The US Environmental Protection Agency (EPA) has published regulations on emissions from stationary diesel engines, as used in data centers. In Europe, there are similar stage IV regulations. But there is a lot of small print to understand. 

With the advent of the EPA’s final Tier 4 regulations, many data center facilities managers are feeling a little flummoxed about whether or not the new rules apply to them. Deciding which applications the rules apply to can certainly be a little tricky to work through. This is especially true for facilities managers who keep track of multiple generators or even multiple facilities.

kohler industrial power systems diesel genset
– CK Power

A different kind of Tier

Before we go further, it’s worth pointing out, that Tier 4 emissions standards have nothing to do with the Uptime Institute’s Tier system for certifying data center reliability to prevent outages. These tiers classify the stringency of the regulations - but  understanding these new rules is incredibly important to making sure your data center’s diesel power generation equipment meets necessary performance levels.

Knowing how to classify your generator’s power application is the first step in definitively deciding if a generator falls under the umbrella of final Tier 4 emission standards. But before we delve too deeply into which generator applications are governed by the new rules, let’s pause for a brief refresher on the how, what and why of the final Tier 4 standards.

Final Tier 4 background

The new Tier 4 rules were enacted to further reduce two key pollutants which are emitted by diesel engines: particulate matter (PM) and nitrogen oxides (NOx). NOx are known to contribute to the formation of ground-level ozone, one of the key ingredients in the formation of smog. PM exposure has been shown to adversely affect the respiratory system, with finer particles being capable of making it deep into a person’s lungs or heart, according to the EPA.

Prior to 1998, the EPA’s Tiered emissions scheme covered only diesel engines designed for on-highway use, such as with trucks and buses. After a health assessment conducted in 2002 concluded that long-term inhalation of diesel exhaust fumes posed a substantial lung cancer hazard to humans, final Tier 4 emission standards were designed to cut exhaust emissions from diesel engines by 90 percent. 

The deadline for the implementation of these new rules arrived at the end of 2015. New diesel engines contracted or purchased in 2016 must comply with these rules, as long as they meet certain size and application criteria.

So, what does this all mean for facilities managers? Do final Tier 4 rules matter at all? When it comes to prime power and standby backup diesel generators in facilities like universities, hospitals and data centers, which rules apply?

Do these rules apply to my generator?

Prime versus standby, or emergency, power is the essential dichotomy for determining if your generator application falls under final Tier 4’s authority. When a generator is routinely expected to be the main provider of power (it’s the “prime power” source), then it does need to comply with the new Tier 4 rules. This is true even if the generator is a mobile one, brought to a data center with the intention of it providing all of that site’s power only for a period of time. Mobile generators acting in a prime power application are governed by final Tier 4.

Generators intended to provide power only in emergency situations, on the other hand, are not governed by the rules. Backup diesel generators are considered to be in use so infrequently that they can not contribute meaningfully to the levels of PM and NOx present in the atmosphere and hence are exempt. This means that, for FMs whose buildings or campuses have emergency generators because going without power isn’t an option, there’s no need to update those generators to be final Tier 4 compliant.

That doesn’t mean, however, that there aren’t maintenance and efficiency best practices that should be ignored, but that’s a topic for another day. For more background on the final Tier 4 rules and help determining if your application is subject, check out this handy final Tier 4 infographic.

Clayton Costello is operations manager at CK Power