Portland's pathways to net-zero carbon by 2050

Visualization of Portland’s path to net-zero carbon emissions by 2050.
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Pathways overview

BPS used a tool called Portland Decarbonization Pathways Tool and Analysis to inform the decarbonization priorities in the City’s new Climate Emergency Workplan.

It’s important to note the distinction between:

  • remaining carbon emissions: (+) carbon emissions released into the atmosphere, in any given year; and
  • reduction strategies: (-) strategies that over time remove or prevent carbon emissions, through actions like energy efficiency or renewable energy.

The graphic on page 4 in the Climate Emergency Workplan, shown below in Figure 1, is a forecast of remaining carbon emissions for each year through 2050, after reduction strategies have been applied.

The reduction strategies, shown in Figure 2, are the direct output of the Pathways tool. The reduction strategies stack up to achieve – in the case presented below – a 60 percent reduction in emissions by 2030 and net-zero emissions by 2050.

The two graphics essentially are the inverse of each other.

Graph showing the different sources of carbon emissions each reducing to net-zero by 2050.
Figure 1: Climate Emergency Workplan graphic showing remaining carbon emissions after reduction strategies are applied. Reduction strategies are in the grey area.
Graph showing colored bands widening over time, showing increasing emissions reductions
Figure 2: Portland’s Decarbonization Pathways tool output, showing one combination of reduction strategies (or the reduced carbon emissions) in the colored wedges. Each colored wedge represents a different reduction strategy, such as energy efficiency, renewable energy, or electric vehicles.

Learn more about each strategy by exploring the Pathways tool:

The Pathways tool only provides total remaining emissions for each year of the forecast and does not model remaining emissions by sector. In contrast, the Workplan graphic shows the remaining emissions broken out by sector and in slightly different categories than Portland’s emissions have been reported previously. BPS chose to present remaining emissions, rather than the reduction strategies, in the Workplan for ease of communication with the general public. Showing how remaining emissions drive down toward zero over time is a more intuitive presentation of the data. BPS made a set of assumptions and calculations to derive Figure 1. The following section explains this methodology.


Setting baseline and current emissions by category

To develop the emissions graphic presented in the Workplan, BPS first began with baseline (1990) and current (pre-2020) carbon emissions by source (electricity, natural gas, gasoline, etc.) rather than by sector. This data was used to reallocate sectors to create the categories presented in the Workplan graphic — Electricity Supply, Buildings, Transportation, Industry, and Other — as shown in Table 1. (NOTE: For this analysis, BPS utilized pre-2020 emissions because the global pandemic caused significant temporary reductions in carbon emissions. BPS has seen no evidence to support assumptions that the 2020 emission reductions will be maintained and as such, emissions are expected to return to pre-pandemic levels.)

Electricity supply includes all electricity generation, breaking those emissions out of buildings and industry to create a new category. The emissions that remain in the Buildings and Industry categories include natural gas, propane, fuel oil, and other fossil fuels used in buildings and industrial processes. The Transportation category includes emissions from transportation fuels like gasoline and diesel. The Other Emissions category includes the remaining emissions from other sources like wastewater treatment, landfilled solid waste, and fugitive carbon emissions. Learn more about Portland’s emissions sources.

Electricity Supply4,922,2403,327,630
Total emissions (in Metric Tons of CO2e)10,523,635.648,880,195

Table 1: Emissions by category from Portland Decarbonization Pathways Visualization tool

Assumptions and settings in the Decarbonization Pathways Analysis

The next step applied the reductions modeled in the Pathways tool. The Pathways results are based on underlying models, as described in the Portland Decarbonization Pathways Tool and Analysis.

To develop the scenario used in the CEW graphic, BPS had to set the scenario in Pathways, using additional assumptions about level of adoption or penetration of various reduction strategies. This section documents those assumptions. These assumptions about the level of reduction achievable from each strategy (energy efficiency, renewable energy, etc.) are all additional to the business-as-usual assumptions that are documented in the Pathways tool (state and federal adopted climate and energy policy).

Electricity supply in 2030

For the purposes of the CEW, BPS estimated that we could achieve 80 percent renewable electricity by 2030 in the City of Portland, which is roughly equivalent to one of the City’s two utilities, Portland General Electric, supplying the city with 100 percent renewable electricity by 2030. The model shows a resulting reduction in carbon emissions in 2030 of 728,987 MT CO2e.

Buildings in 2030

BPS estimated that by 2030, by utilizing incentives from Energy Trust of Oregon, making grants from the Portland Clean Energy Community Benefits Fund, and enacting policy drivers like climate and health standards for existing buildings, carbon emission reductions of 15 percent can be achieved through residential energy efficiency and 15 percent from commercial energy efficiency. These reductions are about 167,952 MT CO2e and 153,549 MT CO2e, respectively. BPS also assumed that we can electrify 10 percent of all commercial and residential buildings by 2030 to take advantage of the grid decarbonization, delivering an additional 13,230 MT CO2e in 2030. We assumed no advances in building energy codes for new construction until after 2030.

Transportation in 2030

This category assumes that Portland Bureau of Transportation implements all of the actions in the Preferred Transportation Policy Scenario by 2030. This scenario envisions managing and building a transportation system that improves mobility for everyone and reduces the amount of driving by using roadway and parking pricing, combined with financial incentives and regulations, to help activate and manage demand for safe, attractive, multimodal infrastructure.

This combination of strategies produces substantial VMT and carbon emissions reductions. The cumulative effect of the above strategies is not simply a sum of its parts as there is synergy between the components. Strategies that reduce VMT in turn decrease the amount of fuel consumed and the number of vehicle miles to electrify — as such, there is less reliance on measures that reduce the carbon intensity of fuel or electrify fleets to do the heavy lifting of reducing emissions. The model shows that the combination of these activities can reduce emissions by 582,951 MT CO2e in 2030.

In addition, we assume that we can further reduce these emissions by replacing fossil diesel fuel at the pump with renewable fuels in the City of Portland. This is priority T-9 in the Climate Emergency Workplan. The Pathways tool estimates that replacing fossil diesel sales with renewable fuel sales in the city limits can reduce carbon emissions by an additional 509,260 MT COe in 2030.

Industrial and other emissions in 2030

For the purposes of the CEW, BPS assumes no further reduction in emissions from current levels for industry or other emissions sources (like landfilled solid waste, wastewater treatment, and fugitive emissions) until after 2030.

Forecasted emissions reductions

Next, the 2030 forecasted reductions from the Pathways, including the modeled business-as-usual reductions, were subtracted from the current emission levels in each of the new categories, as shown in the Table 2 below.

BPS assumed that the bulk of building sector business-as-usual reductions would come from more renewable energy in the electricity supply, rather than from energy efficiency and code improvements in buildings. As such, BPS allocated 90 percent of those reductions to the electricity supply category and 10 percent to the buildings category.

CategoryRemaining Emissions (MT CO2e)
Electricity supply (current)3,327,630
  Business-as-usual reduction(1,599,294)
  Renewable electricity reduction(728,987)
  Subtotal Electricity supply (2030)999,349
Buildings (current)1,333,179
  Business-as-usual reduction(177,699)
  Residential energy efficiency reduction(167,953)
  Commercial energy efficiency reduction(153,549)
  Residential electrification(5,393)
  Commercial electrification(7,838)
  Subtotal Buildings820,747
Transportation (current)3,215,985
  Business-as-usual reduction(726,197)
  Policy scenario reduction(582,951)
  Renewable fuels reduction(509,260)
  Subtotal Transportation1,397,576
Industry (2030)693,391
Other (2030)310,010
Total 2030 Emissions4,221,074

Table 2: Reductions from pre-2020 levels to 2030 as forecast in Portland’s Decarbonization Pathways Visualization tool. This assumes no reductions in emissions from Industry or Other Emission categories before 2030, holding steady at current levels (pre-2020).

Finally, estimates were made for further reductions from 2030 to 2050 to achieve net zero emissions by 2050. This required maximizing all remaining reduction strategies in the Pathways tool, assuming that by 2050:

  • 100 percent renewable grid is achieved by both electric utilities;
  • Remaining efficiency and electrification strategies are implemented for buildings;
  • Energy codes are maximized for new construction in Oregon;
  • Remaining natural gas (20 percent) is replaced with renewable natural gas;
  • Remaining fossil fuel powered vehicles are fully electrified;
  • Industrial emissions reach zero; and
  • 100 percent of plantable land in Multnomah County is forested to sequester remaining emissions from other sources, about 99,000 acres.

The CEW graphic simply shows straight line reductions for three points in time by category, as modeled in the Pathways tool: current levels, 2030 modeled results in Pathways, and net zero emissions in 2050.

The Pathways modeling shows that these net zero reductions can be achieved, but the work required will be significant. Reaching these targets requires an unprecedented level of action and investment across all sectors compared to Portland’s last 30 years of climate planning. We are living in a climate emergency today and it’s time to act like it by rapidly scaling climate action across all sectors.

Note about electricity supply emissions

Both the CEW and Pathways are based on different emission factors than Portland has previously reported publicly. Global emission reporting protocols require publicly disclosed emissions by greenhouse gas, especially for the electricity generation sector. BPS worked with Portland’s electric utilities (Portland General Electric and Pacific Power), but they were unable to report their emissions by greenhouse gas back to Portland’s 1990 baseline. As a result, Portland’s publicly reported carbon emission inventories utilize eGRID emission factors for the Northwest Power Pool published by the U.S. Environmental Protection Agency, to comply with global reporting protocols.

Due to the significant hydroelectric generation in the Pacific Northwest, eGRID emission factors for the region tend to be 10-15 percent lower than Portland’s actual emissions for its electricity supply. As a result, Portland maintains two different inventories to account for these differences. Both of the models discussed here, and the graphic presented in the CEW are based on those higher utility-specific emission factors for PGE and Pacific Power.

Learn more

We encourage Portlanders to read the Climate Emergency Workplan, including the full list of priority actions to decarbonize the city and make residents more resilient:

Read the Climate Emergency Workplan