The U.S. Environmental Protection Agency (EPA) mandated all diesel-powered vehicles with engines greater than 3 liters of displacement, manufactured after Jan. 1, 2010, must significantly reduce nitrogen oxide (NOx) emissions. The federal and separate California standards are the strictest exhaust regulations in the world, requiring near-zero emissions of particulates and NOx.
The two technologies designed to comply with EPA 2010 diesel emissions legislation are EGR (exhaust gas recirculation) and SCR (selective catalytic reduction).
About 85 percent of truck and engine manufacturers have chosen SCR to comply with the new regulations. Some of the companies utilizing SCR technology are Cummins, Daimler Trucks (Freightliner & Western Star), General Motors, Hino, Isuzu, PACCAR (Kenworth & Peterbilt), AB Volvo (Volvo & Mack), and John Deere.
One reason most truck manufacturers chose SCR is many are currently using the technology in Europe, Japan, and Australia. For instance, Volvo already has 25 billion miles of experience using SCR technology.
Navistar/International will utilize enhanced EGR technology to comply with the standards. EGR technology reduces the amount of oxygen molecules by introducing cooled exhaust gas, which is lower in oxygen, into the intake system. This reduces the combustion temperature and lowers NOx production.
NOx formation is the byproduct of the high combustion temperature in diesel engines. As the combustion temperature rises, more NOx is exponentially created from oxygen and nitrogen molecules.
"The engine manufacturers that have chosen SCR will continue to use cooled EGR, but at a reduced rate," said Jim Tipka, VP of engineering for the American Trucking Associations (ATA).
DEF Requirements for Use in SCR Diesel Engines
SCR technology uses an ultra pure urea, more commonly known as diesel exhaust fluid (DEF), and a catalytic converter to significantly reduce NOx emissions. SCR works by injecting a very precise amount of DEF into the vehicle's hot exhaust stream. Once inside the SCR catalyst, the ammonia gas forms a chemical reaction with the NOx emitted by the engine. As a result of this chemical reaction, SCR converts NOx into water vapor and harmless nitrogen gas.
With the projected growth in DEF consumption, a nationwide DEF refueling infrastructure is emerging.
A recent milestone occurred when Gilbarco Veeder-Root shipped its first Encore S Diesel Exhaust Fluid dispensers for North America Sept. 2, 2009.
The Gilbarco Encore S DEF dispenser was the first of its kind produced specifically for the North American market. Gilbarco Veeder-Root supplies gas pumps, payment systems, point-of-sale systems, and other equipment and services to the retail and commercial petroleum market.
It is anticipated there will be strong competition in the DEF dispensing market in North America. All major truck stops have committed to carrying and selling DEF. Early front-runners in establishing DEF refueling facilities are Pilot and TA Travel Center.
"DEF dispensers will be located at truck stops catering to over-the-road trucks and at high-velocity fuel providers," said Richard Browne, vice president of marketing for North America at Gilbarco Veeder-Root.
In addition, a growing number of public sector fleets are dispensing DEF at on-site fueling facilities, such as the New Hampshire DOT; City of Philadelphia; City of Rockville, Md.; and City of Colorado Springs, Colo., according to Kevin DeVinney, director of dispensers and fleet systems marketing for Gilbarco Veeder-Root.
"Starting Jan. 1, engine NOx emissions must be reduced by 85 percent from current levels. This new level of reduction results in a cumulative NOx reduction of 99 percent from 1974 levels," said Browne. "The 2010 emission standards will make diesel cleaner than natural gas."
SCR technology is not limited to medium- and heavy-duty trucks. Passenger cars and light-truck manufacturers around the world are also adopting SCR technology to meet increasingly stringent emission requirements being legislated.
Diesel engines manufactured before Dec. 31, 2009 are not subject to the 2010 EPA diesel emission regulation.
DEF Onboard Technology
Trucks with SCR-diesels are manufactured with onboard tanks to hold DEF, ranging 7-8 gallons for light trucks, up to 23 gallons for a Class 8.
"The 7-8 gallons for light trucks was determined by estimating how much DEF would be consumed between oil changes. The minimum size of tank for each type of truck is set by the EPA, as announced in the Nov. 9, 2009 Federal Register," said Tipka. "Heavy work trucks, such as dump trucks and concrete mixers that return to the same location at the end of each work day (centrally fueled), must have a tank with the capacity to hold enough DEF to last at least twice as long as the diesel fuel will last."
The DEF tank is always located on the driver side of the vehicle. The DEF nozzle is smaller than nozzles used to dispense diesel fuel.
The average DEF consumption per truck is expected to be approximately 2 percent of fuel consumption, depending on vehicle operation, duty cycle, geography, and load ratings. This works out to 1 gallon of DEF required for every 300 miles traveled (assuming fuel economy of 6 mpg), said Chad Johnson, marketing manager for Gilbarco Veeder-Root. At this rate, a heavy-duty truck traveling 120,000 miles annually would require approximately 400 gallons of DEF per year. Another way to calculate usage is that DEF will be consumed at a 50 to 1 ratio with diesel. (For example, for every 50 gallons of diesel fuel burned, 1 gallon of DEF will be used.)
"A medium-duty truck will probably only have to fill up 10 times a year with DEF," said John Lounsbury, director of marketing for Terra Environmental Technologies in Sioux City, Iowa, which produces nitrogen products as reagents to industrial customers to help them meet local, state, and federal air quality standards.
Failure to refuel the DEF tank will cause the truck to exceed allowable NOx emissions. For this reason, EPA requires OEMs to have a visual and audible warning to alert a driver when DEF fluid is low - less than 2.5 percent of the DEF tank capacity. However, this alert occurs while the truck is still able to drive hundreds of miles more before the tank is empty. If the driver chooses to ignore the numerous alerts and runs out of DEF, the engine will shift to a performance-restricted mode and eventually no longer restart. However, the engine will not stop running and strand the driver if the vehicle runs out of DEF while moving. Once the DEF tank is empty, a derating of engine power will occur and eventually the truck will be restricted to a maximum speed of 5 mph.
An SCR system requires minimal maintenance. The system has a DEF dosing unit filter, which should be replaced about every 200,000 miles (or every 1-2 years) as part of routine maintenance. This is a simple spin-on cartridge filter. All other vehicle maintenance intervals will be unchanged.
For instance, lube filter service intervals will remain unchanged on SCR-equipped vehicles since the SCR process treats exhaust emissions after they are produced by the engine.
"DEF is corrosive to copper and brass, as well as other materials. Only approved materials, such as high-density polyethylene (HDPE), can be used in the DEF tank, packaging, and dispensing equipment," said Johnson.
If DEF is spilled on a vehicle, no damage will occur, and drivers are advised to simply rinse with water.
North American DEF Market
The market for DEF is estimated to reach more than $930 million by 2015 and more than $2.1 billion by 2019, according to a recent study by Integer, a market research company that analyzed DEF production, consumption, and future market demand. Integer forecasts North American DEF consumption will reach 800 million gallons in 2019 for on-highway SCR trucks and buses, and 260 million gallons for off-highway vehicles using SCR technology.
Revenues from DEF in a fully developed North American market are forecast to exceed $5 billion annually.
The initial DEF supply will most likely be sold in prepackaged containers while bulk dispensing options are installed. Overall DEF pricing will be lower than diesel fuel. Smaller containers of DEF sold at dealerships will likely be priced higher.
"DEF costs below $2 per gallon in the U.S., but can be as high as $4 per gallon in small bottles," said Lounsbury. In Europe, DEF costs the equivalent of $2.50 per gallon.
DEF distribution at truck stops, diesel refueling stations, and retail service stations is anticipated to satisfy the needs of 80 percent of the total Class 3-8 vocational truck market.
"The majority of customers who come into a truck stop will not need the DEF product for the next several years, since it is only required for 2010 and newer vehicles," said Holly Alfano, vice president, government affairs for the National Association of Truck Stop Operators (NATSO), a national trade association representing travel plaza and truck stop owners and operators. "Initially, DEF will be sold through bottles and jugs, but eventually through dispensers. Most truck stops will acquire island dispensers."
Johnson of Gilbarco Veeder-Root foresees DEF dispensing evolving from hand pumps to all-in-one mini bulk (skid tank) or dispensers with a skid tank.
"Most truck plazas are looking at skid tank above-ground dispensers," said Johnson. "As demand for DEF increases, so too will use of underground tanks with dispensers."
Close to 80 percent of diesel demand in the U.S. is east of the Rockies. DEF demand is expected to geographically mirror diesel demand.
Truck stops are expected to play a central role for fleets that fuel primarily over the road. This will include off-the-shelf, 1- and 2.5-gallon prepackaged jugs, island dispensers, top-off services sold with PMs, and emergency roadside refills using 1- and 2.5-gallon jugs. Truck dealers are expected to offer top-off services as part of scheduled PM.
The shelf life of DEF is influenced by the ambient storage temperature. DEF will degrade over time depending on temperature and exposure to sun light. If stored between 10 and 90 degrees F, shelf life is easily one year. If the maximum temperature does not exceed approximately 75 degrees F for an extended period of time, the shelf life is two years. All DEF packages will have a date code located on the product to indicate the date it was manufactured.
DEF is Not a New Technology
Urea (DEF) is a compound of nitrogen that turns into ammonia when heated. It is used as a fertilizer in agriculture. The raw materials used to produce DEF include natural gas, coal, or other petroleum products.
"DEF is not a new technology," said Lounsbury. "However, only a handful of companies make urea," said Lounsbury.
DEF is less toxic than other automotive fluids and is classified as a nonhazardous substance by the EPA and Department of Homeland Security. "Using OSHA criteria, DEF is considered non-hazardous," said Lounsbury.
SCR is an aftertreatment technology that treats exhaust gas downstream of the engine.
"The urea is sprayed as a fine mist into the hot exhaust gas," said Lounsbury. "This breaks it apart into ammonia and CO2."
The ammonia is the desired product, which in conjunction with the SCR catalyst, converts NOx to harmless nitrogen and water.
DEF is a carefully blended aqueous urea solution of 32.5-percent high purity urea and 67.5-percent de-ionized water. The fluid is colorless and largely odorless. All vehicles equipped with SCR will use the same specifications for DEF.
The 32.5-percent urea concentration is the ideal solution, as it provides the lowest freeze point. Also, SCR systems will be calibrated to 32.5 percent to optimize NOx reduction during vehicle operation.
A 32.5-percent solution of DEF begins to crystallize and freeze at 12 degrees F (-11 degrees C). At 32.5 percent, both the urea and water freeze at the same rate, ensuring that as it thaws, the fluid does not become diluted or over-concentrated. "The freezing and unthawing of DEF will not cause degradation of the product," said Lounsbury. DEF has been used in Europe for years and cold-weather use in Scandinavian countries has never been an issue.
During vehicle operation, SCR systems are designed to provide heating for the DEF tank and supply lines. If DEF freezes when the vehicle is shut down, start-up and normal operation of the vehicle is not inhibited. The SCR heating system is designed to quickly return the DEF to liquid form, and vehicle operation is not impacted.
DEF expands by approximately 7 percent when frozen. DEF packaging and tanks are designed to allow for expansion. In terms of dispensers, Johnson of Gilbarco Veeder-Root said a specialized heater design is used with the Encore S DEF dispenser.
DEF’s Widespread Use in the European Truck Fleet Market
The North American DEF market will most likely parallel the European market, according to Johnson.
Although used for the first time in the U.S., SCR-technology has been in extensive and widespread use in Europe, Japan, and Australia.
All European truck manufacturers currently offer SCR-equipped models, and the future Euro VI emission standard is set to reinforce the demand for this technology. Europe has more than 600,000 trucks using SCR, and the SCR-equipped fleet is growing by approximately 25,000 trucks per month.
In Europe, DEF is marketed as AdBlue, a registered trademark for AUS-32 (Aqueous Urea Solution 32.5 percent). The AdBlue trademark is currently held by the German Association of the Automobile Industry (VDA), which ensures quality standards are maintained in accordance with ISO 22241 70070 specifications. DEF sold in the U.S. will meet the same specifications as the fluid sold in Europe.
The use of SCR technology in Europe made it necessary to develop an AdBlue supply infrastructure. AdBlue is available at thousands of service stations and can be purchased in canisters of 5 or 10 liters throughout Europe. Larger quantities of AdBlue can be delivered in 200-liter drums, 1,000-liter Intermediate Bulk Containers (IBCs), and in bulk.
The current generic name in North America for AUS-32 is diesel exhaust fluid (DEF). Some truck industry OEMs have developed branded SCR solutions, such as Daimler's BlueTec in the U.S.
Detroit Diesel, owned by Daimler, has been testing the Daimler-developed BlueTec system for more than 25 million miles of on-road driving.
According to Detroit Diesel, in addition to clean exhaust, BlueTec-equipped engines can provide a 5-percent fuel economy boost over the same engines certified under existing 2007 EPA standards.
Evolution of DEF Dispensing
The first retail DEF dispenser sold in North America was the Encore S shipped by Gilbarco Veeder-Root last September.
The trucking industry is moving to develop a national distribution network for DEF since SCR-equipped trucks will need to fill onboard tanks with DEF approximately 10-20 times a year.
Initially, DEF will be most widely available in jugs and bulk drums or totes with hand pumps through truck dealerships, truck stops, and direct distribution to fleets. But, as more SCR-equipped trucks are sold, bulk distribution through automated dispensers is expected to grow rapidly.
Pilot Travel Centers, headquartered in Knoxville, Tenn., was the first to roll out DEF availability at its North American truck stops. Last August, it rolled out the new Gilbarco Encore S DEF dispensers at 100 locations. In third quarter 2009, Pilot started rolling out 25 bulk dispensing units per quarter so that approximately 100 Pilot locations ultimately will have bulk dispensing capabilities at fuel islands. All 328 Pilot truck stops will have the packaged quantities available.
A typical bulk dispenser for use at a truck stop or large central refueling facility costs between $15,000 and $50,000.
"Gilbarco's Encore DEF dispenser operates the same as all Gilbarco Encore S dispensers; however, users cannot upgrade their existing fuel dispenser to dispense DEF," said Johnson. The Encore S DEF dispenser incorporates a familiar customer user interface and provides consistent branding. It incorporates a stainless steel mass flow meter instead of a volumetric flow meter, as used to dispense diesel fuel.
"A mass flow meter provides accurate dispensing and greater durability since there are no moving parts, and as a consequence, no wear and tear," said Johnson.
The Encore S DEF dispenser is designed specifically to prevent DEF freezing and crystallization with a thermostat-controlled heated insulated cabinet and specially-designed optional hanging hardware. Mounted in the DEF cabinet is a 750 watt/120v heater. The heater turns off when the ambient temperature in the cabinet reaches 41 degrees F.
The Encore S DEF dispenser's hydraulics are stainless steel to protect against corrosion, offering a four-year corrosion warranty. The design will feature a sliding nozzle cover to further minimize crystallization, said Johnson.