[Due to the increasing size of the archives, each topic page now contains only the prior 365 days of content. Access to older stories is now solely through the Monthly Archive pages or the site search function.]
BAL scientists engineer yeast to produce ethanol from brown seaweed; brown seaweed biorefinery
December 03, 2013
An international team of researchers from Bio Architecture Labs, a synthetic biology and enzyme design company focused on the production of biofuels and biochemicals from macroalgae (seaweed) (earlier post), reports the development of a synthetic yeast platform based on Saccharomyces cerevisiae that can efficiently produce ethanol from brown seaweed; the paper is published in the journal Nature.
In January 2012, BAL scientists reported the engineering a strain of Eschericia coli that could break down and then ferment alginate—one of the most abundant sugars in brown algae, but a sugar that industrial microbes can’t metabolize—into ethanol. That paper was featured on the cover of the journal Science. (Earlier post.)
Ford researchers present physics-based model of mass-induced fuel consumption for better insight into lightweighting benefits
November 25, 2013
A pair of researchers from Ford Motor Company’s Systems Analytics and Environmental Sciences Department in Dearborn have developed a novel physics-based model of mass-induced fuel (MIF) consumption which can be used in vehicle life cycle assessments to provide better insight—i.e., from a more firm scientific foundation—on the potential benefits of lightweighting.
To illustrate the method, they used their model to estimate the MIF values for 2013 model year internal combustion engined using the US Environmental Protection Agency’s (EPA’s) fuel economy certification data. They found MIF values in the range of 0.2−0.5 L/(100 km 100 kg). As described in a paper on their work in the ACS journal Environmental Science & Technology, the results showed that lightweighting has the most benefit when applied to vehicles with high fuel consumption and high power.
Average carbon intensity of oil sands production has dropped ~36% in last 40 years; still 12-24% higher than conventional oil CI
November 21, 2013
|Trends in well-to-wheel pathway-specific CI. In situ production began in 1974, so no value is computable for 1970. Click to enlarge.|
The carbon intensity (CI) of Alberta oil sands production has significantly decreased over the last 40 years, according to a new study by a team from Stanford University published as an open access paper in the journal Environmental Research Letters.
Relying entirely on public and peer-reviewed data sources for the period from 1970 to 2010 (inclusive), the team found that industry-average full-fuel cycle (well-to-wheels, WTW) CI declined about 36% from 165 gCO2e MJ-1 higher heating value (HHV) of reformulated gasoline (RFG) to 105 (-12, +9) gCO2e MJ-1 HHV RFG. 2010 averages by production pathways are 102 gCO2e MJ-1 for mining and 111 gCO2e MJ-1 for in situ production.
TÜV SÜD Technical Inspectorate confirms BMW i3 can emit 30-50% less total life cycle greenhouse gases than comparable conventional vehicles
November 13, 2013
The BMW i3 battery electric vehicle can emit 30-50% less total life cycle greenhouse gases than comparable conventional vehicles depending upon the source of its electricity, according to its ISO 14040/14044 certificate from the TÜV SÜD Technical Inspectorate. (Earlier post.) Market launch for the i3 is on 16 November.
The 30% reduction is achieved by using energy from the EU 25 electricity mix, which takes account of all electricity generation in the European Union. The 50% reduction compared with conventional automobiles results as soon as the BMW i3 is powered exclusively by energy generated from renewables such as wind or solar power. ISO 14040/14004 are international standards for lifecycle assessment.
Georgia Tech study finds MD electric urban delivery trucks have cost advantages over diesel in some conditions; relative benefits depend on numerous factors
September 26, 2013
Researchers at Georgia Tech have compared medium-duty (MD) electric and diesel urban delivery trucks in terms of life-cycle energy consumption, greenhouse gas (GHG) emissions, and total cost of ownership (TCO). One surprise among their findings was that the electric truck had cost advantages over the diesel vehicle under some conditions. The team had expected that electric truck costs would always be higher, especially since the purchase price of the electric truck studied was higher than that of the diesel truck.
In a paper published in the ACS journal Environmental Science & Technology, they report that the relative benefits of electric trucks depend heavily on vehicle efficiency associated with drive cycle; diesel fuel price; travel demand; electric drive battery replacement and price; electricity generation and transmission efficiency; electric truck recharging infrastructure; and purchase price.
U-Mich researcher’s first-principles analysis challenges conventional carbon accounting for biofuels; implications for climate policy
September 24, 2013
In a paper that could have a significant impact on climate policies for transportation fuels, Dr. John M. DeCicco of the Energy Institute at the University of Michigan, Ann Arbor presents a rigorous first-principles analysis that undermines the common “biofuels recycle carbon” argument.
Published in the journal Climactic Change, the open access paper shows that while the carbon mitigation challenge for liquid fuels has been seen—incorrectly—as a fuel synthesis and substitution problem, it is in reality a net carbon uptake problem. Accordingly, DeCicco concludes, strategies should move away from a downstream focus on replacing fuel products to an upstream focus on achieving additional CO2 uptake through the most cost-effective and least damaging means possible. “All parties with an interest in the issue are advised to rethink their priorities accordingly,” he finishes.
Study finds HTL algal biofuels offer 50-70% lifecycle CO2 reduction compared to petroleum fuels; EROI and GHG comparable to or better than other biofuels
September 20, 2013
A new life cycle analysis by a team led by researchers at the University of Virginia has concluded that biofuel produced from algae via hydrothermal liquefaction (HTL) can reduce life cycle CO2 emissions by 50 to 70% compared to petroleum fuels, and also has energy burdens and GHG (greenhouse gas) emission profiles that are comparable to or better than conventional biofuels, cellulosic ethanol and soybean biodiesel.
HTL algae-derived gasoline has a considerably lower GHG footprint and a better EROI relative to conventional ethanol made from corn on a per MJ basis, the team found. The data suggest that a shift to algae-derived gasoline could have immediate climate benefits even using existing technologies, the authors noted. In addition, given expected technological improvements, the benefits of algae-derived gasoline will likely improve.
European Parliament backs 6% cap on land-based biofuels, switchover to advanced biofuels; no mandate
September 11, 2013
In a vote on draft legislation, the European Parliament has backed a cap on the use of biofuels produced from starch-rich crops, sugars, oil and other crops grown on land and a speedy switchover to new biofuels from alternative sources such as seaweed and waste. The measures aim to reduce greenhouse gas emissions that result from the turnover of agricultural land to biofuel production.
According to current legislation, member states must ensure that renewable energy accounts for at least 10% of energy consumption in transport by 2020. In the adopted text, MEPs (Members of the European Parliament) say land-based biofuels should not exceed 6% of the final energy consumption in transport by 2020. (The proposal by the European Commission on which the draft legislation was based had suggested an even lower 5% cap.)
Georgia Tech study suggests unlinking EVs from CAFE and coordinating with power sector for low-cost benefits
September 08, 2013
A team from Georgia Tech suggests, based on their modeling of electric vehicle (EV) adoption scenarios in each of six regions of the Eastern Interconnection (containing 70% of the US population), that coordinating EV adoption with the adoption of controlled EV charging, unlinking EVs from consideration in the CAFE fuel economy regulations; and implementing renewable electricity standards would deliver low-cost reductions in emissions and gasoline usage. (For the study, they define EVs as including both battery-electric (BEV) and plug-in hybrid electric (PHEV) vehicles.
Only in the case of high EV market share and a high renewable electricity standard (RES) do EVs make a material contribution to greenhouse gas (GHG) reductions, they found. However, managed EV adoption can reduce the cost of achieving GHG reductions through a RES, they concluded in their paper published in the ACS journal Environmental Science & Technology.
EPA grants Aemetis’ sorghum ethanol and biogas the D5 advanced biofuel RIN category
September 03, 2013
The US Environmental Protection Agency (EPA) has granted Aemetis, an advanced fuels and renewable chemicals company formerly known as AE Biofuels, approval to produce ethanol using grain sorghum and biogas at its converted corn ethanol plant to generate D5 Advanced Biofuels Renewable Identification Numbers (RINs).
Until now, the D5 Advanced Biofuels RIN portion of the RFS (Renewable Fuel Standard) has been mostly met by imported Brazilian sugarcane ethanol or by substituting D4 biodiesel RINs due to a lack of advanced ethanol production.
IHS-CERA concludes “no material impact” on US GHG from Keystone XL; heavy crude from Venezuela most likely replacement
August 09, 2013
The proposed Keystone XL pipeline for transporting oilsands-derived crude to Gulf Coast refineries would have “no material impact” on US greenhouse gas (GHG) emissions, according to a new Insight report by IHS CERA. In a June speech at Georgetown University, President Barack Obama said that the controversial Keystone XL pipeline would only be built if the project “does not significantly exacerbate the problem of carbon pollution.” (Earlier post.)
In the absence of the pipeline, alternate transportation routes would result in oilsands production growth being more or less unchanged, IHS CERA found. The study also found that any absence of oil sands on the US Gulf Coast would most likely be replaced by imports of heavy crude oil from Venezuela, which has the same carbon footprint as oilsands crude.
Lifecycle analysis of energy use and pollution from gasoline, CNG and electric vehicles in 6 southwestern states highlights variability of benefits
July 29, 2013
|Comparison of greenhouse gas emissions from new vehicles in 2020, EVs by state power mix. Percentages are relative to gasoline baseline. Click to enlarge.|
A report for policymakers issued by the Southwest Energy Efficiency Project (SWEEP) has found that in Arizona, Colorado and Nevada, electric vehicles offer the cleanest ride, while in New Mexico, Utah, and Wyoming that’s not necessarily the case. SWEEP promotes greater energy efficiency in a six-state region that includes Arizona, Colorado, Nevada, New Mexico, Utah, and Wyoming.
The report, “Transportation Fuels for the Southwest”, compared the well-to-wheels energy use and air pollution emitted by vehicles fueled by gasoline, compressed natural gas and electricity in order to determine which fuel is cleanest in each of the six southwestern states.
GM to double models with 40 mpg highway or better by 2017; ongoing manufacturing efficiency improvements
July 12, 2013
Describing its product goals and tracking progress toward its 2020 manufacturing priorities in its 2012 Sustainability Report, General Motors reaffirmed its commitment to further reduce the energy used and the environmental impacts of building and operating an automobile.
GM has made three product commitments for 2017 related to its sustainability strategy: to have 500,000 vehicles on the road in the US with some form of electrification (earlier post); to double the number of US models that can achieve an EPA-estimated 40 mpg US (5.9 l/100 km) highway or better; and to reduce the average CO2 tailpipe emissions of its US fleet by 15%. Opel also estimates it will reduce the average carbon tailpipe emissions from its fleet by 27% by 2020.
New LowCVP report highlights need to go “beyond the tailpipe” for CO2 metrics for vehicles
July 11, 2013
|Proportion of lifecycle CO2e emissions for future cars 2020-2030. The new study projects the increasing dominance of the production phase in terms of lifecycle CO2 impacts. Click to enlarge.|
The introduction of new energy technologies in road transport will mean that the current tailpipe measures of the climate impact of vehicles will become increasingly inadequate in future.
A new report—“Life Cycle CO2e Assessment of Low Carbon Cars 2020-2030”—prepared for the UK’s LowCVP Low Carbon Vehicle Partnership by PE International and validated by Partnership stakeholders—shows how total life cycle CO2e emissions will change for different vehicle technologies in the future and estimates how the balance of emissions will alter for different stages in the life cycle for the varying technologies.
Renault makes public its lifecycle study of Fluence ICE vs Fluence EV
|Renault’s comparison of the carbon footprint of EV and ICE vehicles over production, operation and end of life. The EV footprint (Fluence Z.E.) is shown with both UK and French grid mixes. Click to enlarge.|
Renault recently made public the findings of an internal study, published first in October 2011, detailing and comparing the lifecycle assessments (LCAs) of the battery-electric and two internal combustion engined versions (gasoline and diesel) of the Renault Fluence. The study used the series production versions launched in 2011, with the assumption of operation for 150,000 km (93,205 miles). (Since the BEV version has a shorter range, Renault noted, the way in which the miles are accumulated could differ from that of the ICE vehicles.)
The publication gives the opportunity for an “apples-to-apples” comparison between the environmental impacts of the two types of powertrains: same manufacturer, same model, same boundary conditions. Nevertheless, Renault noted, the study is contrasting a new technology (EVs) with a well-developed one; “environmental progresses are expected in a short term thank to key process improvement and massification of the production.”
Georgia Tech life-cycle study finds TCO of medium-duty electric and diesel delivery trucks similar; electric life-cycle energy use and GHG lower than diesel
July 06, 2013
|Life-cycle energy use and GHG emissions normalized with NYCC diesel case (8.06 MJ/t·km and 0.63 kgCO2e/t·km) at 100%. Numbers in red are net total including recycling effect. Credit: ACS, Lee et al. Click to enlarge.|
Comparing life-cycle energy consumption, greenhouse gas (GHG) emissions, and total cost of ownership (TCO) of medium-duty electric and diesel urban delivery trucks for a range of drive cycles and electricity generation scenarios, a team from Georgia Tech found that all in all, the life-cycle energy use and GHG emissions of the electric truck are lower than that of the diesel truck, particularly for the frequent stop and low average speed (NYCC- and OCTA-type) drive cycles.
They also found that the total costs of ownership (TCO) of the electric and diesel trucks are similar. Over an array of possible conditions, the median TCO of electric trucks is 22% less than that of diesel trucks on the NYCC. However, the cost-competitiveness of the electric truck diminishes in drive cycles with higher average speed. Battery replacement along with EVSE will also greatly affect the relative TCO of the electric truck. The study is published in the ACS journal Environmental Science & Technology.
CEPS task force report identifies tightening emissions standards as key policy to hit EU 60% reduction in transport GHG; full life-cycle emissions optimal metric
July 01, 2013
The report from a task force assembled by the CEPS (Centre for European Policy Studies), a Brussels-based think tank, on European transport policy has concluded that the EU’s goal of a 60% greenhouse gas (GHG) emissions reduction in the transport sector in 2050 compared to 1990 levels is possible, but at a cost.
Achieving the goal will require a comprehensive policy strategy that needs to be both “credible and adequate”, the report found. Credibility requires beginning to implement policies now—i.e. measures such as standards, taxation or infrastructure development—consistent with the long-term objective. Adequacy requires the measures, in their entirety, to have the potential to meet the target while neither undermining the internal market for transport nor its affordability.
Abt life-cycle analysis of different Li-ion chemistries for PHEVs and EVs identifies opportunities for improving environmental profile of batteries
June 30, 2013
|Generic process flow diagram for lithium-ion batteries for vehicles (color coded to present LCI data sources). Source: “Application of LCA to Nanoscale Technology”. Click to enlarge.|
A recent Abt Associates, Inc. life-cycle study of three Li-ion battery chemistries for plug-in hybrid (PHEV) and battery-electric (BEV) vehicles generated a number of findings and identified opportunities for improving the environmental profile of Li-ion batteries for use in plug-in and electric vehicles.
The study, carried out through a partnership with EPA, the US Department of Energy, the Li-ion battery industry, and academicians, was the first life-cycle assessment to bring together and to use data directly provided by Li-ion battery suppliers, manufacturers, and recyclers. It assessed three currently manufactured Li-ion battery technologies for EVs and two for a PHEV with a 40-mile all-electric range: lithium-manganese oxide (LiMnO2); lithium-nickel-cobalt-manganese-oxide (LiNi0.4Co0.2Mn0.4O2, Li-NCM); and lithium-iron phosphate (LiFePO4). In addition, a single-walled carbon nanotube (SWCNT) anode technology for possible future use in these batteries was assessed.
Study finds climate impact of long distance trip can vary by factor of 10 depending upon mode, efficiency and occupancy
June 27, 2013
A team from Austria and Norway has found that the climate impact from a long-distance trip (500–1,000 km, or 310–621 miles) can easily vary by a factor of 10 per passenger depending on mode choice, vehicle efficiency, and occupancy. Among the findings of the study, published in the ACS journal Environmental Science & Technology, is that a car’s fuel efficiency and occupancy are central to whether the impact from a trip is as high as from air travel or as low as from train travel.
With only one passenger in a car, corresponding to 20−25% occupancy, the climate impact is at the level of an average air trip, whereas a car with three or more passengers, 60% occupancy or more, it is at the low level of average trains or coaches. A notable exception is for the small diesel car; with two passengers ( i.e., 50% occupancy), the specific climate impact is lower than for an average train or bus trip.
Ford LCA harmonization study clarifies benefits of lightweighting for vehicle life cycle energy use and GHG emissions
May 29, 2013
|Correlation between weight reduction and life cycle primary energy demand for (a) component and (b) total vehicle scenarios. Credit: ACS; Kim and Wallington. Click to enlarge.|
While reducing vehicle weight (lightweighting) by replacing steel and iron with alternatives such as aluminum, magnesium, and composites decreases fuel consumption and greenhouse gas emissions during vehicle use, it can increase energy consumption and GHG emissions during vehicle production.
Hyung Chul Kim and Timothy J. Wallington at Ford Motor’s Systems Analytics and Environmental Sciences Department set out to clarify the lifecycle benefits of vehicle lightweighting in a meta-analysis of previously published life cycle assessments (LCAs). While numerous studies assay the benefits of lightweighting, the wide variety of assumptions used makes it difficult to compare results from the studies, the pair noted in their paper, published in the ACS journal Environmental Science & Technology.
New open-source lifecycle analysis tool for oil production using field characteristics
May 25, 2013
|Schematic chart showing included stages within OPGEE. El Houjeiri et al., Supplemental Information. Click to enlarge.|
A team from Stanford University and the California Air Resources Board (ARB) has developed a new open-source lifecycle analysis (LCA) tool for modeling the greenhouse gas emissions of oil and gas production using characteristics of specific fields and associated production pathways. The team describes the Oil Production Greenhouse Gas Emissions Estimator (OPGEE) in a paper in the ACS journal Environmental Science & Technology.
Existing transportation fuel cycle emissions models are either broad—i.e., lacking process-level detail for any particular fuel pathway—and calculate nonspecific values of greenhouse gas (GHG) emissions from crude oil production, or are not available for public review and auditing, the authors note.
Researchers propose evaluating alt fuel efficiency based on energy rather than volume; impact of ethanol on vehicle efficiency and GHGs
May 17, 2013
|Relative changes in vehicle energy efficiency (VEE) (km/MJ) on ethanol/gasoline blends over those on gasoline for different blending levels. Credit: ACS, Yan et al. Click to enlarge.|
In a policy analysis in the ACS journal Environmental Science & Technology, researchers from the Universities of Cambridge, Exeter and Oxford argue that, due to the increased emphasis on alternative fuels with drastically differing energy densities, vehicle efficiency should be evaluated based on energy rather than volume.
With that as a premise, they go on to show that the efficiency of existing vehicles can be both positively and negatively affected by ethanol content, ranging from −15% to +24%. As a result, they conclude, uncertainties in the net greenhouse gas (GHG) effect of ethanol, particularly when used in a low-level blend with gasoline, are considerably larger than previously estimated. Standard deviations increase by >10% and >200% when used in high and low blends, respectively.
Study finds large-scale ramp-up in biofuel crops could result in warming in some tropical regions, cooling in temperate and polar regions
May 08, 2013
Global land-use changes caused by a major ramp-up in biofuel crops—enough to meet about 10% of the world’s energy needs—could make some regions warmer, according to a new integrated modeling study by researchers from MIT and the Marine Biological Laboratory, Woods Hole.
Using an integrated assessment model that links an economic model with climate, terrestrial biogeochemistry, and biogeophysics models, the team examined the biogeochemical and biogeophysical effects of possible land use changes from an expanded global second-generation bioenergy program on surface temperatures over the first half of the 21st century.
NTNU study finds ships’ and spare parts’ contribution to offshore wind power lifecycle impacts has been underestimated
March 04, 2013
A new analysis by researchers at the Norwegian University of Science and Technology (NTNU) suggests that, notwithstanding significant uncertainties, previous studies have underestimated the contributions from installation and use phases—e.g., “ships and spare parts”—to the total life cycle impacts of offshore wind power. Their analysis is published in the ACS journal Environmental Science & Technology.
In the study, they developed and assessed life cycle inventories of a the proposed Havsul I offshore wind farm in Norway using a hybrid life cycle assessment (LCA) methodology. The study put special emphasis on aspects of installation, operation, and maintenance, as these stages have been given only cursory consideration in previous LCAs, they noted.
State Department issues Draft Supplemental Environmental Impact Statement on Keystone XL Pipeline: climate change impacts
March 02, 2013
|Comparison of proposed Keystone XL route to previously proposed project segment. Source: Draft SEIS. Click to enlarge.|
The US Department of State (DOS) has released its Draft Supplemental Environmental Impact Statement (SEIS) in response to TransCanada’s May 2012 application for the Keystone XL pipeline that would run from Canada’s oils sands in Alberta to Nebraska. The document is a detailed draft technical review of potential environmental impacts associated with the segment of the pipeline in the US, including: impacts from construction, impacts from potential spills, impacts related to climate change, and economic impacts.
Aside from the potential construction and spill impacts of the pipeline, the scope of the climate change impacts have become the most contentious and politicized issue surrounding the pipeline. The DOS SEIS accordingly takes a detailed look at life-cycle greenhouse gas emissions of petroleum products from Western Canadian Sedimentary Basin (WCSB) oil sands crudes compared with reference crudes and the potential impact the pipeline might have on climate change as well as on the future development of the oils sands resource in Canada.
DeCicco: Transportation GHG reduction policy should focus upstream on fuel supply rather than downstream on choice of fuels in vehicles
January 25, 2013
In a new working paper, Prof. John DeCicco at the University of Michigan argues that to reduce transportation sector greenhouse gas emissions, the proper policy focus should be upstream in sectors that provide the fuel, rather than downstream on the choice of fuels in the automobile.
More specifically, he suggests that other than supporting fundamental R&D, programs to promote alternative fuel vehicles (AFVs) “are not currently warranted for climate protection. In addition to managing travel demand and improving vehicle efficiency, the implied climate policy priority is limiting net GHG emissions in fuel supply sectors.” The paper is available from the Social Science Research Network (SSRN).
New Argonne lifecycle analysis of bioethanol pathways finds corn ethanol can reduce GHG emissions relative to gasoline by 19-48%; long-term, cellulosic offers the most benefits
January 22, 2013
|Well-to-wheels results for greenhouse gas emissions in CO2e for six pathways. Source: Wang et al. Click to enlarge.|
A new lifecycle analysis of five bioethanol production pathways by a team from Argonne National Laboratory led by Dr. Michael Wang found that, relative to petroleum gasoline, ethanol from corn; sugarcane; corn stover; switchgrass; and miscanthus can reduce lifecycle greenhouse gas (GHG) emissions [P10-P90 (P50)] by 19–48% (34%); 40–62% (51%); 90–103% (96%); 77–97% (88%); and 101–115% (108%), respectively when including land use change emissions. They researchers reported similar trends with regard to fossil energy benefits for the five bioethanol pathways. An open access paper on the study in published in the journal Environmental Research Letters.
While the results for cellulosic ethanol (stover, switchgrass and miscanthus) are in line with recent studies, and the findings for sugarcane ethanol are only slightly lower than other similar studies, the results for corn ethanol are in sharp contrast to other studies predicting that corn ethanol would have a greater life-cycle GHG impact than gasoline, the authors noted.
Tsinghua University provincial-level lifecycle study finds fuel-cycle criteria pollutants of EVs in China could be up to 5x those of natural gas vehicles due to China’s coal-dominant power mix
January 12, 2013
|Consumption-based power mixes and NG transmission distances by Chinese province in 2010. Credit: ACS, Huo et al. Click to enlarge.|
A province-by-province life cycle analysis of natural gas and electric vehicles by a team from Tsinghua University concludes that while, from the perspective of reducing greenhouse gas (GHG) and criteria pollutant emissions, natural gas vehicles (CNGVs) are “an option with no obvious merits or demerits”, electric vehicles (EVs) are “an option with significant merits and demerits in this regard” due to China’s heavily coal-based electricity generation (national average of about 77%).
In regions where the share of coal-based electricity is relatively low, EVs can achieve substantial GHG reduction, the team reports in a paper in the ACS journal Environmental Science & Technology. However, the fuel-cycle PM10, PM2.5, SO2, and NOx emissions of EVs could be up to five times higher than those of ICEVs (internal combustion engine vehicles) and CNGVs. While the increases in PM10 and PM2.5 emissions are less important because of the low contribution of light duty vehicles to national PM10 and PM2.5 emissions, the NOx and SO2 increases are significant enough to notably change total national emissions, they conclude.
Spatially explicit life cycle assessment of 5 sun-to-wheels pathways finds photovoltaic electricity and BEVs offer land-efficient and low-carbon transportation
January 04, 2013
A new spatially-explicit life cycle assessment of five different “sun-to-wheels” conversion pathways—ethanol from corn or switchgrass for internal combustion vehicles (ICVs); electricity from corn or switchgrass for battery-electric vehicles (BEVs); and photovoltaic electricity for BEVs—found a strong case for PV BEVs.
According to the findings by the team from the University of California, Santa Barbara and the Norwegian University of Science and Technology, published in the ACS journal Environmental Science & Technology, even the most land-use efficient biomass-based pathway (i.e., switchgrass bioelectricity in US counties with hypothetical crop yields of more than 24 tonnes/ha) requires 29 times more land than the PV-based alternative in the same locations.
Cornell team quantifies uncertainty in life cycle assessments of algae biofuel production; suggests reporting results as ranges of expected values
January 01, 2013
A Cornell University team has used a Monte Carlo approach to quantify the role of uncertainty associated with process parameters in life cycle analysis (LCA) of algae-to-biofuel schemes for determining metrics such as Energy Return on (Energy) Invested (EROI) and global warming potential global warming potential (GWP). The results, reported in a paper in the ACS journal Environmental Science & Technology, show that uncertainties exist at all stages of biofuel production from microalgae, from cultivation to dewatering to conversion processes and production of coproducts.
This indicates, the researchers suggest, that the values reported in earlier studies are not incorrect, but, rather each represent a specific case. These cases should not be used solely to conclude whether algal biofuels are expected to be energetically viable or environmentally sustainable, the authors say. Instead, LCA results, especially those associated with developing technologies such as algal biofuel, should be reported as ranges of expected values to provide decision makers with reliable results, they conclude.
New petroleum refining lifecycle model finds the variability in GHG emissions from refining different crudes as significant as magnitude expected in upstream operations
December 09, 2012
|Comparison of GHGenius, JACOBS, TIAX, and the new PRELIM gasoline greenhouse gas (GHG) estimates using base case estimates and variations from the scenario analysis. Credit: ACS, Abella and Bergerson. Click to enlarge.|
Researchers at the University of Calgary (Canada) have developed the Petroleum Refinery Life-cycle Inventory Model (PRELIM). PRELIM uses a more comprehensive range of crude oil quality and refinery configurations than used in earlier models and can quantify energy use and greenhouse gas (GHG) emissions with detail and transparency the better to inform policy analysis, the duo suggests.
Using a scenario analysis to explore the implications of processing crudes of different qualities in different refinery configurations, and with a focus on oil sands products, they found differences of up to 14 g CO2eq/MJ of crude, or up to 11 g CO2eq/MJ of gasoline and 19 g CO2eq/MJ of diesel (the margin of deviation in the emissions estimates is roughly 10%). Put another way, “the variability in GHG emissions in the refining stage that results from processing crudes of different qualities is as significant as the magnitude expected in upstream operations”, they found.
Report from Victoria EV Trial reinforces importance of source of electricity and EV efficiency in reducing greenhouse gas emissions
December 07, 2012
The Victoria (Australia) EV Trial—a major 5-year initiative (earlier post)—has released a comparative lifecycle assessment of the environmental impacts of electric vehicles relative to conventional gasoline vehicles in Victoria from now until 2030.
The lifecycle analysis, “Environmental Impacts of Electric Vehicles in Victoria”, found that the impacts from vehicle operation far outweigh those from vehicle production—true even if allowing for an EV battery replacement over the vehicle life. Vehicle disposal impacts, including those of the EV battery, were found to be negligible due to the expected high rate of material recycling. The dominant influence of vehicle operation during the EV lifecycle thus highlights the importance of the source of electricity, how efficient the energy conversion in the vehicle is, and the way a vehicle is used, the report found.