At first glance, the Environmental Protection Agency’s off-highway emissions standards seem like a bunch of technical regulations that apply more to engine manufacturers than the average contractor. But getting an understanding of these regulations is important to even the smallest construction company because current and future emissions regulations are changing the industry.
This year, Tier 3 low-emission off-road diesel engines in the 175- to- 300-horsepower class began rolling off the assembly lines as a continuation of pollution reduction standards mandated by the EPA in 1996. These regulations were designed to reduce the amount of nitrogen oxide (NOx), particulate matter, carbon monoxide and hydrocarbons that engines release into the air. The EPA issued rules for on-road and off-road simultaneously, but the on road regulations kicked in earlier and have been more strict. Next year the Tier 3 standards will apply to the off-road engines in the 100- to- 175-horsepower class and in 2008 regulations for engines in the 50- to- 100-horsepower range kick in. After that comes the introduction of even more stringent Tier 4 emissions standards in 2011. But how will these standards affect you and your fleet?
The silver lining in all of this is that manufacturers used the emissions requirements to introduce new technology into the market, upgrading their engines with things like high pressure common rail fuel injection, computerized controls, sophisticated electronic monitoring systems, better air-handling and improved combustion.
Caterpillar developed the ACERT (Advanced Combustion Emissions Reduction Technology) engine, which uses multiple injections in different combinations into the cylinder for each combustion cycle and has an advanced air system that provides needed air for different loads and speeds.
Most other OEMs produced different variations of Exhaust Gas Recirculation (EGR) designs to get a more complete combustion cycle. During combustion, an EGR engine diverts a small portion of the exhaust gas back into the cylinder, lowering combustion temperatures and reducing NOx. The engines produced by Cummins use in-cylinder combustion technology to optimize fuel and air parameters and reduce emissions without the need for EGR, after treatment or variable geometry turbochargers. John Deere’s PowerTech models use cooled EGR with variable geometry turbochargers and four-valve cylinder heads. Volvo’s Advanced Combustion Technology (V-ACT) has a flexible fuel injection system with high-pressure capability.
Doug Laudick, product manager for John Deere’s Tier 3/Stage III A engine programs, says contractors need to understand the fundamental impact of these changes on such things as engine performance, cold-weather performance and fuel economy. “While some engines show fuel economy gains with Tier 3,” he says, “other engines might be less efficient and require a larger fuel tank to maintain previous running times between fill-ups.”
“Emissions regulations are bringing some significant benefits to contractors in their operations,” says Bruce Farrar, off-highway communications manager for Cummins. “These include less white smoke at start-up, quieter operation, better cold-weather starts, and idle stability – all significantly improved with Tier 3 over Tier 2.”
Meeting regional standards
The EPA’s regulations only affect manufacturers. But in certain areas of the country – high population urban areas with substandard air quality – state and local environmental agencies have imposed a different and somewhat varied set of rules that apply to contractors. In these areas (primarily Texas, California, Illinois and New York) contractors wanting to bid on government jobs must have all the machines in their fleets certified as Tier 3 or else retrofit existing machines to meet Tier 3 emissions standards. Examples of state standards include rules imposed by California’s Air Resources Board, the Texas Emissions Reduction Plan, and various programs offered by the Illinois Environmental Protection Agency’s Bureau of Air.
“There isn’t a regulation that says that you have to make all of your machines meet Tier 3 standards,” says Fred Schmidt, director of sales for Donaldson, which produces after treatment devices for retrofitting. “These rules are much more project-oriented than regulation-oriented. For example, if there is a highway contract that stipulates using clean diesel equipment, you have to meet those standards to even be eligible to bid on the project. That’s the reality. If there is a contract requirement and the contractor has to retrofit, then it’s the price of admission even if they met regulations at the time of purchase.”
And these modifications can be substantial. One way to modify a machine is to replace the old engine with a new Tier 3 engine. This is called repowering. The other way is to add aftermarket exhaust devices that scrub particles out of the exhaust stream.
Currently, there are two types of after-treatment devices on the market available for both on-road and off-road. The first is the diesel oxidation catalyst. The DOC is a flow-through device that acts as a catalytic converter, just like in an automobile. Exhaust gases blow past a heated catalyst, which burns the contaminants at a relatively low temperature and reduces them to carbon dioxide and water vapor. The other type is the diesel particulate filter (DPF), which burns exhaust gases but also traps hard carbon particles in the exhaust stream and then burns them up. The particulate filters look like an oxidation catalyst except every other channel is plugged at one end to create a filtration effect.
The price for retrofitting these aftermarket devices depends on the horsepower. Schmidt says you can expect to spend about $8,000 to $10,000 for a DPF and $2,000 to $4,000 for a DOC. Compared to the on-road truck market, retrofitting off-road equipment is a lot more complex.
“If you try to retrofit a particulate filter, it won’t always fit in the same sized envelope as the OEM muffler,” says Schmidt, “so you have to put it outside of the housing. When you install these devices on the outside of your cab you create line-of-sight problems for the operator.”
DOCs are approximately 20-percent efficient, while DPFs are 90-percent efficient, although their efficiency depends on the specs of your engine. Tier 0 engines are too much for DPFs to handle because older engines put out such a high volume of emissions that the filter can get clogged. Tier 1 engines can sometimes use DPFs, depending on their emissions, but Tier 2 engines do fine with DPFs.
To help contractors retrofit their fleets to meet local and regional clean air requirements, the U.S. Government established the Diesel Emissions Reduction Act in August 2005. The DERA is a grant and loan program designed to reduce emissions through clean diesel retrofits. The law designated $200 million for contractors interested in retrofitting older machines – but President Bush’s budget for this year dropped that amount to $50 million.
As of this writing, Congress still has yet to make the funds available. According to Chris Cashman, spokesperson for the Diesel Technology Forum, the amount coming will probably be at the $30 million level. “It will definitely be a program contractors can apply for in 2007,” he says. “It is all up to the budget process.”
When the funds become available, 70 percent will be administered by the EPA, and 30 percent will go to states to develop their own loan and grant programs. The EPA will set guidelines on the application process after the authorization of these funds.
Tier 4, a peek into the future
The next major change in emission control for off-road engines comes in 2011 with Tier 4. These changes will affect engine technology in several ways.
“Contractors should start thinking about what they need to do a year in advance,” says Dan Arcy, technical manager for Shell Lubricants. “That will give them plenty of time to make adjustments. They will have to take into consideration handling the changeover and the type of fuels and oils they use.”
Tier 4 engines will mandate a 90-percent reduction in NOx and particulate emissions. To achieve these standards, engines will come off the assembly line with after-treatment devices already attached. A year before Tier 4 standards take effect, all off-road engines are required to use diesel fuel with a maximum sulfur content of 15 parts per million, and the engines manufactured will likely use CJ-4 oil. By 2014, high-efficiency NOx after treatments will be required for off-road engines.
The ultra low sulfur diesel (USLD) rules for off-road are taking effect later than on-road, which went into place this October. The benefit of ULSD is it produces less particulate matter than fuels with higher sulfur content.
EGR engine designs create high levels of soot and heat and CJ-4 will help manage these. You can use CJ-4 in older engines, but using the older CI-4 spec oils on the newer engines can clog after-treatment devices, resulting in increased maintenance costs. CJ-4 does have cost issues and restrictions that contractors need to be aware of.
“The cost of CJ-4 oil is estimated to be anywhere from 10 to 30 percent more than current CI-4 Plus formulations,” says Ken Chao, petroleum products support, John Deere. “The CJ-4 engine category has a reduced ability to handle diesel fuels with more than 15 ppm sulfur content, so its use with these higher sulfur fuels will likely result in a reduced service life as compared to existing CI-4 or especially CI-4 Plus oils.”
Because the technology for these standards isn’t yet developed, it is hard to tell how much Tier 4 engines will add to the cost of equipment.
“Clean air isn’t cheap,” says Farrar. “We have seen the same thing happen in the automotive industry. When you look at how to keep emissions cost-effective, keeping it simple is important. But the more add-on components there are, the more costs there are.”
Other NOx reduction methods
In addition to DPFs and DOCs manufacturers are looking at several other technologies to help them attain the Tier 4 standards for off-road engines. These include:
Selective Catalytic Reduction (SCR): Uses a chemical reductant, such as urea, which converts to ammonia in the exhaust system and reacts with NOx over a catalyst to form nitrogen gas and water vapor. Urea injection rate is important with this system. If injection is too high, the ammonia reacts with the NOx and some will slip through the catalyst. If rate is too low, NOx reaction is not achieved. SCRs are tolerant to high sulfur fuels.
NOx absorbers: Developed in the late 1990s, this method uses a combination of base metal oxide and precious metal coatings to control NOx. A base metal such as barium oxide, for example, reacts with the NOx to form barium nitrate, effectively storing the NOx on the surface of the catalyst. When the available storage sites are occupied, the catalyst is operated briefly under fuel-rich, low-oxygen exhaust gas conditions. This releases the NOx from the base metal and allows it to be converted over the precious metal components to nitrogen and water vapor. NOx absorbers are not tolerant to high sulfur fuels.
Lean-NOx Catalysts: Uses unburned hydrocarbons to reduce NOx over a catalyst. The catalyst may contain precious metals such as platinum or zeolite. The successful operation of a lean-NOx catalyst requires continuous injection of fuel upstream of the catalyst. Lean-NOx is often an excellent option for retrofits. They are easy to install with existing engine systems.
