Engine emission impacts in portable power

11 September 2012

Cummins’ 150 kW (187 kVA) output C150D6R generator is certified to US Tier 4 Interim standards and a

Cummins’ 150 kW (187 kVA) output C150D6R generator is certified to US Tier 4 Interim standards and also boasts lower noise emissions.

The latest wave of engine emission laws in Europe, the US and Japan is having a profound impact on the design of portable compressors and generators, as well as their cost.

A major overhaul is underway in the industry - from the start of last year, the US Tier 4 Interim and EU Stage IIIB laws began to apply to many of the off-road diesel engines that are used in generators and compressors, putting stricter limits on emissions levels from diesel engines in off-highway applications. The laws cover compressors in Europe and both compressors and generators in the US.

The first wave of the legislation, which took effect from the start of 2011, applied to 130 kW to 560 kW engines - the larger end of the portable power market. The start of 2012 saw 56 kW to 130 kW engines affected, followed by 37 kW to 56 kW units at the start of 2013.

The Tier 4 Interim legislation calls for a -90% reduction in particulate matter (PM) along with a -50% drop in nitrous oxide (NOx).

To achieve these reductions in pollutants, engine manufacturers are using a range of exhaust aftertreatment systems with other technologies. Depending on the engine size, this could mean a combination of cooled exhaust gas recirculation (EGR), selective catalytic reduction (SCR), diesel oxygenation catalysts (DOC) and diesel particulate filters (DPFs).

At the same time as making exhaust fumes cleaner and improving fuel efficiency, such technology adds significant cost to machines like compressors and generators. There is also the extra bulk of the engine package, making it more difficult to keep machines small and easily portable.

Another issue is where you can use the Tier 4 Interim/Stage IIIB engines - they are very sensitive to fuel quality and can only run on ultra-low sulphur diesel. While this high quality diesel is widely available in regulated countries like the US and Europe, it is more difficult to find consistently elsewhere in developing regions. And the wrong fuel won't just cause minor problems for these engines, it could be fatal.

The rental industry is a primary target market for manufacturers of generators and compressors, and the fact that the strict emissions laws limit their scope in terms of travel will present a challenge for both hire companies and, further down the line, the second hand market.

Director of sales at Multiquip Jim Rose also explained that these significant technological improvements had also not come without a cost.

"Today's Tier 4 Interim diesel engines are certainly more expensive than similar sized engines of just a few years ago. With Tier 4 Final regulations looming in the horizon [January 2014] they will likely prove to be even more expensive in the future," Mr Rose said.

"Consumers will have to adjust to the changing market, in the form of higher rental and purchase costs. There simply is no choice as all engine manufacturers must adhere to the Federal emissions standards," he added.

Noise reduction

Mr Rose said another trend affecting generator design today is noise control. "Companies are facing industry pressure to suppress engine noise. Much of this stems from mandated codes and standards from city, county and state authorities. These mandates, along with engine emission requirements, have forced builders to design packages to meet these operational needs."
Multiquip has launched new Tier 4 Interim-compliant generators that reflect these design challenges - the DCA150SSC (150 kVA), DCA180SSC (180 kVA), DCA220SSC (220 kVA) and DCA300SSC (300 kVA) units. Each is equipped with a DPF which traps soot from the diesel engine exhaust and cleans itself either automatically or through operator selection in a burn-off process called regeneration.

"The design packages allow for necessary engine emission hardware to be installed within unit enclosures. There are no requirements for external fixtures," Mr Rose said, adding that the manufacturer had recorded significant fuel savings with the new generators, compared to predecessor models.

Cummins' latest mobile generator sets - the 150 kW (187 kVA) output C150D6R and 200 kW (250 kVA ) output C200D6R models - are also certified to US Tier 4 Interim standards and boast a range of new features, including lower noise emissions.

Larry Fetting, general manager of Cummins Power Generation's Americas rental segment said, "Our customers require the new Tier 4 Interim generator sets to be consistent with the units they are successfully operating today so that they can seamlessly expand their fleet. We have managed to do this as well as add the benefit of doubling the oil change interval."

Caterpillar, too, has introduced new mobile diesel generators that meet Tier 4 Interim regulations. The XQ200 is rated for prime operation at 182 kW (228 kVA) while the XQ350 is rated for prime operation at 320 kW (400 kVA).

Caterpillar's Clean Emissions 2 module, a key component helping the generators achieve Tier 4 Interim certification, features a passive regeneration process that runs in the background without affecting the unit's running capacity.

Other environmental considerations also incorporated into the XQ200 and XQ350 include a solar powered battery maintainer which keeps the batteries fully charged when not in use. The generators are also in sound-proofed containers which are said to reduce operating noise.

Both the XQ200 and XQ350 are equipped with the manufacturer's new EMCP 4.2 control panel. The system automatically adjusts performance parameters to match voltage and speed positions - an advantage when moving between multiple job sites with differing voltage or frequency needs, and particularly useful for the rental market.

Rental target

The rental market is also a key target for Doosan Portable Power (DPP), whose latest launches include the G150-IIIA and G200-IIIA portable generators and a five-model range of new Stage IIIB/ Tier 4 Interim-compliant compressors.

Alex Persyn, business director at Doosan Infracore Portable Power Europe Middle East and Africa said the new emissions laws were resulting in a change of culture in the portable power rental industry.

"Stage IIIB technology is less forgiving than the Stage IIIA technology - if there is too much sulphur in either the diesel or the oil, the DOC and the DPF can stop working so performance will be affected. This is affecting where our customers can take their products," he said, explaining that one trend may well be for rental companies to own two tiers of fleets - one to service portable power needs in highly regulated markets, and another tier of machines with less sophisticated engines that can cope with a range of fuel qualities.

Mr Persyn also noted that the new components necessary to achieve compliance with the latest emissions laws don't come cheap.

"Depending on the size of the compressor, the Stage IIIB units can be up to +45% more expensive than the previous stage machines," he said. "It is a difficult economic environment to be pushing through this kind of price increase, so I think in the short term people will be hanging on a bit longer before they repurchase, and I think the price of second hand equipment will also increase."

On the compressor side, Doosan's Stage IIIB 9/275, 9/305, 12/250, 17/240 and 21/220 models are based on a new platform and offer air deliveries from 21.5 to 30.0 m3/min. Powered by Cummins QSL9 engines incorporating EGR, DOC and DPF after-treatment, the new units offer a smaller footprint than their predecessors - a feat which Mr Persyn said was a major design effort.

Mr Persyn also revealed that Doosan is working on a new, Stage IIIB-compliant high pressure compressor which will boast a new platform that is -18% smaller than older models - the 25/280.

Offering 28.3 m³/min of free air delivery at a rated pressure of 25 bar, the new unit will also offer 10 hours of run time at full load using its Caterpillar C13 engine. Designed for construction drilling, quarry and geothermal drilling applications, the 25/280 will also sport a new control system with full colour digital display
"We always want to be offering value and doing something different. I hope to have the first machine on show towards the end of the year," Mr Persyn said.

Kaeser Kompressoren, in contrast to Doosan, opted to use Mercedes-Benz diesel engines with SCR systems to comply with the Stage IIIB emissions laws. Its new model, the Mobilair M 350, can also deliver up to 34 m³/min of air (+20% more than its predecessor), but Kaeser Kompressoren claims it is "barely heavier" than the model it replaces.

The new compressor also comes with a range of options to increase versatility. For instance, air treatment components can be added to provide cool, dry, technically oil-free air of various classes to meet special demands, for example to adhere to German regulations for concrete repair work.

Other manufacturers are also adding to the range of outputs they offer. IMT has expanded its compressor line up with the launch of the CAS45R and CAS60R rotary screw air compressors and the CAS40P reciprocating model. Rotary screw compressors are normally used in applications above 30 hp (22 kW) and for air up to 150 psi (10 bar), while reciprocating models cover lower horsepower but demanding applications where reliability is essential.

The CAS45R offers a rated capacity of 45 cfm (76 m3/hr) at 150 psi (10 bar), while the CAS60R provides air delivery of 60 cfm (102 m3/hr) at 150 psi (10 bar) and have been designed to provide high-volume air for use in pneumatic tools.

The CAS40P delivers a rated capacity of 40 cfm (68 m3/hr) at 100 psi (7 bar) and is a two-stage, four-cylinder compressor designed for mobile applications that do not have high-volume air needs.

Next phase

There can be no doubt that emissions laws in Europe and the US have shaped many of this year's product launches, but manufacturers which have worked hard to meet this challenge cannot breathe a sigh of relief yet.

With Tier 4 Final and Stage IV laws looming on the horizon, many of today's designs will need to change again.

Multiquip's Jim Rose said, "Once the Tier 4 Final regulations are in full effect, engine manufacturers will be able to stabilise their designs without having to plan forward for further changes. This will help stabilise generator package designs and allows companies like Multiquip the opportunity to focus on other design criteria such as further noise reduction and environmental containment."
These are areas which Doosan's Alex Persyn also highlighted as possible future directions for the portable power market.

"The next changes will be more customer driven than regulation driven," he said. "There is no European directive for containment bases, for instance, but all our new designs currently feature them as standard because they're in demand. Ecology will definitely continue to be an important theme in the future,"
Mr Persyn added.

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