Chapter 7: Greenhouse Gas Emissions Forecasts

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Note: The forecasts in this chapter are being reviewed in accordance with pending rulemaking from the Oregon Department of Environmental Quality. Final versions will be made available in November.

The City of Salem has set ambitious targets, aiming for a 50% reduction in GHG emissions by 2035 and net-zero emissions by 2050. Forecasting was completed to show possible pathways for Salem to achieve these goals.

Greenhouse gas (GHG) emissions are produced primarily by the burning of fossil fuels for purposes such as transportation and electricity,31 and are the main driver of climate change. Activities such as driving a gas-powered vehicle, heating a home, or flipping on a light switch all contribute to GHG emissions in Salem. A sector-based GHG inventory completed in 2019 details the sources of all GHG emissions in Salem and forms the baseline from which future emissions reductions can be measured.

To complement the sector-based GHG inventory, a consumption-based GHG inventory was completed in 2020. This inventory measured emissions that are associated with the goods and services that are purchased and used by Salem residents. This alternate way of measuring emissions takes into account the production, transport, sale, use and eventual disposal of any purchased item or service, and thus has a global footprint.

The consumption-based GHG inventory showed that the purchase, use, and disposal of vehicles, food and beverages, and furnishings were the three largest categories of consumer-driven GHG emissions in Salem (see Appendix 2).

In accordance with industry norms and protocols, the sector-based GHG inventory was the version used as the baseline for planning emissions reductions.

Salem’s success is highly reliant on its three utility companies (Salem Electric, Portland General Electric, and NW Natural) achieving their goals to reduce emissions. Salem needs to continue to collaborate and communicate with these partners, as well as with residents, to ensure Salem can meet its goals.

Baseline Forecast Overview

To measure the impact of GHG reduction strategies, Salem first needs a baseline from which to measure reductions. Unlike most baselines, which measure the past, GHG baseline forecasts make assumptions about what the future might look like. Salem has a GHG Protocol compliant sector-based GHG inventory measuring emissions from 2016, from which the baselines were projected. Commonly, Climate Action Plans include a “Business As Usual” (BAU) forecast, which generally assumes only small changes in emissions intensity coupled with population growth. Typically these forecasts predict a significant increase in GHG emissions over time, which leads to an overstatement of the impact of target reductions. This is true because these forecasts often make an unrealistic assumption by holding per-capita emissions steady, so emissions grow with population. However, outside of these simulations and in the real world, per-capita emissions in many parts of the US are trending downward over time for numerous reasons, such as increases in energy efficiency standards. If BAU forecasts do not take these decreases into account, then municipalities may unduly claim credit for decreased emissions in future GHG inventories—decreases that would have occurred regardless. Typical BAU forecasts also rarely include a quantitative or qualitative measurement of certainty, which can lead to overconfidence in the model projection. To address these problems, Salem developed three baseline forecasts from which to measure emissions. These forecasts provide a range of possible BAU outcomes and provide a qualitative estimate of forecast certainty (see Appendix 5). Based on the outcomes of these three forecasts, the model which represented the middle outcome was used to perform further analysis.

Salem’s baseline forecast showed a 38% reduction in emissions between 2016 and 2050. Emissions peaked in 2020-2021 before declining until 2045, after which emissions began to increase, primarily because of increased natural gas emissions from population growth, which was no longer being offset by reductions in electricity or transportation emissions. Electricity emissions reached near-zero in 2040. Transportation emissions declined until 2045 and then stabilized. Natural gas emissions increased slowly throughout and were the second largest source of emissions in 2050 after transportation.

BASELINE GREENHOUSE GAS (GHG) EMISSIONS FORECAST

Figure 10: Baseline forecast.

Given the forecasting results, it appears likely that absolute GHG emissions will decline in Salem and reach lower levels in 2050 than in 2016 even without direct intervention by the city of Salem. This is because of factors such as expected increases in energy efficiency, renewable energy, and the use of electric vehicles. However, without local action to pursue opportunities to reduce net GHG emissions, Salem will not achieve its 2035 or 2050 GHG emissions goals.

Salem Emissions Reductions Projections

Salem produced future emissions projections for two scenarios measured from the baseline discussed above. The first projection, labeled “Scenario 1,” shows a challenging but achievable pathway for Salem to significantly reduce emissions. While it may be achievable with serious effort, this scenario shows that Salem will miss its goal of reducing emissions 50% by 2035 and achieving net zero by 2050. The second projection, labeled “Scenario 2,” shows one model of what it would take for Salem to meet both the 2035 and 2050 goals. In order to achieve either scenario, the Salem community will need to implement a number of highly impactful GHG reduction strategies.

Scenario 1

In the first scenario, ten emissions reduction assumptions were selected for modeling based on subjective criteria. The majority of assumptions reflect areas in which there are significant opportunities to reduce emissions. For example, because transportation is the largest source of emissions, the majority of reductions tackle different ways to reduce emissions from the transportation sector. Reducing transportation emissions can be pursued by reducing the number of miles driven or the emissions intensity per mile. These reductions can be further broken down, for example, into whether the reduction in emissions intensity per mile is pursued while retaining vehicles (e.g. electric vehicles) or by shifting more trips to public transit, biking, or walking.

The need for significant reductions in GHG emissions was weighed with the desire to model the outcomes of a wide variety of strategies. Therefore some emissions reduction assumptions, such as increasing carbon sequestration, have a small impact on total emissions. However, modeling these reductions provides information on their relative impact and informs the value of pursuing relevant strategies. Further, these ten target source reductions are interdependent, so reducing investment in one area may result in additional carbon offset by another target scenario. Listed in the table below are the ten emissions reduction assumptions modeled:

Table 1The ten target emissions reductions led to a decrease of 428,000 MtCO2e in 2050 from forecast levels. Most of these reductions can be attributed to transportation (306,000 MtCO2e remaining in 2050, 47%), but reductions in natural gas also played an increasingly important role (179,000 MtCO2e remaining in 2050, 29%).


The Scenario 1 projection resulted in the following outcomes:

  • 40% net reduction from 2016 levels by 2035
  • 58% net reduction from 2016 levels by 2050

In this scenario, Salem would not meet its goal of reducing emissions 50% by 2035 and achieving net zero by 2050.

SCENARIO 1 GREENHOUSE GSA (GHG) EMISSIONS FORECATS

Figure 11: Scenario 1.


Why Wasn’t the Target Met?

Given that the Scenario 1 target reductions did not achieve the target goals, it is worthwhile to examine the remaining GHG emissions to understand their sources. The projected remaining emissions in 2050 fall into the following categories:

1. Waste

Waste comprises a small fraction of remaining emissions (33,000 MtCO2e, 5%). No change in per-capita landfill emissions was assumed, which means that as the population grows, materials are disposed of at the same per-person rate and that the material is sent to the landfill and Covanta at the same proportion as 2016. Programs that address per-capita waste generation or that reduce landfill emissions could further reduce GHG emissions. A number of strategies in the CAP could impact GHG emissions from waste.

2. Wastewater

Wastewater GHG emissions (121,000 MtCO2e, 19%) were projected to grow with the population, and it was assumed that additional growth was entirely connected to the wastewater treatment system. It was also assumed that wastewater in the future was treated using the same methods as today. Operational changes in wastewater treatment or capture and use of methane could lead to a reduction or elimination of wastewater emissions depending on GHG protocol guidance.

3. Natural Gas

Commercial (105,000 MtCO2e, 16%) and residential (74,000 MtCO2e, 12%) natural gas constitute a third of the remaining emissions projected in 2050. Although eliminating natural gas would remove these emissions, no comparable city has yet enacted a comprehensive natural gas ban that terminates current connections. Natural gas bans that eliminate future growth are becoming more common, and Salem would be ahead of its peers and most cities in the U.S. if it were to enact this kind of ban. Additionally, these models assumed that offset natural gas did not result in an increased electricity emissions factor (although it did lead to increased electricity use). Fully offsetting natural gas with electricity for all uses might lead to an increase in the electricity emissions factor due to a need for increased electricity generation capacity.

NW Natural is seeking several opportunities to reduce emissions by blending in clean hydrogen that could eventually constitute 15% of the fuel mix. This hydrogen is produced through hydrolysis, an energy-intensive process that can be employed when there is excess energy available on the grid. With increases in solar and wind generation, periods of excess generation are becoming increasingly common. Hydrolysis acts like a battery to store excess energy in hydrogen which can then be burned as clean fuel. NW Natural is also pursuing extensive customer efficiency opportunities and is seeking a 47% efficiency improvement from 2002 by 2037. These two activities, combined with elimination of new natural gas hookups, reduces emissions by 155,000 MtCO2e from the 2050 forecast.

NW Natural is also pursuing renewable natural gas, which is methane sourced from biogenic sources such as landfills, wastewater treatment, and dairies. This methane would have otherwise been released directly to the atmosphere from activities already taking place. NW Natural is planning to switch entirely from fossil fuel natural gas to renewable natural gas. Burning methane releases carbon dioxide, which is a far less potent greenhouse gas than methane itself. By burning methane that otherwise would have been released, NW Natural would reduce total GHG emissions. However, these sources are largely outside of Salem’s jurisdiction, and GHG protocol guidance today does not include detailed guidelines for renewable natural gas. Therefore, while emissions at the state level would decline due to this activity, Salem would not account for this change at a local level. Guidance may change in the future, which could lead to a reduction or elimination of these emissions.

4. Transportation

Transportation emissions are the largest remaining contributor to total emissions in 2050 (306,000 MtCO2e, 47% of total remaining emissions). Although there are many strategies to reduce GHG emissions, there are also many sources of transportation emissions. Emissions from heavy-duty trucking are projected to make up the majority of GHG emissions from transportation in 2050 (149,000 MtCO2e, 49%), followed by emissions from non-resident passenger vehicles (101,000 MtCO2e, 33%). These emissions are particularly challenging to reduce because most strategies target residential passenger vehicles, and Salem’s ability to directly impact heavy trucking vehicle miles traveled (VMT) or miles per gallon (MPG) is far more limited, as is Salem’s ability to reduce non-resident traffic. These emissions assume heavy trucking remains dependent on fossil fuels, which may change as electric options or other fuels become available. However, those changes would likely be driven by federal, state, or market forces rather than Salem. Although this model assumes 100% electric vehicle (EV) adoption in Salem by 2050, there are out-of-jurisdiction vehicles that are not subject to the EV rate used in the model. Removing all internal-combustion engine vehicles before 2050 is unlikely, although federal, state, or market forces might eliminate these emissions further than the model shows. The remaining emissions come from light trucking, commercial vehicles, and air travel, and can be eliminated in much the same way as heavy-trucking and passenger cars—by switching to cleaner fuels or batteries.

BREAKDOWN OF REMAINING Ghg emissions

Figure 12: Breakdown of remaining GHG emissions in 2050 in Scenario 1 after achieving all ten target reductions

Scenario 2

The results of Scenario 1 show that reaching net-zero emissions by 2050 will require more significant reductions in GHG emissions. To that end, a second model was run to show what it would take to meet Salem’s emissions reduction goals.

In the Scenario 2 model, an analysis was performed to drive down the remaining GHG emissions from Scenario 1 to hit both the 2035 and 2050 goals for the purposes of better understanding where more effort may need to be applied in order to achieve these goals. It is important to note that there are many possible iterations of the model that could lead to the reduction targets; the results presented here are but one possible outcome.

Achieving the outcome of Scenario 2 requires attaining the same ten target reductions modeled in Scenario 1, plus attaining nine more emissions reduction outcomes. Thus, Scenario 2 assumes the following targets are achieved:

  1. Improve building efficiency by an average of 10% by 2050
  2. Maximize onsite solar
  3. Maximize carbon sequestration of plants and trees
  4. Halt all growth in natural gas emissions
  5. Double the rate of EV adoption
  6. Double the rate at which residents use biking and walking
  7. Quadruple the rate of transit ridership
  8. Reduce the amount of passenger vehicle traffic coming into and out of Salem by 40%
  9. Reduce the amount of traffic within Salem by 10%
  10. Transition to a zero-emissions bus fleet
  11. Halt the entry of non-resident internal combustion engine traffic
  12. Halt the entry of internal combustion engine heavy trucking
  13. Halt internal combustion air traffic
  14. Ensure a 100% renewables-only electricity grid
  15. Remove all fossil fuel-derived natural gas systems in the built environment
  16. Remove all other building fossil fuels (e.g. propane, diesel) in the built environment
  17. Achieve zero waste through circular economy, compost, recycling
  18. Capture all wastewater emissions
  19. Halt all septic emissions by requiring locations on septic to join centralized wastewater treatment

In the Scenario 2 modeling, remaining transportation emissions were driven down by 10% aggressively between 2030-2040, natural gas and other building fossil fuels were phased out between 2040-2050, and waste and wastewater were phased out from 2030-2050 (Table 2).

Table 2: Percentage of 2016 emissions projected to decrease by year in order to achieve Scenario 2.

The Scenario 2 projection resulted in the following outcomes:

  • 57% reduction from 2016 levels by 2035
  • Net zero emissions by 2050.
Table 2: Continued

Neither the Scenario 1 or 2 models includes carbon offsets, virtual power purchase agreements (VPPAs), or other options for achieving net zero through increasing investment in carbon sinks outside of tree planting within Salem’s geographic boundary. Carbon offsets could be considered as a strategy for Salem to reach net zero emissions, but would likely be cost-prohibitive. In 2021, lower-range offsets typically cost between $6-$15 USD/MtCO2e. With Scenario 1 showing close to 600,000 MtCO2e remaining in 2050, the annual cost to the City of Salem to offset those emissions in today’s dollars would range from $3.9M - $9.7M per year. Options for carbon offsets vary, but the most common is to fund reforestation and afforestation efforts. VPPAs are more complex and can result in profits over the long term. Funding is likely better spent on projects to reduce or sequester carbon emissions locally. The most likely outcome to achieve net zero will probably include some carbon offsets or other similar strategies to offset hard-to-eliminate niche GHG emissions sources.

Technological solutions that cannot yet be quantified may play an important role by 2050, as would actions that may be deemed infeasible today for technological or political reasons.

With strategic planning, determined resolve, collaborative partnerships, and collective will, the Salem community can achieve significant progress in reducing emissions and becoming a climate-smart city.

Scenario 2 Greenhouse gas (GHG) Emissions forecast


Figure 13: Remaining emissions under Scenario 2


.


Note: The forecasts in this chapter are being reviewed in accordance with pending rulemaking from the Oregon Department of Environmental Quality. Final versions will be made available in November.

The City of Salem has set ambitious targets, aiming for a 50% reduction in GHG emissions by 2035 and net-zero emissions by 2050. Forecasting was completed to show possible pathways for Salem to achieve these goals.

Greenhouse gas (GHG) emissions are produced primarily by the burning of fossil fuels for purposes such as transportation and electricity,31 and are the main driver of climate change. Activities such as driving a gas-powered vehicle, heating a home, or flipping on a light switch all contribute to GHG emissions in Salem. A sector-based GHG inventory completed in 2019 details the sources of all GHG emissions in Salem and forms the baseline from which future emissions reductions can be measured.

To complement the sector-based GHG inventory, a consumption-based GHG inventory was completed in 2020. This inventory measured emissions that are associated with the goods and services that are purchased and used by Salem residents. This alternate way of measuring emissions takes into account the production, transport, sale, use and eventual disposal of any purchased item or service, and thus has a global footprint.

The consumption-based GHG inventory showed that the purchase, use, and disposal of vehicles, food and beverages, and furnishings were the three largest categories of consumer-driven GHG emissions in Salem (see Appendix 2).

In accordance with industry norms and protocols, the sector-based GHG inventory was the version used as the baseline for planning emissions reductions.

Salem’s success is highly reliant on its three utility companies (Salem Electric, Portland General Electric, and NW Natural) achieving their goals to reduce emissions. Salem needs to continue to collaborate and communicate with these partners, as well as with residents, to ensure Salem can meet its goals.

Baseline Forecast Overview

To measure the impact of GHG reduction strategies, Salem first needs a baseline from which to measure reductions. Unlike most baselines, which measure the past, GHG baseline forecasts make assumptions about what the future might look like. Salem has a GHG Protocol compliant sector-based GHG inventory measuring emissions from 2016, from which the baselines were projected. Commonly, Climate Action Plans include a “Business As Usual” (BAU) forecast, which generally assumes only small changes in emissions intensity coupled with population growth. Typically these forecasts predict a significant increase in GHG emissions over time, which leads to an overstatement of the impact of target reductions. This is true because these forecasts often make an unrealistic assumption by holding per-capita emissions steady, so emissions grow with population. However, outside of these simulations and in the real world, per-capita emissions in many parts of the US are trending downward over time for numerous reasons, such as increases in energy efficiency standards. If BAU forecasts do not take these decreases into account, then municipalities may unduly claim credit for decreased emissions in future GHG inventories—decreases that would have occurred regardless. Typical BAU forecasts also rarely include a quantitative or qualitative measurement of certainty, which can lead to overconfidence in the model projection. To address these problems, Salem developed three baseline forecasts from which to measure emissions. These forecasts provide a range of possible BAU outcomes and provide a qualitative estimate of forecast certainty (see Appendix 5). Based on the outcomes of these three forecasts, the model which represented the middle outcome was used to perform further analysis.

Salem’s baseline forecast showed a 38% reduction in emissions between 2016 and 2050. Emissions peaked in 2020-2021 before declining until 2045, after which emissions began to increase, primarily because of increased natural gas emissions from population growth, which was no longer being offset by reductions in electricity or transportation emissions. Electricity emissions reached near-zero in 2040. Transportation emissions declined until 2045 and then stabilized. Natural gas emissions increased slowly throughout and were the second largest source of emissions in 2050 after transportation.

BASELINE GREENHOUSE GAS (GHG) EMISSIONS FORECAST

Figure 10: Baseline forecast.

Given the forecasting results, it appears likely that absolute GHG emissions will decline in Salem and reach lower levels in 2050 than in 2016 even without direct intervention by the city of Salem. This is because of factors such as expected increases in energy efficiency, renewable energy, and the use of electric vehicles. However, without local action to pursue opportunities to reduce net GHG emissions, Salem will not achieve its 2035 or 2050 GHG emissions goals.

Salem Emissions Reductions Projections

Salem produced future emissions projections for two scenarios measured from the baseline discussed above. The first projection, labeled “Scenario 1,” shows a challenging but achievable pathway for Salem to significantly reduce emissions. While it may be achievable with serious effort, this scenario shows that Salem will miss its goal of reducing emissions 50% by 2035 and achieving net zero by 2050. The second projection, labeled “Scenario 2,” shows one model of what it would take for Salem to meet both the 2035 and 2050 goals. In order to achieve either scenario, the Salem community will need to implement a number of highly impactful GHG reduction strategies.

Scenario 1

In the first scenario, ten emissions reduction assumptions were selected for modeling based on subjective criteria. The majority of assumptions reflect areas in which there are significant opportunities to reduce emissions. For example, because transportation is the largest source of emissions, the majority of reductions tackle different ways to reduce emissions from the transportation sector. Reducing transportation emissions can be pursued by reducing the number of miles driven or the emissions intensity per mile. These reductions can be further broken down, for example, into whether the reduction in emissions intensity per mile is pursued while retaining vehicles (e.g. electric vehicles) or by shifting more trips to public transit, biking, or walking.

The need for significant reductions in GHG emissions was weighed with the desire to model the outcomes of a wide variety of strategies. Therefore some emissions reduction assumptions, such as increasing carbon sequestration, have a small impact on total emissions. However, modeling these reductions provides information on their relative impact and informs the value of pursuing relevant strategies. Further, these ten target source reductions are interdependent, so reducing investment in one area may result in additional carbon offset by another target scenario. Listed in the table below are the ten emissions reduction assumptions modeled:

Table 1The ten target emissions reductions led to a decrease of 428,000 MtCO2e in 2050 from forecast levels. Most of these reductions can be attributed to transportation (306,000 MtCO2e remaining in 2050, 47%), but reductions in natural gas also played an increasingly important role (179,000 MtCO2e remaining in 2050, 29%).


The Scenario 1 projection resulted in the following outcomes:

  • 40% net reduction from 2016 levels by 2035
  • 58% net reduction from 2016 levels by 2050

In this scenario, Salem would not meet its goal of reducing emissions 50% by 2035 and achieving net zero by 2050.

SCENARIO 1 GREENHOUSE GSA (GHG) EMISSIONS FORECATS

Figure 11: Scenario 1.


Why Wasn’t the Target Met?

Given that the Scenario 1 target reductions did not achieve the target goals, it is worthwhile to examine the remaining GHG emissions to understand their sources. The projected remaining emissions in 2050 fall into the following categories:

1. Waste

Waste comprises a small fraction of remaining emissions (33,000 MtCO2e, 5%). No change in per-capita landfill emissions was assumed, which means that as the population grows, materials are disposed of at the same per-person rate and that the material is sent to the landfill and Covanta at the same proportion as 2016. Programs that address per-capita waste generation or that reduce landfill emissions could further reduce GHG emissions. A number of strategies in the CAP could impact GHG emissions from waste.

2. Wastewater

Wastewater GHG emissions (121,000 MtCO2e, 19%) were projected to grow with the population, and it was assumed that additional growth was entirely connected to the wastewater treatment system. It was also assumed that wastewater in the future was treated using the same methods as today. Operational changes in wastewater treatment or capture and use of methane could lead to a reduction or elimination of wastewater emissions depending on GHG protocol guidance.

3. Natural Gas

Commercial (105,000 MtCO2e, 16%) and residential (74,000 MtCO2e, 12%) natural gas constitute a third of the remaining emissions projected in 2050. Although eliminating natural gas would remove these emissions, no comparable city has yet enacted a comprehensive natural gas ban that terminates current connections. Natural gas bans that eliminate future growth are becoming more common, and Salem would be ahead of its peers and most cities in the U.S. if it were to enact this kind of ban. Additionally, these models assumed that offset natural gas did not result in an increased electricity emissions factor (although it did lead to increased electricity use). Fully offsetting natural gas with electricity for all uses might lead to an increase in the electricity emissions factor due to a need for increased electricity generation capacity.

NW Natural is seeking several opportunities to reduce emissions by blending in clean hydrogen that could eventually constitute 15% of the fuel mix. This hydrogen is produced through hydrolysis, an energy-intensive process that can be employed when there is excess energy available on the grid. With increases in solar and wind generation, periods of excess generation are becoming increasingly common. Hydrolysis acts like a battery to store excess energy in hydrogen which can then be burned as clean fuel. NW Natural is also pursuing extensive customer efficiency opportunities and is seeking a 47% efficiency improvement from 2002 by 2037. These two activities, combined with elimination of new natural gas hookups, reduces emissions by 155,000 MtCO2e from the 2050 forecast.

NW Natural is also pursuing renewable natural gas, which is methane sourced from biogenic sources such as landfills, wastewater treatment, and dairies. This methane would have otherwise been released directly to the atmosphere from activities already taking place. NW Natural is planning to switch entirely from fossil fuel natural gas to renewable natural gas. Burning methane releases carbon dioxide, which is a far less potent greenhouse gas than methane itself. By burning methane that otherwise would have been released, NW Natural would reduce total GHG emissions. However, these sources are largely outside of Salem’s jurisdiction, and GHG protocol guidance today does not include detailed guidelines for renewable natural gas. Therefore, while emissions at the state level would decline due to this activity, Salem would not account for this change at a local level. Guidance may change in the future, which could lead to a reduction or elimination of these emissions.

4. Transportation

Transportation emissions are the largest remaining contributor to total emissions in 2050 (306,000 MtCO2e, 47% of total remaining emissions). Although there are many strategies to reduce GHG emissions, there are also many sources of transportation emissions. Emissions from heavy-duty trucking are projected to make up the majority of GHG emissions from transportation in 2050 (149,000 MtCO2e, 49%), followed by emissions from non-resident passenger vehicles (101,000 MtCO2e, 33%). These emissions are particularly challenging to reduce because most strategies target residential passenger vehicles, and Salem’s ability to directly impact heavy trucking vehicle miles traveled (VMT) or miles per gallon (MPG) is far more limited, as is Salem’s ability to reduce non-resident traffic. These emissions assume heavy trucking remains dependent on fossil fuels, which may change as electric options or other fuels become available. However, those changes would likely be driven by federal, state, or market forces rather than Salem. Although this model assumes 100% electric vehicle (EV) adoption in Salem by 2050, there are out-of-jurisdiction vehicles that are not subject to the EV rate used in the model. Removing all internal-combustion engine vehicles before 2050 is unlikely, although federal, state, or market forces might eliminate these emissions further than the model shows. The remaining emissions come from light trucking, commercial vehicles, and air travel, and can be eliminated in much the same way as heavy-trucking and passenger cars—by switching to cleaner fuels or batteries.

BREAKDOWN OF REMAINING Ghg emissions

Figure 12: Breakdown of remaining GHG emissions in 2050 in Scenario 1 after achieving all ten target reductions

Scenario 2

The results of Scenario 1 show that reaching net-zero emissions by 2050 will require more significant reductions in GHG emissions. To that end, a second model was run to show what it would take to meet Salem’s emissions reduction goals.

In the Scenario 2 model, an analysis was performed to drive down the remaining GHG emissions from Scenario 1 to hit both the 2035 and 2050 goals for the purposes of better understanding where more effort may need to be applied in order to achieve these goals. It is important to note that there are many possible iterations of the model that could lead to the reduction targets; the results presented here are but one possible outcome.

Achieving the outcome of Scenario 2 requires attaining the same ten target reductions modeled in Scenario 1, plus attaining nine more emissions reduction outcomes. Thus, Scenario 2 assumes the following targets are achieved:

  1. Improve building efficiency by an average of 10% by 2050
  2. Maximize onsite solar
  3. Maximize carbon sequestration of plants and trees
  4. Halt all growth in natural gas emissions
  5. Double the rate of EV adoption
  6. Double the rate at which residents use biking and walking
  7. Quadruple the rate of transit ridership
  8. Reduce the amount of passenger vehicle traffic coming into and out of Salem by 40%
  9. Reduce the amount of traffic within Salem by 10%
  10. Transition to a zero-emissions bus fleet
  11. Halt the entry of non-resident internal combustion engine traffic
  12. Halt the entry of internal combustion engine heavy trucking
  13. Halt internal combustion air traffic
  14. Ensure a 100% renewables-only electricity grid
  15. Remove all fossil fuel-derived natural gas systems in the built environment
  16. Remove all other building fossil fuels (e.g. propane, diesel) in the built environment
  17. Achieve zero waste through circular economy, compost, recycling
  18. Capture all wastewater emissions
  19. Halt all septic emissions by requiring locations on septic to join centralized wastewater treatment

In the Scenario 2 modeling, remaining transportation emissions were driven down by 10% aggressively between 2030-2040, natural gas and other building fossil fuels were phased out between 2040-2050, and waste and wastewater were phased out from 2030-2050 (Table 2).

Table 2: Percentage of 2016 emissions projected to decrease by year in order to achieve Scenario 2.

The Scenario 2 projection resulted in the following outcomes:

  • 57% reduction from 2016 levels by 2035
  • Net zero emissions by 2050.
Table 2: Continued

Neither the Scenario 1 or 2 models includes carbon offsets, virtual power purchase agreements (VPPAs), or other options for achieving net zero through increasing investment in carbon sinks outside of tree planting within Salem’s geographic boundary. Carbon offsets could be considered as a strategy for Salem to reach net zero emissions, but would likely be cost-prohibitive. In 2021, lower-range offsets typically cost between $6-$15 USD/MtCO2e. With Scenario 1 showing close to 600,000 MtCO2e remaining in 2050, the annual cost to the City of Salem to offset those emissions in today’s dollars would range from $3.9M - $9.7M per year. Options for carbon offsets vary, but the most common is to fund reforestation and afforestation efforts. VPPAs are more complex and can result in profits over the long term. Funding is likely better spent on projects to reduce or sequester carbon emissions locally. The most likely outcome to achieve net zero will probably include some carbon offsets or other similar strategies to offset hard-to-eliminate niche GHG emissions sources.

Technological solutions that cannot yet be quantified may play an important role by 2050, as would actions that may be deemed infeasible today for technological or political reasons.

With strategic planning, determined resolve, collaborative partnerships, and collective will, the Salem community can achieve significant progress in reducing emissions and becoming a climate-smart city.

Scenario 2 Greenhouse gas (GHG) Emissions forecast


Figure 13: Remaining emissions under Scenario 2


.


Page last updated: 15 November 2021, 15:12