Abstract  Methods are presented for calculating the energy required, directly and indirectly, to produce all types of goods and services. Procedures for combining process analysis with input-output analysis are described. This enables the analyst to focus data acquisition effects cost-effectively, and to achieve down to some minimum degree a specified accuracy in the results. The report presents sample calculations and provides the tables and charts needed to assess total energy requirements of any technology, including those for producing or conserving energy.

Abstract  In 2003, the U.S. Department of Agriculture surveyed 21 dry-mill ethanol plants to estimate their 2002 production costs, including both variable (feedstock and plant operation) and capital expenses. These plants produced about 550 million gallons of ethanol in 2002. Net feedstock costs for the surveyed plants ranged from 39 to 68 cents per gallon in 2002. For cash operating expenses, the average energy expenditure was 17.29 cents per gallon. Labor costs ranged from 3 to 11 cents per gallon, maintenance costs from 1 to 7 cents, and administrative costs from 1 to 18 cents. For capital expenditures, new plant construction costs from $1.05 to $3.00 per gallon of ethanol. Average investment to expand existing ethanol production capacity was 50 cents per gallon; hence, expansion tends to cost less than new capacity. Comparison with a 1998 survey of ethanol producers showed that total operating costs in 2002 had changed very little from 1998. It also showed that the average cost of building new plants had dropped, possibly due to designs that emphasize economies of scale.

Abstract  We assessed current water consumption during liquid fuel production, evaluating major steps of fuel lifecycle for five fuel pathways: bioethanol from corn, bioethanol from cellulosic feedstocks, gasoline from U.S. conventional crude obtained from onshore wells, gasoline from Saudi Arabian crude, and gasoline from Canadian oil sands. Our analysis revealed that the amount of irrigation water used to grow biofuel feedstocks varies significantly from one region to another and that water consumption for biofuel production varies with processing technology. In oil exploration and production, water consumption depends on the source and location of crude, the recovery technology, and the amount of produced water re-injected for oil recovery. Our results also indicate that crop irrigation is the most important factor determining water consumption in the production of corn ethanol. Nearly 70% of U.S. corn used for ethanol is produced in regions where 10–17 liters of water are consumed to produce one liter of ethanol. Ethanol production plants are less water intensive and there is a downward trend in water consumption. Water requirements for switchgrass ethanol production vary from 1.9 to 9.8 liters for each liter of ethanol produced. We found that water is consumed at a rate of 2.8–6.6 liters for each liter of gasoline produced for more than 90% of crude oil obtained from conventional onshore sources in the U.S. and more than half of crude oil imported from Saudi Arabia. For more than 55% of crude oil from Canadian oil sands, about 5.2 liters of water are consumed for each liter of gasoline produced. Our analysis highlighted the vital importance of water management during the feedstock production and conversion stage of the fuel lifecycle.

Abstract  Mandated Environmental Protection Agency biofuel qualifications focused on greenhouse gas (GHG) emissions and fossil fuel use are limited in perspective and have the potential to encourage burden shifting. When a broader host of environmental impacts are examined, environmental trade-offs often exist when biofuels are compared to gasoline. Multivariate analysis methods examining a wide variety of weighting value systems and methodology assumptions were used to determine process design options with the lowest overall environmental impact. A multivariate environmental analysis was applied to the dilute acid pre-treatment process followed by enzymatic hydrolysis and the fermentation process for converting loblolly pine, eucalyptus, natural hardwood, switchgrass, and sweet sorghum biomass to ethanol. The influence of co-product treatment method choices, inclusion of direct land-use change, and electrical grid assumptions were examined using 16 different weighting methods to create a single score result. Biofuel system rankings based on GHG emissions following the Renewable Fuel Standards 2 (RFS2) methods were very sensitive to the co-product treatment method, inclusion of land-use change emissions, and energy grid assumptions. The multivariate analysis ranking was heavily influenced by other environmental impacts resulting from the production of process chemicals used in ethanol conversion. Weighting methods examined had no influence on the environmental preference ranking of the biofuel scenarios. Additionally, the biofuel ranking based on the RFS2 methodology was different than the ranking following the multivariate approach examining additional impacts. These findings demonstrate a robust approach to biofuel life cycle assessment (LCA) scenario analysis and suggest that the limited scope of the RFS2 environmental analysis could result in burden shifting. (C) 2015 Society of Chemical Industry and John Wiley & Sons, Ltd

Abstract  A biorefinery may produce multiple fuels from more than one feedstock. The ability of these fuels to qualify as one of the four types of biofuels under the US Renewable Fuel Standard and to achieve a low carbon intensity score under Californias Low Carbon Fuel Standard can be strongly influenced by the approach taken to their life cycle analysis (LCA). For example, in facilities that may co-produce corn grain and corn stover ethanol, the ethanol production processes can share the combined heat and power (CHP) that is produced from the lignin and liquid residues from stover ethanol production. We examine different LCA approaches to corn grain and stover ethanol production considering different approaches to CHP treatment. In the baseline scenario, CHP meets the energy demands of stover ethanol production first, with additional heat and electricity generated sent to grain ethanol production. The resulting greenhouse gas (GHG) emissions for grain and stover ethanol are 57 and 25 g-CO(2)eq/MJ, respectively, corresponding to a 40 and 74 % reduction compared to the GHG emissions of gasoline. We illustrate that emissions depend on allocation of burdens of CHP production and corn farming, along with the facility capacities. Co-product handling techniques can strongly influence LCA results and should therefore be transparently documented.

Abstract  This paper showcases the suitability of an environmentally extended input–output framework to provide macroeconomic analyses of an expanding bioeconomy to allow for adequate evaluation of its benefits and trade-offs. It also exemplifies the framework’s applicability to provide early design stage evaluations of emerging technologies expected to contribute to a future bioeconomy. Here, it is used to compare the current United States (U.S.) bioeconomy to a hypothetical future containing additional cellulosic ethanol produced from two near-commercial pathways. We find that the substitution of gasoline with cellulosic ethanol is expected to yield socioeconomic net benefits, including job growth and value added, and a net reduction in global warming potential and nonrenewable energy use. The substitution fares comparable to or worse than that for other environmental impact categories including human toxicity and eutrophication potentials. We recommend that further technology advancement and commercialization efforts focus on reducing these unintended consequences through improved system design and innovation. The framework is seen as complementary to process-based technoeconomic and life cycle assessments as it utilizes related data to describe specific supply chains while providing analyses of individual products and portfolios thereof at an industrial scale and in the context of the U.S. economy.

Abstract  The biodiesel industry in the United States has realized significant growth over the past decade through large increases in annual production and production capacity and a transition from smaller batch plants to larger-scale continuous producers. The larger, continuous-flow plants provide operating cost advantages over the smaller batch plants through their ability to capture co-products and reuse certain components in the production process. This paper uses a simple capital budgeting model developed by the authors along with production data supplied by industry sources to estimate production costs, return-on-investment levels, and break-even conditions for two common plant sizes (30 and 60 million gallon annual capacities) over a range of biodiesel and feedstock price levels. The analysis shows that the larger plant realizes returns to scale in both labor and capital costs, enabling the larger plant to pay up to $0.015 more per pound for the feedstock to achieve equivalent return levels as the smaller plant under the same conditions. The paper contributes to the growing literature on the biodiesel industry by using the most current conversion rates for the production technology and current price levels to estimate biodiesel production costs and potential plant performance, providing a useful follow-up to previous studies.

Abstract  Trap grease is an environmental burden and its management has been costly and ineffective. Utilizing trap grease as a feedstock for biodiesel has the potential to reduce the cost of waste removal and biofuel production. This study presents a life cycle analysis to evaluate the energy consumption and greenhouse gas (GHG) emission from the trap grease-to-biodiesel production process. It was shown that utilizing the solids in the trap grease for anaerobic digestion (AD) was crucial in reducing both energy consumption and GHG emissions. Monte Carlo simulation revealed significant variation in both the life cycle energy consumption and GHG emission, which was caused by the uncertainties within several key variables. The result of the sensitivity analysis indicated that trap grease has the potential to be a more energy efficient and low-GHG-emission feedstock under certain conditions, as compared with the current common feedstocks (e.g. soybean and algae).

Abstract  Two fields of scientific inquiry can be interconnected effectively only through a clear conceptual overlap. Moreover, the overlapping (that is, the common) concepts must have proven their internal operational effectiveness separately in each one of the adjoining disciplines (Leontief 1959, 1985).

Abstract  Throughout the past two decades, numerous studies characterized the greenhouse gas (GHG) emissions and net energy balance of corn ethanol production in the USA. A wide range of reported values resulted from differences in the vintage of the data used to evaluate the ethanol conversion technology and the agricultural practices of corn production, which evolved substantially during the rapid growth phase of the industry. Methodological differences in life cycle assessments also caused the reported values to vary widely. With corn dry mills growing from 30% of total installed ethanol production capacity in 1990 to 80-90% from 2006 to 2011, we document the evolution of this industry using vintage-specific data to analyze selected energy and environmental metrics, including GHG emissions, fossil energy use, direct land use, and GHG emissions reduction per hectare of land harvested for ethanol production. Our estimates indicate that production and use of corn ethanol emitted 44% fewer GHG emissions, consumed 54% less fossil energy and required 44% less land in 2010 compared to 1990 (on a life cycle basis). Our review and analysis point to strategies for reducing the carbon footprint of the corn dry mill industry by building on the progress already achieved. Using biomass (e.g. residues from corn production) for process heat or combined heat and power is one such strategy. Additional environmental benefits are projected from the adoption of integrated gasification combined cycle technology (using corn residues), which leads to energy-self-sufficient mills or net electricity producers depending on the power system configuration. (c) 2013 Society of Chemical Industry and John Wiley & Sons, Ltd

Abstract  To meet greenhouse gas (GHG) emissions for the transportation sector, the United States is expected to expand infrastructure for producing and distributing lignocellulosic biofuels over the next decade. To compare the life-cycle GHG footprint of biofuels to the petroleum baseline, emissions associated with feedstock and fuel handling, storage, and transportation must be included. U.S.-specific life-cycle GHG emission factors were developed for each major distribution chain activity by applying a hybrid life-cycle assessment methodology to the construction, manufacturing, operation and maintenance of each component. A projection was then made for the fleet of infrastructure components necessary to distribute 21billion gal. (79.5billion L) of ethanol derived entirely from Miscanthus grass for comparison to the baseline petroleum system. Owing to geographic, physical, and chemical properties of biomass and alcohols, the distribution system for Miscanthus-based ethanol is more capital- and energy-intensive than petroleum per unit of fuel energy delivered and was estimated to be over five times more GHG-intensive than petroleum (i.e.,1718 versus 3.2gCO2-e/MJ of consumed fuel, ignoring feedstock production and conversion). Lower life-cycle emissions could be attained by employing more efficient and durable equipment and vehicles; reducing material losses; minimizing feedstock delivery, biofuel delivery, and consumer refueling errand distances; and producing more energy-dense biofuels than ethanol. (C) 2013 American Society of Civil Engineers.