GOING FARTHER ON A GALLON OF GASOLINE
Making our cars and trucks go farther on a gallon of gas is the biggest single step we can take to curb global warming, cut America’s oil addiction and save money at the gas pump.
By using existing technology, automakers can build all their vehicles—from sedans to pickups to SUVs—to get better fuel efficiency. We can drive a new fleet of fuel-efficient vehicles that are more advanced and safer.
Automakers boast that they have improved their energy efficiency. But most of these gains have gone to making cars bigger and more powerful. If all the efficiency improvements since 1988 had instead been directed at getting more miles per gallon, cars would have averaged 45mpg instead of 30.3 in 2008, Feng An and John DeCicco found in a study published by the Society of Automotive Engineers. Light trucks would have achieved an average of 31.0 rather than 22.5, they determined. Increasing fuel economy reduces global warming emissions from cars and trucks. Each gallon of gasoline burned creates 28 pounds of carbon dioxide, the main global warming pollutant. Nearly 20 pounds come directly from the tailpipe and eight additional pounds are emitted from extracting, transporting and refining oil. So, driving cars and light trucks that use less gasoline reduces the heat-trapping emissions. Using existing technology, we can reduce global warming emissions from American vehicles by more than 50 percent by 2025—and do so in a cost-effective way.
Improved fuel economy delivers real savings at the gas pump. Unfortunately, there are very few cures for rising gasoline prices – except to consume less gas. Better fuel economy means that you have to fill up less often. Taking advantage of current engineering, the average consumers could save more than $8,000 at the gas pump over the life of their vehicles, even after paying for the fuel-saving technology.
One key benefit: Cutting gasoline consumption reduces our nation’s dependence on oil. The United States consumes nearly 19 million barrels of oil each day. As a result, we send hundreds of billions of dollars to oil-producing countries each year to sustain our dangerous dependence on their oil. Oil drilling also despoils America’s landscape and coasts. Because most of this oil goes to fueling our cars and trucks, we can help break this dependence by boosting fuel economy. If we require all new vehicles to use the best existing technology, by 2020 we could save more oil than we currently import from the entire Persian Gulf.
FUEL-SAVING TECHNOLOGY IS READY FOR USE TODAY
Automakers have a wide range of existing technology that can improve the fuel economy of a conventional car or light truck. These include more-efficient engines, better aerodynamics and smarter transmissions, the mechanism that shifts gears.
Advanced Engine Design
Increasing the efficiency of a vehicle’s engine is one of the most effective methods to boosting fuel economy. Such technologies as variable valve control allow an engine to adjust the intake of oxygen into the cylinders to improve the efficiency of the engine at all speeds. Lean-burn technology, which introduces a higher ratio of air to fuel into the combustion chambers, also improves engine efficiency. Cylinder deactivation saves gas by shutting down unnecessary cylinders during the drive cycle when additional horsepower is not needed. This technology is particularly applicable in truck engines.
Smarter Transmissions: Better transmission design can also improve a vehicle’s fuel economy. A Continuously Variable Transmission (CVT) replaces individual gears with a continuous belt, providing an infinite number of gear ratios for the most efficient combination of engine speed and wheel speed. This can dramatically cut the gasoline consumption of a vehicle with an automatic transmission. Similarly, eight- and nine-speed automatic transmissions can improve efficiency over four- or five-speed transmissions.
Advanced Ignitions: In city driving, vehicles can burn as much as 15 percent of their gasoline sitting in traffic. Replacing conventional starter and alternator components with an Integrated Starter Generator (ISG) allows a gasoline engine to momentarily shut off when a vehicle is idling. The ISG restarts the motor instantaneously as the driver presses the accelerator. This is similar to moving a computer mouse to awaken a sleeping computer.
Aerodynamic Design: Improving the design of a vehicle to reduce wind resistance can achieve substantial fuel economy improvements. Installing low rolling resistance tires also cuts friction on the road, improving fuel economy and reducing emissions.
High-strength, Light-weight Materials: Substituting new high-strength, light-weight steel, aluminum and plastic compounds can help reduce weight while enhancing safety. These strong and light-weight materials save gas by reducing the amount of work the engine does to move the car or truck.
HYBRIDS: WAVE OF THE PRESENT
We can make substantial gains using conventional technology, but there are also new choices on the road that demonstrate the next stage of automotive technology. The most exciting of these are hybrid-electric vehicles. Hybrids combine the range and convenience of gasoline power with the low emissions and efficiency of an electric motor.
While there are different hybrid designs, all hybrid vehicles draw power from both sources—electricity and gas–to maximize fuel economy in different driving situations. When necessary, the gasoline engine is used to recharge the electric battery. At the same time, by using regenerative braking, hybrids capture energy normally lost during braking. A hybrid-electric Toyota Prius releases less than half the global warming pollution of a conventional sedan, due to its impressive fuel economy. Even though hybrids cost more up front, their drivers save money by buying less gas. By 2013, Toyota had sold more than 5 million Prius cars.
Plug-In Hybrids Are on the Road Today: These vehicles utilize larger electric battery packs to expand the all-electric range of a hybrid vehicle. They can be plugged into electric outlets to recharge. Unlike conventional hybrids, plug-in hybrids can run long distances at moderate speeds on just the electric motor. This can dramatically boost the vehicle’s fuel economy.
Plug-in vehicles have tremendous potential, but currently their batteries are expensive and heavy. In addition, because plug-in hybrids draw electricity from the electric grid, it is important to consider the global warming emissions created by power plants when assessing the full environmental impact of these vehicles. As a result, it is critical that we create a clean electricity grid with low greenhouse gas emissions before moving to substantial deployment of plug-in hybrids.
NEW TECHNOLOGY ON THE HORIZON
Automotive engineers are continuing to develop additional fuel-saving technology. While these technologies are not ready for widespread sale, they are coming closer to reality and may help achieve greater emissions reductions in the future. Indeed, by 2025 something other than conventional gasoline engines may power roughly one-third of the cars on the road, some automotive experts predict.
Advanced Clean Diesel Engines
Due to its design, a diesel engine is more fuel-efficient than conventional gasoline-powered engines. In some cases, diesel engines can achieve a 20 to 25 percent improvement in fuel economy. Unfortunately, diesel engines tend to release dramatically higher smog and cancer-causing particulate pollution. In an effort to protect public health, environmentalists and health advocates have opposed using diesel engines in a large part of the passenger vehicle fleet.
However, new diesel engine designs, combined with better tailpipe pollution controls and cleaner low-sulfur diesel fuels, are beginning to put diesel vehicles on the path to meeting stricter air quality standards. If engineers succeed in reducing diesel tailpipe emissions to make diesels no more polluting than gasoline vehicles, diesel engines can play a key role to help boost fuel economy in certain vehicles.
Fuel cells are chemical batteries that produce electricity using hydrogen as the fuel. In fuel-cell vehicles, this electricity powers the vehicle, replacing the need for a gasoline engine. Because a fuel cell’s only byproduct is water, these vehicles are truly zero-emissions in that they do not release carbon dioxide. While fuel-cell vehicles are similar to electric vehicles in that they operate using an electric motor, unlike either the all-electric or plug-in hybrid vehicles, they do not have to be recharged. Instead, fuel-cell vehicles have storage tanks that can be filled with hydrogen.
While fuel-cell vehicles show tremendous promise, technological and economic problems must be solved before they can enter widespread use. Electricity is required to produce hydrogen fuel. So, for these vehicles to be placed in a true zero-emissions category, the hydrogen must be created using renewable energy sources that themselves do not release heat-trapping global warming emissions. At the same time, we need to develop systems to efficiently and safely distribute hydrogen fuel for these vehicles. Finally, fuel cells are currently expensive to produce; their price must come down dramatically before they are affordable for average consumers.
Battery Electric Vehicles
A battery electric vehicle (EV) runs exclusively on electricity. EVs have battery packs that store electricity. The electricity is used to power motors that turn the whee;s. Instead of filling up with liquid fuel, EVs recharge using electricity form the grid or such stand-alone electricity sources as solar panels. Because these vehicles operate solely on electricity, they achieve the ultimate goal: They produce no tailpipe emissions.
However, just like fuel-cell vehicles and plug-in hybrids, battery electric vehicles face technological challenges. Current battery technology limits the range of electric vehicles to a shorter distance than conventional gasoline vehicles. Most electric vehicles have a range of 50 to 100 miles per charge. Because most drivers travel fewer than 50 miles most days, electric vehicles can meet many people’s commuting needs. But the cost of the battery packs makes electric vehicles more expensive than conventional vehicles. With advances in battery technology these costs will come down–and often tax credits help even out the costs. Finally, just as with plug-in vehicles, the full environmental impact depends on the emissions given off by the source of the vehicle’s electricity. Ultimately, battery electric vehicles will need to rely on renewable energy sources for their electricity to achieve true zero-emissions status.
All this can be done in cars and SUVs similar to those we are accustomed to driving. If we are willing to take another second or two to hit 60 miles per hour and shave some of the bulk from our vehicles, we can slash our oil addiction, global warming emissions and gas costs even more. Think of what we can save: Oil, money, and our planet.
To read about Policy Solutions to global warming, click here.