Beginning Jan. 1, 2015, the Environmental Protection Agency (EPA) will require the final phase of transition to Tier 4 Final-compliant diesel engines to be installed in mobile generators like those commonly used in the construction and utilities industry. To meet Tier 4 Final standards, engines with advanced emission control technologies similar to those used for highway trucks and buses will be mandated in all newly manufactured generators ranging between 19 to 560 kW. Generators rated 560 kW and larger will have an additional year to transition to Tier 4 Final standards.
Tier 4 Final is the last step in The Clean Air Non-road Diesel Rule, a program aimed at reducing emissions from non-road diesel engines by integrating engine and fuel controls as a system. Once fully implemented, Tier 4 Final compliance is expected to reduce exhaust emissions by more than 90 percent.
Moving Beyond the Interim
The transition to Tier 4 Final began in 2008 and was a two-step transition (Interim and Final) that has occurred in phases as the EPA segmented each transition into horsepower categories with specific emission reduction requirements for each power category, driving development of specific engine technologies to meet those requirements. The most recent stage, Tier 4 Interim or Tier 4i regulations, required manufacturers to address reduction of particulate matter (PM) most commonly through a diesel particulate filter (DPF) or diesel oxidation catalyst (DOC) technology.
Tier 4 Final standards call for a reduction in the emission of oxides of nitrogen (NOx). To meet the requirements, many engine manufacturers are adding a selective catalytic reduction (SCR) after-treatment system to the engine architecture. SCR injects diesel exhaust fluid (DEF) which acts as a catalyst, causing a chemical reaction that produces less harmful exhaust, and in turn, reduces NOx emissions. SCR achieves near-zero emissions, meeting Tier 4 Final regulations and providing end users with uninterrupted generator performance.
Tier 4 Final Technology
While DOC and DPF technology used in the Tier 4i solution is relatively maintenance-free, SCR requires DEF fluid to be refilled regularly, adding maintenance and operational steps to the Tier 4 Final units. In an effort to make the maintenance as convenient as possible, some manufacturers have designed DEF tanks with a runtime similar to fuel tanks, allowing both systems to be refilled at the same time. One significant difference in those tanks, however, is that some manufacturers have chosen to position the DEF fill point on the exterior of the generator package. While DEF is a non-hazardous fluid, it can corrode steel over time. Placing the DEF fill port on the exterior protects internal generator components from potential corrosion and eliminates unintentional mixing of fluids (diesel in the DEF tank; DEF in the diesel tank).
While the expense of DEF fluid will be mostly offset by improved fuel economy, the high costs associated with adding the technology necessary to meet Tier 4 Final standards are passed on to the rental house or the dealer and eventually the contractor. Because of the unavoidable price increase, some manufacturers are designing new innovative features for the Tier 4 Final models to add customer value beyond the greener engine technology. For instance, Doosan Portable Power has redesigned the control system of their Tier 4 Final models to integrate start/stop control and machine diagnostics into one panel. The streamlined design reduces clutter on the control panel and simplifies operation for the contractor. A new digital fault history display allows a service technician to view past generator errors with time stamp information that can assist in troubleshooting.
The contractor will also notice Doosan Portable Power is making the Tier 4 Final mobile generators as safe to operate as possible. At-a-glance monitoring means machine vitals — fuel level, oil pressure and engine temperature — are clearly displayed, as well as volts, amps and frequency. There are automatic shutdowns for low fuel, low coolant, low oil pressure and low DEF. The new control system also provides the option to easily connect to telematics devices and software — an emerging trend in the construction industry. Telematics makes it possible for the dealer, rental house and contractor to remotely monitor machine performance and productivity with a smartphone or computer. This information provides enhanced management of the mobile generator and faster service as well.
Telematics provides a system alert when a generator experiences a malfunction, but it can also minimize downtime by delivering vital diagnostics. The information allows a technician to diagnose the possible cause of a malfunction before arriving onsite, eliminating multiple trips for appropriate parts or tools. Telematics can also provide the exact position of a machine. This geo-mapping capability is especially beneficial for generators used at isolated jobsites, such as powering a pump jack in the middle of an oil field, or heavily congested urban areas with one-way streets and thoroughfares. Telematics can also be used for theft prevention with geo-fencing functionality.
Transitioning to Tier 4F
While contractors are not required to retire or replace non-compliant equipment currently in use, aging equipment will eventually reach the end of its life cycle. Upgrading to a mobile generator with a Tier 4 Final engine may prove more profitable in the short term as environmental standards become more common at jobsites and emissions performance becomes more of a factor in awarding job bids. Local and state regulations are also a consideration. For example, California has adopted its own emissions standards for certain types of new non-road engines or equipment. In those cases, manufacturers must certify their products with the California Air Resources Board.
Tier 4 Final generators are being built to meet emissions standards with the end-user in mind. This means that as the emissions technology evolves, mobile generators will still maintain the same durability and reliability the industry expects with value-added features that improve performance, productivity and operation.
Todd Howe is the global generator products manager at Doosan Portable Power.