Conventional Technologies to Reduce Vehicle Greenhouse Gases
Cars, SUVs, and other internal combustion vehicles are a major cause of global warming pollution. Approximately 40% of carbon dioxide (CO2) emissions in California derive from the combustion of gasoline in cars, SUVs and other passenger vehicles.1 These vehicles are also responsible for about 25% of nitrous oxide emissions (N2O) and about 10% of methane (CH4) emissions, both potent greenhouse gases.2 In addition, vehicle air conditioners leak hydrofluorocarbon-134a (HFC-134a), a greenhouse gas (GHG) that is 1300 times as potent as CO2. The buildup of heat-trapping gases such as plays a significant role in global warming.
However, many vehicle technologies are commercially available today to reduce greenhouse gas (GHG) emissions. Most of the technologies discussed below are already in use on some mass-market vehicles, or are proven technologies ready to be utilized in new car models, often at little or no additional cost.
Engine Modifications
- Engine modifications can reduce GHG emissions through three effects: reduction of pumping losses, reduction in engine friction, and/or improved combustion.
- Variable Valve Timing (VVT) or Variable Valve Lift and Timing (VVLT). By providing a better fuel/air mix and improved combustion, these technologies reduce CO2 emissions.
- Cylinder Deactivation. Also known as “displacement on demand,” this technology shuts down one or more cylinders when the extra power is not needed. This is particularly applicable to larger vehicles with V-6 and V-8 engines.
- Engine Downsizing Combined with Turbocharger or Supercharger. This approach can lead to reduced CO2 emissions with no loss of engine power or performance.
- Some engine technologies on the horizon that could result in GHG emission reductions include: stoichiometric burn direct injection, variable compression ratio engines, and homogeneous charge compression ignition engines.
Improved Transmissions
- New transmission technologies can reduce greenhouse gas emissions by enabling the engine to operate close to (or near) its optimal speed more frequently.
- Five- or six-speed automatic transmissions accomplish this goal when used instead of the four-speed automatic transmission standard on most new cars today.
- Continuously variable transmissions (CVT) take this goal to its full realization by allowing an infinite number of speeds within an automatic transmission.
- Automatic shift manual transmissions can reduce GHG emission by reducing the mechanical losses associated with transmission operation.
Additional Vehicle Technologies
Aerodynamic drag can be reduced through sleeker design.
- Integrated Starter Generators or Belt-driven Starter Generators allow a vehicle to turn off at idle and then quickly restart, thereby eliminating emissions while stopped.
- The use of a 42 Volt Electrical System can reduce the engine load created by vehicle systems or accessories such as power-steering pumps, air conditioners, or lubrication systems.
- Improvements in catalyst technology can reduce N2O and CH4 emissions.
- The use of alternative refrigerants. Leaks of HFC-134a, a refrigerant, from vehicle air conditioners, while small in magnitude, accounts for approximately 2% of the CO2-equivalent GHG emissions released each mile. In part this is because HFC-134a is 1300 times more potent as a GHG than CO2. Research is ongoing into the use of alternative refrigerants. In the meantime, HFC-134a leakage could be greatly reduced by improving air conditioning system seals and hoses, and by recovering HFC-134a from air conditioner units when vehicles are scrapped.
- Low Rolling Resistance Tires. The use of low rolling resistance tires reduces friction between the vehicle and the road, and can result in a 3% reduction in greenhouse gas emissions.
Global warming pollution-reducing technologies currently in use
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Engine Technologies |
Vehicle models |
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VTEC |
Most Honda vehicles |
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Variable valve timing |
Most Toyota vehicles, Ford F-150 |
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Cylinder deactivation |
Honda Accord (V6), |
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Throttleless engine |
BMW 3 series |
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Transmissions technologies |
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Continuously variable transmission |
Nissan Murano, Mini Cooper, Saturn Ion, |
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Six speed automatic transmissions |
Jaguar S-Type and XK series |
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Dual clutch transmission |
Audi TT 3.2 quattro |
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Hybrid Electric Vehicles |
Honda Civic, Honda Insight, |
