Impact of energy supply infrastructure in life cycle analysis of hydrogen and electric systems applied to the Portuguese transportation sector

Hydrogen and electric vehicle technologies are being considered as possible solutions to mitigate environmental burdens and fossil fuel dependency. Life cycle analysis (LCA) of energy use and emissions has been used with alternative vehicle technologies to assess the Well-to-Wheel (WTW) fuel cycle or the Cradle-to-Grave (CTG) cycle of a vehicle's materials. Fuel infrastructures, however, have thus far been neglected. This study presents an approach to evaluate energy use and CO₂ emissions associated with the construction, maintenance and decommissioning of energy supply infrastructures using the Portuguese transportation system as a case study. Five light-duty vehicle technologies are considered: conventional gasoline and diesel (ICE), pure electric (EV), fuel cell hybrid (FCHEV) and fuel cell plug-in hybrid (FC-PHEV). With regard to hydrogen supply, two pathways are analysed: centralised steam methane reforming (SMR) and on-site electrolysis conversion. Fast, normal and home options are considered for electric chargers. We conclude that energy supply infrastructures for FC vehicles are the most intensive with 0.03–0.53 MJ_eq/MJ emitting 0.7–27.3 g CO_2eq/MJ of final fuel. While fossil fuel infrastructures may be considered negligible (presenting values below 2.5%), alternative technologies are not negligible when their overall LCA contribution is considered. EV and FCHEV using electrolysis report the highest infrastructure impact from emissions with approximately 8.4% and 8.3%, respectively. Overall contributions including uncertainty do not go beyond 12%.     

Plug-in hybrid fuel cell vehicles market penetration scenarios

The main objective of this research is to analyze the impact of the market share increase of hydrogen based road vehicles in terms of energy consumption and CO₂, on today's Portuguese light-duty fleet. Actual yearly values of energy consumption and emissions were estimated using COPERT software: 167112 TJ of fossil fuel energy, 12213 kton of CO₂ emission and 141 kton of CO, 20 kton of HC, 46 kton of NO_x and 3 kton of PM. These values represent 20–40% of countries total emissions. Additionally to base fleet, three scenarios of introduction of 10–30% fuel cell vehicles including plug-in hybrids configurations were analysed. Considering the scenarios of increasing hydrogen based vehicles penetration, up to 10% life cycle energy consumption reduction can be obtained if hydrogen from centralized natural gas reforming is considered. Full life cycle CO₂ emissions can also be reduced up to 20% in these scenarios, while local pollutants reach up to 85% reductions. For the purpose of estimating road vehicle technologies energy consumption and CO₂ emissions in a full life cycle perspective, fuel cell, conventional full hybrids and hybrid plug-in technologies were considered with diesel, gasoline, hydrogen and biofuel blends. Energy consumption values were estimated in a real road driving cycle and with ADVISOR software. Materials cradle-to-grave life cycle was estimated using GREET database adapted to Europe electric mix. The main conclusions on CO₂ full life cycle analysis is that light-duty vehicles using fuel cell propulsion technology are highly dependent on hydrogen production pathway. The worst scenario for the current Portuguese and European electric mix is hydrogen produced from on-site electrolysis (in the refuelling stations). In this case full life cycle CO₂ is 270 g/km against 190 g/km for conventional Diesel vehicle, for a typical 150,000 km useful life.     

Environmental and economic assessment of producing hydroprocessed jet and diesel fuel from waste oils and tallow

Animal fats and waste oils are potential feedstocks for producing hydroprocessed esters and fatty acids (HEFA) jet and diesel fuels. This paper calculates the lifecycle greenhouse gas (GHG) emissions and production costs associated with HEFA jet and diesel fuels from tallow, and from yellow grease (YG) derived from used cooking oil. For YG, total CO₂ equivalent (CO₂ eq.) GHG emissions of jet and diesel were found to range between 16.8–21.4 g MJ⁻¹ and 12.2–16.9 g MJ⁻¹ respectively. This corresponds to lifecycle GHG emission reductions of 76–81% and 81–86% respectively, compared to their conventional counterparts. Two different system boundaries were considered for tallow-derived HEFA fuels. In System 1 (S1), tallow was treated as a by-product of the rendering industry, and emissions from rendering and fuel production were included. In System 2 (S2), tallow was considered as a by-product of the meat production industry, and in addition to the S1 emissions, cattle husbandry and slaughtering were also included. The lifecycle emissions (CO₂ eq.) from HEFA jet fuel for S1 and S2 were estimated to be 25.7–37.5 g MJ⁻¹ and 67.1–83.9 g MJ⁻¹ respectively. HEFA diesel lifecycle emissions were found to be 21.3–33.3 g MJ⁻¹ for S1 and 63.4–80.5 g MJ⁻¹ for S2. Production costs for these fuels were calculated using a discounted cash flow rate of return model. The minimum selling price was estimated to be 880 $ m⁻³–1060 $ m⁻³ for YG-derived HEFA, and 1050–1250 $ m⁻³ for tallow-derived HEFA fuels.     

Potential of biodiesel from waste cooking oil in Mexico

The aim of this study is to evaluate the potential use of biodiesel produced from waste cooking oil (WCO) in Mexico and its CO₂ emission reduction potential for the Mexican transport sector and associated costs. The results show, based on 2010 data, that the potential of biodiesel from WCO is between 7.8 PJ and 17.7 PJ that represent between 1.5% and 3.3% of petro-diesel consumption for the road transport sector and can reduce between 0.51 and 1.02 Mt of CO₂, (1.0%–2.7% of CO₂-associated emissions), depending on the recovery ratio of WCO from vegetable oil consumption for cooking and considering CO₂ emissions for biodiesel production and methanol emissions during production and combustion in the blend. Primary energy used to produce 1 MJ of WCO-biodiesel is 0.8727 MJ, while literature reports 1.2007 MJ to produce 1 MJ of petro-diesel. Biodiesel costs are similar to petro-diesel costs if WCO is free. The paper offers suggestions for policies that promote increased recollection of WCO for biodiesel production and reduced illegal marketing of WCO, which is the main barrier to increase biodiesel production from WCO. The data used for the analysis is based on a case study of a WCO biodiesel plant that operates in Mexico City.     

Life cycle assessment of a Brassica carinata bioenergy cropping system in southern Europe

The energetic and environmental performance of production and distribution of the Brassica carinata biomass crop in Soria (Spain) is analysed using life cycle assessment (LCA) methodology in order to demonstrate the major potential that the crop has in southern Europe as a lignocellulosic fuel for use as a renewable energy source.The Life Cycle Impact Assessment (LCIA) including midpoint impact analysis that was performed shows that the use of fertilizers is the action with the highest impact in six of the 10 environmental categories considered, representing between 51% and 68% of the impact in these categories.The second most important impact is produced when the diesel is used in tractors and transport vehicles which represents between 48% and 77%. The contribution of the B. carinata cropping system to the global warming category is 12.7 g CO₂ eq. MJ⁻¹ biomass produced. Assuming a preliminary estimation of the B. carinata capacity of translocated CO₂ (631 kg CO₂ ha⁻¹) from below-ground biomass into the soil, the emissions are reduced by up to 5.2 g CO₂ eq. MJ⁻¹.The production and transport are as far as a thermoelectric plant of the B. carinata biomass used as a solid fuel consumes 0.12 MJ of primary energy per 1 MJ of biomass energy stored. In comparison with other fossil fuels such as natural gas, it reduces primary energy consumption by 33.2% and greenhouse gas emission from 33.1% to 71.2% depending on whether the capacity of translocated CO₂ is considered or not.The results of the analysis support the assertion that B. carinata crops are viable from an energy balance and environmental perspective for producing lignocellulosic solid fuel destined for the production of energy in southern Europe. Furthermore, the performance of the crop could be improved, thus increasing the energy and environmental benefits.     

Sugarcane ethanol production in Malawi: Measures to optimize the carbon footprint and to avoid indirect emissions

Sugarcane ethanol is considered to be one of the most efficient first-generation biofuels in terms of greenhouse gas (GHG) emissions. The carbon footprint (CF), however, increases significantly when taking into account emissions induced by indirect land-use changes (ILUC). This case study investigates sugarcane ethanol production in the Republic of Malawi, in Sub-Sahara Africa (SSA); the research objectives were to identify and quantify direct and indirect emissions and to identify measures to optimize the CF. The CF has been calculated with a life cycle approach and with data obtained from the involved companies; our estimations with regard to ILUC take into account further expansion plans for sugarcane crop production. Under existing production conditions ethanol produced in Malawi leads to GHG emissions expressed as CO_2eq of 116 g MJ⁻¹ of ethanol. However, high optimization potentials exist when the vinasse is used as an input for biogas production and the harvesting switches from pre-harvest burning to green harvesting. ILUC induced by prospective sugarcane expansions in the Southern Region will, according to current planning, probably not occur since these expansions are linked to the implementation of a large-scale irrigation project. However if ILUC takes place, high levels of additional CO₂ emissions of about 77 g MJ⁻¹ of ethanol are to be expected. Although the case study results are only valid for a specific region, some of the findings, such as the high compensation potential regarding ILUC through investments in irrigation systems, may be transferable to other regions in SSA.     

Electric and plug-in hybrid vehicles influence on CO2 and water vapour emissions

The main objective of this research is to quantify the impact of introducing electric vehicles and plug-in hybrid vehicles, including fuel cell on conventional fleets. The impact is estimated in terms of local pollutants, HC, CO, NO_x, PM, and in terms of CO₂ and water vapour global emissions. The specific fleet of Portugal, roughly 6 million light-duty vehicles (30% diesel, 70% gasoline) is considered, and the mobility indicator of the fleet, 90 thousand million p × km, is kept constant throughout the analysis. Probability density functions for energy consumption and emissions are derived for conventional, electric and plug-in hybrid vehicles, in charge depleting and charge sustaining modes. The Monte Carlo method is used to obtain average distribution estimates for discounting values of “old vehicles” that are removed from the fleet, and to add average distribution estimates for the “new vehicles” entering the fleet. Considering the actual Portuguese fleet as the reference case, local pollutant emissions decrease by a factor of 10-53%, for 50% fleet replacement. A potential 23% decrease of CO₂ is foreseen, and a potential 31% increase of H₂O emissions is forecasted. Life cycle water vapour emissions tend to rise and are, typically, 2-4 times higher than CO₂ values at the upstream stage, due to its release in the cooling towers of thermal power plants. It is interesting to note that considering 1 MJ of energy required at vehicle wheels, in an overall life cycle context, both fuel cell and electric modes have nearly twice as much H₂O emissions than internal combustion vehicles. CO₂ emissions tend to decrease with electric drive vehicles penetration due to the higher fleet life cycle efficiency.     

Plastic vs. fuel: Which use of the Brazilian ethanol can bring more environmental gains?

Ethanol from sugarcane is mainly used as fuel for cars in Brazil. However, the chemical industry is considering ethanol also as biotic feedstock for several plastics (e.g. polyethylene and polyvinyl chloride). Both uses are able to cause less environmental impacts than their fossil references if we look to certain specific environmental impact categories such as fossil energy consumption and greenhouse gas (GHG) emissions. However, which use would be able to bring the most environmental gains to society? In order to answer this question, we performed an attributional life cycle assessment of using 1 kg of hydrous ethanol as fuel for transportation and the same amount for monomer production (ethylene), and compared them with the common practice of today in Brazil. Using ethanol to produce ethylene (instead of fossil-based ethylene) would generate environmental gains in the order of 32.0 MJ of fossil energy and 1.87 kg CO₂eq, whereas the use of ethanol for transportation (instead of gasoline mixture, for flex-fuel cars) would generate environmental gains in the order of 27.2 MJ of fossil energy and 1.82 kg CO₂eq. Some uncertainties were quantified, for instance we could observe that when the ethanol-to-ethylene reaction yield was lower than 96%, the fuel route had better results for GHG emission savings.     

CO2 emissions,nuclear energy,renewable energy and economic growth in the US

This study explores the causal relationship between carbon dioxide (CO₂) emissions, renewable and nuclear energy consumption and real GDP for the US for the period 1960–2007. Using a modified version of the Granger causality test, we found a unidirectional causality running from nuclear energy consumption to CO₂ emissions without feedback but no causality running from renewable energy to CO₂ emissions. The econometric evidence seems to suggest that nuclear energy consumption can help to mitigate CO₂ emissions, but so far, renewable energy consumption has not reached a level where it can make a significant contribution to emissions reduction.     

Life cycle energy consumption and GHG emissions of hydrogen production from underground coal gasification in comparison with surface coal gasification

Developing underground coal gasification (UCG)-based hydrogen production (UCG-H₂) is expected to alleviate hydrogen supply and demand contradiction, but its energy consumption and environmental impact need to be clarified. In this paper, comparative study of energy consumption and greenhouse gas (GHG) emissions between UCG-H₂ and typical surface coal gasification (SCG)-based hydrogen production (SCG-H₂) is carried out using life cycle assessment method. Result shows energy consumption of UCG-H₂ is only 61.2% of that of SCG-H₂, which is 1,327,261 and 2,170,263 MJ respectively, reflecting its obvious energy saving advantage. 80% capture rate can achieve an appropriate balance between energy consumption and emissions. Under this capture rate, emissions of UCG-H₂ and SCG-H₂ are roughly equivalent, which are 207,582 and 197,419 kg CO₂-eq respectively. Scenario analysis indicates energy consumption in hydrogen industry can reduce by 38.8% when hydrogen production is substituted by UCG with CCS to fully meet demand of 21 Mt in 2030.     

Comparison of fuel economies of high efficiency diesel and hydrogen engines powering a compact car with a flywheel based kinetic energy recovery systems

Coupling of small turbocharged high efficiency diesel engines with flywheel based kinetic energy recovery systems is the best option now available to reduce fuel energy usage and reduce green house gas (GHG) emissions. The paper describes engine and vehicle models to generate engine brake specific fuel consumption maps and compute vehicle fuel economies over driving cycles, and applies these models to evaluate the benefits of a H₂ICEs developed with the direct injection jet ignition engine concept to further reduce the fuel energy usage of a compact car equipped with a with a flywheel based kinetic energy recovery systems. The car equipped with a 1.2 L TDI Diesel engine and KERS consumes 25 g/km of fuel producing 79.2 g/km of CO₂ using 1.09 MJ/km of fuel energy. These CO₂ and fuel energy values are more than 10% better than those of today’s best hybrid electric vehicle. The car equipped with a 1.6 L DI-JI H₂ICE engine consumes 8.3 g/km of fuel, corresponding to only 0.99 MJ/km of fuel energy.     

CO2 emissions,energy consumption and economic growth in China: A panel data analysis

This paper examines the causal relationships between carbon dioxide emissions, energy consumption and real economic output using panel cointegration and panel vector error correction modeling techniques based on the panel data for 28 provinces in China over the period 1995–2007. Our empirical results show that CO₂ emissions, energy consumption and economic growth have appeared to be cointegrated. Moreover, there exists bidirectional causality between CO₂ emissions and energy consumption, and also between energy consumption and economic growth. It has also been found that energy consumption and economic growth are the long-run causes for CO₂ emissions and CO₂ emissions and economic growth are the long-run causes for energy consumption. The results indicate that China's CO₂ emissions will not decrease in a long period of time and reducing CO₂ emissions may handicap China's economic growth to some degree. Some policy implications of the empirical results have finally been proposed.     

A limited LCA comparing large- and small-scale production of ethanol for heavy engines under Swedish conditions

Ethanol is a renewable fuel that can be produced in small farm-scale plants as well as in medium- and large-scale industrial plants for use in e.g. heavy diesel engines. The purpose of this study was to analyse whether the use of a small-scale production system reduced the environmental load in comparison to a medium- and a large-scale system. Therefore, a limited life cycle assessment (LCA), including air emissions and energy requirements, was carried out for the three plant sizes. For the small plant and with physical allocation, the global-warming potential was 31.5 g CO₂-eq/MJ_fuel, the acidification potential was 198 mg SO₂-eq/MJ_fuel, the eutrophication potential was 30.9 mg PO₄³⁻-eq/MJ_fuel, the photochemical ozone creation potential was 13.8 mg C₂H₄-eq/MJ_fuel and the energy requirement 359 kJ/MJ_fuel. It was shown that the differences in environmental impact and energy requirement between small-, medium- and large-scale systems were small. The longer transport distances to a certain degree outweighed the higher energy efficiency and the more efficient use of machinery and buildings in the large-scale system. The dominating production step was the cultivation, in which production of fertilisers, followed by soil emissions and tractive power, made major contributions to the environmental load. The choice of allocation method had a certain influence on the difference between the scales, whereas the influence of uncertainty in input data and of some alternative production strategies was small.     

Environmental aspects of ethanol derived from no-tilled corn grain: nonrenewable energy consumption and greenhouse gas emissions

Nonrenewable energy consumption and greenhouse gas (GHG) emissions associated with ethanol (a liquid fuel) derived from corn grain produced in selected counties in Illinois, Indiana, Iowa, Michigan, Minnesota, Ohio, and Wisconsin are presented. Corn is cultivated under no-tillage practice (without plowing). The system boundaries include corn production, ethanol production, and the end use of ethanol as a fuel in a midsize passenger car. The environmental burdens in multi-output biorefinery processes (e.g., corn dry milling and wet milling) are allocated to the ethanol product and its various coproducts by the system expansion allocation approach.The nonrenewable energy requirement for producing 1 kg of ethanol is approximately 13.4–21.5 MJ (based on lower heating value), depending on corn milling technologies employed. Thus, the net energy value of ethanol is positive; the energy consumed in ethanol production is less than the energy content of the ethanol (26.8 MJ kg⁻¹).In the GHG emissions analysis, nitrous oxide (N₂O) emissions from soil and soil organic carbon levels under corn cultivation in each county are estimated by the DAYCENT model. Carbon sequestration rates range from 377 to 681 kg C ha⁻¹ year⁻¹ and N₂O emissions from soil are 0.5–2.8 kg N ha⁻¹ year⁻¹ under no-till conditions. The GHG emissions assigned to 1 kg of ethanol are 260–922 g CO₂ eq. under no-tillage. Using ethanol (E85) fuel in a midsize passenger vehicle can reduce GHG emissions by 41–61% km⁻¹ driven, compared to gasoline-fueled vehicles. Using ethanol as a vehicle fuel, therefore, has the potential to reduce nonrenewable energy consumption and GHG emissions.     

The contribution of direct energy use for livestock breeding to the greenhouse gases emissions of Cyprus

This paper presents a methodology for the estimation of the contribution of direct energy use to the greenhouse gases emissions of cattle, pig and poultry breeding in Cyprus. The energy consumption was estimated using the factors of 2034 MJ/cow, 2182 MJ/sow and 0.002797 MJ/bird. The greenhouse gases emissions for each animal species and energy source were estimated using emission factor of each greenhouse gas according to fuel type as proposed by the IPCC 2006 guidelines and for electricity according to national verified data from the Electricity Authority of Cyprus. Livestock breeding in Cyprus consumes electricity, diesel oil and LPG. The results obtained, show that the emissions from energy use in livestock breeding contribute 16% to the total agricultural energy emissions. Agricultural energy emissions contribute 0.7% to the total energy greenhouse gases (GHG) emissions. The three species of animal considered contribute 3% to their total livestock breeding emissions when compared with enteric fermentation and manure management, of which 2.6% is CO₂. These results agree with the findings in available literature. The contribution of direct energy use in the greenhouse gases emissions of livestock breeding could be further examined with the influence of anaerobic digestion to the emissions.     

Reductions in emissions of local air pollutants and co-benefits of Chinese energy policy: a Shanghai case study

To better understand the reductions in local air pollution that will result from the implementation of current Chinese energy policy, as well as the co-benefit for greenhouse-gas emission reductions, a Shanghai case study was conducted. The MARKAL model was used to forecast energy consumption and emissions of local air pollutants under different energy policy scenarios and also to analyze the associated reductions in CO₂ emissions. The results show that energy policies in Shanghai will significantly reduce SO₂ and PM₁₀ emissions and will also achieve the co-benefit of mitigating the increase of CO₂ emissions. In energy policy scenarios, SO₂ emissions during the period 2000–2020 will maintain the same level as in 2000; and the annual rate of increase of CO₂ emissions will be reduced to 1.1–1.2%, compared with 2.7% under a business-as-usual scenario. The problem for the future will be NO_x emissions, which are projected to increase by 60–70% by 2020, due to expansion of the transportation system.     

Techno-economic analysis of processes with integration of fluidized bed heat exchangers for H2 production – Part 2: Chemical-looping combustion

This work covers a techno-economic assessment for processes with inherent CO₂ separation, where a fluidized bed heat exchanger (FBHE) is used as heat source for steam reforming in a hydrogen production plant. This article builds upon the work presented in Part 1 of this study by Stenberg et al. [1], where a process excluding CO₂ capture was examined. Part 2 suggests two process configurations integrating steam reforming with a chemical-looping combustion (CLC) system, thus providing inherent CO₂ capture. The first system (case CM) uses natural gas as supplementary fuel whereas the second system (case CB) uses solid biomass, which enables net negative CO₂ emissions. In both systems, the reformer tubes are immersed in a bubbling fluidized bed where heat for steam reforming is efficiently transferred to the tubes. The processes include CO₂ compression for pipeline transportation, but excludes transport and storage. The CLC system is designed based on key parameters, such as the oxygen carrier circulation rate and oxygen transport capacity. The first system displays a process with net zero emissions and a hydrogen production efficiency which is estimated to 76.2%, which is almost 8% higher than the conventional process. The levelized production cost is 1.6% lower at below 2.6 €/kg H₂. The second system shows the possibility to reduce the emissions to ?34.1 g CO₂/MJ_H2 compared to the conventional plant which emits 80.7 g CO₂/MJ_H2. The hydrogen production efficiency is above 72% and around 2% higher than the conventional process. The capital investments are higher in this plant and the levelized hydrogen production cost is estimated to around 2.67 €/kg. The cost of CO₂ avoidance, based on a reference SMR plant with CO₂ capture, is low for both cases (?4.3 €/ton_CO2 for case CM and 2.7 €/ton_CO2 for case CB).     

Fuel cycle CO2-e targets of renewable hydrogen as a realistic transportation fuel in Australia

The claim of catastrophic man made climate change or global warming through anthropogenic CO₂ has presently focused the interest on the tailpipe emissions of CO₂ per km, with recent legislations obsessively targeting these emissions of CO₂ with defectively implemented procedures. With a variety of different propulsion solutions (electric, hybrid electric, hybrid mechanic, conventional) and different fuels (Diesel, Petrol, alternative fossil, alternative renewable) available in the near future, a more comprehensive approach based on the full fuel cycle, and eventually also the full life cycle of the vehicle appear to be necessary. The paper is a contribution to trigger further improvement to currently implemented procedures. The paper discusses the CO₂ emission data in the present form, some simple but effective measures to improve the accuracy of the data collection procedure, and propose results of fuel cycle CO₂-e analysis of vehicles with electric and thermal engines having different fuels. Vehicles with advanced internal combustion engines and power trains fuelled with Diesel may reach CO₂-e values of 100 g/km in Australia. Use of bio-ethanol in these vehicles may deliver in Australia a significant reduction of CO₂-e emissions to values below 36 g/km. Emission factors for Victoria are presently 1.23 kg CO₂-e/kWh for the purchased electricity and vehicles powered by electric motors will need a significant reduction of this indirect CO2-e emission to become competitive. Values below 0.5 kg CO₂-e/kWh are needed to make electric cars competitive with Diesel cars while values below 0.1 kg CO₂-e/kWh are needed to make electric cars competitive with bio-ethanol cars. Compared with all these alternatives, renewable hydrogen may possibly compete with Diesel when produced with renewable energy sources and made available at the pump for less than 0.1 kg CO₂-e/MJ of fuel energy, and with bio-ethanol if produced and distributed at a cost below 0.02 kg CO₂-e/MJ of fuel energy.     

Cob biomass supply for combined heat and power and biofuel in the north central USA

Corn (Zea mays L.) cobs are being evaluated as a potential bioenergy feedstock for combined heat and power generation (CHP) and conversion into a biofuel. The objective of this study was to determine corn cob availability in north central United States (Minnesota, North Dakota, and South Dakota) using existing corn grain ethanol plants as a proxy for possible future co-located cellulosic ethanol plants. Cob production estimates averaged 6.04 Tg and 8.87 Tg using a 40 km radius area and 80 km radius area, respectively, from existing corn grain ethanol plants. The use of CHP from cobs reduces overall GHG emissions by 60%–65% from existing dry mill ethanol plants. An integrated biorefinery further reduces corn grain ethanol GHG emissions with estimated ranges from 13.9 g CO₂ equiv MJ⁻¹ to 17.4 g CO₂ equiv MJ⁻¹. Significant radius area overlap (53% overlap for 40 km radius and 86% overlap for 80 km radius) exists for cob availability between current corn grain ethanol plants in this region suggesting possible cob supply constraints for a mature biofuel industry. A multi-feedstock approach will likely be required to meet multiple end user renewable energy requirements for the north central United States. Economic and feedstock logistics models need to account for possible supply constraints under a mature biofuel industry.     

A life cycle assessment of pennycress (Thlaspi arvense L.) -derived jet fuel and diesel

Field Pennycress (Thlaspi arvense L.) is a member of the mustard family and may be grown as a winter crop between traditional summer crops to produce renewable biomass for renewable diesel and jet fuel. This paper estimated total annual biofuel production potential of 15 million cubic metres from rotation between corn and soybeans on 16.2 million hectares in the Midwest without impact on food production. This study also investigated the life cycle greenhouse gas (GHG) emissions and energy balance of pennycress-derived Hydroprocessed Renewable Jet (HRJ) fuel and Renewable Diesel (RD). Both system expansion and allocation approaches were applied to distribute environmental impacts among products and co-products along the life cycle of each biofuel. The life cycle GHG emissions (excluding land use change) for RD and HRJ range from 13 to 41 g MJ⁻¹ (CO₂ eq.) and −18 to 45 g MJ⁻¹ (CO₂ eq.), respectively, depending on how the co-products are credited. The majority of the energy required for each biofuel product is derived from renewable biomass as opposed to non renewable fossil. The fossil energy consumptions are considerably lower than the petroleum fuels. Scenario analyses were also conducted to determine response to model assumptions, including nitrogen fertilizer application rate, nitrogen content in crop residues, and sources of H₂. The results show that pennycress derived biofuels could qualify as advanced biofuels and as biomass-based diesel as defined by the Renewable Fuels Standard (RFS2).