the growth of agriculture, forestry, and rural economies; and to foster major new domestic industries--biorefineries--making a variety of fuels, chemicals, and other products. As part of this effort, the Biomass R&D Technical Advisory Committee, a panel established by the Congress to guide the future direction of federally funded biomass R&D, envisioned a 30 percent replacement of the current U.S. petroleum consumption with biofuels by 2030. Biomass--all plant and plant-derived materials including animal manure, not just starch, sugar, oil crops already used for food and energy--has great potential to provide renewable energy for Americas future. Biomass recently surpassed hydropower as the largest domestic source of renewable energy and currently provides over 3 percent of the total energy consumption in the United States. In addition to the many benefits common to renewable energy, biomass is particularly attractive because it is the only current renewable source of liquid transportation fuel. This, of course, makes it invaluable in reducing oil imports--one of our most pressing energy needs. A key question, however, is how large a role could biomass play in responding to the nations energy demands. Assuming that economic and financial policies and advances in conversion technologies make biomass fuels and products more economically viable, could the biorefinery industry be large enough to have a significant impact on energy supply and oil imports? Any and all contributions are certainly needed, but would the biomass potential be sufficiently large to justify the necessary capital replacements in the fuels and automobile sectors? The purpose of this report is to determine whether the land resources of the United States are capable of producing a sustainable supply of biomass sufficient to displace 30 percent or more of the countrys present petroleum consumption--the goal set by the Advisory Committee in their vision for biomass technologies. Accomplishing this goal would require approximately 1 billion dry tons of biomass feedstock per year.

Interactions among bioenergy feedstock choices, landscape dynamics, and land use

Landscape implications of bioenergy feedstock choices are significant and depend on land-use practices and their environmental impacts. Although land-use changes and carbon emissions associated with bioenergy feedstock production are dynamic and complicated, lignocellulosic feedstocks may offer opportunities that enhance sustainability when compared to other transportation fuel alternatives. For bioenergy sustainability, major drivers and concerns revolve around energy security, food production, land productivity, soil carbon and erosion, greenhouse gas emissions, biodiversity, air quality, and water quantity and quality. The many implications of bioenergy feedstock choices require several indicators at multiple scales to provide a more complete accounting of effects. Ultimately, the long-term sustainability of bioenergy feedstock resources (as well as food supplies) throughout the world depends on land-use practices and landscape dynamics. Land-management decisions often invoke trade-offs among potential environmental effects and social and economic factors as well as future opportunities for resource use. The hypothesis being addressed in this paper is that sustainability of bioenergy feedstock production can be achieved via appropriately designed crop residue and perennial lignocellulosic systems. We find that decision makers need scientific advancements and adequate data that both provide quantitative and qualitative measures of the effects of bioenergy feedstock choices at different spatial and temporal scales and allow fair comparisons among available options for renewable liquid fuels.

Production technology status of woody and herbaceous crops

Abstract Several woody and herbaceous energy crop species have been selected as high-potential candidates for supplying biomass feedstocks. Successful methods for their establishment and maintenance have been developed. Recommended species vary as a function of region of the country and soil type. Yields are equally variable. The crops that have received the most research and development include hybrid poplars (fast-growing trees) and switchgrass (a perennial grass). Some information is also available on other tree crops, thick-stemmed perennials and annuals. Supplying large volumes of biomass to energy facilities on a daily basis requires that consideration be taken of the harvest timing, storage and delivery characteristics of different feedstocks as well as their yield, cost and energy properties. Our summary suggests that a combination of crops will be needed to provide large amounts of low-cost and environmentally sustainable year-round supplies of biomass feedstocks.

Biomass management and energy

The impact of managing biomass specifically for the conservation or production of energy can become a significant factor in the global management of atmopsheric CO2 over the next century. This paper evaluates the global potential for: (1) conserving energy by using trees and wood for shading, shelterbelts, windbreaks, and construction material; and (2) increasing the use of biomass and improving its conversion efficiency for producing heat, electricity, and liquid biofuels. The potential reduction in CO2 emissions possible by the anticipated time of atmospheric CO2 doubling was estimated to be up to 50×106t C yr−1 for energy conservation and as high as 4×109 t C yr−1 for energy production. Of the many opportunities, two stand out. Through afforestation of degraded and deforested lands, biomass energy production offers the potential of 0.36 to 1.9×109t C yr−1 emission reduction. Dedicated energy crops, which include short-rotation woody crops, herbaceous energy crops, halophytes, some annual crops, and oilseeds, offer the potential of 0.2 to 1.0×109t C yr−1 emission reduction. Also addressed in the paper, but not quantified, were establishment of new forests, increasing the productivity of existing forests, or protecting forests to sequester C as an offset against CO2 emissions from burning fossil fuels or forest destruction. Also addressed are uncertainties, gaps in scientific knowledge about ecosystems and their management, and policy considerations at the international and national levels.

The potential for short-rotation woody crops to reduce U.S. CO2 emissions

Short-rotation woody crops (SRWC) could potentially displace fossil fuels and thus mitigate CO2 buildup in the atmosphere. To determine how much fossil fuel SRWC might displace in the United States and what the associated fossil carbon savings might be, a series of assumptions must be made. These assumptions concern the net SRWC biomass yields per hectare (after losses); the amount of suitable land dedicated to SRWC production; wood conversion efficiencies to electricity or liquid fuels; the energy substitution properties of various fuels; and the amount of fossil fuel used in growing, harvesting, transporting, and converting SRWC biomass. Assuming the current climate, present production, and conversion technologies and considering a conservative estimate of the U.S. land base available for SRWC (14 × 106 ha), we calculate that SRWC energy could displace 33.2 to 73.1 × 106 Mg of fossil carbon releases, 3–6% of the current annual U.S. emissions. The carbon mitigation potential per unit of land is larger with the substitution of SRWC for coal-based electricity production than for the substitution of SRWC-derived ethanol for gasoline. Assuming current climate, predicted conversion technology advancements, an optimistic estimate of the U.S. land base available for SRWC (28 × 106 ha), and an optimistic average estimate of net SRWC yields (22.4 dry Mg/ha), we calculate that SRWC energy could displace 148 to 242 × 106 Mg of annual fossil fuel carbon releases. Under this scenario, the carbon mitigation potential of SRWC-based electricity production would be equivalent to about 4.4% of current global fossil fuel emissions and 20% of current U.S. fossil fuel emissions.

U.S. Carbon Offset Potential using Biomass Energy Systems

A previous analysis had assumed that about 20% of 1990 U.S. C emissions could be avoided by the substitution of biomass energy technologies for fossil energy technologies at some point in the future. Short-rotation woody crop (SRWC) plantations were found to be the dedicated feedstock supply system (DFSS) offering the greatest C emission reduction potential. High efficiency biomass to electricity systems were found to be the conversion technology offering the greatest C emission reduction potential. This paper evaluates what would be required in terms of rate of technology implementation and time period to reach the 20% reduction goal. On the feedstock supply side, new plantings would have to installed at an average a rate of 1 x 106 ha yr-1 while average yields would have to increase by 1.5%annually over the 35-year period. Such yield increases have been observed for high value agricultural crops with large government research support. On the generation side, it requires immediate adoption of available technologies with a net efficiency of 33% or higher (such as the Whole Tree EnergyTM technology), installation of approximately 5000 MWe of new capacity each year, and rapid development and deployment of much higher efficiency technologies to result in an average of 42% efficiency by 2030. If these technology changes could be achieved at a linear rate, U.S. C emission reduction could progress at a rate of about 0.6% yr-1 over the next 35 years.

Environmental enhancement of U.S. biomass crop technologies: research results to date

Abstract The U.S. continues efforts to develop genetically superior short-rotation woody crops (hybrid poplar and willow) and herbaceous crops (switchgrass). These biomass crops can provide multiple environmental benefits as well as energy and fiber. This paper focuses on results of site-specific studies that are quantifying the environmental potential and ramifications of converting agricultural croplands to biomass crop production. At research-scales, no differences have been found in erosion and movement of nutrients from annual row crops, switchgrass, and tree crops with and without a cover crop in the initial year of establishment. Research- and watershed-scale studies on different soil types, in different regions, and to match tree species with specific site characteristics and management regimes will help determine whether research-scale results can be used to predict effects at larger scales and to identify best management practices to minimize environmental effects while maximizing yields. Studies in different regions of the U.S. are evaluating the habitat value of biomass crops compared to agricultural row crops, grasslands, or natural forests. Results to date from both research- and larger-scale plantings show that SRWCs support greater bird diversity than row crops, but less diversity than natural forests. Switchgrass plantings extended habitat for grasslands birds compared to row crops. Surveys on industrial tree crop plantings in the south-eastern U.S. are addressing the relationship between site characteristics (planting acreage, species, landscape context, and age of plantings) and breeding bird use. The environmental studies of water and soil quality and wildlife diversity are being used to identify management strategies for biomass crops to increase productivity while increasing agricultural sustainability.

Substrate selection as a factor in Hexagenia distribution

Abstract Our observations demonstrate that in laboratory aquaria Hexagenia bilineata (Say) nymphs will leave clay, gravel, and sandy clay and migrate to adhesive mud or fine sandy mud with no response to coarse sandy mud indicated. The nymphs were able to burrow into all substrates offered, but the time required for penetration varied significantly. Burrowing times ranged from 30 s in adhesive mud to 168 s in clay. Ease of penetration (as measured by burrowing time) correlated well with observed substrate preferences. None of the physical or chemical parameters of the substrates which we measured correlated significantly with either selection or burrowing time. Ease of penetration seemed to be dependent upon a combination of factors including particle size and compactness and cohesiveness of the substrates. The characteristics of the two selected substrates include high moisture content (40% for each), low bulk density (0.91 and 0.94 g/ cm3), high organic content (7.1 and 7.9%), and predominantly silt com...

Technical and economic status of wood energy feedstock production

We update the technical status of wood feedstock production and highlight areas where the technology used to produce energy crops has changed since publication of an earlier paper. Most of the research findings presented earlier still hold, but the target dates for achieving them are in the distant future. We estimate current delivered costs in the range of about

Woody biomass production costs in the United States: An economic summary of commercial Populus plantation systems

2.30/GJ in the Pacific Northwest to a high of about