Emissions of Standby Generators

Emissions are the chemicals that are byproducts from engine combustions. Car engines release emissions, which means generator engines do too.

A diesel engine can release:

  • Nitrogen Oxide
  • Hydrocarbons
  • Carbon Monoxide
  • Particulate Matter

These are emissions that are monitored for environmental safety, so engines have to abide by a certain set of standards.

Stationary Diesel Engines Before 1996

Before July 2006, regulations for stationary diesel engines, which were mostly used for power generation up until that point, where “way off” from the regulations for other types of diesel engines. This is because there were no federal emission regulations for the engines used in generators. State and local authorities governed emission regulations and the way they governed it as by hours of operation.

This is when the EPA stepped in to finalize regulations for these engines. The regulations for generator diesel engines were more in-tune with other types of diesel engines.

As a result, engine manufacturers have to certify their engines with the EPA. The regulations are divided into tiers based off of kW hours that are used, horsepower, and the year the engine was produced.


Reciprocating internal Combustion Engines (RICE) is what generator engines are referred to because of how they operate. These engines are used in residential and commercial generators. The EPA regulates RICE because of the impact that common combustion sources can have on the environment. RICE requirements are based on:

  • New or used engine
  • Engine area or the main power source
  • The engine emergency standby power source

There are also a number of federal requirements embedded within a number of codes devised by the EPA. The RICE rule applies to engines that are used as a major power source and are greater than 500 hp (existing engines, new engines, and reconstructed engines constructed on or after 12/19/2002). It also applies to engines that are 500 hp or less and used as major power sources that are existing, new, or reconstructed on or after 6/12/2006.

All in all, the emission requirements help individuals and businesses have the standby power that they need while minimizing their carbon footprint as much as possible, particularly with diesel engines. Diesel standby generators are very efficient and popular among industrial applications, as well as residential.

To ensure that a generator continues to be in compliance, it is very important to maintain a generator. This means having the engine serviced on a schedule so that it is in good working order at all times, making sure the cooling system works well, and checking the air and fuel systems.