When Susan Banks was 8 years old and growing up in a small Pennsylvania town, she and her mother would take the Number Nine bus downtown to shop. They had a car, but Susan's mom, always thinking green, knew that mass transit was better for the environment: the fewer cars on the road, the better. However, when it was time to go back home, they'd wait for the bus not at the terminal, but in the window of Main Street's Woolworth's. The reason - the fumes.
Back then, standing behind a bus was perhaps more dangerous than standing in front of one. Buses, and more specifically, the diesel engines that propelled them, were a major source of particulate matter, nitrogen oxides and air toxics. All of these pollutants can cause serious health problems, but things have changed.
Now, the bus that takes Susan to her ad exec job in Manhattan is nothing like the ones outside the old five and dime. Thanks to the work of the U.S. Environmental Protection Agency (EPA) and the mass transit community, today's buses are cleaner, quieter and more efficient. Because of a number of cost-effective solutions from exhaust filters to idle-reduction strategies, we are working together to make the black puff of smoke, once so characteristic of buses and diesel engines, a thing of the past.
For the past century, diesel engines have been America's economic workhorse - reliable, fuel-efficient and long-lasting. These were qualities that made diesel engines very attractive for a variety of uses, including fleet vehicles. However, because diesel engines operate at high temperatures using low viscosity fuel, they can emit a lot of pollution - large amounts of nitrogen oxides and particulate matter, both of which contribute to serious public health problems.
These problems are manifested by thousands of premature deaths, hundreds of thousands of asthma attacks, millions of lost work days and numerous other health impacts. Because these engines are so widely used, reducing their emissions to protect public health has been one of the EPA's most important air quality challenges.
Both Presidents Clinton and Bush knew the rewards of committing to a new national investment in energy innovation in order to create cleaner diesel engines. The 2007 Heavy Duty Highway Rule (HDHR), adopted by President Clinton's administration and implemented by President Bush, has helped make America's air cleaner than it was 30 years ago, and will help it continue to get cleaner.
In fact, diesel engines and the vehicles they power have become dramatically cleaner. Today's buses emit only oneeighth the pollution of a bus built in 1980, and when the buses featuring the engines compliant with the HDHR hit the road, it will take 60 of them to emit the same amount of soot given off by the tailpipe of one 1980 model year bus. In terms of public health, this means long-term annual benefits of more than $70 billion - 17 times the cost of compliance.
How is this all possible? By an innovative way of seeing the fuel and the engine as a system, and tackling emissions from this stance, the EPA has worked with both the fuel and manufacturing industries to bring these changes to fruition.
One of the first ways drivers will be able to take advantage of the new HDHR and other EPA programs is when filling up. Ultra-low sulfur diesel (ULSD) is available nationwide to help all vehicles reduce emissions and enhance environmental performance.
The first part of the HDHR came into play on June 1, 2006, when refiners began producing clean ultra-low sulfur diesel fuel for use in on-road diesel engines. ULSD's sulfur level is at or below 15 parts per million (ppm), 97 percent lower than the fuel that highway diesels usually run on. This is the biggest advancement in fuels and environmental protection since unleaded gasoline - making diesel engines 90 percent cleaner and dramatically reducing their contributions to smog and soot.
On Oct. 15, this fuel was available nationwide, and though ULSD will be the dominant highway diesel fuel produced, the EPA does not require service stations and truck stops to sell low sulfur diesel (LSD) fuel until Dec. 1, 2010. Right now, 80 percent of on-road diesel produced is required to be ULSD; in 2010, all must be ULSD. Therefore, it is possible that ULSD fuel might not be available at every service station, or that a diesel retailer may choose to sell LSD fuel instead.
Owners of 2006 and earlier model year diesel-powered engines and vehicles may use either until 2010. Engine and vehicle manufacturers expect ULSD fuel to be fully compatible with the existing fleet. In some instances, the initial use of it in older vehicles may loosen deposits in fuel tanks. As part of a good maintenance program, owners are encouraged to monitor their vehicles closely for potential fuel system leaks or premature fuel filter plugging during the changeover.
Owners of 2007 and later model year vehicles must refuel only with ULSD fuel. However, some medium-duty and heavyduty diesel-powered model year 2007 vehicles are built with 2006 model year engines, which do not require ULSD fuel, and the EPA does not require these vehicles to be fueled by it. Nonetheless, vehicles that require ULSD fuel have specific labels on the dashboard and near the fuel inlet.
If your vehicle is designed to use ULSD, improper fuel use may reduce engine durability and fuel efficiency, permanently damage emissions control systems and possibly prevent the vehicle from running at all. Manufacturer warranties are also likely to be voided by improper fuel use.
This summer, high fuel prices made headlines everywhere. With fuel costs at an all-time high, it is reasonable for American businesses to ask questions regarding the expenses associated with this vital resource. In addition, there were some concerns that the changeover to ULSD caused shortages and even higher fuel prices in Colorado and the Midwest. To answer these concerns, the EPA and other government agencies investigated the claims, conducting numerous discussions with the refineries providing fuel for those areas. Not once was the changeover to ULSD cited as the reason for high prices and short supplies. In many cases, the transition to ULSD had occurred before the shortage, and the top reason for the diesel shortages was very high diesel demand due to the extreme drought, which caused the agricultural industry to need more fuel to power irrigation systems.
Even though drought was determined to be the cause of this summer's diesel shortage, the inquiries did prompt the EPA to re-examine the impact of its regulations on the cost of fuel, and its conclusion: ULSD costs about a nickel more per gallon.
The introduction of ULSD will help make this country's buses the cleanest in the world. When fully implemented, EPA's highway clean diesel rule will result in $70 billion in health and welfarerelated benefits every year, such as the prevention of more than 8,000 premature deaths and tens-of-thousands of respiratory illnesses like bronchitis.
Through innovations mandated by the 2007 Heavy Duty Highway Rule, the bus, an urban workhorse, is becoming an environmental role model, and leading the way for other vehicle technologies. Besides reducing emissions from the existing diesel fleet, ULSD will enable the use of advanced aftertreatment technologies on new engines. Technologies like particulate traps, capable of emission reductions of 90 percent or more, will be required under new standards and are set to begin appearing in vehicles in the 2007 models.
For 2007, there are three main technologies for diesel buses, which are enabled by the use of ULSD. These are: advanced fuel systems, better exhaust gas recirculation and particulate filters.
The 2007 model year diesel engines will feature fuel systems optimized for use with ULSD. The EPA is proud of this accomplishment: it is the first time that a fuel and engine have been harmonized to work together to reduce emissions and optimize performance. The key difference is that 2007 HDHR engines will utilize higher injection pressure and multi-injection capabilities, which allows further engine-out emission reductions.
PARTICULATE MATTER FILTERS
Diesel particulate matter filters are ceramic devices that collect particulate matter in the exhaust stream. The high temperature of the exhaust heats the ceramic structure and allows the particles inside to break down (oxidize) into less harmful compounds. They can be installed on new and used buses, but must be used in conjunction with ultralow sulfur diesel. The combination of PM filters and ULSD can reduce emissions of PM, HC and CO by 60 to 90 percent.
Beginning in 2007, PM filters will be standard issue on all diesel vehicles. However, PM filters are also available in a kit to retrofit older buses - though most work best on engines built after 1995. The cost of the kit can range from $5,000 to $10,000, but some buses may need the more expensive filters to compensate for lower exhaust temperatures.
EXHAUST GAS RECIRCULATION
Exhaust gas recirculation (EGR) systems reduce exhaust emissions that are not being cleaned by the other smog controls. Oxides of nitrogen (NOx) are produced when an engine gets too hot, but NOx formation can be reduced by recirculating some exhaust gases.
An EGR system recirculates exhaust into the intake stream. Exhaust gases have already combusted, so they do not burn again. Instead, they displace some of the normal intake and cool the combustion process by several hundred degrees and reduce NOx formation. These systems must precisely control the flow of recirculated exhaust: Too much flow will retard engine performance and cause a hesitation on acceleration. Too little flow will increase NOx and cause engine ping.
Manufacturers are predicting that the 2007 changes will not affect fuel economy. There are also no concerns about power. However, drivers may find a new chore - cleaning the ash from PM traps every 150,000 miles. Nonetheless, the arrival of the 2007 compliant buses will mark one very important departure: the belch of black smoke and fumes that used to characterize all diesel engines will be no more.
For 2010, more advanced NOx aftertreatment and Urea-SCR systems on transit buses will yield another 80 percent emission reduction over the 2007 technology (which already cut pollution in half). Urea-SCR systems are available in Europe and as a retrofit today, so while there are some concerns about how to keep the systems filled, the EPA is confi- dent those problems will be worked out by the time they are in vehicles. Right now, a Urea-SCR system needs to be re-filled every second to third fill-up, but industry is working on alternatives.
Because of the advances in vehicle technology catalyzed by the HDHR, passenger trucks and cars will also benefit, and themselves become more environmentally friendly.
Automakers also envision a cleaner, more efficient future for their vehicles. In the past year alone, several automakers such as Ford, DaimlerChrysler and GM have announced plans to bring new, clean diesel cars, pickup trucks and delivery vehicles to the market.
And industry is only part of the story. As technology innovations driven by the EPA's clean diesel program spreads to cars, since diesel engines tend to be more efficient than gas engines, our nation's energy security will be strengthened. This smart fuel use is part of President Bush's strategy for helping America jump off the treadmill of dependency on foreign sources of oil.
The 2007 Heavy Duty Highway Rule is only part of the story when it comes to the advances made by the EPA to make diesel engines cleaner. The SmartWay Program, a voluntary partnership between the freight industry and the EPA to promote fuel efficiency has recently added a new facet: SmartWay Grow & Go, which focuses on renewable fuels. One of the fuels it will promote, biodiesel, can be used by any diesel engine, regardless of the freight it is carrying.
Not many people look at a farm field and see its potential for powering a bus, but domestic crops can be made into renewable, environmentally friendly fuel. Biodiesel is a nontoxic, biodegradable, renewable fuel produced from agricultural resources like vegetable oils. In the United States, most biodiesel is made from soybean oil; however, canola oil, sunfl ower oil, recycled cooking oils and animal fats are also used.
HOW IT IS MADE
To make biodiesel, the base oil is put through a process called esterification. This refining method uses an industrial alcohol (ethanol or methanol) and a catalyst to convert the oil into the biodiesel.
Biodiesel in its pure form is known as neat biodiesel or B100, but it can also be blended with conventional diesel, most commonly as B5 (5 percent biodiesel and 95 percent diesel) and B20 (20 percent biodiesel and 80 percent diesel). Biodiesel is registered with the EPA and is legal for use at any blend.
Most diesel engines can run on biodiesel without needing any special equipment. If you are interested in using biodiesel in your vehicles, check with the manufacturer for any recommendations and information regarding engine warranties.
In addition, once you have determined the proper blend, make sure to purchase your fuel from a reputable dealer selling commercial grade biodiesel.
BIODIESEL VS. VEGETABLE OIL
There have been stories in the media lately talking about cars, trucks and buses running on used vegetable oil. Though used vegetable oil is a cheap alternative to diesel fuel, it is not biodiesel and also not very good for your engine.
In 1895, Dr. Rudolf Diesel invented the diesel engine with the intention of running it on a variety of fuels, including vegetable oil. In fact, when he demonstrated his engine at the World Exhibition in Paris in 1900, he fueled the vehicle with peanut oil. However, biodiesel and vegetable oil are very different. Cooking oil is thicker, heavier and does not burn as well as regular auto fuel. Because it doesn't burn as well, it is likely to cause more pollution than other types of diesel. Its use may also void manufacturer warranties.
Waste cooking oil that hasn't been processed into esters is not biodiesel, and not registered by the EPA for legal use in vehicles. In addition, vehicles converted to use these oils would likely need to be certified by the EPA; to date the EPA has not certified any conversions.
When running on biodiesel, vehicles have similar horsepower and torque as when run on conventional diesel. Chemically speaking, biodiesel has a higher cetane number, but slightly lower energy content than diesel. To the driver, this means better engine performance and lubrication, but a small decrease in fuel economy (2 to 8 percent). Biodiesel vehicles can also have problems starting at very cold temperatures, but this is more of an issue for higher percentage blends like B100 and easily solved the same way as with conventionally fueled vehicles: by using engine block or fuel filter heaters or storing the vehicles in a building.
In 2004, 25 million gallons of B100 were sold. By 2005, that number had tripled. Today, approximately 600 fleets nationwide use biodiesel blends in their diesel engines, and biodiesel is available in its various blends at approximately 800 locations across the United States.
The price of biodiesel blends varies depending on geographic area, base material (corn, soybeans, etc.) and supplier. Although biodiesel can cost more than traditional diesel, diesel drivers can transition to it and back without purchasing new vehicles. In the case of fleets, managers can transition to biodiesel without acquiring new spare parts inventories or rebuilding refueling stations.
Generally, the use of biodiesel does not cause many maintenance issues. However, when used for the first time, biodiesel can release deposits accumulated on tank walls and pipes, initially causing fuel filter clogs. As a result, vehicle owners should change the fuel filter after their first tank of biodiesel. Also, biodiesel can degrade rubber fuel system components, such as hoses and pump seals. This is especially true with higherpercentage blends and older vehicles. Many newer vehicles feature biodieselcompatible components; contact the manufacturer for specific information.
Biodiesel has a number of benefits. As an alternative to diesel, it can help reduce U.S. dependence on foreign oil. Biodiesel also provides significant greenhouse gas (GHG) emission reductions. In addition, biodiesel offers several emissions bene- fits for the existing vehicle fleet. It reduces emissions of carbon monoxide, particulate matter (PM) and sulfates, as well as hydrocarbon and air toxics emissions.
A 2002 EPA summary analysis of existing data suggests vehicles using biodiesel may emit slightly more nitrogen oxide (NOx) (about 2 percent for B20 and 10 percent for B100). Subsequent studies have yielded mixed results, with some showing small increases and others showing small decreases. The EPA plans a further investigation to fully assess this issue, including the emissions impact of using biodiesel in vehicles equipped with PM traps and NOx aftertreatment designed to meet strict new emission standards.
Headquartered at the EPA's National Vehicle and Fuel Emissions Laboratory in Ann Arbor, Mich., the EPA's engine research focuses on developing engines that are simultaneously clean, efficient and cost-effective.
Clean Diesel Combustion technology is one example of these innovative engine concepts. The EPA's testing suggests the potential for a diesel engine design. It uses a new air, fuel and combustion management with a conventional particulate matter aftertreatment to achieve lower NOx levels. The EPA is developing this technology as a potential alternative to other diesel emissions control approaches. Clean Diesel Combustion technology shows great potential for real world benefits. Thus, the EPA has partnered with several automotive and engine manufacturers to evaluate the production feasibility of this technology.
The EPA is a research leader in the application of hydraulics in vehicles. Hydraulic hybrid technology uses a hydraulic energy storage and propulsion system in the vehicle - and holds great promise for the future of urban driving.
A hydraulic system captures and stores a large fraction of the energy normally wasted in vehicle braking and uses this energy to help propel the vehicle during the next vehicle acceleration. The hydraulic system also enables the engine to operate more efficiently when it is needed.
Hydraulic hybrids draw from two sources of power to operate the vehicle - the diesel or gasoline engine and the hydraulic components. In other words, a typical diesel-powered or gasoline- powered vehicle can be fitted with hydraulic components as a secondary energy storage system.
BENEFITS OF HYDRAULIC TECHNOLOGY
Hydraulic drivetrains are particularly attractive for vehicle applications that entail a significant amount of stop-and-go driving, such as urban delivery trucks or buses. A major benefit of a hydraulic hybrid vehicle is the ability to capture and use a large percentage of the energy normally lost in vehicle braking. Hydraulic hybrids can quickly and efficiently store and release great amounts of energy. This is a critical factor in maximizing braking energy recovered and increasing the fuel economy benefit. While the primary benefit of hydraulics is higher fuel economy, hydraulics also increases vehicle acceleration performance. Hydraulic hybrid technology cost-effectively allows the engine speed or torque to be independent of vehicle speed, resulting in cleaner and more efficient engine operation.
HOW IT WORKS
The newest generation of hydraulic vehicles replaces the conventional drivetrain with a hydraulic drivetrain and eliminates the need for a transmission and transfer case. The primary components are the hydraulic accumulator and one or more hydraulic pump/motor units.
These components work together in a very simple way:
- *The hybrid controller monitors the driver's acceleration and braking, and commands the hybrid system components. The high-pressure accumulator stores energy just like a battery would in a hybrid electric vehicle. However, it uses hydraulic fluid to compress nitrogen gas.
- *The engine pump/motor transfers hydraulic fluid to the rear drive pump/motor.
- *The rear drive pump/motor converts the pressure from the hydraulic fluid into rotating power for the wheels, and recovers braking energy which is stored in the high-pressure accumulator.
- *The low-pressure reservoir stores the low-pressure fluid after it has been used by the pump/motor unit.
The above configuration provides three key design features that provide maximum fuel efficiency:
- Regenerative Braking. The vehicle uses its own stored braking energy for starts and accelerations. This process recovers and reuses more than 70 percent of the energy normally wasted during braking.
- Optimum Engine Control. In the full series hybrid design, there is no conventional transmission and driveshaft connecting the engine to the wheels. This frees the engine to be operated at its maximum efficiency.
- Shutting Engine Off When Not Needed. The unique hybrid design also enables the engine to be completely shut off during certain stages of operation, such as idling at a stoplight. As a result, in stop-and-go urban city driving engine use is cut almost in half.
This technology is currently being evaluated by UPS in real-world package delivery. This vehicle has delivered both packages and environmental benefits to doorstops across Michigan. This evaluation is the next in a series of steps to bring this technology to neighborhoods throughout the entire nation.
UPS expects to see an increase of 60 to 70 percent in urban settings - where most delivery vehicles are driven. The EPA estimates these trucks can save 1,000 gallons of fuel each year. (Imagine the fuel savings for an entire fleet.)
And as efficiency jumps, pollution and greenhouse gas emissions also drop. This technology produces 40 percent fewer greenhouse gas emissions as compared to a conventional delivery truck. Because the hydraulic hybrid system is so cost-effective, UPS estimated that its upfront costs can be recouped within three years. This means the net savings over the vehicle's lifespan could exceed $50,000.
FUTURE OF HYDRAULICS
Using the full hydraulic drive in conjunction with the EPA's Clean Diesel Combustion technology is projected to improve fuel economy even more. Today we are seeing that energy innovation solutions, like hydraulic hybrids, can power our nation's economy, and drive our environmental success.
More than 14 million Americans rely on public transit services to get to work, to school and to neighboring cities. Because of its safety, reliability and efficiency, diesel is the predominant power source for bus services nationwide. More than 95 percent of the nation's full-sized transit buses are powered by diesel. It is less flammable than gasoline, and engine maintenance and durability are unmatched.
Though once in danger of being banned in the United States because of their emissions, diesel vehicles are undergoing a number of revolutionary advancements.
Buses have always been able to be counted on to deliver people, and now they are delivering something even more welcome: clean air.