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The Challenge of Scope 1 Emissions

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Sheshawn Foltzer's picture
Project Specialist, Solmicrogrid

Solmicrogrid Project Manager

  • Member since 2022
  • 5 items added with 3,358 views
  • Mar 29, 2022

In recent posts, we’ve discussed the concept of Science-Based Targets (SBT) which offer organizations a pathway and series of metrics for setting carbon reduction goals. Last week, we outlined some of the challenges and implications related to the just-released Securities Exchange Commission ruling requiring publicly-traded companies to disclose climate-related risks. And we previously discussed the three emissions-related Scopes: (Scope 1 – direct emissions; Scope 2 – emissions related to electricity and steam consumption; and Scope 3 – emissions related to upstream supply chain and downstream use and disposal of products). In this post, we’ll delve into Scope One and the efforts that may be entailed in taking on this challenge.


Scopes 1, 2, and 3


Understanding Scope 1 exposure:


The initial task for organizations addressing their greenhouse gas (GHG) emissions is to know where their emissions are coming from and what they consist of. This involves the creation of a “GHG inventory” from multiple potential emitting sources.


Defining Scope One: The U.S. Environmental Protection Agency (EPA) breaks down Scope 1 emissions into three categories: 


1)    Direct Emissions from Stationary Combustion


2)    Direct Fugitive Emissions from Refrigeration, Air Conditioning, Fire Suppression, and Industrial Gases


3)    Direct Emissions from Mobile Combustion Sources (transportation)


Each of these is worth addressing in its own right.

Direct emissions from stationary combustion sources

These so-called “smokestack emissions” include carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O). The EPA notes that in the U.S., CO2 represents over 99% of the total greenhouse gas emissions from all commercial, industrial, and electric generating resources. However, that does not mean these other gases are immaterial. Methane, for example, is 25 times more effective at trapping the earth’s radiating heat on a pound-for-pound basis. Upon initial release, methane is approximately 100 times more effective, but it lasts only about a decade in the atmosphere, while carbon dioxide sticks around on the order of centuries. So, over the first 20 years, the global warming potential of methane is approximately 72 times that of CO2. N2O is even worse, at 298 times the impact of CO2.

What’s in your smokestack?


Emissions typically come from boilers, heaters, furnaces, kilns, ovens, flares, thermal oxidizers, and dryers. These are often referred to as “hard-to-abate” emissions because in many cases cost-effective technologies do not yet exist to address these applications. 

All of this can get quite complicated quite quickly. For example, the EPA guidance notes that “Emissions of CH4 and N2O depend not only upon fuel characteristics, but also on technology type and combustion characteristics, application of pollution control equipment, and ambient environmental conditions. Emissions of these gases also vary with the size, efficiency, and vintage of the combustion technology, as well as maintenance and operational practices.”


In addition, there is the issue of burning biomass (e.g., agricultural or forestry waste). This is tracked separately, and in this case, it is assumed there is no net carbon dioxide emitted, but there may be net CH4 and N2O. 

Then there’s the question of how to measure all of these emissions.  Here, the EPA notes that there are two ways to do this.  The first is analyzing the fuel inputs used, identifying the carbon content of the fuel being burned, and then calculating overall CO2 emissions based on the volume of fuel consumed. 

The second is Continuous Emissions Monitoring.  This involves an installed monitor that calculates emissions by measuring both the percentage concentration of CO2 and the volume of gas flowing through the flue as an overall function of time.


In each case, the EPA recommends that this be done by an individual facility rather than on an aggregated basis to increase overall accuracy.


Direct fugitive emissions from multiple sources 


The gases tracked here relate to gases leaked (hence the use of the term “fugitive”) from air conditioning, fire suppression, and gases used in industrial processes.  These include hydrofluorocarbons, ammonia, carbon dioxide, propane, and isobutane.  These overall quantities are small, but the impacts of some of the gases are potentially enormous.  The worst of these possess global warming potential that can be 1,000s of times greater than CO2.  


A partial list of the culprits


In calculating the impacts here, four methodologies may be used, depending on how – and with what equipment - these gases are utilized.  We won’t go into these, but you can find all four methodologies discussed at length on the EPA’s associated website.  


Direct emissions from mobile combustion sources

Finally, there are emissions from directly operated mobile sources, which include the proverbial planes, trains, and automobiles, but also cover everything from trucks and buses to ships and forklifts.  If it moves and burns fuel, it falls within this category.  The EPA indicates that the same gases as with stationary storage are included: CO2, CH4, and N2O.

Tracking mobile emissions



Emissions can vary considerably, and of course, it is well beyond the realm of possibility to directly measure emissions from each fuel-consuming asset.  Thus, the EPA suggests that CO2 emissions can be reasonably calculated by applying emission factors based on the fuel quantity consumed. CH4 and N2O emissions, however, will depend largely on the emissions control equipment used (e.g., type of catalytic converter) and vehicle miles traveled. 

There are three potential methodologies used for calculating CO2 emissions, based on whether or not one knows the heat content (amount of energy contained) or carbon content of the fuels consumed. The carbon content approach is the most accurate approach, but that information may not always be available. There are also two separate ways to measure CH4, and N2O – one for on-road vehicles and the other for non-road (ships, forklifts, etc).

Data-intensive and confusing?  Yes. Headed your way?  Also, quite likely a yes, especially if you are engaged in business-to-business transactions if you have any significant associated GHG emissions and your activities may constitute part of somebody else’s supply chain. Sooner or later, your Scope 1 may be tied into somebody else’s Scope 3 emissions accounting, especially if and when the just-announced SEC rule is implemented. So now may be time to start proactively thinking about these issues, before they are forced upon you.

Action Items:

1.    Start to get a handle on what your exposure here might be, especially as it relates to direct “smokestack” types of emissions or any fleets you might own

2.    Review the EPA material as it may relate to your GHG emissions exposure

3.    Begin communicating with peers as to how they intend to address these issues


Yours for a low-carbon future,


Matt Ward and Joyce Bone – Founders, SolMicroGrid

Matt Chester's picture
Matt Chester on Mar 29, 2022

Data-intensive and confusing?  Yes. Headed your way?  Also, quite likely a yes, especially if you are engaged in business-to-business transactions if you have any significant associated GHG emissions and your activities may constitute part of somebody else’s supply chain.

Utilities are in a unique position as to how much of their profile is scope 1. But are there any types of emissions typical to utility that you think may be typically overlooked? 

Sheshawn Foltzer's picture
Thank Sheshawn for the Post!
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