The transportation sector is now the largest source of greenhouse gas (GHG) emissions in the United States, contributing to poor air quality and the climate crisis, and disproportionately impacting underserved and disadvantaged communities. To address this, our goal is to eliminate nearly all GHG emissions from the sector by 2050 while working to achieve a fair and just transportation system that will support economic growth and benefit all citizens.
In December 2022, the U.S. Department of Energy (DOE) joined forces with the Environmental Protection Agency, Department of Transportation (DOT), and the Department of Housing and Urban Development by signing and MOU to coordinate on transportation decarbonization. The first deliverable from that partnership was the January 2023 release of The U.S. National Blueprint for Transportation Decarbonization, a roadmap for how we can address these issues to provide better transportation and fuel options as well as zero-emission vehicles.
Light-duty vehicles (passenger cars, SUVs, pickup trucks, and motorcycles) are responsible for about half of all U.S. transportation GHG emissions. Medium- and heavy-duty vehicles (larger delivery trucks, work vans, and buses) are the second-largest contributor to transportation GHG emissions with 21 percent of all emissions. Aviation is the third largest contributor at 11 percent, including fuel used for all domestic flights and international flights departing the United States
Biofuel – derived from biomass or organic wastes – plays an important role in decarbonizing transportation. The Federal Aviation Administration projects continued growth for the aviation sector and as more EVs enter the market, aviation will become a larger portion of the transportation sector’s GHG emissions.
To reduce aviation GHG emissions, the aviation sector is scaling up sustainable aviation fuel (SAF) use. SAF is a “drop-in” liquid hydrocarbon jet fuel produced from renewable or waste resources that is compatible with existing aircraft engines – a critical near-term solution to reduce GHGs. This led to the creation of the SAF Grand Challenge.
Together, DOE, DOT, and the U.S. Department of Agriculture developed a roadmap to accelerate SAF research, development, demonstration, and deployment (RDD&D) to meet the ambitious government-wide commitment to accelerate production of SAF to 3 billion gallons per year by 2030 – ultimately meeting 100 percent of U.S. aviation fuel needs with SAF by 2050.
DOE’s Bioenergy Technologies Office (BETO) supports RDD&D of technologies that convert domestic renewable carbon resources into biofuels and bioproducts. This effort is already decreasing the price of drop-in biofuels for airplanes, big rigs, and passenger vehicles. To meet the ambitious SAF Grand Challenge goals, BETO has accelerated efforts to scale up these technologies. Scale-up is essential for reducing risks associated with deploying novel technologies at large scale, as is expected in a biorefinery. In doing this, technologies move from the laboratory into relevant and realistic environments.
Public–private partnerships are critical for ensuring that scaleup matches industry needs. For example, BETO is already funding projects with industry partners to turn industrial waste gases into jet fuel, convert biomass into refinery-ready biocrude, reduce GHG emissions from first-generation ethanol plants, and more. These large-scale pilot and demonstration projects enable researchers to test prototype components or subsystems in relevant operating environments. That way, researchers can identify further R&D needs for BETO’s subprograms. Large-scale projects also create larger volumes of target products, supporting quality control testing to verify existing infrastructure compatibility and potential end user specifications. They also provide data that analysts use to evaluate economic and sustainability performance.
BETO saw its first opportunity to fund SAF-focused research in 2021, awarding $64 million to 11 scaleup and demonstration projects. In early 2023, BETO awarded an additional $118 million to 17 projects with industry partners. In recognizing the need for strong designs prior to breaking ground on expensive construction, BETO requires projects to meet necessary criteria to advance from phase 1 into phase 2, which funds construction and operations.
By allocating funding across multiple years and different scales, BETO expects to collapse the time it takes to see success at the demonstration scale. Projects that meet criteria and are ready to go don’t have to wait years for additional opportunities.
As the demand for plane, train, and automobile transportation continues to increase, it is critical that we come together to find innovative solutions to the climate crisis. Biofuels can be a win-win solution, allowing our economy and way of life to thrive while lowering our carbon footprint on a national – and global – level.
Valerie Sarisky-Reed is Director of the U.S. Department of Energy Bioenergy Technologies Office
A steady stream of advanced powertrains, new fuel-efficient systems like stop/start, and more alternative fuels have helped raise fuel economy to new heights in recent years, but the latest breakthrough in energy-efficient cars may surprise you: safety technology.
You got it. Safety equals green. New safety systems are fuel economy game-changers, because fewer crashes mean less congestion, less fuel use, and fewer carbon emissions.
Recently in a white paper on autonomous vehicles, the National Highway Traffic Safety Administration (NHTSA) noted that “Vehicle control systems that automatically accelerate and brake with the flow of traffic can conserve fuel more efficiently than the average driver. By eliminating a large number of vehicle crashes, highly effective crash avoidance technologies can reduce fuel consumption by also eliminating the traffic congestion that crashes cause every day on our roads.”
NHTSA is referring to a new generation of energy-saving, life-saving technologies on our roads – and often these systems are money-saving and time-saving, too.
Real-time navigation in cars helps drivers keep their eyes on the road while diverting them around traffic. The Texas Transportation Institute estimates that, in 2011, congestion in 498 metropolitan areas caused Americans to travel 5.5 billion hours more and buy an extra 2.9 billion gallons of fuel, for a congestion cost of $121 billion.
Adaptive cruise control is a new driver assist that automatically keeps a safe distance from the car ahead, keeping traffic running smoothly. A report by MIT estimates that a 20 percent reduction in accelerations and decelerations should lead to a 5 percent reduction in fuel consumption and carbon emissions.
The Federal Highway Administration estimates that 25 percent of congestion is attributable to traffic incidents, around half of which are crashes. Sophisticated automatic braking technology helps drivers avoid crashes, and fewer fender benders improve fuel economy since drivers spend less time idling in traffic.
In the future, autonomous cars may enhance road safety while giving us a leg up on fuel efficiency. After analyzing government data, Morgan Stanley observed, “To be conservative, we assume an autonomous car can be 30 percent more efficient than an equivalent non-autonomous car. Empirical tests have demonstrated that level of fuel savings from cruise control use/smooth driving styles alone. If we were to reduce the nation’s $535 billion gasoline bill by 30 percent that would save us $158 billion.”
With all these benefits, clearly the traditional definition of ‘fuel economy’ is restrictive and counter-productive. We can achieve much more with a broader view. Here’s how.
The federal government established a national fuel economy/greenhouse gas program with the ambitious goal to nearly double fuel economy by 2025. Our compliance is based on the fuel efficiency of what we sell, not what we offer for sale. While consumers have more choices than ever in energy-efficient automobiles, if they don’t buy them in large volumes, we fall short. So we will need every technology available to make this steep climb.
We can still squeeze more fuel savings from safety and congestion-mitigation technologies, but these systems reduce fuel use in ways not apparent in government mileage tests so the government doesn’t consider them towards meeting federal standards.
The federal government should recognize the real-world fuel economy improvements from these safety technologies. In fact, the government can encourage their deployment by allowing automakers to count the demonstrated fuel economy benefits of these safety technologies towards meeting their compliance with the federal fuel economy program.
While automakers don’t advocate speeding, we are urging regulators to put the pedal to the metal on this priority. More rapid adoption of these new technologies will help keep drivers safer, avoid traffic congestion, save time, save money, and reduce fuel use.
Mitch Bainwol is president and CEO of the Alliance of Automobile Manufacturers, www.autoalliance.org
Recent media coverage of electric vehicles has featured claims of high environmental impact due to the production and disposal phases of the vehicle life cycle. ACEEE’s Green Book, which evaluates such impacts for real vehicle models, helps put this issue into perspective.
Among model year 2012 vehicles, production and disposal emissions were about 30 percent higher for EVs than for comparably-sized conventional vehicles, due to relatively high per-pound battery production emissions. And while these ‘embodied’ emissions accounted for 22 percent of total vehicle impacts on average, they were just above half for EVs.
Nonetheless, EVs received very high Green Scores, reflecting low environmental impact, not a surprise given their zero in-use emissions. And of course, their scores will climb further if and when the ‘upstream’ emissions associated with electricity generation decline.
More broadly, as vehicles’ in-use emissions and energy consumption fall, production and disposal will indeed be increasingly important determinants of environmental impact. Material substitution to reduce vehicle weight, which in turn allows downsizing of vehicle systems and further weight reduction, is already a key strategy to boost fuel economy. Production of advanced, lightweight materials can be energy-intensive, and net impacts will reflect this, together with material recyclability and the fuel savings these materials enable. But careful analyses of these considerations to date have shown a clear net reduction in energy use and GHG emissions from the use of high-strength steel and aluminum, for example.
The recent light-duty vehicle fuel economy and GHG emissions rule provoked a lively discussion of the possibility of standards based on full life cycle emissions. At present, this would be quite a challenge, given the paucity of data on the content and production of individual models and differing views on life cycle analysis.
And for now, fuel economy remains the undisputed heavyweight in vehicle environmental impacts. But we should prepare for a time when, thankfully, that will no longer be the case.
Therese Langer is Transportation Program Director of the American Council for an Energy-Efficient Economy, www.ACEEE.org
