12 research outputs found
Life Cycle Assessment of Vehicle Lightweighting: A Physics-Based Model To Estimate Use-Phase Fuel Consumption of Electrified Vehicles
Assessing the life-cycle benefits of vehicle lightweighting requires
a quantitative description of mass-induced fuel consumption (MIF)
and fuel reduction values (FRVs). We have extended our physics-based
model of MIF and FRVs for internal combustion engine vehicles (ICEVs)
to electrified vehicles (EVs) including hybrid electric vehicles (HEVs),
plug-in hybrid electric vehicles (PHEVs), and battery electric vehicles
(BEVs). We illustrate the utility of the model by calculating MIFs
and FRVs for 37 EVs and 13 ICEVs. BEVs have much smaller MIF and FRVs,
both in the range 0.04â0.07 L<sub>e</sub>/(100 km 100 kg),
than those for ICEVs which are in the ranges 0.19â0.32 and
0.16â0.22 L/(100 km 100 kg), respectively. The MIF and FRVs
for HEVs and PHEVs mostly lie between those for ICEVs and BEVs. Powertrain
resizing increases the FRVs for ICEVs, HEVs and PHEVs. Lightweighting
EVs is less effective in reducing greenhouse gas emissions than lightweighting
ICEVs, however the benefits differ substantially for different vehicle
models. The physics-based approach outlined here enables model specific
assessments for ICEVs, HEVs, PHEVs, and BEVs required to determine
the optimal strategy for maximizing the life-cycle benefits of lightweighting
the light-duty vehicle fleet
Life Cycle Assessment of Vehicle Lightweighting: A Physics-Based Model of Mass-Induced Fuel Consumption
Lightweighting is
a key strategy used to improve vehicle fuel economy.
Replacing conventional materials (e.g., steel) with lighter alternatives
(e.g., aluminum, magnesium, and composites) decreases energy consumption
and greenhouse gas (GHG) emissions during vehicle use, but often increases
energy consumption and GHG emissions during materials and vehicle
production. Assessing the life-cycle benefits of mass reduction requires
a quantitative description of the mass-induced fuel consumption during
vehicle use. A new physics-based method for estimating mass-induced
fuel consumption (MIF) is proposed. We illustrate the utility of this
method by using publicly available data to calculate MIF values in
the range of 0.2â0.5 L/(100 km 100 kg) based on 106 records
of fuel economy tests by the U.S. Environmental Protection Agency
for 2013 model year vehicles. Lightweighting is shown to have the
most benefit when applied to vehicles with high fuel consumption and
high power. Use of the physics-based model presented here would place
future life cycle assessment studies of vehicle lightweighting on
a firmer scientific foundation
Strategic Materials in the Automobile: A Comprehensive Assessment of Strategic and Minor Metals Use in Passenger Cars and Light Trucks
A comprehensive component-level assessment
of several strategic
and minor metals (SaMMs), including copper, manganese, magnesium,
nickel, tin, niobium, light rare earth elements (LREEs; lanthanum,
cerium, praseodymium, neodymium, promethium, and samarium), cobalt,
silver, tungsten, heavy rare earth elements (yttrium, europium, gadolinium,
terbium, dysprosium, holmium, erbium, thulium, ytterbium, and lutetium),
and gold, use in the 2013 model year Ford Fiesta, Focus, Fusion, and
F-150 is presented. Representative material contents in cars and light-duty
trucks are estimated using comprehensive, component-level data reported
by suppliers. Statistical methods are used to accommodate possible
errors within the database and provide estimate bounds. Results indicate
that there is a high degree of variability in SaMM use and that SaMMs
are concentrated in electrical, drivetrain, and suspension subsystems.
Results suggest that trucks contain greater amounts of aluminum, nickel,
niobium, and silver and significantly greater amounts of magnesium,
manganese, gold, and LREEs. We find tin and tungsten use in automobiles
to be 3â5 times higher than reported by previous studies which
have focused on automotive electronics. Automotive use of strategic
and minor metals is substantial, with 2013 vehicle production in the
United States, Canada, EU15, and Japan alone accounting for approximately
20% of global production of Mg and Ta and approximately 5% of Al,
Cu, and Sn. The data and analysis provide researchers, recyclers,
and decision-makers additional insight into the vehicle content of
strategic and minor metals of current interest
Smoke Point Measurements of Diesel-Range HydrocarbonâOxygenate Blends Using a Novel Approach for Fuel Blend Selection
The
use of oxygenated fuels decreases particulate matter (PM) emissions
from diesel engines. Studies using engines, experimental flames, and
modeling have shown that the decrease in soot emissions depends on
the oxygenate molecular structure. To provide a better understanding
of the complex processes occurring in engines leading to PM emissions,
fundamental and systematic studies of the sooting tendency trends
for diesel-range hydrocarbonâoxygenate blends are needed. We
present a new approach to selecting fuel blends for sooting tendency
measurements that minimizes the confounding effect of dilution of
highly sooting components in the base fuel by maintaining constant
concentrations of those components in the blends. This novel approach
is illustrated by sooting tendency (smoke point) measurements in a
diffusion flame for a variety of diesel-range hydrocarbonâoxygenate
blends with different molecular structures. The oxygenates included
primary alcohols (1-butanol, 1-undecanol), diesters (dibutyl succinate,
dibutyl maleate), esters (methyl decanoate and methyl oleate), and
a glycol triether (triÂ(propylene glycol) methyl ether). The hydrocarbons
included an aromatic (1,2,4-trimethylbenzene), a straight-chain alkane
(<i>n</i>-hexadecane), and a highly branched alkane (2,2,4,4,6,8,8-heptamethylnonane).
The fuels were investigated as three-component blends, with an oxygenate
in a hydrocarbon base fuel consisting of a highly sooting hydrocarbon
component (1,2,4-trimethylbenzene) and a low-sooting hydrocarbon (<i>n</i>-hexadecane). The oxygen-extended sooting index (OESI)
provided sooting tendency trends that were generally consistent with
expectations for both hydrocarbon-only and oxygenated fuels. The dominant
chemical structure factors influencing the sooting tendency of the
hydrocarbons were aromaticity and branching. For the oxygenates, the
primary alcohols, the saturated monoester, and the glycol triether
exhibited the lowest sooting tendency, followed by the shorter-chain
diesters, and then the unsaturated monoester, with unsaturation increasing
the sooting tendency
Atmospheric Chemistry of (CF<sub>3</sub>)<sub>2</sub>CHOCH<sub>3</sub>, (CF<sub>3</sub>)<sub>2</sub>CHOCHO, and CF<sub>3</sub>C(O)OCH<sub>3</sub>
Smog
chambers with in situ FTIR detection were used to measure rate coefficients
in 700 Torr of air and 296 ± 2 K of: <i>k</i>(Cl+(CF<sub>3</sub>)<sub>2</sub>CHOCH<sub>3</sub>) = (5.41 ± 1.63) Ă
10<sup>â12</sup>, <i>k</i>(Cl+(CF<sub>3</sub>)<sub>2</sub>CHOCHO) = (9.44 ± 1.81) Ă 10<sup>â15</sup>, <i>k</i>(Cl+CF<sub>3</sub>CÂ(O)ÂOCH<sub>3</sub>) = (6.28
± 0.98) Ă 10<sup>â14</sup>, <i>k</i>(OH+(CF<sub>3</sub>)<sub>2</sub>CHOCH<sub>3</sub>) = (1.86 ± 0.41) Ă
10<sup>â13</sup>, and <i>k</i>(OH+(CF<sub>3</sub>)<sub>2</sub>CHOCHO) = (2.08 ± 0.63) Ă 10<sup>â14</sup> cm<sup>3</sup> molecule<sup>â1</sup> s<sup>â1</sup>. The Cl atom initiated oxidation of (CF<sub>3</sub>)<sub>2</sub>CHOCH<sub>3</sub> gives (CF<sub>3</sub>)<sub>2</sub>CHOCHO in a yield
indistinguishable from 100%. The OH radical initiated oxidation of
(CF<sub>3</sub>)<sub>2</sub>CHOCH<sub>3</sub> gives the following
products (molar yields): (CF<sub>3</sub>)<sub>2</sub>CHOCHO (76 ±
8)%, CF<sub>3</sub>CÂ(O)ÂOCH<sub>3</sub> (16 ± 2)%, CF<sub>3</sub>CÂ(O)ÂCF<sub>3</sub> (4 ± 1)%, and CÂ(O)ÂF<sub>2</sub> (45 ±
5)%. The primary oxidation product (CF<sub>3</sub>)<sub>2</sub>CHOCHO
reacts with Cl atoms to give secondary products (molar yields): CF<sub>3</sub>CÂ(O)ÂCF<sub>3</sub> (67 ± 7)%, CF<sub>3</sub>CÂ(O)ÂOCHO
(28 ± 3)%, and CÂ(O)ÂF<sub>2</sub> (118 ± 12)%. CF<sub>3</sub>CÂ(O)ÂOCH<sub>3</sub> reacts with Cl atoms to give: CF<sub>3</sub>CÂ(O)ÂOCHO
(80 ± 8)% and CÂ(O)ÂF<sub>2</sub> (6 ± 1)%. Atmospheric lifetimes
of (CF<sub>3</sub>)<sub>2</sub>CHOCH<sub>3</sub>, (CF<sub>3</sub>)<sub>2</sub>CHOCHO, and CF<sub>3</sub>CÂ(O)ÂOCH<sub>3</sub> were estimated
to be 62 days, 1.5 years, and 220 days, respectively. The 100-year
global warming potentials (GWPs) for (CF<sub>3</sub>)<sub>2</sub>CHOCH<sub>3</sub>, (CF<sub>3</sub>)<sub>2</sub>CHOCHO, and CF<sub>3</sub>CÂ(O)ÂOCH<sub>3</sub> are estimated to be 6, 121, and 46, respectively. A comprehensive
description of the atmospheric fate of (CF<sub>3</sub>)<sub>2</sub>CHOCH<sub>3</sub> is presented
Oxidation and Polymerization of Soybean Biodiesel/Petroleum Diesel Blends
Fuels
in modern diesel engine fuel systems are exposed to highly
oxidizing conditions, thus it is important to understand their degradation
mechanisms. A range of chemical and physical properties was monitored
during the oxidation and polymerization of soybean methyl ester biodiesel
(B100), a diesel fuel (B0), and their blends (B10, B30) at 90 °C
with aeration. The initial rapid oxidation of polyunsaturated fatty
acid methyl esters (FAMEs) provided a transient pool of peroxides
that led to the formation of aldehydes, ketones, and acids as secondary
products. Monounsaturated and saturated FAMEs were oxidized concurrently
with polyunsaturated FAMEs in B10, B30, and B100, but only B100 showed
significant oxidation reactions continuing after the polyunsaturated
FAMEs were depleted. New esters were a major oxidation product, eventually
comprising 40â60% of the incorporated oxygen. Carboxylic acids
and alcohols react to form esters and water, with vaporization of
water driving the equilibrium toward ester formation. Polymers with
ester linkages are likely contributors to the higher molecular weight
materials formed and resulting increase in viscosity under these conditions
Review of the Fuel Saving, Life Cycle GHG Emission, and Ownership Cost Impacts of Lightweighting Vehicles with Different Powertrains
The
literature analyzing the fuel saving, life cycle greenhouse
gas (GHG) emission, and ownership cost impacts of lightweighting vehicles
with different powertrains is reviewed. Vehicles with lower powertrain
efficiencies have higher fuel consumption. Thus, fuel savings from
lightweighting internal combustion engine vehicles can be higher than
those of hybrid electric and battery electric vehicles. However, the
impact of fuel savings on life cycle costs and GHG emissions depends
on fuel prices, fuel carbon intensities and fuel storage requirements.
Battery electric vehicle fuel savings enable reduction of battery
size without sacrificing driving range. This reduces the battery production
cost and mass, the latter results in further fuel savings. The carbon
intensity of electricity varies widely and is a major source of uncertainty
when evaluating the benefits of fuel savings. Hybrid electric vehicles
use gasoline more efficiently than internal combustion engine vehicles
and do not require large plug-in batteries. Therefore, the benefits
of lightweighting depend on the vehicle powertrain. We discuss the
value proposition of the use of lightweight materials and alternative
powertrains. Future assessments of the benefits of vehicle lightweighting
should capture the unique characteristics of emerging vehicle powertrains
Atmospheric Chemistry of Benzyl Alcohol: Kinetics and Mechanism of Reaction with OH Radicals
The atmospheric oxidation
of benzyl alcohol has been investigated
using smog chambers at ICARE, FORD, and EUPHORE. The rate coefficient
for reaction with OH radicals was measured and an upper limit for
the reaction with ozone was established; <i>k</i><sub>OH</sub> = (2.8 ± 0.4) Ă 10<sup>â11</sup> at 297 ±
3 K (averaged value including results from Harrison and Wells) and <i>k</i><sub>O<sub>3</sub></sub> < 2 Ă 10<sup>â19</sup> cm<sup>3</sup> molecule<sup>â1</sup> s<sup>â1</sup> at 299 K. The products of the OH radical initiated oxidation of
benzyl alcohol in the presence of NO<sub>X</sub> were studied. Benzaldehyde,
originating from H-abstraction from the âCH<sub>2</sub>OH group,
was identified using in situ FTIR spectroscopy, HPLC-UV/FID, and GC-PID
and quantified in a yield of (24 ± 5) %. Ring retaining products
originating from OH-addition to the aromatic ring such as <i>o</i>-hydroxybenzylalcohol and <i>o</i>-dihydroxybenzene
as well as ring-cleavage products such as glyoxal were also identified
and quantified with molar yields of (22 ± 2)%, (10 ± 3)%,
and (2.7 ± 0.7)%, respectively. Formaldehyde was observed with
a molar yield of (27 ± 10)%. The results are discussed with respect
to previous studies and the atmospheric oxidation mechanism of benzyl
alcohol
Atmospheric Chemistry of Benzyl Alcohol: Kinetics and Mechanism of Reaction with OH Radicals
The atmospheric oxidation
of benzyl alcohol has been investigated
using smog chambers at ICARE, FORD, and EUPHORE. The rate coefficient
for reaction with OH radicals was measured and an upper limit for
the reaction with ozone was established; <i>k</i><sub>OH</sub> = (2.8 ± 0.4) Ă 10<sup>â11</sup> at 297 ±
3 K (averaged value including results from Harrison and Wells) and <i>k</i><sub>O<sub>3</sub></sub> < 2 Ă 10<sup>â19</sup> cm<sup>3</sup> molecule<sup>â1</sup> s<sup>â1</sup> at 299 K. The products of the OH radical initiated oxidation of
benzyl alcohol in the presence of NO<sub>X</sub> were studied. Benzaldehyde,
originating from H-abstraction from the âCH<sub>2</sub>OH group,
was identified using in situ FTIR spectroscopy, HPLC-UV/FID, and GC-PID
and quantified in a yield of (24 ± 5) %. Ring retaining products
originating from OH-addition to the aromatic ring such as <i>o</i>-hydroxybenzylalcohol and <i>o</i>-dihydroxybenzene
as well as ring-cleavage products such as glyoxal were also identified
and quantified with molar yields of (22 ± 2)%, (10 ± 3)%,
and (2.7 ± 0.7)%, respectively. Formaldehyde was observed with
a molar yield of (27 ± 10)%. The results are discussed with respect
to previous studies and the atmospheric oxidation mechanism of benzyl
alcohol
Sustainable Mobility, Future Fuels, and the Periodic Table
Providing sustainable mobility is a major challenge that
will require
new vehicle and fuel technologies. Alternative and future fuels are
the subject of considerable research and public interest. A simple
approach is presented that can be used in science education lectures
at the high school or undergraduate level to provide students with
an understanding of the elemental composition of future fuels. Starting
from key fuel requirements and overlaying the chemical trends evident
in the periodic table, it can be demonstrated that future chemical
fuels will be based on three elements: carbon, hydrogen, and oxygen.
Liquid hydrocarbons are the most convenient transportation fuels because
of their physical state (easier to handle than gases or solids) and
their high gravimetric and volumetric energy densities. Challenges
remain for storage of electricity and gaseous fuels. Recognizing the
need to address climate change driven by increasing emissions of CO<sub>2</sub>, sustainable mobility will be powered by low-CO<sub>2</sub> hydrogen, low-CO<sub>2</sub> hydrocarbons, low-CO<sub>2</sub> oxygenates,
low-CO<sub>2</sub> electricity, or a combination of the above