What Are Generator EPA Tier Ratings?
When buying a new generator, you’ll likely see that different types have different Environmental Protection Agency (EPA) Tier levels. The Tiers relate to the amount of pollutants the generators can produce while meeting the emissions standard. To understand what these Tiers mean for your generator, you should note the EPA diesel emissions standards and how they change over time. A greater appreciation of EPA Tiers will make purchasing models that emphasize generator emission reduction easier.
In 1970, the U.S. government produced a set of regulations and guidelines to strategically reduce harmful emissions and release of pollutants into the atmosphere to improve the overall air quality. These regulations put a limit on exhaust emissions for non-road diesel engines, which ended up regulating the very generators that we rely on today. Over time, these regulations became stricter and enforced greater control and requirements that generator manufacturers must adhere to and are regulated by the Environmental Protection Agency (EPA).
How DO EPA Emissions Standards Impact Generators?
The EPA regulates emissions for many types of engines — both vehicular and non-vehicular. This especially pertains to backup power generators, which are known as nonroad engines. Within this category, the EPA has different rules for compression-ignition engines, which run on diesel, and spark-ignition engines, which often use natural gas and, if converted to accept it, propane.
Because commercial generators can produce more power, they also consume more fuel and produce greater emissions. Therefore, when getting a backup generator for your business, be sure to check generator emissions requirements in your area and whether your model meets the latest requirements from the EPA based on Tier ratings.
EPA Tier ratings refer to the generator emissions requirements, corresponding to the year and size of the generator. Each Tier has increasingly strict requirements for newer generator emissions. As a result, the most recent models must adhere to the tightest regulations under Tier 4 Final emissions. The benefit of following these guidelines is a reduction in overall pollutants added to the atmosphere and a healthier workplace when the generator runs.
Diesel Engine Pollutants Regulated by EPA Standards
Diesel engines produce by-products from burning the fuel that contribute to particulate matter released into the atmosphere. The EPA standards set out to regulate these pollutants by putting limits on the amount generators can emit. As technology in fuel-burning became more efficient over time, the Tiers required tighter restrictions on emissions levels. The pollutants covered in the EPA Tiers are the following:
Nitrogen Oxides
Nitrogen oxides (NOx) include both nitrogen oxide (NO) and nitrogen dioxide (NO2). NO is an odorless, colorless gas. NO2, on the other hand, has a distinctively pungent smell and a reddish-brown color. Though both are dangerous to human health, nitrogen dioxide poses a much greater threat than nitrogen oxide. NO2 can irritate the lungs and raise the chances of getting respiratory illnesses.
While diesel engines produce more NO than NO2, the former eventually evolves into the latter after introduction into the atmosphere. Consequently, while initially less dangerous, nitrogen oxide will eventually become the more hazardous form, nitrogen dioxide. Both forms of nitrogen oxides contribute to the production of acid rain. Therefore, the EPA includes regulations to cover both under its nitrogen oxides requirements.
Engines that run at higher temperatures and have greater amounts of oxygen in combustion produce more nitrogen oxides. Regulating these factors can reduce emissions of nitrogen oxides from diesel engines.
Hydrocarbons
Hydrocarbons (HC) can be dangerous for the environment by contributing to the development of ground-level ozone. Humans breathing air with HC have greater chances of cancer and respiratory irritations. Reducing HC in emissions can lead to better health and less pollution.
HC emissions result from unburned fuel when the temperature inside the combustion chamber is not high enough. Generally, diesel engines produce fewer hydrocarbons than other types of engines. However, when operated with a lean air to fuel ratio, diesel engines have a greater likelihood of producing more hydrocarbons. Therefore, regulating the combustion temperature and the oxygen levels can reduce HC formation in exhaust from a diesel engine.
Carbon Monoxide
Carbon monoxide (CO) is an odorless and colorless gas, making it undetectable to humans. In excessive amounts, it can bind the oxygen-carrying hemoglobin, reducing the oxygen reaching the tissues and causing carbon monoxide poisoning. CO poisoning can damage organs, cause asphyxiation and be fatal.
Compared to gas-burning engines, diesel engines produce less CO in their emissions because diesel engines typically run with a lean air-fuel mixture compared to gas engines. CO often forms in rich air to fuel mixtures found more often in gas-burning engines. However, due to its dangerous nature to people in large quantities, CO falls under the EPA emissions standards.
Particulate Matter
Particulate matter (PM) is a more significant concern from diesel engines than from gasoline engines, creating fewer PM. These particulates include unburned fuel, partially burned lubricating oil, ash and other solids, which form spherical particles that leave the exhaust. In diesel engines, several factors contribute to the creation of particulate matter, including:
- Cooling of exhaust gas
- Lube oil quality
- Fuel quality
- Combustion and expansion of the fuel
- Temperature of combustion
Because PM includes minuscule solid matter, the particles cause many more problems than gases. Unlike colorless and odorless gasses, particulate matter has soot, which appears as black smoke from the engine.
PM pollution can cause agricultural problems, visibility issues and stains on building exteriors from soot. Plus, it leads to the fouling of air, soil and water. People exposed to PM can have higher chances of lung problems, cardiovascular disease, asthma and premature death. Improving diesel engine burning to reduce particulate matter can make people healthier and places that use these engines less polluted.
What Are The 4 Tiers of EPA Emission Standards?
Today’s EPA regulations were not carried out overnight but were rolled out in phases, or tiers. This provides manufacturers time to develop new technology that adheres to the EPA rules and regulations of emissions while mitigating any negative impact to the overall business. This also means that engines produced earlier have less strict Tiers to follow. Each Tier has a timeline of initial, interim and final conditions, and new generator emissions must match the requirements for their production year.
EPA Tier 1 Emissions
The first federal standard for off-road mobile diesel engines came in 1994, when the EPA adopted Tier 1 emission standards. Specifically, this standard applied to any nonroad compression-ignition engine of at least 37 kilowatts. Tier 1 was phased in starting in 1996 and continued being the standard manufacturers followed until it was gradually phased out in 1997 by the introduction of Tier 2.
EPA Tier 2 Emissions
In 1998, the EPA declared that a new program was underway to reduce emissions from nonroad diesel engines by up to two-thirds. This program would be implemented in two tiers over the course of a decade.
First came Tier 2, which initially went into effect in 2001 for generators producing power between 225 kilowatts and 450 kilowatts. Tier 2 enforced stricter regulations of Nitrogen Oxides (NOx), Hydrocarbons (HC), Diesel Particulate Matter (DPM), and Nitrogen Oxides (NOx) emitted and defined restrictions for the amount of sulfur allowed in gasoline and diesel fuel, since sulfur can interfere with the operation of advanced exhaust treatment systems, such as selective catalytic converts and particulate filters. Tier 2 continued to be phased in for various classes of nonroad diesel engines over the next five years.
EPA Tier 3 Emissions
Some nonroad engines skipped straight from Tier 2 to Tier 4. However, for engines with a power output between 37 and 569 kilowatts, Tier 3 was an additional step toward fulfilling the EPA’s goal of reducing emissions. This Tier was phased in over the course of 2006-2008 and continued to be the standard until Tier 4 was instated. EPA Tier 3 required that all new diesel generators were to be in compliance starting in 2007.
EPA Tier 4 Emissions
The current, and strictest, regulations standards for new generator emissions are EPA Tier 4. Signed into law in 2004 and first taking effect in 2008, Tier 4 was intended to regulate both nonroad diesel engines and diesel fuel to reduce particulate matter by 95%, reduce nitrogen oxides by 90% and virtually eliminate sulfur oxides completely.
EPA Tier 4 is divided into two stages — EPA Tier 4 Interim (Tier 4i) and EPA Tier 4 Final (Tier 4F):
- Tier 4i: Also called Tier 4 Transitional, Tier 4i was a stepping stone from Tier 3 to Tier 4 in its final stage. Some classes of engines skipped this interim phase, transitioning straight to Tier 4F.
- Tier 4F: The lower-output engines that went straight from Tier 2 to Tier 4F were the earliest to adhere to the current standards, starting in 2008. By 2015, all classes of nonroad compression engines were governed by this new tier of regulations.
Which EPA Tier Does My Generator Need to Comply With?
While newly manufactured prime generators must meet Tier 4F requirements, emergency or standby generators are still subject to Tiers 2 and 3. The basis for this is that these backup emergency generators are only used temporarily in case of emergencies and therefore do not have to adhere to these stricter Tier 4 regulations, as long as they comply with Tier 2 or Tier 3 regulations. This is because Tier 2 and Tier 3 generator engines already exhibit adequate reductions in emissions, run between 200 to 500 hours per year, and the emissions produced by Tier 2 and Tier 3 generators have a low impact on local air quality.
It’s important to note that though backup emergency generators are federally exempt from EPA Tier 4 regulation standards, authorities within your state or local municipality can enforce strict regulations or guidelines that you must adhere to. For example, the state of California may require you to be in compliance with EPA Tier 4 regulations or CARB compliance (if using a natural gas generator).
Emergency vs. Non-Emergency Generator Emissions
When it comes to emergency versus non-emergency generators, Tier 4F standards don’t apply across the board. In fact, new prime generators must adhere to Tier 4F. These generators provide primary, non-emergency power for businesses.
Examples of these generators may include those that provide extra power or offer mobile power on site. However, standby emergency generators don’t have to meet Tier 4F requirements, only Tier 2 or 3 standards. These guidelines apply to standby generators as long as they only turn on in emergencies and supply power to locations that’d experience severe consequences from a loss of energy. For instance, hospitals or servers that route 911 calls are uses for emergency generators.
The EPA requires emergency generators to have inspections to change the oil and filters and check the system at least once a year or every 500 hours. For every 1,000 hours, the units require air cleaner inspections for diesel generators or annually. Plus, diesel standby generators must have meters that monitor the hours the engines operate.
What If My Generator Doesn’t Comply With EPA Standards?
If your generator fails to meet certain EPA standards, there is an option available aside from replacing the generator entirely, such as a generator emission upgrade. The upgrade is essentially an aftermarket attachment that is installed on the generator called a diesel oxidation catalyst (or DOC for short).
The diesel oxidation catalyst (DOC) is designed to oxidize carbon monoxide (CO), gas phase hydrocarbons (HC), and diesel particulate matter (DPM). What it does is it converts carbon monoxide (CO) and hydrocarbons (HC) into carbon dioxide (CO2) and water vapor. This results in less harmful emissions released into the atmosphere.
This upgrade reduces carbon monoxide (CO) by up to 99%, hydrocarbons (HC) by up to 90%, diesel particulate matter (DPM) by up to 95%, and nitrogen oxides (NOx) by up to 99%.
It should be noted that not all commercial generators will automatically become compliant with EPA Tier 4 standards and regulations with an upgrade, but it may be a sound solution worth looking into if you’re looking to get your current generator in compliance with EPA Tier 2 or Tier 3 standards.
More information on generator emission upgrades can be found here: Generator Emissions Upgrades
Which Generators Need to Adhere to EPA Tier 4?
There are quite a few generator applications that must be in compliance with EPA Tier 4, but the most common are the following:
Prime Power Generators
Prime power generators are used as a primary power source for power needs when disconnected from or working off the main power grid and runs continuously to provide power for key equipment and machinery. Due to this fact, these generators are not considered emergency generators and must adhere to EPA Tier 4 regulations.
Portable Generators
Portable or mobile generators used for specific applications are required to adhere to EPA Tier 4 regulations, especially when used for commercial or industrial applications, such as construction projects off the main power grid, events off the main power grid, or peak shaving.
Management & Incentive Programs
Generators used in load management, peak shaving, or demand response incentives are subject to EPA Tier 4 regulations and include any generator sets that are paralleled with the local utility and used for these applications. While generators used for these applications are technically also able to be used for emergencies, the capability of load management disqualifies these generators from Tier 4 regulations.
Is There a Tier 5 EPA Regulation on Diesel Engines?
Over the years, the EPA has upgraded its Tiers to require engine manufacturers to constantly reduce pollutants. The next Tier will be Tier 5, which is currently in development in the United States. For now, we can look to Europe to see their most recently updated emissions standards.
In Europe, Stage V emissions regulations began phasing in during 2018 with new models in 2019 needing to follow the standards. For Americans, the importance of Stage V standards is how they correlate to possible EPA Tier 5 requirements.
Thus far, European Stages closely match EPA Tiers, so they could be a blueprint for a future Tier 5 by the EPA. For instance, Stage IV mirrored Tier 4F. As a result, Americans can view Stage V requirements to see how the EPA might change current guidelines for Tier 5.
The good news for manufacturers is the ability of the existing technology to meet Stage V standards in Europe. Therefore, new generators in the United States likely won’t need to have significant technological upgrades to meet any future Tier 5 standards.
The EPA hasn’t announced any upcoming changes to its Tiers or other changes in standards, so the high-tech Tier 4F generators will remain at the forefront for at least the foreseeable future. Plus, meeting any new standards will require using existing products and parts to slightly boost the current requirements.
THE WOODSTOCK POWER COMPANY EXPERIENCE
Now that you know how the EPA Tiers system works, you can have even more confidence in purchasing the correct generator for your business. At Woodstock Power, we provide machines to help you supply backup power for your company. We’re the most notable brand in the industry, working to help our customers get the power they need with a large catalog of generators to browse.
We are industry leaders in buying and selling used generators to fit the needs of many businesses, including commercial, industrial, medical, agricultural, and university. This includes facilities like hospitals, better living centers, nursing home, airports, hotels, resorts, restaurants, retail centers, manufacturing, production, and more.
Our experts are ready to assist you from answering any questions you may have about power generator sets to helping you find the best selection in our inventory based on:
- Peak & Average Power Requirements
- Fuel Preference (Natural Gas or Diesel)
- Portability & Stationary Power
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- Available Space & Exhaust Restrictions
We carry only the most top rated new, used, and surplus power generator sets for sale, providing you with a great value generator that will fit your budget.
Our generators have been thoroughly inspected, serviced, and verified, which ensures that you will be buying a quality generator that you can depend on. If a generator is not up to par with industry standards, we make all necessary repairs or modifications, and fully test every generator before we sell. This ensures a full turnkey generator that’s ready to fire up and go!
Due to our wide selection of generator sets, we’re confident that we can find the model that best suits your operational needs and budget.
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Feel free to contact us with any questions, concerns, or inquiries to learn more about the Woodstock Power Company experience and the quality level of products & services we provide.