A Roadmap to Low-Carbon Transportation

Given that transportation one of America's leading sources of climate-warming pollution, there is no question that we must transition to low-carbon modes of travel to avoid the worst impacts of climate change.
We can meet carbon goals with cleaner vehicles and more mobility options.

This is part of a series of blogs on NRDC’s new report, “America’s Clean Energy Frontier: The Pathway to a Safer Climate Future”

Given that transportation is one of America's leading sources of climate-warming pollution, there is no question that we must transition to low-carbon modes of travel to avoid the worst impacts of climate change. That’s also one of the key messages from a new NRDC report, “America’s Clean Energy Frontier: The Pathway to a Safer Climate Future,” which concludes that we can do it with known technologies.

The NRDC analysis includes options ranging from increasing the miles per gallon we get from our vehicles, to shifting to electric cars and trucks, to providing alternatives like high-quality public transit and widespread access to walk- and bike-friendly communities. 

Based on comprehensive modeling by NRDC and Energy + Environmental Economics (E3), the report outlines a cost-effective pathway reduce America’s greenhouse gas emissions 80 percent by 2050—which scientists say is necessary to keep the increase in global warming below 2°C—using today’s proven clean energy solutions. The big news is not just that we can do it. It’s how—with a bold and rapid expansion of energy efficiency and renewable energy, all supported by a modernized grid and with rapid progress to get the carbon out of the transportation sector. We don’t need to wait for new breakthroughs, or rely on risky or costly strategies like new nuclear or unsustainable levels of biomass. Instead, we need to keep pushing forward—hard—on existing clean energy solutions.

Cleaning up the transportation sector is crucial to meeting these goals, especially since transportation recently surpassed the power generation sector in annual carbon dioxide emissions. Fortunately, we already have the tools for achieving clean mobility and providing alternatives to gas-guzzling cars.

Three Strategies to Clean Transportation

NRDC’s new report describes the three fundamental thrusts to cleaning up transportation.

1. Make vehicles as efficient as possible. Automobiles and freight trucks emit 80 percent of transportation carbon pollution. Applying technologies that take them farther on a gallon of gasoline or diesel will immediately cut their emissions.

In our analysis, we assume that new conventional passenger vehicles (those powered by internal combustion engines, including hybrids) continue to improve from 25 miles per gallon (mpg) today to 95 mpg by 2050. This assumption is based on a National Academies of Sciences report that found feasible technology pathways for new conventional automobiles to achieve 75 mpg by 2030 and 100 mpg by 2050. This results in an average on-road fuel efficiency for the entire gasoline-powered automobile fleet (including all model years) of around 40 mpg by 2030 and approximately 80 mpg by 2050. Additionally, we assume freight trucks cut fuel consumption by at least 50 percent through conventional powertrain and aerodynamic improvements in long-haul tractor-trailers and widespread hybridization of more urban delivery trucks.

2. Shift to clean, non-petroleum fuels such as electricity to power vehicles. Today, more than 95 percent of energy in transportation comes from oil. A clean energy future fuels our cars and buses with electricity, increasingly produced from pollution-free renewable power like solar and wind.

We assume that the electric vehicle market continues to expand, reaching about 30 percent of automobile annual sales in 2030 and 85 percent of sales in 2050. This will result in 60 percent of all passenger vehicle miles being powered by grid electricity. Crucially, this electricity will be clean—our analysis shows that by 2050, we can get at least 80 percent of our power from renewables such as solar, wind and hydropower.

3. Reduce demand for vehicle travel by expanding personal mobility choices. Today our vehicles are becoming more efficient and less polluting, but those gains are being offset by increasing vehicle activity, or vehicle miles traveled (VMT). By providing alternatives to individual car use such as convenient and reliable transit options, infrastructure to support safe walking and cycling, as well as newer mobility choices like carsharing, bikesharing and on-demand, flexible transit options we can dramatically reduce solo-driving VMT. Coupling these mobility choices with the adoption of demand management strategies, such as incentives or market signals provided by road and congestion pricing, can further accelerate reduction in single-occupancy vehicle use.

Our model assumes that best practices in transportation and land use planning and infrastructure investment can reduce vehicle miles traveled by 25 percent below business-as-usual by 2050. 

In summary, NRDC’s analysis finds that these three strategies will ensure the transportation sector does its part to reduce economy-wide emissions. NRDC’s overall pathway cuts 4.8 billion metric tons of carbon pollution (CO2e) in 2050: from 5.8 billion metric tons of annual carbon pollution with business-as-usual to just 1 billion metric tons. That also means reducing the transportation sector’s carbon pollution by 1.5 billion metric tons, alone—31 percent of the needed economy-wide reduction in 2050.

Key Policies for Achieving Low-Carbon Transportation

The transportation sector is already undergoing a transition to cleaner vehicles as required by federal and state vehicle standards but we need to accelerate the adoption of clean transportation technologies and practices to achieve climate-safe mobility. Here are some of the report’s detailed policy recommendations:

  • Maintain existing clean car and truck standards and strengthen them for future years. These standards include federal greenhouse gas and fuel economy standards that the Trump Administration is working to roll back in response to automaker attacks. California should also forge ahead with strengthening its Zero Emission Vehicle (ZEV) Program to require an increasing mix of electric-drive vehicles over time. It’s programs like ZEV that have prompted increased electric vehicle production and help drive a 73 percent drops in battery cell costs since 2010.
  • Extend tax credits for electric vehicles. Electric vehicle (EV) sales are steadily growing but are still in a nascent stage at about 1 percent of total automotive sales. Extending existing $7,500 federal tax credits (and complementary state rebates) will be important for helping consumers overcome currently higher purchase prices in this early market phase.
  • Invest in EV infrastructure and programs. Electric utilities can accelerate the market for electric vehicles by installing charging infrastructure along highway corridors, in cities, at workplaces and at residences, including apartment complexes following  key principles such as increasing EV access to disadvantaged communities, including in areas historically plagued with poor air quality.
  • Encourage innovative city and state programs that increase low-carbon transportation choices over single-occupant vehicle miles, like high-quality transit and widespread access to walk- and bike-friendly communities. Local, State and federal transportation funds should prioritize these low-carbon mobility options through greenhouse gas performance planning and spending criteria. The Trump administration has tried to roll back these commonsense spending rules but NRDC fought back in court and preserved them. The performance standard and complementary policies can ensure car-sharing and other forms of new mobility are advanced in ways to ensure carbon reductions. Cities can also be piloting innovative demand management strategies such as pricing to further incent use of transportation choices other than solo driving.

America has the roadmap to a clean transportation and safer climate future. Ultra-efficient, electric and shared vehicles—along with community and street design that encourage walking, biking and public transportation—are the destination. We can shed our dangerous dependence on oil and breathe easier if we work together to build the clean transportation system of the future.