It was exciting to be part of the discussion in Paris this past December when countries came together to make a renewed commitment to limit climate warming to two degrees or less, with each country committing to what it felt it can deliver. The United States, for its part, has committed to cutting CO2 by 26-28% by 2030 (compared to 2005 levels).
This should be achievable, but there’s one sector in the U.S. that is increasing its CO2 emissions at a rapid pace—trucking. Currently, trucks move 72% of the tonnage and 70% of the goods’ value nationwide. By 2050, truck travel is expected to increase by 80% nationally and by 50% in California. Given current trends, the Energy Information Administration projects trucks will account for a large and growing share of freight transport energy use (Figure 1) and CO2 emissions through 2040.
But this CO2 future does not have to happen—there are a range of measures that can be taken to dramatically cut truck CO2 emissions. One is fuel economy improvements, and this is being tackled via the federal government’s truck fuel economy standards program, with measures nearly set through 2027. That is great news, but it’s not enough—it will probably keep truck CO2 emissions at a fairly constant level rather than reducing them.
Another measure is to replace fossil diesel and natural gas with renewable fuels. Low carbon diesel alternatives (e.g. made from waste oils or natural gas captured from landfills and waste water treatment facilities) could make a significant contribution to cutting carbon emissions from trucks. But, competition for these fuels from hard-to-electrify sectors like aviation and limitations on the amount of low carbon renewable feedstocks will constrain their overall impact.
Therefore, to go for deep CO2 reductions from trucks, we will very likely also need very low CO2 emission technologies—namely fuel cell and battery electric vehicles, both of which are “ZEVs” – zero emission vehicles. The only CO2 they will emit is from upstream processes to produce the fuel, and these are progressing towards very low CO2 emissions over time. ZEV trucks can also help tackle a related problem—air pollution. These vehicles do not emit any pollutants at the tailpipe, a huge co-benefit, particularly in polluted areas such as around Los Angeles.
The benefits and barriers to ZEVs
But we have a problem: there are almost no ZEV trucks on the nation’s roads at this point. Why not? An obvious reason is that the key technologies (e.g. batteries and hydrogen/fuel cell systems) are new and more expensive.
Another issue is the “range problem.” Trucks often need to drive long distances in a day, and battery systems typically do not have sufficient energy density to meet the needs of high-mileage trucking, particularly given their long recharge times. Fuel cell trucks can typically travel farther and refuel much faster (like diesel trucks), but need hydrogen fuel, which is not easily available in many locations, another major challenge.
But shoots of grass are emerging in the cracks, as some types of trucks can more easily run on batteries than others. For example urban delivery trucks, large refuse collection trucks, and drayage trucks which operate at ports often have a daily use pattern that can fit with a battery system, and some electric trucks are appearing in these markets. Battery costs for cars have been dropping rapidly, and this also helps to lower battery costs for other vehicle types—so electric truck costs are declining even if very few are being built today.
Other types of trucks that “return to base” once or twice per day can operate on hydrogen that is dispensed at that base—they don’t need a widespread refueling infrastructure. A few hydrogen trucks and bus projects are underway around the country. AC Transit, located in Oakland, California, has been operating fuel cell buses for ten years, and the California Air Resources Board (CARB) recently proposed a very large demonstration program for ZEV trucks and buses at California ports and in disadvantaged communities across the state.
Another challenge will be “scale-up”—how do we get from a few promising applications and projects to much more widespread use of these technologies? The needed rate of scale up is one question; we produced a white paper on this topic in 2015 that shows that a major transition to ZEV trucks needs to begin fairly soon if it is to be completed by 2050. As shown in the figure below, even with a very rapid transition, it takes a long time to go from niche markets to dominating the large markets, so each year counts.
In our paper (and in the figure to the right) we also show that widespread use of advanced biofuels in conventional trucks could really help, since some types of biofuels do not require changing truck technologies—a big plus. But drop-in diesel replacement biofuels require advanced technologies. Producing high volumes of these biofuels from sustainable feedstocks resulting in low greenhouse gas emissions will be a significant challenge.
Transitioning to the “Virtuous Circle”
So, what’s to be done? There are in fact a number of things that our local, state and federal governments can do to get moving on a transition to ZEV trucks:
- Invest a much bigger commitment to demonstrating the relevant technologies in more markets (and more market applications).
- Educate and incentivize trucking companies to adopt these technologies where they make sense today.
- Better understand how some freight might be moved differently, so as to use trucks in a manner more in line with the patterns that work well for ZEV trucks.
- Continue improving key technologies and encouraging more manufacturers to get serious about producing these vehicles (currently very few electric or fuel cell models are available).
- Finally, we need to move towards renewable production of the electricity and hydrogen used in these vehicles.
In this process, there is an important “virtuous circle” we can benefit from: the more we produce and use these vehicles, the better and cheaper they will become. Governments have a critical role to play to help the truck manufacturing industry and truck purchasers/operators to get onto that circle. This can be done, for example, with price incentives to produce and purchase these technologies, perhaps starting with the applications that make the most sense.
Overall the outlook is bright for moving to very low emissions trucking in the U.S. We have several ways to do it and we are getting some initial experience in some “pioneer” applications. But we have to take up the challenge to move this along faster, and create a sense of urgency that may be lacking today on many fronts. 2050 is just around the corner…
Dr. Lewis Fulton has worked internationally in the field of transport/energy/environment analysis and policy development for over 25 years. He is Co-Director of the Sustainable Transportation Energy Pathways (STEPS) program within the Institute of Transportation Studies at the University of California, Davis. There he leads a range of research activities around new vehicle technologies and new fuels. He is also a lead author on the recent IPCC 5th Assessment Report, Mitigation (“Climate Change 2014: Mitigation of Climate Change”, transport chapter).
Dr. Marshall Miller received his B.S.E. from the University of Michigan and his Ph.D. in physics from the University of Pennsylvania in 1988. After a postdoc at the University of Chicago, he joined the Institute of Transportation Studies at UC Davis. For over 20 years he has worked on advanced fuels and technologies to increase vehicle fuel economy and reduce vehicle criteria pollutants and greenhouse gases. Dr. Miller runs a laboratory on campus where he studies advanced batteries and ultracapacitors for use in electric and hybrid vehicles.
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