Article > Tech

Emissions, Hybrids And Diesels: The Rules Keep Changing

By Larry Carley

Emission regulations have always been one of the major driving forces behind new vehicle technology.

The rules of the game keep changing. Emission regulations have always been one of the major driving forces behind new vehicle technology (with safety regulations being the other major factor). Regulators set emissions and fuel economy goals, and the automakers have to achieve those goals with whatever technology it takes to meet the new standards.

The amount of smog-forming pollutants in automotive exhaust today are a tiny fraction of what they were only a few decades ago. Exhaust emissions of hydrocarbons (HC) and carbon monoxide (CO) are only a few parts per million on most vehicles, and oxides of nitrogen (NOX) is less than a tenth of a gram per mile. That’s pretty clean.
But the issue today isn’t so much about pollutants as it is about global warming. Some gases, notably carbon dioxide (CO2), retain heat much more so than nitrogen or oxygen. Nitrogen makes up about 78 percent of the Earth’s atmosphere, and oxygen about 21 percent. CO2, by comparison, only accounts for a tiny amount (0.04 percent). The rest of the air we breathe is argon (0.93 percent), water vapor (varies depending on humidity), and other trace gases.

Though CO2 only accounts for a tiny fraction of the atmosphere,

scientists say it has a huge impact on heat retention and global warming (which itself is still being hotly debated). Scientists say the amount of CO2 in the atmosphere has been steadily rising in recent years. The assumption is that CO2 from the burning of fossil fuels and other man-made gases (such as R134a refrigerant) is the cause.

This assumption is highly questionable because CO2 from natural sources is about 30 times greater than all the man-made sources combined. What’s more, atmospheric moisture plays a much greater role in heat retention than CO2, methane, NOX and all the other man-made pollutants put together, according to various scientific sources. Even so, the regulatory effort today is now focused on reducing carbon emissions (CO2) to counter global warming and climate change.

Another point worth noting about CO2 is that coal-fired power plants are the largest emitters of CO2, not automobiles. According to the Intergovernmental Panel on Climate Change (IPCC), power plants are
responsible for about 36 percent of all man-made CO2. All forms of transportation account for 21 percent. But if you take out aircraft, ships, trains and heavy trucks, cars and light trucks only account for 11 percent of global CO2 emissions.

As far as automotive tailpipe emissions are concerned, exhaust is about as clean as it can reasonably get with current technology. Yet the amount of CO2 in automotive exhaust has not changed. Prior to the flap over global warming and climate change, CO2 was not considered a problem because it is essentially an inert harmless gas. It does not cause smog. It is not harmful or toxic to breathe (assuming there is sufficient oxygen present). Plants absorb it to grow, and use it with photosynthesis to create cellulose and sugars. In fact, we all exhale CO2 every time we take a breath.

CO2 is also a natural byproduct of combustion. When any hydrocarbon fuel is burned (gasoline, diesel fuel, alcohol, biodiesel, propane, jet fuel, wood, coal, you name it), the byproducts of combustion are always carbon dioxide and water vapor (H20). There’s no changing the equation unless you burn a fuel that contains no carbon (such as pure hydrogen).

To reduce overall CO2 emissions, therefore, you have to burn less fuel. That means either higher corporate average fuel economy (CAFE) ratings, or smaller displacement engines, or more fuel efficient engines that get better mileage, or less driving, or any combination thereof.

For many years, CAFE fuel economy standards have hovered around 27.5 mpg in spite of “flex fuel” credits for automakers and other improvements in engine technology such as more fuel-efficient direct injection fuel injection systems on some engines, and the widespread use of thinner viscosity 5W-20 and 5W-30 fuel-saving motor oils. Such gains have been more than offset by the growth in truck, SUV and crossover vehicle sales (which are larger and heavier than most passenger cars, and thus use more fuel).

This past April, President Obama announced an new initiative to increase the CAFE standard for automakers to 35.5 mpg by 2016, which will reduce greenhouse gas (GHG) emissions to 250 grams per mile. Achieving this goal will require roughly a 5 percent increase in fuel efficiency each year, starting in model year 2012. The gains will be achieved by switching to smaller displacement, more efficient engines. Many of these will have direct fuel injection, be turbocharged, and have additional add-on fuel-saving features such as cylinder deactivation under light load, and/or start-stop systems to turn the engine off when the vehicle is not moving.

They say the new CAFE standards will cut oil consumption by an estimated 1.8 billion barrels of oil over the life of the program, and reduce greenhouse gas emissions by 900 million metric tons. It will have the same effect as removing 1.7 million cars from the road.

Higher fuel prices may also help reduce CO2 by discouraging unnecessary driving and encouraging the purchase of more fuel-efficient vehicles. In Europe, heavy taxes on fuel have made driving very expensive. Fuel taxes have already gone up in many areas, and more taxes are likely as local, state and federal governments all scramble to satisfy their unquenchable thirst for more tax dollars in a sagging economy.

Another factor that will continue to push fuel prices higher (besides expensive oil spills), is an expanding world car population. China’s car population has exploded in recent years, and will eventually catch up and probably surpass that in the U.S. Last year, Chinese auto makers built more cars and light trucks than the U.S. auto industry. That’s a lot of new cars that will all be consuming fuel and emitting CO2 into the atmosphere.

Until model year 2000, China had no automotive emissions regulations. But in 2000, it adopted emission standards similar to Europe’s Euro 2 rules (which went into effect back in 1992). Prior to the summer Olympics of 2008, Beijing implemented tougher emission regulations similar to Euro 4. These same regulations were extended nationwide for model year 2010. Though China’s new emission regulations reduce the level of pollutants in the exhaust, they do nothing to thwart the growth of China’s exploding CO2 emissions from their rapidly growing car population.

It’s the same story in India, eastern Europe and other developing areas of the world. Though many countries have adopted or ramped up their emission rules to Euro 2 or higher standards, their growing car populations are all adding more and more CO2 into the atmosphere. That leaves new technologies as the primary means of reducing the carbon footprint of a growing vehicle population.

Diesel-powered trucks have long been popular because of their fuel efficiency and torque. Compression ignition engines are up to 30 percent more fuel-efficient than spark ignition engines. Because of this, Europe long ago turned to the diesel as a more fuel-efficient alternative to gasoline engines. Today, roughly 60 percent of all European cars are diesel powered. Most of these are relatively small displacement engines, and many are turbocharged for added boost and horsepower.

New clean diesel technologies such as electronic common rail high-pressure fuel systems with piezo injectors, exhaust gas recirculation (EGR), diesel oxidation catalysts and particulate traps (to eliminate soot), and low sulfur fuel have reduced diesel emissions dramatically. The latest focus, however, is on diesel exhaust aftertreatment with urea to meet even stricter NOX requirements.

Injecting urea into the exhaust stream creates ammonia, which reacts with NOX and breaks it down into harmless byproducts (nitrogen, oxygen and water vapor). Such systems require a separate control module, a special secondary catalyst, a urea reservoir (which needs to be topped off periodically), exhaust injection nozzle and temperature and NOX sensors.

As for CO2, the amount produced by a diesel engine depends on its displacement. Smaller displacement low revving engines produce less CO2 than larger engines or higher revving engines. By using small displacement, high-torque diesel engines in more passenger cars, overall CO2 emissions can be reduced.

Hybrids have been hot for some time now, and are continuing to grow — though they only represent a very small percentage (about 2 percent) of the overall vehicle population. Those numbers will grow, but to date growth has been limited by two factors: the higher initial cost of a hybrid and limited production capacity by hybrid battery suppliers. Auto makers would like to build and sell more hybrids, but due to the present limits on battery production, they can’t. But that too is changing.

To boost hybrid battery production, several new hybrid battery plants are being built in the U.S. and abroad. This should make batteries more available and also drive down their cost. At the recent Society of Automotive Engineers (SAE) Congress, some industry experts were predicting that 25 percent of all passenger car and light trucks in the U.S will be hybrids, plug-in hybrids or full electrics by 2020. Similar projections are also being made for Europe and China (though China may be ramping up its production of hybrids and full electric vehicles at a much faster pace).
The Chevy Volt hybrid electric goes on sale this fall, and GM says it will increase the car’s production from 10,000 units in 2011 to 30,000 or more in 2012. The car will sell for around $41,000 (minus a $7,500 tax credit), and offer buyers a range of up to 40 miles in full electric mode. The new Nissan Leaf, by comparison, is not a hybrid but a full electric, and offers a driving range of 100 miles. But it won’t be available until next year.

Though hybrid and plug-in hybrid vehicles still produce CO2 from their gasoline (or diesel) engines, the engines can be smaller and designed to run more efficiently than those in ordinary vehicles. The start/stop system also reduces engine run time when the vehicle is not moving or is decelerating or coasting to reduce overall fuel consumption and CO2 emissions.

The least amount of CO2 is produced by full electric vehicles. With no internal combustion engine, no fuel is burned to propel the vehicle, so there are no direct CO2 emissions. However, depending on how the electricity is generated to charge the vehicle’s batteries, there may still be indirect CO2 emissions from a coal or gas-fired power plant. Electricity produced by wind farms, solar panels, geothermal wells, hydroelectric dams or a nuclear power plant, on the other hand, have no carbon emissions. Several new nuke plants have already been approved in the U.S. (the first in decades), and wind farms are popping up across much of the West and Midwest to reduce the demand on natural gas and coal fired power plants.

Automakers have been incorporating all kinds of new technologies to improve fuel economy and performance (and thus lower CO2 emissions) in late model vehicles. Almost every new gasoline engine that is being introduced uses direct fuel injection, which boosts fuel economy about 15 percent over multiport injection. Many engines also have variable valve timing, which improves torque and performance. Cylinder deactivation and start/stop systems are also being added to some engines.

Internal engine changes that have also helped to reduce friction and boost fuel economy include thinner low tension rings, roller cams and roller followers for overhead cams, higher static compression ratios for improved thermal efficiency, and lighter viscosity 5W-20 synthetic motor oils to save fuel.

Today’s engine control systems are also smarter and faster than ever before, which provides greater control over combustion for improved efficiency and fuel economy.

Assuming regulators stay the course on trying to reduce CO2 in an attempt to curtail global warming and its impact on climate change, we will certainly see more innovations in technology designed to improve fuel economy and/or eliminate our dependence on oil altogether. It will take time, but automakers are moving forward to meet the goals that have been placed in front of them. That means more direct injection gasoline engines, smaller engine displacements, fewer V8s, more complex emission control systems, more clean diesel engines in light trucks and passenger cars, more hybrid vehicles, and eventually mass produced full electric vehicles.

Industry experts predict that 2016 will probably be the time frame for the appearance of some full electric cars in significant numbers from major manufacturers. The pace of development will depend on the price of fuel, the availability of batteries, and the availability of electrical power to recharge these vehicles. The capacity of the power grid will have to grow if it is to meet the demand of a growing fleet of electric powered cars.

Some experts say that as many as 30 percent of all new car sales could be electric vehicles by the year 2030. That’s 20 years away, but think back how much automotive technology has changed over the past 20 years (OBD I & II, CAN electrical systems, the growth of hybrids, etc.).

The internal combustion engine will be around for many years to come, though in the future it will probably be used more to drive a generator for an electric propulsion system rather than driving the vehicle directly — and all of these vehicles will still require replacement parts and maintenance. Automotive technology will certainly change in the years ahead, as will the types of parts that will be stocked on your store shelves. But vehicles will still need to be maintained and repaired — and that’s good news for the aftermarket.

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