Retrofit Reluctance

Even as off-highway manufacturers adapt to new, clean diesel engines, the push to reduce emissions from existing equipment is gaining momentum. Several state governments, including California, Texas and New Jersey, have implemented retrofit programs, and the federal government is in the process of funding the first year of a five-year national program to help cover the costs of turning older "dirty" diesel equipment into clean machines.

Because diesel engines can last 20 to 30 years, it would take decades to replace existing equipment with low-emission engines. That's too long for regulators, because off-highway equipment is responsible for between 55 and 75% of all particulate emissions. They see equipment retrofits — basically the addition of oxidation catalysts or particulate filters to existing equipment — as an economical way to reduce emissions quickly.

"For cities and states struggling to meet strict new air quality standards, clean diesel retrofit projects have proven themselves to be one of the most cost-effective, immediate solutions for reducing emissions," says Allen Schaeffer, executive director of the Diesel Technology Forum, a trade group that represents manufacturers of engines, fuel and emission control systems.

A cost-efficient solution

It costs about $5,390 to remove one ton of nitrogen oxides (NOx) through retrofits, compared to $126,400 for alternative fuels, according to estimates compiled by the trade group.

Oxidation catalysts use a chemically coated, honeycomb substrate to reduce PM emissions by 20 to 50%, and HC and carbon monoxide (CO) emissions by 60 to 90%. Particulate filters use fiber-wound cartridges, sintered metal or impregnated paper to trap soot particles, effectively reducing PM, HC and CO emissions by up to 90%. NOx emissions can be reduced using exhaust gas recirculation, selective catalytic reduction (SCR) devices and NOx catalysts.

"Oxidation catalysts are definitely the preferred technology for off-highway because they can be a direct muffler replacement," says Joseph Kubsh, executive director of the Manufacturers of Emission Controls Assoc. "They take up the same space and have the same noise attenuation."

While several companies have received regulatory approval for their emission-reduction devices, original equipment manufacturers remain cautious.

"There certainly is a general reluctance out there," says Kubsh. "Some OEMs are gung ho; others are trying to understand all of the ramifications. There are concerns about safety and performance."

Back pressure generated by low-quality or poorly maintained aftermarket components could lower fuel economy and damage engines. Some components may not work without electronically controlled engines or low-sulfur fuel, which will not be available nationwide for another year. In addition, customers and dealers will have to deal with space concerns, especially on smaller equipment.

"Retrofits have to be accommodated in the space that is there, which means some, smaller off-highway equipment is going to be difficult to retrofit," Kubsh says.

The California mandate

It may not be long before fleet owners won't have an option. The California Air Resources Board is considering substantially more stringent guidelines for reducing particulate emissions from existing construction, mining, industrial and airport ground service equipment. It would ban the sale of Tier 0 (pre 1996) equipment, unless it is retrofitted with emission-reducing components. The proposed regulations are intended to help the state meet its aggressive goal of reducing diesel particulate emissions by 75% in the next four years.

The federal government is relying on money instead of regulations to encourage compliance. The Energy Policy Act of 2005, passed last fall, authorizes $1 billion in funding over five years to help fleet owners pay for the cost of retrofits. While the program represents a significant symbolic commitment, funding isn't guaranteed. For 2007, the Bush Administration has only budgeted $50 million in funding, one-fourth the amount authorized by the enacting legislation. Engine manufacturers are hopeful that Congress will set aside more money than the White House requested.