Cat moves ACERT into power generation

Diesel Progress North American Edition, Feb, 2006 by Mike Osenga

Marking its next progression in the application of its ACERT emissions technology, Caterpillar has announced the availability of a new line of engines for stationary diesel-fueled generator sets.

As has been well documented, Caterpillar announced ACERT for the truck markets first, moved it into off-highway uses (including its own machines) almost immediately thereafter and more recently announced marine ACERT engines.

Now Cat's attention turns to electrical power generation uses. The Cat generator sets involved in this announcement encompass a power range from 225 kW to 1000 kW for the 60 Hz markets, and 250 kVA to 1100 kVA for 50 Hz uses. Standby, prime and load management applications are seen as the primary uses.

At the top end of the new ACERT range, Cat C32 diesel-powered packages include ratings from 900 to 1000 kW, and 1000 to 1100 kVA. Cat added that the standby rated 60 Hz 900 and 1000 kW sets are available in low BSFC and Tier 2 compliant configurations, as well as meeting New Source Performance Standard for Stationary Reciprocation Compression Ignition Engines (NSPS) requirements.

Ratings for Cat's new C18-powered package include 550 to 600 kW (standby) and 500 to 545 kW (prime) in a 60 Hz model, and 550 to 700 kVA (standby) and 500 to 635 kVA (prime) in a 50 Hz model. The 60 Hz model in this range meets Tier 2 EPA certification and the 50 Hz model is available in low BSFC and low emissions configurations, Cat said, as well as NSPS requirements.

Smaller sets, all powered by Cat's C15 diesels, have ratings for the 60 Hz markets, from 350 to 550 kW (standby) and 320 to 455 kW (prime). These units are EPA Tier 3 certified (320 to 450 kW), Tier 2 certified (455 to 550 kW), and low BSFC (320 to 500 kW) ratings. EPA Tier 1-capable models also became available in the fourth quarter of 2005 to meet the requirements of the NSPS.

Below that, C9-powered sets include a 250 to 300 kW standby rating and 225 to 275 kW prime power rating, all with Tier 3 certification, Cat said.

Cat said the ACERT technology used in these Cat generator sets along with meeting U.S. EPA Tier 2 and Tier 3 stationary emissions standards, will also serve as the foundation for meeting EPA Tier 4/EU Stage 3B emission levels in 2011.

While some have viewed ACERT as a fixed technology package, the system has changed depending on application, and this foray into electrical power generation is no different. This is not simply the truck ACERT technology going on a gen-set.

For this introduction, Caterpillar is describing ACERT as "a synergistic approach utilizing a suite of complementary building-block technologies that can be individually adapted to accommodate a specific application."

Further, Cat said, "the building blocks of ACERT Technology have been tailored to meet the emissions requirements for stationary diesel generator sets in a variety of applications." It lists a smaller footprint and increased power density, resulting in lowered installation costs and more flexible installation options as major benefits.

Specifically, for electric power generation applications, the three building blocks of this ACERT include integrated electronics, advanced air management and precise fuel delivery.

Compared to truck uses, this means no intake valve activation, a single turbocharger (vs. series turbos) and no oxidation catalyst. All in all, a technology package applied specifically for power gen uses, said Mark W. Craig, division manager, Caterpillar Inc. Global Engine Development.

"At this point, this is the system we need to meet the needs of the electrical power generation markets," Craig said, acknowledging it was a simpler, lower-priced system than needed for truck or off-road applications.

The ADEM A4 electronics used for power gen ACERT engines are designed to reduce emissions, as well as optimize power and fuel economy, Cat said. The ADEM A4 electronic control module sends out signals that fuel injectors convert into mechanical responses, resulting in precise fuel delivery and better response, Cat said.

On the air management side, Craig said, "the system automatically adjusts to the airflow requirements on the engine, allowing for higher boost levels and increased airflow. This ultimately means better engine performance, as well as maintained fuel economy."

Cat said the third and final building block of this ACERT system is fuel delivery. Engines with ACERT Technology in the 225 to 300 kW power range will use Cat's HEUI electronic fuel system. Determined by the engine's electronic control module, small amounts of fuel are injected at the appropriate times to achieve fuel economy and lower emissions.

Larger engines, with ranges above 300 kW, use Cat's Mechanically Actuated Electronically Controlled Unit Injector (MEUI) fuel system that uses a multiple injection technology similar to the HEUI fuel system.