This ebook provides an introductory discussion of steps an organization or facility can take to evaluate its emissions of greenhouse gases (GHGs).
By JON F. ELLIOTT BSE, MPP, JD, writing for SPECIALTY TECHNICAL PUBLISHERS (STP), an EHSQ Alliance Affiliate.
CALCULATING GHG EMISSIONS
Once an entity has developed an inventory of GHG acquisition and use, it can assess its emissions of GHGs – this inventory often is referred to loosely as an entity’s “carbon footprint” since carbon dioxide (CO2) is the most common GHG. As noted in Part 1 of this ebook, North American entities should already have extensive chemical inventory and use information. Several steps must be followed to produce an emissions inventory.
At the very least, an entity’s emissions inventory should address direct emissions by its own activities. These are often referred to as Scope 1 emissions. Indirect emissions are referred to as Scope 2 and 3 emissions.
Preparing a Source Inventory
The first step is to identify where GHGs are used in the entity’s operations, and how. As noted above, source inventories should include the following:
- Facility inventory (e.g., if multi-facility entity, to guide further steps)
- Stationary source inventories
- Mobile source inventories
- Fuel inventories
- Process chemical inventories
A variety of data sources should be accessed. These include:
- Direct emissions from stationary combustion: fuel purchase records, utility bills (gas), (change in) fuel inventory, continuous emission monitoring system (CEMS) required by Clean Air Act permits and/or other compliance data, inventory of stationary combustion facilities, emission factors (if not default).
- Direct emissions from mobile combustion: fuel purchase records, (change in) fuel inventory, vehicle miles traveled, vehicle inventory, emission factors (if not default).
- Direct process emissions: raw materials inputs; production outputs, CEMS, emission factors.
- Fugitive emissions: purchase records (inputs, refrigerants, etc.), monitoring data and reporting, emission factors.
- Indirect sources (indirect and supply chain issues are addressed below): bills for electricity, imported steam, heating or cooling (Scope 2).
- Other purchased goods/services treated as indirect sources (Scope 3).
- If more than one data source is used, additional steps may be necessary to reconcile these sources to provide consistent information. Quality assurance and quality control efforts will also vary among multiple sources.
Quantifying Direct Emissions
Once data are collected, the entity can process them to calculate emissions. For example:
- Determine combustion activities (boilers, generators, vehicles, etc.)
- Determine usage of each fuel (diesel, natural gas, etc.)
- Apply emission factors: e.g., diesel emits 10.15 kg CO2/gal);
- Calculate CO2 emissions
- Calculate CO2 equivalent (CO2e) emissions from other GHGs: e.g., diesel emits 0.0014 kg methane per gallon (CH4/gal), 0.0001 kg nitrous oxide per gallon (N2O/gal)
- Total emissions (TCO2 and/or TCO2e)
- Determine annual fuel use (gasoline, diesel, liquefied petroleum gas (LPG));
- Select appropriate emission factor(s) – e.g., gasoline (8.81 kg CO2/gal); diesel (10.15 kg CO2/ gal); LPG (5.79 kg CO2/gal) [note: the United States Environmental Protection Agency and others provide information to apply mileage-based factors to vehicle-miles travelled]
- Determine total annual emissions (TCO2 and/or TCO2e)
CONSIDERING GHG EMISSIONS
The preceding discussion has focused primarily on GHG emissions that result directly from an entity’s activities. These are commonly referred to as “Scope 1” emissions. However, GHGs are emitted not only from an entity’s own facilities, but from its suppliers of products (including heat and light) and services. For example, 40 – 60% of a typical manufacturing-based corporation’s total GHG emissions are outside its direct control, and result from activities such as processing, packaging, and transportation. This figure can be as high as 80% for retailers.
To capture these emissions, increasing numbers of entities also evaluate GHG emissions from third party activities, by suppliers and other entities that support the entity’s own activities. These commonly include generation of electricity purchased by the entity, and production and transport of inputs purchased by the entity (“supply chain”). They may also include transport of the entity’s products to its customers (“value chain”) and may include emissions associated with the ultimate post-use fate of those products.
Emissions Associated With Purchased Electricity (“Scope 2” Emissions)
GHG emission calculation methodologies distinguish emissions associated with purchased electricity from other third party emissions. In most areas, electricity is purchased from regulated utilities that publish the GHG emissions per kilowatt-hour of electricity (CO2e/kWh) they generate.
Emissions from the supply chain (“Scope 3” emissions)
“Scope 3” covers all the other inputs in an entity’s supply chain, so is vastly more heterogeneous than electricity supplies. However, the customer’s Scope 3 is each supplier’s Scope 1, so emissions all along a supply chain can be calculated if every entity in that supply chain calculates its own GHG emissions and makes the results available. A growing number of large multinational firms–those with the market power to demand information from their suppliers – have created supply chain surveys, and even begun to establish incentives for carbon footprint reductions. Notable examples include Walmart and Procter & Gamble.
Where Can I Go For More Information?
Climate Change and GHG websites:
STP SELF-ASSESSMENT CHECKLISTS
The professional experience of Jon F. Elliott, BSE, MPP, JD, includes:
- Practicing attorney in California.
- Compliance consultant and legal advisor (since 1985), specializing in projects that address multiple legal frameworks simultaneously.
Jon Elliott has made a major contribution to the Specialty Technical Publishers (STP) product range for over 30 years. Examples include:
Mr. Elliott has a diverse educational background. In addition to his Juris Doctor (University of California, Berkeley Boalt Hall School of Law–1981), he holds a Master of Public Policy (Goldman School of Public Policy, UC Berkeley–1980) and a Bachelor of Science in Mechanical Engineering (Princeton University–1977).
Lorraine O’Donovan is a Marketing Specialist for Specialty Technical Publishers.
[Editors' Note: Republished with permission. Copyright © 2018 Specialty Technical Publishers. All Rights Reserved. This publication does not constitute legal, accounting or other professional advice. STP Specialty Technical Publishers and its authors make no warranties, whether express or implied, regarding the accuracy of any information or materials contained herein or the results of any course of action described herein, and STP and its authors expressly and specifically disclaim the implied warranties of merchantability and fitness for a particular purpose.]
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