SUVs vs. Trees Emissions & The Environment, Larry Carley, Counterman, May 2001

The automotive industry has come a long way in its struggle to reduce pollution. Today's vehicles are the cleanest ever, and getting cleaner all the time. As the next levels of emission standards are phased in for cars, light trucks and heavy trucks, emissions will be reduced even more. Reduced sulfur content in fuels and "Tier II" emission regulations should lower vehicle emissions another 20-25 percent.

Today's emission controls have done an amazing job of minimizing pollution from motor vehicles. But one thing emission control technology has not been able to change is the basic chemistry of combustion itself. The issue now is CO2 (carbon dioxide) and as CO2 levels continue to rise, scientists fear it will cause a gradual warming of the Earth's average temperature. This, they say, has the potential to upset ocean currents, global weather patterns and rainfall, which may have far-reaching and negative consequences for agriculture, fishing and life in general. Some fear it may even lead to a melting of the polar ice caps causing the oceans to rise and flood coastal areas.

To reduce our CO2 emissions, we would have to drive smaller, more fuel-efficient cars, raise the fuel economy requirements for trucks, and adopt a variety of conservation measures to reduce energy consumption.

FUTURE CONSEQUENCES?
We now have more motor vehicles than licensed drivers in this country (210 million). The worldwide vehicle fleet is estimated to be about 430 million cars and trucks (up from 50 million in 1950), and will surpass 650 million within the next 8-10 years! Most of this growth is occurring in developing nations that do not have the strict emission requirements that we do. And even if they do adopt the same emission standards as Europe, Japan and the U.S., all of these vehicles will still produce millions of tons of CO2 as a byproduct of burning gasoline and diesel fuel.

With fewer trees left to absorb carbon and more vehicles producing carbon, don't expect the atmosphere's carbon balance to improve any time soon. The scales have probably tipped irreversibly towards higher and higher levels of CO2 for the foreseeable future.

Nobody argues with the fact that the amount of CO2 in the atmosphere is steadily rising because of human activity. What we don't know is what the long-term consequences of a CO2 imbalance will be or how it will actually affect our daily lives. Waiting to find out may prove costly if we miss the window of opportunity to make significant changes now.

Many environmentalists say one step we can take now to reduce CO2 emissions is to improve the fuel economy of all classes of vehicles. U.S. fuel economy standards have nearly doubled since the energy crisis days of 1973 - but have remained relatively flat at 27.5 mpg for passenger cars for the last 15 years. For trucks, the average fuel economy is only about 20 mpg. Yet because of the increased popularity of trucks and SUVs in recent years, the average fuel economy of all new vehicles in the U.S. has sunk to the lowest level since 1980!

According to the Sierra Club, every day America consumes 18 million barrels of oil. Not all of that is for transportation, but in a year's time we burn up about 120 billion gallons of gasoline.

If the Corporate Average Fuel Economy (CAFE) standards for trucks were raised to match that of cars (27.5 mpg), it could save one million barrels of oil per day. That's a lot of carbon! Raising the CAFE standards for cars to 45 mpg and light trucks to 34 mpg would increase the savings to three million barrels of oil per day.

Rising fuel prices rather than Congressional action (or inaction as the case may be) will likely provide the strongest incentive to get motorists to buy more fuel-efficient vehicles and reduce their driving. But it's hard to cut back on the number of miles driven (we drive over two trillion miles a year now) because our cities and suburbs are sprawled out. Most people are totally dependent on a motor vehicle to get to work, school, to shop and do everything else in life (thankfully for those of us in the parts and service business). Mass transit doesn't work outside the central cities because things are too spread out. And in rural America, a car or a truck is the only way to get to town or any place else.

TECHNOLOGY TO THE RESCUE
One solution that can allow us to keep our big SUVs and get good fuel economy too is "hybrid-electric" technology. With this approach, a small displacement, fuel-efficient gasoline or diesel engine is used in conjunction with an electric motor and battery to power the vehicle. The regular motor is used for highway driving and to charge the battery. The rest of the time the vehicle runs on electric power or a combination of battery and gasoline.

Depending on how the control strategy is set up, a hybrid-electric may deliver double the fuel economy of a conventional vehicle in normal driving, and it may even triple the usual mileage in urban stop-and-go driving. Instead of wasting fuel at a stoplight, a hybrid-electric shuts the engine off when the vehicle stops. The engine remains off until the light changes and the vehicle accelerates on battery power up to a certain speed.

As promising as this new technology is, there are currently only two vehicle manufacturers producing hybrid-electric vehicles: Toyota and Honda. The Toyota Prius is a compact four-door car that has an EPA rating of 52 mpg in the city and 45 mpg on the highway. But production is limited and the waiting list is reportedly six to eight months to get one. Dealers are also getting full list price plus as much more as the market will bear.

Ford says it will have a hybrid-electric version of its Escape SUV on sale in 2003. This will be followed by a hybrid-electric version of the six-cylinder Explorer in another year or two. But like the Prius, both will be produced in limited numbers and will be in short supply. Buyers will also pay a premium for the fuel-saving technology. So unless there is a large-scale shift to mass-produced hybrid-electric vehicles over the next three to six years, we won't see any significant improvement in CAFE numbers for a long time.

Electric vehicles are still on the fringe and will probably stay there because of lagging battery technology. Electric vehicles that emit no pollutants and no CO2 certainly make sense in polluted urban environments. They're the ultimate energy-efficient vehicles for stop-and-go driving because they waste no energy when they're stopped in traffic. But nobody has yet come up with a cheap, lightweight, safe, quickly rechargeable battery. And even if they did, it would take years for the new technology to go into mass production and for the public to accept it.

There's also the issue of whether or not electric vehicles would actually reduce pollution. The electricity needed to recharge the battery has to come from another power source. Unless that power source is nuclear, hydroelectric, wind, solar or geothermal, there is little or no net reduction in pollution or CO2 because most electrical power in this country is generated by burning coal or natural gas. No new nuclear power plants have been built in the U.S. for over 25 years, and many nukes are now reaching retirement age and will have to be decommissioned. Unless there is a rebirth of nuclear energy or a large-scale shift to alternative sources of clean power (which are more expensive and require huge financial investments), electric vehicles aren't going far.

Even with an advanced battery breakthrough, it's questionable whether the existing power infrastructure has the capacity to supply the needs of an expanding fleet of electrical vehicles. California has been experiencing a mini-energy crisis of its own recently. Imagine how bad their situation would be today if only five to 10 percent of their vehicles were electric.

FUEL CELLS & HYDROGEN
Fuel cells currently hold the greatest promise for solving our environmental concerns over pollution and CO2. A fuel cell produces electricity by combining hydrogen and oxygen. The only byproduct is water vapor - provided the fuel source is pure hydrogen.

Hydrogen is one of the most abundant elements on Earth. It can be made from natural gas, oil or even coal or by using electricity to break down water into hydrogen and oxygen. Even so, it's not cheap to produce and contains less energy than hydrocarbon fuels.

Hydrogen is also a hard-to-store fuel. Because it's a gas, it has to be compressed at extremely high pressure (3,000 to 4,800 psi). This requires large, heavy, expensive fuel tanks that reduce a vehicle's driving range and fuel economy. It can be liquefied to increase its storage density, but this requires special insulated cryogenic storage tanks to keep the fuel at -253 degrees C. Another storage method is to use "metal hydrides" or activated carbon that can absorb hydrogen like a sponge. But these approaches are also bulky, heavy and expensive. What's more, there is no distribution system for hydrogen like there is for gasoline, diesel fuel or even natural gas. So even if you had a hydrogen-powered vehicle, you'd have a hard time finding a place to fill it up.

One solution for storing hydrogen is to not store it as a gas but to extract it from another fuel such as gasoline or methanol alcohol. A device known as a "reformer" can break down these fuels to release the hydrogen. But adding a reformer adds cost and complexity, and also reduces its fuel efficiency. Even so, DaimlerChrysler, Mercedes, BMW and several other vehicle manufacturers have all demonstrated prototype fuel cell powered vehicles that use reformers to extract hydrogen from gasoline or methanol.

Why not just burn hydrogen in an internal combustion engine and forget the high-tech fuel cell and reformer? You can, but compared to other fuels, hydrogen is a lousy motor fuel. It has a very low octane number, which means it causes detonation and pre-ignition unless the compression ratio is cut way down. It also tends to backfire through the intake manifold. And it doesn't get very good fuel mileage, either. A gallon of liquefied hydrogen has only about one-fourth the energy content of a gallon of gasoline.

Time will tell which technologies will eventually help us meet our environmental challenges. It's not just motor vehicles that bear the brunt of reducing pollution and CO2 emissions. It's all forms of energy consumption and power generation worldwide as well as the issue of deforestation. Hopefully, we can come up with solutions that satisfy everybody's concerns and needs while there is still time.