Reducing the Fuel Consumption and Greenhouse Gas Emissions of Medium- and Heavy-Duty Vehicles, Phase Two First Report (2014) / Chapter Skim
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5 Natural Gas Vehicles: Impacts and Regulatory Framework(
5 Natural Gas Vehicles: Impacts and Regulatory Framework(
Pages 52-66
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From page 52... ...
emissions of the low price of NG, which is used as both a fuel and a (primarily carbon dioxide, or CO2) and fuel economy stan- feedstock for petrochemicals.
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Updated: May 9, 2011 FIGURE 5-1 Shale gas plays in the continental United States. SOURCE: Energy Information Administration (EIA)
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From page 54... ...
One analysis exports, and higher prices, as shown in Table 5-1. concluded that after taking into account current estimates of leakage, converting heavy-duty diesel trucks would have a net negative effect on climate change for centuries.4 One NATURAL GAS ENGINES AND VEHICLES estimate of gas leakage, based on measurements at 190 onshore gas production sites, is 0.42 percent of the total Technology gas production (Allen et al., 2013)
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From page 55... ...
; or it can supply all the energy to a high-pressure natural gas fuel, the most significant differences from cur- direct-injection (HPDI) CI engine, in which a small amount rent vehicles are the onboard fuel storage method and, for of diesel fuel is needed to achieve ignition.
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From page 56... ...
to achieve the durability and reliability expected for trucking applications. For example the Fuel Consumption and GHG Comparisons of Natural Gas Cummins-Westport engine has over 80 percent of its parts and Diesel Engines in common with the base diesel-fueled engine (ISX12)
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From page 57... ...
0.75 1.1 1.1 1.5 1.8 2 2.1 Combustion System SI-stoic SI-stoic SI SI-stoic SI-stoic SI-stoic CI Compression Ratio >10.5 12.1 15.6 Electronic Electronic Electronic Electronic Electronic LNG-diesel dual Fuel System Description Port injection throttle body throttle body throttle body throttle body throttle body fuel injectors; mixing mixing mixing injection mixing diesel pilot Air Handling System naturally WG-Turbo; CAC Turbocharged WG-Turbo; CAC Turbocharged, WG-Turbo; CAC VGT; CAC Description aspirated CAC EGR (Y/N) N Y-HPL N Y-HPL Y-LPL Y-HPL Y Aftertreatment Descrptn: TWC TWC TWC TWC TWC DOC,DPF & SCR 2010 Criteria Emissions Rated RPM 5000 2600 3400 2200 2200 2100 1700 Rated kW/L 28.1 36.1 22.7 26.9 22.9 25 27.9 Rated kW(HP)
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From page 58... ...
Rollovers are the most frequent source of fatalities NG tanks available for the heavy truck market, the crash for both vehicle types, but that is likely to be true no matter characteristics, and associated risks, a review of technical which fuel is used. Heavy trucks are 30 to 40 times heavier standards and safety-related issues appears to be warranted, than passenger vehicles.
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From page 59... ...
Higher carbon content hydrocarbons in LNG tanks can lead to fluid Base Engine Aftertreatment stratification, and the composition of CNG tanks can affect Improved air handling Improved three-way catalyst autoignition, combustion behavior, and engine power den- High-efficiency turbo Better methane oxidation Low pressure loss EGR Increased oxygen storage sity. The Engine Manufacturers Association recommends Low restriction ports a minimum methane number of 80 for CNG, a maximum Improved controls inert content of 4 percent, and a 16,200 BTU/lb minimum Higher energy ignition Advanced air/fuel ratio dithering energy content, in addition to limits on contaminants such strategies as water and sulfur compounds, among others (EMA, 2010)
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From page 60... ...
, increasing fewer stations will be needed for servicing trucks. its volumetric energy density about 600-fold and allowing There are two basic types of CNG fueling systems: fast- it to be stored at relatively low pressure in highly insulated fill and time-fill, shown in Figure 5-6 (AFDC, undated)
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In a in the heart of one of the large shale gas plays. CI engine its performance is similar to that of diesel fuel.
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From page 62... ...
study produced GHG emissions than direct combustion of NG in engines a longer-term projection to 2050 (Figure 5-10) , which estidue to the inherently high efficiency of battery electric and mated that about 40 percent of Class 7 and Class 8 vehicles fuel cell vehicles.
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From page 63... ...
Greenhouse Gas Emission and Fuel Economy Standards for Engines In August 2011 the federal government adopted CO2 and fuel economy standards for new medium- and heavy-duty trucks and engines. The CO2 emission standards for new engines vary by engine type and duty cycle.
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From page 64... ...
The flexibility of using CO2 reduction to offset methane emissions that are NG engines have to meet the same emission standards as higher than the standard, as discussed in the section on GHG gasoline- or diesel-fueled engines. NG engines are classified emissions and fuel economy standards for engines, suggests for criteria emissions based on the combustion cycle of the the methane standard will not be a barrier to compliance for engine the NG engine is derived from.
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From page 65... ...
This issue should be monitored same CO2 levels for trucks using either diesel or NG, then to determine if the availability of NG engines derived from it is conceivable a NG truck could meet the standards with gasoline engines will be impacted, and if this has an effect fewer advanced fuel economy technologies than a diesel on achieving the maximum feasible reduction in fuel use and counterpart. In contrast, a NG leakage correction to GHG GHG emissions.
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From page 66... ...
2010. Issues Affecting Lubricants, and Aftertreatment Symposium: Achieving Fuel Economy Adoption of Natural Gas Fuel in Light- and Heavy-Duty Vehicles.
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