• Skip to primary navigation
  • Skip to footer navigation
  • Skip to main content
  • Skip to primary sidebar
  • Skip to footer

Check out our best resources to get an AQMD permit

Envera Consulting

California Air Quality Compliance

  • Home
  • About
  • Articles
    • Air Permits
    • Annual Emission Reports
    • SCAQMD Basics
    • SCAQMD Rules
    • Environmental Compliance
    • EPA Regulations
    • Envera News
  • Services
  • Resources
    • Annual Emission Report (AER) Resources
    • What Is the South Coast Air Quality Management District (SCAQMD)?
    • SCAQMD Air Quality Permitting Resources
    • A Short Guide to the SCAQMD’s RECLAIM Program
    • Web Resources
  • Air Rules App
  • Contact
You are here: Home / SCAQMD Basics / 2.5 Tips for Calculating Emissions From an Engine

2.5 Tips for Calculating Emissions From an Engine

March 3, 2017 By Grant T. Aguinaldo

2.5 Tips to Remember for Calculating Air Emissions from an Engine
2.5 Tips to Remember for Calculating Air Emissions from an Engine
(Credit: Pugo Design Studio)

Anyone who’s sat through high school physics or college calculus has heard the phrase “plug-and-chug.”

“Plug-and-chug,” explains Gerd Kortemeyer, an associate professor at Michigan State University, means “plug[ging] numbers into formulas without considering the physical meaning of the equations, then frequently [taking] the result and [plugging] it into the next formula.”

In previous newsletters, I’ve written about the general formula for estimating air emissions from almost any piece of equipment:

E = A x EF x (1 – control)

While at face value, the formula implies a plug-and-chug type of exercise, there are a few problems when applying this method to calculating emissions from engines, so I’ve come up with the 2.5 tips to help you along.

1. EPA Method 19 Is Your Friend

Depending on what the engine emissions will be used for, there are cases, particularly when accuracy is a key factor, where using actual data is preferred over default emission factors.

In most cases, “actual data” is derived either from a stack (source) test or data from a continuous emissions monitoring system (CEMS). And while these sources of actual data are more accurate, they come with their own set of problems.

For one, actual data is typically expressed in the form of an emission concentration (e.g., parts per million), which is quite different than a “plug-and-chuggable” type of emission factor, which expresses the amount of of emission in terms of volume or time. In other words, in order to get a usable number, it’s back to the conversion methods you learned in high school physics. In this case, the conversion method is known as EPA Method 19.

By using Equation 19.1 and the conversion factors in Table 19.1 (both found in EPA Method 19), you can convert an emission concentration into an emission factor. Taking this one step further, if you wanted mass per fuel consumed on a volume basis, you would then need to multiply by the higher heating value of the fuel (assumed to be 1,050 MMBTU/MMSCF for natural gas).

Method 19 takes some getting used to, but once you do, it’ll help you get one step closer to being able to plug and chug your emission calculations.

2. Data Won’t Come in a Nice, Neat Package

You can’t plug and chug if your data isn’t in the right form. And, more often than not, you’ll have to do some extra work to get it there.

One reason is that gathering the data needed to calculate emissions from an engine typically requires you to ask someone else for different parts of the information. This can be challenging. For example, you may be looking for the volume of fuel consumed, but the engine operator may only have records of the elapsed time because the engine has a timer and no fuel meter. Or an operator may tell you that the only available records state that five gallons of diesel were used in July, giving you an incomplete overview of the year’s consumption. In both of these examples, you may need to start with the data on hand and extrapolate to the value you need.

Because field data will come in different units and time frames and will be associated with different parameters, your job is to know how to convert the data so it’s usable in your equation. Conversion methods vary greatly, and a full explanation would take too long to explain here, so contact us if you need help with data conversions.

2.5 Sometimes More Data Is Needed

This point is somewhat related to #2 but is important enough that it deserves its own (half) section. Going off what we just discussed, you may also need to research additional information. For example, depending on the type of emission factor, you may need to know the size of the engine. Three of the most common types of emission factors for engines include:

  • Mass per fuel volume (ex: 469 lbs NOx (nitrogen oxide)/1,000 gallons of diesel combusted)
  • Brake-specific emission factor (ex: 0.25 g NOx/bhp-hr)
  • Mass per time (ex:10 lbs NOx/hr)

In the case of a brake-specific emission factor, you also need the engine rating (e.g., 525 brake horsepower, or bhp) in order to complete the equation. You can usually find the engine rating either on the equipment’s air permit or in the manufacturer’s documentation.

Another example of when additional data is needed is when emission factors combine pollutants together, such as with volatile organic compounds (also referred to as non-methane hydrocarbons, or NMHC) and NOx. Sometimes engine manufacturers provide engine-specific emission factors in terms of NOx + NMHC (e.g., 1.5 g NOx + NMHC/bhp-hr). This can be problematic because, in most cases, you need to report the emissions of NOx and organics separately, which means you need to determine the separate distributions of each.

 

The overall takeaway is that, before you can plug-and-chug, you need to be prepared for the possibility that you’ll need to supplement your existing data set.


If you need help sifting thorough all of the data needed to calculate emissions from an engine, contact us and we’ll be happy to help.

Related

Filed Under: SCAQMD Basics Tagged With: continuous emission monitoring system (CEMS), emission factors, engine compliance, EPA Method 19, source tests, volatile organic compounds (VOC)

Want More Environmental Compliance Tips?

Ensure you stay in compliance by getting news and updates delivered right to your inbox. Sign up for the Envera newsletter.

Sign Up

About Grant T. Aguinaldo

Grant is a principal at Envera Consulting. As the Sherlock Holmes of environmental consulting, Grant solves current-day problems using modern tools. More on Twitter or LinkedIn.

Primary Sidebar

Sign Up for Our Newsletter

Get weekly tips and news on California’s air quality regulations right in your inbox.

Recent Articles

  • What Happens If the SCAQMD Denies Your Air Permit December 7, 2018
  • A 4-Tiered Analytics Maturity Model for Environmental Compliance November 16, 2018
  • Parking Tickets, Environmental Noncompliance & the SCAQMD’s Variance Process October 5, 2018
  • Why Emissions Guarantees Are So Crucial for Permit Applications September 21, 2018
  • The Compliance Trifecta: Monitoring, Recordkeeping, and Reporting September 7, 2018

Footer

Contact Information

Envera Consulting
1107 Fair Oaks Avenue #295
South Pasadena, CA 91030
grant.aguinaldo@enveraconsulting.com
415-203-0520

Let’s Get Started on Your Project!

Let Envera Consulting help you navigate your business to compliance.
Work With Us

Search

  • LinkedIn
  • Instagram
  • Facebook
  • Twitter

Copyright © 2014 - 2018 ENVILEARN, LLC DBA ENVERA CONSULTING ENVERABYTE IS A REGISTERED TRADEMARK OF ENVILEARN, LLC · Log in
Privacy Policy · Terms of Service