Greenhouse Gas Emissions in Rockport, Maine
An Inventory of Rockport's GHG Emissions in 2019 and Proposed Reduction Actions
Introduction
Why Create a Greenhouse Gas Emissions Inventory?
In response to global, national, and statewide efforts to reduce greenhouse gas (GHG) emissions and mitigate the effects of climate change, many municipalities across the state of Maine have developed greenhouse gas emissions inventories. Inventories allow towns to inform their emissions reductions goals and strategies with sector-specific data.
The Rockport Conservation Commission (RCC) and the Maine Climate Science Information Exchange (MCSIE) created the following inventory to aid the town of Rockport, Maine in estimating its total GHG emissions and identifying its largest emission sources. This report calculates estimated emissions for the base year of 2019. Using the results of this analysis, Rockport will create specific plans to meet statewide emissions reductions targets outlined in Maine’s 2020 action plan, Maine Won’t Wait.
In accordance with Maine Won’t Wait, Rockport must reduce their GHG emissions from base-year levels by 45% by 2030 and 80% by 2050, and achieve carbon neutrality by 2045.
The state’s reduction targets are more ambitious than those of national and global plans, so in meeting statewide goals, Rockport will also meet the others.
To track their progress towards these goals, Rockport will use the methods outlined below to replicate this GHG emissions inventory every 3-5 years. This will allow Rockport to measure the percentage by which they have reduced their emissions from 2019 levels, and determine whether they need to intensify their efforts in order to meet targets.
There are two types of emissions inventories that were completed for the town of Rockport: a community-wide inventory and a municipal inventory.
- Community-Wide Inventory: Accounts for all GHG emissions resulting from activity within town boundaries or caused by citizens of that town. This includes emissions from residential, commercial, industrial, and municipal activities.
- Municipal Inventory: Accounts for only the portion of emissions in the community-wide inventory created by municipal government activity. Municipal emissions make up a small percentage of Rockport’s emissions, and are also included in the community-wide inventory. Looking at these emissions separately, however, can help the government of Rockport take actions to lead by example in their emissions reduction efforts.
Creating the Inventory
An array of tools exist to assist in creating GHG emissions inventories. The Greenhouse Gas Inventory Protocol for Southern Maine Cities and Towns written by the Southern Maine Planning and Development Commission (SMPDC) outlines straightforward steps for collecting data and calculating greenhouse gas emissions.
This protocol is designed for use with the ICLEI’s ClearPath tool . The ClearPath tool has been used by a number of Maine cities and towns, but can be cost prohibitive. A free alternative is provided by the US EPA.
Rockport used both the ClearPath and EPA tools to create emissions inventories for 2019. A joint method for calculating emissions information to input into either tool is described below.
What is a Greenhouse Gas (GHG)?
The EPA defines a greenhouse gas as a gas that traps heat in the atmosphere.
Human activities such as the burning of fossil fuels for heating and transportation, intensive agriculture, and waste disposal have resulted in the emission of GHGs which have accumulated in the atmosphere. This has already caused the planet to warm, and will continue to do so unless measures to significantly reduce GHG emissions are taken.
There are many types of gasses emitted from human activity that have a greenhouse effect on the atmosphere. For the purposes of this report, we will focus on the three with the largest impact: carbon dioxide (CO 2 ), methane (CH 4 ), and nitrous oxide (N 2 O). These three gasses have different global warming potentials (ex: one unit of CH4 causes more warming than one unit of CO 2 ), so all emissions in this report have been converted into metric tons of CO 2 equivalent (MTCO 2 e) emissions. This allows for easier comparison across emissions of varying compositions from different sources.
Emissions Scopes
GHG emissions inventories use three scopes to categorize emission sources and better understand their sources. The SMPDC Protocol defines the three scopes as follows:
" Scope 1 emissions are those that physically occur within the boundary of the community."
" Scope 2 emissions are those that result from energy use within the boundary of the community but whose emissions occur outside the boundary."
" Scope 3 emissions occur outside of the community boundary but are driven by activities within the community."
Emissions Included in This Inventory
The GHG emissions resulting from the below activities are included in Rockport’s 2019 community-wide and municipal emissions inventories:
Emissions Source | Scope |
|---|---|
Electricity Use | Scope 2 |
Discrete Fuel Combustion | Scope 1 |
On-Road Transportation | Scope 1 and Scope 3 |
Marine Transportation | Scope 1 and Scope 3 |
Municipal Solid Waste | Scope 3 |
Wastewater Treatment | Scope 1 and Scope 3 |
Emissions Included in Inventory.
Emissions That Were Not Included
This inventory does not include all emissions resulting from Rockport’s activities, as the inventory is purely an estimate intended to inform emissions reduction strategies.
The inventory excludes emissions for which data is unavailable or estimation is not possible. Among the emissions not included are:
- Those resulting from the production and transport of food and other consumer goods purchased by Rockport citizens.
- Emissions due to longer-distance travel by Rockport citizens, whether by car or public transportation.
Although we are unable to calculate emissions for these sources, efforts to reduce these emissions can still be implemented.
2019 Community-Wide Results
In 2019, this inventory estimates that the town of Rockport's activities created 43,207.5 MTCO 2 e greenhouse gas emissions. Using Rockport's 2019 population, we estimate that the town's per-capita GHG emissions for the inventory year were 12.8 MTCO 2 e.
In 2019, Rockport created 43,207.5 MTCO 2 e of GHG emissions. That is 12.8 MTCO 2 e from each Rockport resident.
When compared with other Maine cities and towns that have completed GHG emissions inventories, Rockport's per-capita emissions are in the middle range. Below we compare different town's per-capita emissions with their median household incomes to explore whether there is a relationship there.
2022 median household income compared with per-capita base year GHG emissions for five Maine towns. Point 1 is Biddeford in 2019, 2 is Freeport in 2019, 3 is Saco in 2021, 4 is Rockport in 2019, and 5 is Kennebunk in 2018.
These inventory years range from 2018-2021, so are not perfectly comparable. Additionally, median income data for all five towns is from 2022 rather than the inventory year, which further diminishes this data quality, and there are only 5 data points.
Despite these issues, however, it appears that there is a positive relationship between median income and GHG emissions from this simple analysis. This indicates that wealthier Maine towns might have higher levels of per-capita GHG emissions, although further and more detailed analysis is necessary.
Below we break down Rockport's 2019 total emissions by different categories.
The majority of Rockport's emissions are scope 1, or physically occurring within the town boundary.
On road transportation (ORT), discrete fuel use, and electricity are Rockport's largest sources of GHG emissions. We will further break down sources of ORT and discrete fuel use emissions below. The "other" category contains emissions from burning wood for home heating, and marine fuel use.
Emissions from both discrete fuel use for heating and ORT are primarily created by residential sources, with a smaller portion created by Rockport businesses.
Keep reading to learn about Rockport's largest sources of GHG emissions, and what actions we can take to reduce them.
On-Road Transportation
On-road transportation (ORT) is Rockport's largest source of GHG emissions, and was responsible for 32% of the town's emissions in 2019. Emissions from ORT were calculated from the number of trips occurring between Rockport and surrounding counties in 2019, and vehicle populations in Rockport.
Below we explore which routes were responsible for the largest portion of Rockport's ORT emissions in 2019.
Within Knox County: 58%
Trips between Rockport and other towns in Knox county (excluding trips within Rockport) were responsible for 58% of Rockport's ORT emissions in 2019.
Rockport to Waldo: 17%
Trips from Rockport to towns in Waldo County were responsible for 17% of Rockport's ORT emissions in 2019.
Rockport to Lincoln: 13%
In 2019, trips from Rockport to Lincoln County were responsible for 13% of the town's ORT emissions.
Within Rockport: 9%
Trips within the town boundary of Rockport were responsible for only 9% of the towns ORT emissions in 2019.
Rockport to Sagadahoc: 2%
In 2019, trips from Rockport to Sagadahoc County were responsible for 2% of the town's ORT emissions.
Community-Wide Suggestions
Environmental Leader Certification for Hotels
Many hotels and lodging businesses across the state are participating in the Maine Department of Environmental Protection's Environmental Leader Certification Program.
According to the Maine DEP:
"More than 100 Maine lodging businesses have earned points for practices such as using biodegradable cleaning supplies; placing recycling bins in guest rooms and common areas; providing refillable amenity dispensers rather than individual containers for shampoo, conditioner, soap and lotion in guest rooms; using water conserving faucets and showerheads; and educating patrons about the facility’s green initiatives."
Tourism is an important industry in Maine, especially in its coastal towns. Lodging establishments therefore have the opportunity to be leaders in their sustainability efforts.
This incentive program can help Rockport's hotels reduce their GHG emissions and overall environmental footprints. For more information, explore these self-certification workbooks from the Maine DEP:
Small-Scale Sustainable Forestry
According to USDA , the state of Maine is 89% forested. This forest cover has an exceptional potential for capturing CO 2 from the atmosphere, which can help offset GHG emissions created by Maine towns.
Using a tool called OurTrees by i-Tree , we estimate that this year, trees in Rockport have sequestered a total of 22,568 MTCO 2 e emissions from the atmosphere. Although this value is not from the inventory year, we can assume that it is similar to the amount of CO 2 that was sequestered by Rockport's trees in 2019.
This means that Rockport's forests and trees sequestered approximately half of the GHG emissions that the town's residents created in 2019.
According to this application, existing tree canopy in Rockport covers 8,888 acres of land, and there are an additional 11,863 acres of land that could be planted. Planting trees in these areas could help to further offset Rockport's GHG emissions.
To explore the OurTrees tool, follow the link below.
Additionally, landowners in Rockport can take actions to manage their existing forested land in a way that promotes increased carbon sequestration. If you are interested in managing your forestland in a way that allows you to sell carbon credits, contact Rockport's district forester at the link below. Both small and large scale forest owners can participate.
Home Weatherization
Home weatherization and insulation is a great way to reduce home heating needs. The burning of fuel for building heat was responsible for 26% of Rockport's GHG emissions in 2019, and residential heating accounts for 64% of that.
Therefore, reducing the amount of heat that leaks out of homes by improving insulation will both reduce heating fuel costs, and reduce emissions.
To the right is a financial model from Efficiency Maine's page on home insulation. You can swipe between their pamphlet's pages using the arrows.
Cost-Benefit Analysis: Home Insulation/Weatherization
The graph on the right estimates the financial costs and benefits of improving home insulation for the average Maine customer at different income levels. These costs and benefit estimates are totaled over 10 years.
Data from Efficiency Maine's pamphlet above was used to create this simplified cost-benefit analysis. This analysis does not include the impacts of inflation on fuel, and is estimated for an average home size. Real prices will vary.
Costs | |
|---|---|
Insulation Installation | $6,800 |
Costs of improved insulation.
Benefits | |
|---|---|
Efficiency Maine Rebate | Low Income: $5,440 |
Moderate Income: $4,080 | |
Any Income: $2,720 | |
Federal Tax Credit | Low Income: $204 |
Moderate Income: $408 | |
Any Income: $612 | |
Energy Savings: | $420 / year |
Benefits of improved insulation.
If you were to upgrade your average sized home's insulation to Efficiency Maine's standards in year 1, by the end of that year your total costs related to this weatherization process be approximately $6,800. This total cost will remain the same over the 10 year period. There is no annual cost of insulation.
Your benefit (rebate, tax credit, and reduced fuel oil or propane bill) would depend on your income level. After 1 year, this benefit would be $6,046 for a low income household, $4,908 for a moderate income household, and $3,752 for a household of any higher income.
Looking at this played out over 10 years, with benefit for all households increasing by $420 a year due to savings in energy use, a low income household would "break even" after about 2.5 years (point 1). This means that their benefit is equal to their costs related to insulating their home. After this point, they are making a net savings from their weatherization project.
A moderate income home would "break even" after about 5.5 years (point 2). and a home of any income would break even after about 8 years (point 3).
Based on this information, upgrading an average sized home's insulation per Efficiency Maine standards seems like a worthwhile investment. It will benefit both your finances and the environment in the long run.
Heat Pumps
Heat pumps are an efficient alternative to heating with fuel oil or propane, both in terms of GHG emissions and cost. They "offer highly efficient heating, air conditioning, and dehumidification" (Efficiency Maine). In conjunction with home weatherization, they are an effective way to significantly reduce heating fuel needs.
Efficiency Maine offers a rebate program to incentivize the commercial and residential installation of heat pumps. The graphic on the right is an estimate created by Efficiency Maine of the cost of residential heat pump installation based on customer income.
To learn more about the cost of installation with Efficiency Maine's rebate program, see their website.
Cost Benefit Analysis: 3-Unit Heat Pump Installation
The graph on the right estimates the financial costs and benefits of installing a 3-unit heat pump for a residential customer. These costs and benefit estimates are totaled over 10 years.
Data from Efficiency Maine's website was used to create this simplified cost-benefit analysis. This analysis does not include the impacts of inflation on electricity prices, and is estimated for the average home size in Maine. Real prices will vary.
Costs |
|
|---|---|
Initial Installation | $13,800 |
Increased Electricity Bill | $1,434 / year |
Costs of heat pump installation.
Benefits | |
|---|---|
Efficiency Maine Rebate | Low Income: $8,000 |
Moderate Income: $6,000 | |
Any Income: $4,000 | |
Federal Tax Credit | Low Income: $1,740 |
Moderate Income: $2,000 | |
Any Income: $2,000 | |
Reduced Fuel Oil or Propane Bill | $3,334 / year |
Benefits of heat-pump installation.
If you were to install a 3-unit heat pump in your home in year 1, by the end of that year your total costs related to the heat pump installation and your home's new cost of electricity would be approximately $15,234.
Your benefit (rebate, tax credit, and reduced fuel oil or propane bill) would depend on your income level. This benefit would be $13,074 for a low income household, $11,334 for a moderate income household, and $9,334 for a household of any higher income.
After the end of year 1, heat pump installation in households of all income levels will still have cost a net positive amount (total cost minus total benefit).
Slightly more than 2 years after installation (point 1), a low income household will break even in terms of their total costs and benefits related to heat pump installation. After this point, they will be saving money compared to if they had kept their original form of heating and cooling.
At around 3 years after installation (point 2), a moderate income household will break even, and after 4 years (point 3), a household of any higher income will break even.
After these three "break even" points, households will begin to make net savings compared to if they had not installed a heat pump. After each income level's respective "break even" point, the distance between their benefit line and the cost line represents their total savings over the x years since they installed a heat pump.
From this graphic, it is apparent that after 2, 3, and 4 years depending on income level, a heat pump becomes a very worthwhile investment.
For a more home specific cost model, explore the link below.
Efficiency Maine tracks the amount of heat pumps that have been installed across Maine using their heat pump rebate program. The amount of heat pumps installed annually is measured in "heat pump equivalent" units, which allows for comparison across heat pumps used in buildings of different sizes
From 2019 to 2023, the amount of heat pumps installed per year in Rockport using Efficiency Maine's rebate program has increased six-fold. Continuing this increasing trend of heat pump installations will help to reduce Rockport's GHG emissions from discrete fuel use.
This data does not include heat pumps installed without using the rebate program, but because the rebate is available to households of all income levels, we can assume that the trend seen is close to accurate.
Residential Renewable Energy
Solar Panel Installation
According to Efficiency Maine , installing solar panels at your home or business is a great way to reduce GHG emissions from electricity use, and to create electricity that costs little to nothing after installation and does not fluctuate in cost.
If you were to couple this with insulation improvement and the installation of heat pumps, you could reduce both heating fuel and electricity uses.
To find a solar installer, explore this link:
Installing Solar Panels with EV Purchase
Purchasing or leasing an electric vehicle (EV) and installing solar panels can offset the increased electricity bills that come with charging your EV at home. Your electricity and vehicle fuel costs would both be significantly reduced.
All of these actions have large upfront costs, but also have the significant long term benefits of reduced electricity, heating fuel, and vehicle fuel costs.
Electric Vehicles
On-road transportation (ORT) was responsible for 32% of Rockport's GHG emissions in 2019, with 80% of that being from residential sources.
One way that Rockport residents can help to reduce this important emissions source is to opt for an electric vehicle (EV) when purchasing or leasing a new car.
The graph on the right shows data on populations of different types of EVs. It was created using data from the Maine DEP.
This graph shows that from 2020-2022, EV populations in Rockport have significantly increased.
2019 Municipal Results
We estimate that in 2019 the Rockport's municipal departments were responsible for 467.51 metric tons of CO 2 equivalent greenhouse gas emissions. This is equivalent to 1.08% of the town's community-wide emissions.
In 2019, Rockport's municipal government was responsible for 1.08% of community-wide emissions.
Although government operations are responsible for only a small portion of the town's total GHG emissions, it is important to understand this sector's emissions. Utilizing this information, Rockport's government can take informed emissions reduction actions that will serve as an example for what businesses and residents can do to effectively reduce their own GHG emissions.
Discrete fuel used for building heating, coupled with employee commute, were responsible for the majority of Rockport's municipal emissions in 2019. Electricity use also contributes significantly.
A further breakdown of combined GHG emissions from municipal electricity use and discrete fuel use shows which of Rockport's buildings contributed the most to the towns emissions in 2019.
Largest Municipal Emitters
Below we breakdown what municipal buildings are responsible for largest portions of emissions from electricity and discrete fuel use.
Public Works
Rockport's Public Works building is responsible for nearly half, 49%, or the town's municipal emissions.
Opera House
The Opera House is responsible for 13% of Rockport's municipal emissions.
Public Safety Building
Responsible for 10% of municipal emissions.
Harbor
Responsible for 6% of municipal emissions.
Town Office
Responsible for 5% of municipal emissions.
West Rockport Fire Department
Responsible for 3% of municipal emissions.
Marine Park
1% of municipal emissions.
Municipal Suggestions
Reduce ORT Emissions
EV Charging Stations
On the map to the right, you can see the locations of all public EV charging stations in Knox County. Charging stations are primarily concentrated in towns in the county.
Trips within Knox County were responsible for 58% of Rockport's ORT emissions in 2019. Given this information, we recommend the addition of more EV charging stations along commonly travelled routes between Rockport and other towns in Knox County.
We advise that Rockport encourage inland Knox County businesses to add charging stations to their parking lots.
There are many charging stations in the coastal region of the county, but a scarcity of stations more inland. If EV charging stations became more available throughout Knox County, and easier to access than buying gasoline or diesel, it would encourage citizens of Rockport and surrounding towns to purchase electric vehicles.
Public Transportation
Travel within Knox County contributed significantly more to Rockport's 2019 ORT emissions than travel within the town of Rockport. Therefore, providing sustainable alternatives to driving a personal car for travel from Rockport to other Knox towns would help reduce ORT emissions.
We suggest the addition of public transit routes between the most frequented towns in Knox County.
In summer months, a bus service between Knox's coastal towns could help to significantly reduce emissions associated with summer tourism. Examples of well functioning public transit systems in small towns include:
- The Nantucket Regional Transit Authority , which offers free bus routes to all areas of the Island during summer months.
- Maine's Amtrak Downeaster , which connects many of southern Maine's towns with each other and Boston.
These transit systems, along with other public services connecting small towns, could serve as an example for Rockport and Knox County.
Within Rockport
Although travel within Rockport was only responsible for 9% of ORT emissions in 2019, actions to reduce GHG emissions from this source should still be taken.
One action that the Rockport government could take is to promote walking and biking as modes of transportation, especially within the town.
Efforts to increase the safety of bike paths, road shoulders, side walks, and walking paths could motivate Rockport citizens to opt for active transit options for their trips within the town.
Lead by Example
Emissions from municipal government activity accounts for only 1.08% of Rockport's total emissions.
However, the town government should still take steps to reduce their emissions, and to publicize their efforts, encouraging residents and businesses to do the same.
Actions that could be taken include:
- Incentivize employees to switch to electric vehicles to reduce employee commute emissions (39% of municipal emissions).
- Upgrade insulation and install heat pumps in municipal buildings to reduce fuel oil use (45% of municipal emissions).
- Install solar panels on municipal building roofs to decarbonize electricity use (15% of municipal emissions).
All of these actions, and any others taken by the town of Rockport, should be made public to residents and businesses.
Detailed Inventory Methods
Community-wide Inventory Methods:
The ICLEI ClearPath tool and the EPA tool were used to convert the following data into MTCO2e emissions. Detailed instructions from the SMPDC Greenhouse Gas Inventory Protocol for Southern Maine Cities and Towns were followed to the greatest extent possible given data available for the town of Rockport.
Stationary Energy: Electricity
Central Maine Power (CMP) supplies electricity to Rockport, and provided data on the town’s electricity consumption in 2019. This data included monthly usage (in KWH) and the number of accounts in each of the following sectors for 2019: streetlights, commercial, industrial, residential, and Rockport’s municipal account. The monthly usage data was summed to get the total electricity usage (KWH) in each sector during the year 2019. This activity data is high quality, as it was obtained directly from CMP.
Sector | Total Usage (2019) |
|---|---|
Streetlights | 161,286 KWH |
Commercial | 22,532,300 KWH |
Industrial | 647,901 KWH |
Residential | 15,773,418 KWH |
Town of Rockport's Account | 105,590 KWH |
Data Input into ClearPath and the EPA Tool
Stationary Energy: Natural Gas
The town of Rockport is not serviced by a natural gas utility, so this source was not included in Rockport’s inventory.
Stationary Energy: Discrete Fuel Use
Residential: Residential discrete fuel use was estimated by first obtaining both statewide and Rockport specific home heating characteristics from the 2019 5-year American Community Survey (number of households that use each fuel type to heat their homes). Additionally, statewide residential fuel consumption data by fuel type was obtained from the US Energy Information Administration. The statewide fuel consumption was divided by the statewide home heating characteristics for each fuel type, and then multiplied by the Rockport specific home heating characteristics. This generated an estimate of the consumption of each fuel type (in MMBTU) in Rockport in 2019. After this calculation, the estimates for the following fuel types were eliminated from the analysis because they either do not generate GHG emissions or had already been accounted for: utility gas, electricity, solar energy, and other fuel. This activity data is lower quality, as it is largely based on estimates.
Fuel Type | Residential Consumption (2019) |
|---|---|
Bottled, Tank, or LP Gas | 20,615.45 MMBTU |
Fuel Oil, Kerosene, etc. | 80,432.91 MMBTU |
Coal or Coke | 0 MMBTU |
Wood | 56,482.38 MMBTU |
Data Input into ClearPath and the EPA Tool
Commercial & Industrial: Commercial and industrial discrete fuel use was also estimated. This was done by obtaining annual industry establishment data for Rockport from Maine's Quarterly Census of Employment and Wages program The total number of establishments in Rockport in 2019 for each of the following building types was summed: other, office, warehouse and storage, mercantile, service, health care, public assembly, lodging/food service, and education. Mean square footage estimates from the SMPDC for each building type were multiplied by the number buildings of each type in Rockport to get the total square footage for each sector. Estimates provided by the SMPDC of fuel oil intensity (gallons used annually per square foot) for each building type were multiplied by the total square footage for each building type. This calculation provided an estimate of the total fuel oil used in Rockport for each building type in 2019. This activity data is low quality.
Building Type | Fuel Oil Use (2019) |
|---|---|
Other | 127,710 gal |
Office | 61,242 gal |
Warehouse and Storage | 11,418 gal |
Mercantile | 54,384 gal |
Service | 30,118 gal |
Health Care | 0 gal |
Public Assembly | 18,029 gal |
Lodging/Food Service | 43,197 gal |
Education | 42,120 gal |
Data Input into ClearPath and the EPA Tool
Large Emitting Facilities: No large emitting facilities were identified in Rockport by the EPA’s Facility Level Information on Greenhouse Gases Tool (FLIGHT), so this source was not included in Rockport’s inventory.
Transportation: On-Road Transportation (ORT)
On-road transportation emissions were calculated using transportation data obtained from the Streetlight cloud-based transportation data platform. From Streetlight, we were able to obtain data for the number of trips between Rockport and nearby counties, and within the town of Rockport. The trips that occurred most frequently on a daily basis and were included in this calculation are as follows. Longer range trips were not counted.
- Rockport → Rockport
- Sagadahoc → Rockport
- Waldo → Rockport
- Knox → Rockport
- Lincoln → Rockport
- Rockport → Sagadahoc
- Rockport → Knox
- Rockport → Waldo
- Rockport → Knox
- Rockport → Lincoln
Streetlight provided the number of daily trips between each destination, and the average length of each of these trips. By multiplying the number of daily trips by the average trip length of each route by 365 days, we calculated the annual vehicle miles traveled (VMT) for 2019. The adjusted VMT was then calculated by dividing the trips that were to or from Rockport by 2, so as to not double count emissions between towns. The VMT from trips that took place within the town of Rockport were not divided. Rockport’s total adjusted VMT for 2019 was 29,959,072 miles.
The ClearPath tool divides ORT emissions into three categories based on vehicle type: emissions from passenger vehicles, public transit, and commercial/freight vehicles. To estimate the distribution of the total adjusted VMT between these three categories, 2019 data from the Maine DEP on Knox County’s percent VMT by vehicle type was obtained. This data was not available at the municipality level, so county level percentages were used. From this information, Rockport’s total VMT was distributed into these three categories. Fuel efficiency data for each vehicle type (mpg gasoline or mpg diesel) from the U.S. Department of Energy allowed us to convert the VMT to gallons burned of either gasoline or diesel for each category. These gallon amounts for each transportation category were then converted into MTCO 2 e using an EPA conversion tool. These emissions were input in MTCO 2 e into the EPA tool, but ClearPath requires that ORT emissions data be in gas-specific form.
Vehicle Category | Total Emissions (2019) |
|---|---|
Passenger Vehicles | 10,957 MTCO 2 e |
Public Transit | 309.80 MTCO 2 e |
Commercial/Freight | 2,430.29 MTCO 2 e |
Data Input into the EPA Tool
From the above emissions data, the gas-specific emissions from Rockport’s ORT were calculated using the following emissions factors provided by the SMPDC report:
- CO 2 emissions = Total emissions x 0.9966
- N 2 O emissions = Total emissions x 0.0022
- CH 4 emissions = Total emissions x 0.0012
Each vehicle category's total emissions in MTCO 2 e was multiplied by these emissions factors to get the emissions of the three main GHGs. This data was input in MT into the ClearPath tool. This activity data quality is medium.
Vehicle Category | Gas Specific Emissions (2019) |
|---|---|
Passenger Vehicles | 10,920 MT CO 2 |
24 MT N 2 O | |
13 MT CH 4 | |
Public Transit | 308.7 MT CO 2 |
0.7 MT N 2 O | |
0.4 MT CH 4 | |
Commercial/Freight | 2,422 MT CO 2 |
5 MT N 2 O | |
3 MT CH 4 |
Data input into ClearPath
Transportation: Marine Vessels
GHG emissions from marine vessels in Rockport were calculated by obtaining the total sales of fuel loaded onto marine vessels in 2019 from Rockport Marine, which sells both diesel and gasoline. This data activity data quality is medium, as it comes from real sales, but many of Rockport’s marine vessels purchase fuel outside of the town boundaries from larger scale suppliers.
Fuel Type | Amount Sold in Rockport (2019) |
|---|---|
Gasoline | 7,459 gal |
Diesel | 11,140 gal |
Data Input into ClearPath and the EPA Tool
Waste: Municipal Solid Waste
In 2019, municipal solid waste (MSW) in Rockport was collected and brought to the EcoMaine waste management plant in Portland Maine. This plant employs a combination of a waste-to-energy incineration, recycling, and landfilling. There is a small landfill (Midcoast Solid Waste) located in Rockport, but this landfill now only collects construction demolition waste (C&D) and serves as a transfer station. Methane emissions resulting from the landfilling of C&D waste are negligible. Therefore, only scope 3 emissions from MSW processed at EcoMaine were considered in these calculations.
The exact amount of MSW produced by the town of Rockport was unavailable for the 2019 year, so a population based estimate of total MSW was used. The EPA estimates that the average person in the US produces 4.9lbs of uncategorized solid waste per day. Based on this estimate, in 2019 the town of Rockport produced 6,030,822 lbs of waste. However, in 2019 Rockport started a new composting program called ScrapDogs , and during that year the program diverted 40,840 lbs of food waste from ending up at EcoMaine. This number was subtracted from the total estimate above. We can assume that Rockport sent the remainder (5,989,982 lbs or 2,995 tons) of MSW to EcoMaine to be incinerated in 2019.
The EcoMaine website provides data on the total amount of MSW incinerated at their facility each year. In 2019, this number was 172,695 tons. By dividing the total tonnage of MSW sent to EcoMaine by Rockport by the total that was incinerated, we get the percent of EcoMaine's emissions that Rockport was responsible for: 1.73%. The EPA’s facility level information on greenhouse gasses tool (FLIGHT) provided the emissions of the following GHGs by EcoMaine in 2019: CO 2 , Biologic CO 2 , CH 4 , and N 2 O.
Each of these gas-specific totals were then multiplied by the emissions percentage calculated above (1.73%) to get the emissions data input. This activity data quality is medium, because a portion is based on estimates using nationwide waste production averages.
Type of Gas Emitted | Emissions (2019) |
|---|---|
CO 2 | 920.4 MT |
Biologic CO 2 | 1,416.2 MT |
CH 4 | 0.8 MT |
N 2 0 | 0.1 MT |
Data Input into ClearPath and the EPA Tool
Waste: Wastewater
Wastewater in Rockport is treated at two facilities outside of the town’s boundaries: the Camden Wastewater Plant, and the Rockland Wastewater Plant; in addition to private septic systems within Rockport.
Neither Camden nor Rockport’s wastewater treatment plants use lagoon systems, rather they utilize nitrification and denitrification in aerated storage tanks. Because both plants use nitrification and denitrification, the combined population served by the two plants was input into the ClearPath sections “Process N 2 O Emissions from Wastewater Treatment,” and “Process N 2 0 from Effluent Discharge to Rivers and Estuaries” sections. Additionally, the remaining population served by private septic systems was input into the “Fugitive Emissions from Septic Systems” section.
Approximately 67% of Rockport citizens are serviced by private septic systems. Of the remainder, 22% of the population’s wastewater is sent to the Camden plant and 11% is sent to Rockland.
The ClearPath tool converted wastewater treatment information into MTCO 2 e emitted. The activity data is medium quality, as it estimates the population served by each WWTP and private septic systems based on Rockport’s average household size.
Wastewater Treatment Location | Rockport Population Served (2019) |
|---|---|
Rockland Wastewater Plant | 374 people |
Camden Wastewater Plant | 749 people |
Private Septic Tanks in Rockport | 2,249 people |
Data Input into ClearPath
The EPA tool calculates emissions from wastewater treatment in a slightly different way, but the same numbers were able to be used.
Wastewater Treatment Method | Rockport Population Served (2019) |
|---|---|
Nitrification/Denitrification | 374 + 749 = 1,123 people |
Aerobic Treatment | 374 + 749 = 1,123 people |
Private Septic Tanks | 2,249 people |
Data Input into the EPA Tool
Municipal Inventory Methods
As with the community-wide inventory, the municipal inventory used the ICLEI ClearPath tool and the EPA tool to convert the following data into MTCO2e emissions. Unlike the community-wide inventory, a protocol designed specifically for Maine cities and towns does not exist. Therefore, the EPA tool’s data input requirements were used as guidelines for municipal data collection.
As most of this information is maintained by the town of Rockport, the data collection methods were much simpler for municipal inventory than for the community-wide inventory.
Stationary Energy: Electricity
Municipal electricity use data was collected from the 2019 town account data used in the community-wide inventory. This data is broken down by account number, which was compared with a list of account numbers and buildings supplied by the town. Electricity use in KWH for the year of 2019 was entered into the tools that we used. This activity data quality is high, as it is real 2019 electricity use data obtained from CMP .
Municipal Department | Electricity Use (2019) |
|---|---|
Streetlights | 166,260 KWH |
Public Safety | 30,471 KWH |
Harbor | 16,118 KWH |
Village Green | 28,72 KWH |
Public Works | 40,395 KWH |
West Rockport Fire Dept. | 4,474 KWH |
West Street Residence | 348 KWH |
Marine Park | 8,267 KWH |
Opera House | 43,119 KWH |
Town Office | 5,404 KWH |
Data Input into ClearPath and the EPA Tool
Stationary Energy: Discrete Fuel Use
Data on discrete fuel use was not available for the year 2019, so data on municipal buildings fuel consumption for the year-long period from July 2020 to June 2021 was used as a proxy. These years are close in proximity, and because heating requirements are fairly consistent across years, we can use this data in our inventory for the 2019 year.
For this year, the town of Rockport provided the name and building type of all municipal buildings, and each building’s use of different fuel types in gallons. The EPA tool and ClearPath converted this data into MTCO2e. This activity data quality is medium, as it is real data obtained from the town, but is not 2019.
Municipal Department | Heating Fuel Use (2020) | Diesel Use (2020) |
|---|---|---|
Town Office | 1,341.7 gal | |
West Rockport Fire Dept. | 726.5 gal | |
Harbor | 1,149.0 gal | |
Public Safety | 2,156.7 gal | |
Public Works | 1,946.45 gal | 12,142.3 gal |
Library | 132.6 gal | |
Opera House | 2,776.7 gal |
Data Input into ClearPath and the EPA Tool
Transportation: On-Road Transportation (ORT)
Municipal emissions from ORT were calculated by estimating town employee commute. Although other ORT emissions sources contribute to municipal level emissions, this was the only available data for this sector. Using an estimate of 45 town employees, the percentage of Rockport’s population that was employees was calculated at 1.33%. This percentage was multiplied by Rockport’s community-wide ORT emissions in MTCO2e to get the contribution of employee commute to municipal emissions. This emissions value was manually entered into ClearPath and the EPA tool.
Waste: Municipal Solid Waste and Wastewater
This data was unavailable at the municipal level for the 2019 inventory year.
