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 carbon intensity (CI) of biofuel's well-to-pump life cycle is calculated by life cycle analysis (LCA) to account for the energy/material inputs of the feedstock production and fuel conversion stages and the associated greenhouse gas (GHG) emissions during these stages. The LCA is used by the California Air Resources Board's Low Carbon Fuel Standard (LCFS) program to calculate CI and monetary credits are issued based on the difference between a given fuel's CI and a reference fuel's CI. Through the Tier 2 certification program under which individual fuel production facilities can submit their own CIs with their facility input data, the LCFS has driven innovative technologies to biofuel conversion facilities, resulting in substantial reductions in GHG emissions as compared to the baseline gasoline or diesel. A similar approach can be taken to allow feedstock petition in the LCFS so that lower-CI feedstock can be rewarded. Here we examined the potential for various agronomic practices to improve the GHG profiles of corn ethanol by performing feedstock-level CI analysis for the Midwestern United States. Our system boundary covers GHG emissions from the cradle-to-farm-gate activities (i.e. farm input manufacturing and feedstock production), along with the potential impacts of soil organic carbon change during feedstock production. We conducted scenario-based CI analysis of ethanol, coupled with regionalized inventory data, for various farming practices to manage corn fields, and identified key parameters affecting cradle-to-farm-gate GHG emissions. The results demonstrate large spatial variations in CI of ethanol due to farm input use and land management practices. In particular, adopting conservation tillage, reducing nitrogen fertilizer use, and implementing cover crops has the potential to reduce GHG emissions per unit corn produced when compared to a baseline scenario of corn–soybean rotation. This work shows a large potential emission offset opportunity by allowing feedstock producers a path to Tier 2 petitions that reward low-CI feedstocks and further reduce biofuels' CI. The prevalence of significant acreage that has not been optimized for CI suggests that policy changes that incentivize optimization of this parameter could provide significant additionality over current trends in farm efficiency and adoption of conservation practice.

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  Argentine fuel ethanol production and consumption are forecast to increase to a record 1.15 billion liters in 2018 as the local industry expands in order to fulfill the official quota and a growing demand of gasoline. Biodiesel production in 2018 is forecast at 2.76 billion liters, a drop from the previous two years because of expected lower exports. The US government set in late 2017 anti-subsidy duties and in April 2018 anti-dumping duties on biodiesel coming from Argentina. In practice, this means that local biodiesel will not enter the United States. During the first seven months of the year, there were large volumes of biodiesel exported to the EU. However, following a complaint from the European industry, Argentine biodiesel imports could be affected by higher import duties in the near future. At the same time, the Argentine government has increased biodiesel export taxes from 8 to 15 percent, effective July 2018.

Abstract  To evaluate the quality of biodiesel (B100) fuel being produced in the United States, research staff members at the U.S. Department of Energy's National Renewable Energy Laboratory conduct periodic B100 quality surveys. In order to be a legal fuel and qualify for tax credits, B100 must meet ASTM International D6751 specifications. For the 2007 survey, samples were collected directly from U.S. producers between April and November 2007. The samples were compared against the National Biodiesel Accreditation Program (BQ-9000) critical properties (except sulfur) and metals using ASTM International test methods. These properties are a subset of the full ASTM D6751 B100 requirements. Samples were requested from all 107 producers, as determined from the National Biodiesel Board at the start of the survey. The 56 producers that provided samples represented 52% of the producers in the marketplace. Of the other 51 producers, 38 did not have product available, 7 did not respond, four declined to participate, one had shut down its plant to perform upgrades, and one no longer existed. The samples were tested for properties deemed critical for engine operation: oxidation stability, flash point and alcohol content, cloud point, water and sediment, acid value, and free and total glycerin. They were also analyzed for the following elements: phosphorus, sodium, potassium, magnesium, and calcium. These elements are potent poisons for advanced emission control equipment.

Abstract  This is the first triennial Report to Congress required under Section 204 of the 2007 Energy Independence and Security Act (EISA). EISA increases the renewable fuel standards (RFS) to 36 billion gallons per year by 2022. Section 204 requires an assessment of environmental and resource conservation impacts of the RFS program. Air and water quality, soil quality and conservation, water availability, ecosystem health and biodiversity, invasive species, and international impacts are assessed, as well as opportunities to mitigate these impacts. Feedstocks compared include corn starch, soybeans, corn stover, perennial grasses, woody biomass, algae, and waste. Biofuels compared include conventional and cellulosic ethanol and biodiesel. This report is a qualitative assessment of peer-reviewed literature. This report concludes that (1) the extent of negative impacts to date are limited in magnitude and are primarily associated with the intensification of corn production; (2) whether future impacts are positive or negative will be determined by the choice of feedstock, land use change, cultivation and conservation practices; and (3) realizing potential benefits will require implementation and monitoring of conservation and best management practices, improvements in production efficiency, and implementation of innovative technologies at commercial scales. This report provides a foundation for comprehensive environmental assessments of biofuel production.

Abstract  Expelling and hexane extraction are two typical processes for soybean oil production used in industry. The main issues for these two processes are the low efficiency and hazardous chemical problems respectively. Enzyme assisted aqueous extraction process (EAEP) was proposed to increase the efficiency without using organic solvent, which is replaced by water. The environmental impact analysis of these three processes are based on their mass flows, energy consumption and global warming potential. For mass flows, the environmental impact indices were calculated based on material flow of input and output components. Energy consumption was used to evaluate the carbon dioxide, other greenhouse gas (GHG), and criteria pollutants emissions by GREET models. According to our results, hexane extraction has the highest environmental impact due to the application of organic solvent. Expelling has the highest GHG and criteria pollutants emissions because of the high energy requirement for heat pressing processes. EAEP has similar environmental impacts to the expelling process, but it also lowers GHG and criteria pollutants emissions. EAEP has the potential to be a green process adopted by industry although a high energy intense pretreatment to produce finer soybean flakes for increasing oil recovery is still a challenge. © 2018 Institution of Chemical Engineers

Abstract  Microalgae are considered promising feedstock for the production of biofuels and other bioactive compounds, yet there are still challenges on commercial applications of microalgae-based products. This review focuses on the economic analysis, environmental impact, and industrial potential of biofuels production from microalgae. The cost of biofuels production remains higher compared to conventional fuel sources. However, integration of biorefinery pathways with biofuels production for the recovery of value-added products (such as antioxidants, natural dyes, cosmetics, nutritional supplements, polyunsaturated fatty acids, and so forth) could substantially reduce the production costs. It also paves the way for sustainable energy resources by significantly reducing the emissions of CO2 , NOx , SOx , and heavy metals. Large-scale biofuels production has yet to be successfully commercialized with many roadblocks ahead and heavy competition with conventional fuel feedstock as well as technological aspects. One of the prominent challenges is to develop a cost-effective method to achieve high-density microalgal cultivation on an industrial scale. The biofuels industry should be boosted by Government's support in the form of subsidies and incentives, for addressing the pressing climate change issues, achieving sustainability, and energy security.

Abstract  The EPAct/V2/E-89 gasoline fuel effects program collected emissions data for 27 test fuels using a fleet of 15 high-sales cars and light trucks from the 2008 model year (all with port fuel injection). The test fuel matrix covered values of T50, T90, vapor pressure, ethanol content, and total aromatic content spanning ranges typical of market gasolines. Emission measurements were made over the LA92 cycle at a nominal temperature of 24°C (75°F). The resulting emissions database of 956 tests includes a particulate matter (PM) mass measurement for each. Emission models for PM fuel effects were fit based on terms for which the fuel matrix was originally optimized, with results published by EPA in a 2013 analysis report. This paper presents results of a subsequent modeling analysis of this PM data using the PM Index fuel parameter, and compares these models to the original versions. Two related observations of interest are also discussed: the first is a significant reinforcing interaction between ethanol and PM Index; the second is the wide variation in sensitivity of PM emissions to fuel parameters across the 15 vehicles in the test fleet, indicating that fuel interacts in important ways with engine and vehicle design characteristics, calibrations, and control algorithms.

Abstract  BT16 is the third DOE-sponsored report to evaluate biomass resource availability in the conterminous United States. Each report addressed different goals. The 2005 Billion-Ton Study (BTS) was a strategic assessment of the potential biophysical availability of biomass. It identified the potential to produce more than one billion tons per year of agricultural and forest biomass sources—sufficient to produce enough biofuel to displace 30% of then-current petroleum consumption. However, this biophysical potential was not restricted by price, which is a key factor in the commercial viability of bioenergy and biofuels strategies. The 2011 U.S. Billion-Ton Update (BT2) evaluated the availability of biomass supply as a function of price. Employing an economic model to simulate potential biomass supply response to market demands, BT2 evaluated the potential economic availability of biomass feedstocks under a range of offered prices and yield scenarios between 2012 and 2030. It again projected the potential for more than 1 billion dry tons of biomass per year to be potentially available by 2030, assuming market prices of $60 per dry ton at the farmgate or roadside (i.e., after harvest, ready for delivery to a processing facility). This report (BT16) builds on previous research to address key questions: • What is the potential economic availability of biomass resources using the latest-available yield and cost data? • How does the addition of algae, miscanthus, eucalyptus, wastes, and other energy crops affect potential supply? • With the addition of transportation and logistics costs, what is the economic availability of feedstocks delivered to the biorefinery?

Abstract  The US Midwest is the largest and most intensive corn (Zea mays, L.) production region in the world. However, N losses from corn systems cause serious environmental impacts including dead zones in coastal waters, groundwater pollution, particulate air pollution, and global warming. New approaches to reducing N losses are urgently needed. N surplus is gaining attention as such an approach for multiple cropping systems. We combined experimental data from 127 on-farm field trials conducted in seven US states during the 2011-2016 growing seasons with biochemical simulations using the PNM model to quantify the benefits of a dynamic location-adapted management approach to reduce N surplus. We found that this approach allowed large reductions in N rate (32%) and N surplus (36%) compared to existing static approaches, without reducing yield and substantially reducing yield-scaled N losses (11%). Across all sites, yield-scaled N losses increased linearly with N surplus values above similar to 48 kg ha(-1). Using the dynamic model-based N management approach enabled growers to get much closer to this target than using existing static methods, while maintaining yield. Therefore, this approach can substantially reduce N surplus and N pollution potential compared to static N management.

Abstract  Many organizations have attempted to develop an accurate well-to-pump life cycle model of petroleum products in order to inform decision makers of the consequences of its use. Our paper studies five of these models, demonstrating the differences in their predictions and attempting to evaluate their data quality. Carbon dioxide well-to-pump emissions for gasoline showed a variation of 35 %, and other pollutants such as ammonia and particulate matter varied up to 100 %. Differences in allocation do not appear to explain differences in predictions. Effects of these deviations on well-to-wheels passenger vehicle and truck transportation life cycle models may be minimal for effects such as global warming potential (6 % spread), but for respiratory effects of criteria pollutants (41 % spread) and other impact categories, they can be significant. A data quality assessment of the models' documentation revealed real differences between models in temporal and geographic representativeness, completeness, as well as transparency. Stakeholders may need to consider carefully the tradeoffs inherent when selecting a model to conduct life cycle assessments for systems that make heavy use of petroleum products.

Abstract  BACKGROUND: Corn oil recovery and conversion to biodiesel has been widely adopted at corn ethanol plants recently. The US EPA has projected 2.6 billion liters of biodiesel will be produced from corn oil in 2022. Corn oil biodiesel may qualify for federal renewable identification number (RIN) credits under the Renewable Fuel Standard, as well as for low greenhouse gas (GHG) emission intensity credits under California's Low Carbon Fuel Standard. Because multiple products [ethanol, biodiesel, and distiller's grain with solubles (DGS)] are produced from one feedstock (corn), however, a careful co-product treatment approach is required to accurately estimate GHG intensities of both ethanol and corn oil biodiesel and to avoid double counting of benefits associated with corn oil biodiesel production.

RESULTS: This study develops four co-product treatment methods: (1) displacement, (2) marginal, (3) hybrid allocation, and (4) process-level energy allocation. Life-cycle GHG emissions for corn oil biodiesel were more sensitive to the choice of co-product allocation method because significantly less corn oil biodiesel is produced than corn ethanol at a dry mill. Corn ethanol life-cycle GHG emissions with the displacement, marginal, and hybrid allocation approaches are similar (61, 62, and 59 g CO2e/MJ, respectively). Although corn ethanol and DGS share upstream farming and conversion burdens in both the hybrid and process-level energy allocation methods, DGS bears a higher burden in the latter because it has lower energy content per selling price as compared to corn ethanol. As a result, with the process-level allocation approach, ethanol's life-cycle GHG emissions are lower at 46 g CO2e/MJ. Corn oil biodiesel life-cycle GHG emissions from the marginal, hybrid allocation, and process-level energy allocation methods were 14, 59, and 45 g CO2e/MJ, respectively. Sensitivity analyses were conducted to investigate the influence corn oil yield, soy biodiesel, and defatted DGS displacement credits, and energy consumption for corn oil production and corn oil biodiesel production.

CONCLUSIONS: This study's results demonstrate that co-product treatment methodology strongly influences corn oil biodiesel life-cycle GHG emissions and can affect how this fuel is treated under the Renewable Fuel and Low Carbon Fuel Standards.

Abstract  Waste grease lipids used in animal feeds have been the cause of food recalls in Europe, where such materials were incorporated into animal feedstuffs. This resulted in unwanted residues in human food. The composition of such lipid sources has been lacking. Seventeen composite trap grease and isolated brown grease samples were analyzed. Analytes included nutrients, metals, and volatile organic compounds. Analytes were selected for relevance to wastewater treatment and resource reuse potential. Moisture averaged 89.4% and the pH was 3.8. The 5-day biological oxygen demand was 32,531 mg/liter, solids were 7.5%, and fats, oil, and grease were 48,970 mg/liter. Non-polychlorinated biphenyl volatile organic compounds were surveyed. In the 17 grease samples, 14 contained an average of 102.5 μg/liter chloroform; 11 samples contained acetone, averaging 369 μg/liter; 9 samples contained 2-butanone, with an average of 484 μg/liter; and 8 contained an average of 710 μg/liter methylene chloride and toluene at 311 μg/liter. The mean concentration of copper in 17 composite samples ranged from 15 to 239 mg/liter, iron averaged 314 mg/liter, lead means ranged from 2.5 to 24 mg/liter, and magnesium averaged 975 mg/liter. It is hypothesized that food preparation facility cleaning and chlorinated cleaning-disinfection agents combined with the organics in the low-pH environment of the traps produce potentially carcinogenic compounds. It is recommended that these waste grease materials be used as a feedstock for biofuel.

Abstract  To address issues of energy security and greenhouse gas (GHG) mitigation, substantial amounts of corn-derived ethanol are used in U.S. gasoline. Currently, ethanol comprises 10% of the U.S. gasoline pool (E10), but there is interest in increasing this - possibly doubling the amount currently used. Production of corn ethanol raises several concerns with respect to environmental and ecological impacts. This paper reviews the available literature regarding the impacts on water, soil, and air quality. A companion paper addresses issues of biodiversity, ecosystems, land use change, greenhouse gas (GHG) emissions, and sustainability. We emphasize recent information appearing since comprehensive reports on this topic were issued by the U.S. EPA and NRC/NAS in 2011. The principal environmental concerns arise from the intensive agricultural activities associated with corn cropping. Nutrient runoff contributes to eutrophication, algal growth, and hypoxia in downstream water bodies; in addition to elevated nitrate pollutant levels in drinking water sources. Water requirements of corn ethanol vary by over 2-orders of magnitude among corn-growing states, depending upon the amount of irrigation used. Significant increases in corn production would likely involve expansion into areas requiring more intensive irrigation. Expansion into Conservation Reserve Program (CRP) lands raises concerns about increased erosion, deterioration of soil quality, loss of biodiversity, and reduction of ecosystem services. Largely because of energy-intensive agricultural activities (including fertilizer production), upstream emissions of most air pollutants of concern are considerably higher for corn ethanol compared to gasoline. Current fuel ethanol levels do not provide any benefit with respect to ground level ozone, and this is unlikely to change with use of E20. However, externalities associated with life-cycle emissions (such as eutrophication, acidification, health effects, etc.) are greater - and more costly - for corn ethanol compared to gasoline. Such externalities are expected to worsen in moving from E10 to E20 fuels.