EPA Tier Ratings for Generators

In the mid-1950s, the U.S. government started controlling atmospheric pollutants. The passage of Environmental Protection Agency (EPA) regulations governing diesel engine emissions forced manufacturers to improve engine performance and limit the amount of pollutants these engines send into the atmosphere.

While diesel generators were not the original target, they are now subject to EPA regulations. Currently, stationary and non-road mobile diesel engines, such as those used in generator sets, are included in the stringent oversight of the U.S. EPA. 

Phased Emission Generator Tier Ratings

The EPA implemented emissions reductions in phases to allow scientists, manufacturers and the market to develop technologies, knowledge and funds necessary for compliance. Each tier level provides a cap at which point emissions must be restricted, and each advancing tier builds off of the last.

EPA Tier 1 Emission Standards

The first phase, which came in 1990, gave a substantial increase in authority and responsibility to the federal government to authorize the issuance of operating permits to stationary sources. It provided the first set of emission standards covering all new non-road mobile diesel engines, regardless of horsepower categories, except those engines used in locomotives and marine vessels.

EPA Tier 2 Emission Standards

The second phase was adopted in 1999, tightening pollution regulations. It addressed NOx (a generic term for the mono-nitrogen oxides NO and NO2), carbon monoxide, unburned hydrocarbons and particulate matter emitted. Tier 2 covered all engine sizes from 2001 to 2005. Tier 1 standards were still applicable to engines over 37kW.

EPA Tier 3 Emission Standards

Tier 3 regulations were implemented between 2006 and 2008, restricting exhaust emissions for engines between 50 and 750 hp.

EPA Tier 4 Emission Regulations

The final ruling was signed on May 11, 2004 with guidelines to phase it in over the period from 2008 to 2015. Since Tiers 1-3 sulfur content was not covered by stringent environmental regulation, Tier 4 was mandated by EPA to reduce sulfur content.

The new standards require a 90 percent reduction of PM and NOx emissions. The emission reductions are to be achieved through the use of new control technologies similar to the 2007 to 2010 requirements for highway engines that included advanced after-treatment of exhaust gas.

Key Features of Tier 4 Standards

Tier 4-certified generators have no run-time restrictions as they can be used as backup power anytime they are needed. Owners of Tier 4-certified generators have a lot of flexibility to use their machines as needed.

Tier 4-certified generators are targeted at environmentally-conscious customers. They use the best emissions-reduction technology available with the aim of diminishing the exhaust emissions to nearly zero. It is expected that by the year 2030, 12,000 premature deaths will be prevented annually due to the implementation of these higher standards.

EPA Regulations on Diesel Engines Today

The New Source Performance Standards require most stationary diesel engines to meet the emission requirements of Tiers 2-4, depending on the engine’s power range. Beginning in 2011, non-emergency diesel engines using less than 10 liters per cylinder and greater than 175 horsepower are covered by Tier 4 regulations. Owners and operators of non-emergency generators are required to keep records of all run-time hours, indicating the reason for and the duration of use.

A generator classified as an emergency generator must not run unless the primary source of electrical power is not available. It is allowed to run for testing and maintenance but not for more than 100 hours per year in non-emergency situations. This is a result of the EPA’s efforts to reduce pollutants, air toxics and other harmful emissions from diesel fuel that have led to significant health and environmental benefits, as well as new advanced technology.

Americas Generators’ Tier 4 Diesel Generators

Power outages do not spare facilities such as hospitals, schools, airports and emergency dispatch centers. Power interruption to these facilities could result in unimaginable damages that may compromise people’s lives. These entities need standby generators to provide continuous power, even when the regular electrical lines are not working.

Americas Generators offers a wide selection of top-performing generators that will keep essential services up and running in times of need. This selection includes EPA-certified diesel generators that are ready to ship, complete with all required EPA certifications.