Committing to Accessible, Zero-Emission Transportation in CO

This is the third in a series of blogs unpacking and diving deeper into aspects of the report, "Committing to Climate Action: Equitable Pathways for Meeting Colorado’s Climate Goals."

Pedestrians crossing a dedicated bus lane in Denver, Colorado.

Matt Nager for NRDC

The transportation sector is the single largest source of greenhouse gas (GHG) emissions, both in Colorado and nationwide. Though the state passed ambitious climate legislation last year setting GHG reduction targets, a recent report from Evolved Energy Research, GridLab, NRDC, Physicians, Scientists, and Engineers for Health Energy (PSE), and Sierra Club found that the state’s current trajectory will miss those targets without new, strong commitments. Luckily, there are plenty of policies capable of supporting carbon reductions, or decarbonization, of the transportation sector and get Colorado on track to reach deep, equitable emissions reductions.

The Destination

In order to reach our climate goals, it’s essential to transform the present-day inefficient transportation sector dominated by fossil fuels into a system that efficiently moves people and is powered primarily by clean electricity. Our report’s lowest-cost scenarios to achieve the state’s economy-wide GHG reduction targets show that the state should achieve 18 percent emission reductions by 2025 and 35 percent emission reductions by 2030 relative to 2005 levels in the transportation sector. From 2030 to 2050, emissions must then drop even more rapidly to net zero by 2050—or even net negative if you count a small amount of biofuels, sourced from a limited supply of sustainable feedstocks. 

Even with these levels of reductions, our report’s “Core” scenario found that the state will not meet its goals without rapid, deep decarbonization of the electric sector—more than 90 percent emissions reductions by 2030 relative to 2005 levels. If the electric sector does not achieve these reductions, the transportation sector will need to decarbonize even more quickly to compensate (see below). Illustrating this point, beyond this Core scenario, our analysis also explored a “Slow Electricity” scenario where the electric sector decarbonized more slowly than our Core scenario, and the results showed the need for transportation emissions to plummet down to 35 percent below 2005 levels by 2025—reaching this level five years earlier than in the Core Scenario—and 57 percent by 2030, nearly double the reductions in the Core scenario. 

In addition to striving for GHG reductions, climate policy planning must also center pollution, cost, and access considerations for disproportionately impacted communities. Our report found that a zero-emission transportation system could lower statewide criteria air pollutants such as the particulate matter, sulfur oxides, and nitrogen oxides that contribute to cardiovascular and respiratory diseases. A recent American Lung Association report exploring the health benefits of transportation electrification reinforces these findings, reporting between $1.5 billion and $72 billion in avoided health impacts due to decreased air pollutant emissions in 2030 and between 150 to 6,300 avoided premature deaths in the United States.

While air pollutant emissions will decrease on average throughout the state if the climate goals are met (see the above figure), the report also highlights how air pollution may still increase in parts of the state from 2020 to 2030 (see the below figure) due to an increase in vehicle miles traveled and a slower transition to zero-emission medium- and heavy-duty vehicles. This air pollution is not evenly distributed: rural areas where trucks are a larger fraction of vehicle miles traveled and urban areas near highways suffer the most. Since low-income communities and communities of color are more likely to live adjacent to freight hubs and corridors due to decades of racist housing and transportation practices, the rise in air pollution and residual emissions means that pollution will continue to disproportionately burden these communities in the absence of targeted policies. Consequently, achieving the state climate targets alone will not ensure an equitable transportation system or guarantee the elimination of harmful pollution for all Coloradans.

Finally, the report underscores the linkages between income, affordability, and clean vehicle adoption. Our analysis showed that vehicle electrification significantly reduces average transportation costs, cutting per-capita transportation expenditures by 6 percent by 2050 compared to business as usual. Further demand reduction measures are likely to reduce personal transportation costs even more. However, without targeted policies, these cost savings will not equitably reach all Coloradans. The report outlines the current distribution of electric vehicle (EV) registrations in Colorado, showing that the top 20 percent of households by income adopt electric vehicles at eight times the rate of the bottom 20 percent of households by income, which indicates that adoption occurs faster among higher-income households than low-and moderate-income households. Additionally, we see lower-income households spending a greater fraction of their annual income on transportation fuel costs. Taken together, we see the households and communities who would benefit the most from the pollution reductions and cost benefits associated with zero-emission vehicles are also currently the least likely to afford and adopt them. To address these issues, policies must explicitly work to reverse the inequitable distribution of pollution, alleviate cost burdens, and remove accessibility barriers for medium- and low-income communities and communities of color.

Mapping Success

Colorado can plot a course for success by focusing on three buckets of work: increasingly electrifying vehicles and transit, expanding mobility options, and reducing vehicle use altogether. We must advance electrification of passenger cars, buses, and trucks, and build the charging infrastructure to keep them going. At the same time, we must drive development for more walkable, bikeable streets and expanded, affordable, and accessible public transit. All policies will need to prioritize vulnerable and historically marginalized communities, including low-income communities, communities of color, and rural communities.

Reducing vehicle use and expanding mobility can be a win-win strategy by cutting pollution and making the transportation system more equitable if done right. Our “Low Demand” scenario—in which vehicle use declines thanks to increased transit use, better urban design, and more people choosing to walk or bike instead of drive—shows greater pollution reductions and cost savings than if Coloradans continue to drive more each year, even with high electric vehicle adoption. 

Alongside policies to reduce vehicle use, the state must ensure all vehicles are electric or zero-emission as quickly as possible. For passenger vehicles, this means that electric vehicles should make up at least 27 percent of new car sales and 8 percent of new light truck sales by 2025. This jumps to at least 66 percent of new car sales and 40 percent of new light truck sales by 2030 and 100 percent for both cars and light trucks by 2035. These percentages amount to over 200,000 passenger electric vehicles on Colorado roads by 2025 and 900,000 on the road by 2030.


As for the medium- and heavy-duty sector in our analysis, the timeline slightly lags the passenger vehicles trajectory. Over the next five years, zero-emission medium- and heavy-duty vehicles should grow to become about 4 percent of the new sales. By 2030, this hits a little over 20 percent of new sales and by 2040, all new medium- and heavy-duty vehicles should be zero emission. Because electrification of these larger vehicles is slower and large diesel trucks release more criteria air pollution than passenger vehicles, the state must also take measures to ensure that the air pollution from this sector does not continue to be concentrated in low-income communities and communities of color. 

The report also considered the impact on electricity demand from all these new electric vehicles hitting the streets. Fortunately, many electric vehicles have flexible operations, meaning that half of the electricity needed for charging can happen during off-peak hours such as overnight. Enabling this load flexibility requires policy solutions, including strategic rate structures to incentivize energy use to improve grid operation.

The substantial gap between current electric vehicle adoption and future targets, coupled with the challenge of decarbonizing large stocks of vehicles, and land use that lacks robust public transit means that state policymakers must move quickly. The report highlights key recommendations to curb emissions from Colorado's transportation sector:

1. Adopt Clean Medium- and Heavy-Duty Truck Rules

Colorado should adopt the Advanced Clean Truck Rule and the Heavy-Duty Omnibus Rule as soon as possible in 2021. These rules will collectively increase the number of zero-emission trucks available for sale, while requiring emissions reductions from new fossil fuel truck sales. These two policies are the foundation for a successful transition to a clean medium- and heavy-duty market because they signal that zero-emission trucks are coming and can unlock additional resources for incentives and infrastructure within the state to support a robust zero-emission truck market. These standards also have a built-in two-year delay to ease implementation and allow for the necessary supporting policies and investments to be made. Delaying adoption of these rules until after 2021 means missing at least two model years of compliance, making future adoption harder as these rules ramp-up steeply after the first two-years. Moving quickly on medium- and heavy-duty truck rules is particularly meaningful for communities bearing the impact of years of truck pollution. Any plan intent on addressing environmental justice in transportation must include adoption of these rules as soon as possible in 2021. 

2. Facilitate Investment In EV Charging Infrastructure

The second recommendation is for the Public Utilities Commission to direct investor-owned utilities to propose new tariffs that allow them to design, install, and maintain the grid infrastructure on the utility side of the meter and all associated construction work. This so-called ‘make-ready’ infrastructure can reduce barriers to widespread electrification at a scale that may put downward pressure on rates for all consumers and streamline utility applications. It would also shave hundreds of thousands of dollars off charging station installation costs, enabling the cost-effective build-out of a robust charging network. 

3. Support Adoption Of Zero-Emission Vehicle Standards For 2026 To 2035

The Advanced Clean Cars Program, which requires zero-emission vehicles to make up an increasing share of passenger vehicle sales, currently runs until 2025. Once the program is reinstated, Colorado must ensure the rule is extended beyond 2025 and that the level of EV sales are sufficient to reach the state’s goals. A priority for decision makers should be to ensure that adoption of the ZEV standards will ultimately increase access and reduce transportation costs particularly for low-income families and communities of color.

4. Reform The Gas Tax

We are currently relying upon a funding structure based on a fuel we’re actively working to phase out. Colorado must move to a model that is more compatible with and sustainable in an increasingly decarbonized transportation system. To that end, the legislature should revise the gas tax to remove disincentives for EV adoption and create a simple, efficient, and stable source of transportation funding. This can be accomplished by indexing motor-fuel taxes to inflation and inversely indexing them to total fuel consumption, so that taxes automatically adjust annually. 

As our analysis showed, adoption rates for electric vehicles is substantially lower for those with lower household incomes which puts them at risk of being locked into paying the increasing amounts for transportation. Financial assistance programs will be needed to ensure all families can afford more efficient vehicles.

5. Invest In Public Transit Options

Lastly, prioritizing state funding, policies, and planning capacity to reduce vehicle use will be critical to ensure Colorado is capable of reaching its targets. Colorado needs to craft a vision of a future transportation system that enables people to drive less and embrace other modes of mobility like walking, biking, and public transit. Again, accessibility and affordability will be especially important for low-income communities and communities of color to make sure that they can take advantage of all modes of travel and not be displaced if transit options in their neighborhoods improve. These communities have long endured decades of underinvestment and neglect that requires correction. A more equitable transportation system in Colorado will provide affordable, accessible transportation, builds safe communities, and ensures all Coloradans reap the benefits.

About the Authors

Ariana Gonzalez

Director, Colorado Policy, Climate & Clean Energy Program

Patricio Portillo

Transportation Analyst, Climate & Clean Energy Program

Arjun Krishnaswami

Policy Analyst, Climate & Clean Energy Program
Blog Post

A new report outlines pathways for the state to achieve the greenhouse gas emissions reductions required by HB-1261—as well as the health and equity implications of statewide climate actions.

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