Transitions to Alternative Transportation Technologies A Focus on Hydrogen (2008) / Chapter Skim
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4 Alternative Technologies
4 Alternative Technologies
Pages 44-64
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From page 44... ...
That approach yielded briefly below. numerous important changes in major components, includ The ultimate goal of this chapter is to estimate the extent ing switching to unleaded fuel, addition of the catalytic to which continuing evolution of light-duty vehicle technolo converter, engine computer control, port fuel injection, the gies, increased use of improved hybrid electric vehicles, and four-speed automatic transmission with torque-converter the use of biofuels can reduce oil imports and greenhouse lock-up, and approximately 1,000 pounds of weight reducgas emissions through 2050.
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From page 45... ...
Since 1987, only a small fraction of these improvements These technologies continue to improve. have been directed to fuel economy, as shown in Figure 4.1 In 1997, the hybrid electric vehicle was introduced in (EPA, 2006)
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From page 46... ...
can also reduce fuel consumption under part-load vehicle operation. Efficiency is improved by having fewer cylinders Potential for Reducing Oil Use in working at higher load.
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From page 47... ...
Estimates of potential These engine efficiency gains can be translated into reduc- weight reductions range from 10 to 33 percent (Weiss et al., tions in fuel consumption and CO2 emissions.
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From page 48... ...
Vehicles Expected from Advances in Conventional Vehicle The Heywood fuel consumption improvements result Technology by Category, Projected to 2025 from changes in the engine and transmission and include 2006-2015 2016-2025 appropriate vehicle weight reductions as well. It is assumed that the improvements are entirely dedicated to reduced fuel Engine and transmission 12-16% 18-22% Weight, drag, and tire loss reduction 6-9% 10-13% consumption.
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From page 49... ...
Thus, the committee judges that evolutionary vehicle Hybrid Electric Vehicles technologies could, if focused on vehicle efficiency, reduce When HEVs were first developed, the technology was fuel consumption by 2.6 percent per year through 2025, 1.7 dedicated almost exclusively to improving fuel economy. percent per year in the 2025-2035 time frame, and 0.5 percent However, as with other power trains, as HEV technology per year between 2035 and 2050.
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From page 50... ...
reductions relative to conventional vehicles by 2009 and As indicated in Figure 4.3, analysis from MIT indicates future improvements in hybrid fuel economy will be due, that CO2 emissions and fuel consumption could be as much primarily, to the same technologies used to improve convenas 37 percent lower than those from a competitive 2030 tional vehicles. As a result this analysis assumes that hybrid spark-ignition gasoline vehicle (Kromer and Heywood, vehicles reduce fuel consumption by 2.6 percent per year 2007)
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From page 51... ...
It then reviews the production and CO2 emissions through improved fuel economy, but technology for those biofuels that are commercial or close policy measures and/or significant long-term increases to commercialization. It also briefly discusses biofuel techin fuel costs probably will be required to realize these nologies that have longer-term potential but are today in the potential fuel economy gains in a significant number of research stage.
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From page 52... ...
(2005) projected mill residues and 150 million dry tons per year of agricultural that today's technically available biomass amount could be crop residues.
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From page 53... ...
. Perennial energy increases by 50 percent to 225 million dry tons of total stover crop production is assumed on 60 million acres and woody produced, and when 75 percent of this is recovered, corn energy crop production is assumed on 5 million acres, with stover available for biofuel production is 170 million dry tons significant yield increases for each included.
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From page 54... ...
Most studies, including that of Perlack Beyond 2030, if the sustainable amount of biomass et al., estimate technically available biomass as a function obtainable from forest lands, estimated at 200 million dry of cost per tonne, typically to about or exceeding $100 per tons per year, is added to the estimated sustainable biomass dry tonne, and different biomass types have different cost available from agricultural lands (~500 million dry tons per profiles. At these prices, particularly by 2050, both algae year)
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Current experience is that the price of corn doubled when ~20 percent of the crop was directed Cellulosic Ethanol to ethanol production.
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From the total estimated currently available crop residue Further, the total residence time in the process is about twice of 160 million dry tons per year (see Table 4.3) , including as long as for grain ethanol production.
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The major issue is cost. The other option involves producing diesel fuel via biomass gasification, pyrolysis, or Fischer-Tropsch synthe sis.
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From page 58... ...
and European groups are developing to a mixture of carbon monoxide, hydrogen, carbon dioxide, advanced biomass gasification technologies, and there are methane, and other organics including bio-oils and tars, ash, about 10 different biomass gasifiers with a capacity greater and small char particles. The concentration of these gases and than 100 tonnes per day operating in the United States and other materials depends on the process design and operating worldwide.
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From page 59... ...
from Shell estimated the cost of other energy sources in megajoules of primary energy and Fischer-Tropsch diesel from biomass gasification to be about the estimated greenhouse gas emissions in kilograms CO2 $1.80 per gallon. Using a consistent basis for comparison, equivalent per megajoule of fuel for gasoline production rapeseed methyl ester biodiesel was estimated at about $4.50 and per megajoule of product energy for ethanol production, per gallon.
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From page 60... ...
TABLE 4.4 CO2 Emissions from Today's Conventional Production Potential of Biofuels Light-duty Gasoline and Diesel Engines in a Typical Production of ethanol from grain is fully commercial. FigFamily Sedan and from Fuels from Less Conventional ure 4.8 shows the corn-ethanol production capacity growth Sources from 1990 to 2007.
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From page 61... ...
The committee commercially ready and there are 335 million dry tons of expects the commercial and economic viability of cellulosic biomass available in the near term, increasing to 500 mil ethanol to remain a key issue for some time. lion dry tons available per year for conversion to biofuels by Cellulosic ethanol or other alternatives (e.g., biomass 2050.
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From page 62... ...
is the most logical case for comparison with the hydrogen Biobutanol is included in the scenario by assuming that it is cases. It also shows the maximum impact that biofuels can produced at 10 percent of the cellulosic ethanol production have on oil import reduction and on greenhouse gas emission level and is offset by 5 years.
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From page 63... ...
vide significant reductions in projected oil imports and Grain ethanol has a 20 to 25 percent energy gain over the CO2 emissions. However, the rate of growth of benefits fossil fuel inputs used for its production and, on average, from each of these two measures slows after two or three reduces CO2 emissions by 18 to 25 percent over the use decades, while the growth rate of projected benefits from of gasoline on an energy-equivalent basis.
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From page 64... ...
2006. Tires and Passenger Vehicle Fuel Economy.
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