The Future of Freight

The primary mode of biomass transport—diesel power—continues to get cleaner and more efficient.
By Ron Kotrba | June 21, 2016

Whether it is hauling logs from the forest to the processing site, or shipping wood pellets from the U.S. to Europe, virtually 100 percent of biomass is transported by diesel power. And that won’t change. What has changed is that diesels continue to provide cleaner, more fuel-efficient and less carbon-intense transportation of goods such as biomass.

Diesel power is the workhorse of the global economy. Compression-ignition engines are more fuel-efficient, long-lasting and provide much-needed torque for load-bearing transport compared to gasoline engines. “There’ll always be diesel engines,” says Allen Schaeffer, executive director of the Diesel Technology Forum. “There’s no suitable alternative at the moment.”

Over the years, there has been much discussion of natural gas conversions, but Schaeffer says even after decades of investment in bellwether states such as California, the air resources board still considers it a niche fuel. “The diesel industry doesn’t feel like natural gas is a threat,” he says. “It’s been talked about so long, it’s not even funny. As soon as the technology comes along, fuel prices move in the other direction.”

Criteria Pollutants
Historically, diesel transport has been pegged as dirty. Plumes of soot, or particulate matter (PM), and smog-forming nitrogen oxide (NOx) emissions have characterized diesel for a century. U.S. diesel technology changes that stem from regulations by the U.S. EPA and target these criteria pollutants have been nothing short of a revolution. “Clean diesel” has become part of the new vernacular.

“Beginning in 2000, EPA established a framework for getting to what we call new clean diesel technology today,” Schaeffer says. “It began in the on-road commercial truck sector and filtered down into other sectors, including off-road, locomotives and marine.” While the journey started in 2000, the big switch to ultra-low sulfur diesel came in 2006. Sulfur is problematic for catalysts in aftertreatment systems used to cut PM and NOx. In 2007, heavy-duty truck manufacturers introduced the first trucks with diesel particulate filters (DPFs), which slashed PM by 95 percent compared to previous models. Manufacturers had a phase-in period from 2007-’10 for lower NOx emissions. One pervasive technology used to greatly reduce NOx is what’s called selective catalytic reduction (SCR). “In 2010, commercial trucks effectively had 95 percent lower NOx and 95 percent lower PM emissions compared to 2006 models,” Schaeffer says. “At the end of 2010, we find ourselves with very different diesel technologies, and the new trucks that have hit streets since are ‘near zero’ [for PM and NOx emissions].” 

Today, more fine-particle emissions come from grilling a one-third pound hamburger than from driving a new clean diesel tractor-trailer 140 miles, according to the DTF. A 1988 diesel truck would generate a penny’s weight in NOx in just a quarter mile, while a 2016 truck would have to drive 5 miles. Today in Southern California, brake dust and tire wear contribute more to fine particle emissions than do heavy-duty diesel truck engines.

For marine vessels, Schaeffer says much of EPA’s recent work has been reducing port emissions for social and environmental justice reasons. “A lot of communities are in close proximities to major ports,” he says. “EPA is going to release three documents in June that will identify a range of things, including control strategies and technical guidance to reduce emissions in environmentally sensitive areas around ports.” He says EPA has invested “a lot of retrofit dollars” under the Diesel Emissions Reduction Act. Even though new vessels are regulated under tighter emissions standards, legacy models are in service for decades, making retrofitting a necessary path to reduce port emissions. “This money has been used, for instance, to repower a ferry with a Tier 0 or Tier 1 engine with a Tier 3 or 4, so the boat might be 20 years old but with brand new power and a whole new emissions profile,” he says. “That kind of activity will increase.”

There is also a move afoot to bring more of these marine criteria pollutants in control 100 miles off the coast of California and elsewhere, Schaeffer says. “Some vessels have two fuel tanks, using bunker oil to transit across the ocean, and then as they get close to shore, they switch to ULSD,” he says. Furthermore, some boats pull into the dock for unloading and are plugged into the electrical grid as to not run diesel at all in the ports. “These trends will continue to get bigger,” Schaeffer says.
Jeremy Martin, a senior scientist with the Union of Concerned Scientists’ clean vehicles program, says it makes sense that biomass producers and users would take interest in how clean transport is for their supply chain. “The renewable industry should work together to get the cleanest fuel, and to create and use clean fuel,” he says. “It’s about cleaning up the supply chain. If you’re trying to clean up electricity, for instance, then the supply chain is part of that as well.” Today, great focus is on global greenhouse gas (GHG) emissions to combat climate change, and while this is important, Martin says emissions such as PM and NOx have major health impacts on local communities.

The U.S. is not alone in its push to reduce criteria pollutants from diesel transport. Salman Zafar, CEO of India-based BioEnergy Consult, notes that NOx and PM emissions from heavy-duty transport in Europe have improved considerably over the past two decades, thanks to fuel quality and emissions legislation implemented by the EU. And, he says, India is hoping to follow suit. “In February, the Ministry of Road Transport and Highways issued a draft notification of Bharat Stage VI emissions standards for all major on-road vehicle categories in India, including heavy-duty vehicles,” Zafar says. The regulations follow Euro VI specifications. India has not, however, worked out a comprehensive strategy to reduce CO2 emissions from heavy-duty vehicles in freight transport, he adds.

GHG Reductions
Zafar says only four governments—the U.S., Canada, China and Japan— have adopted fuel economy, or GHG reduction, standards for heavy-duty vehicles. Dave Cooke, a vehicles analyst with UCS, says Japan was the first country to implement heavy-duty truck standards. “However,” he says, “those standards expired in 2015 and no follow-up standards have been implemented.” Cooke says Europe continues to work towards a model-based standard, “but there is nothing on the books to-date,” he says, adding that countries like India have used Europe’s lack of regulation as reason for their own delays. “The U.S. is a clear global leader on this front, with Canada having adopted Phase 1 standards and planning to adopt Phase 2 upon finalization,” Cooke says. “China is the only real mover on this front, having recently passed standards, but their engine technologies are sufficiently behind those of manufacturers in the U.S. and Europe, so the standards are not as strong. However, they do plan further standards on a timeline similar to that of the U.S.”

The U.S.’s GHG emissions and fuel efficiency standards for heavy-duty vehicles comes in two phases. Phase 1 began implementation in 2014 and will be fully implemented in 2018, mostly using what the industry refers to as “off-the-shelf” technologies. The proposed Phase 2 standards would be met through wider deployment of existing and advanced technologies, according to EPA, and will begin in model-year 2021. Phase 2 will, for the first time, include requirements for trailers, and will begin implementation in model-year 2018. Phase 2 will culminate in standards for model-year 2027. The Phase 2 final rule is expected to be released by EPA in August.

“This is a program that looks at three categories of vehicles and trailers, which is a new thing,” Schaeffer says. “Each one of those three categories of vehicles have different targets to achieve, fuel economy improvements and GHG emissions reductions, the largest and most significant of which is heavy-duty Class 8. The vision was to slash GHG emissions by 40 percent from the 2010 baseline.”
Cooke says in total, the combined Phase 1 and 2 regulations should increase average fuel economy from tractor-trailers from just under 6 miles per gallon (mpg) to more than 10 mpg for the average new tractor-trailer. “However,” he says, “with growing miles traveled by freight and commercial traffic, these rules will only act to maintain current levels of emissions from this sector in the 2030-’35 timeframe. Further improvements will be necessary to meet long-term GHG objectives.”

Since most of the technologies employed to date have been off the shelf, there has not been a tremendous physical appearance change in heavy-duty transport so far. “We’re talking basic things like idle reduction has become more standard, greater optimization of the combustion process of the engine, and making the powertrain work better together,” Schaeffer says. “But with Phase 2, now things get interesting.”

In part, these new standards will help offset fuel economy losses resulting from criteria pollutant reductions through use of aftertreatment systems that use extra diesel fuel for regeneration in DPFs, for instance, and greater backpressures from additional catalysts in the exhaust system. “Improving the engine efficiency is first and foremost, via reducing losses from aftertreatment systems, recovering wasted exhaust heat and turning that into usable energy, improved air flow and more efficient turbochargers, and more,” Cooke says. “The rise in automated manual transmissions allows for not just more efficient drivers, but also an integrated powertrain that maximizes the amount of time an engine spends at its most efficient points. And, of course, we continue to see reductions in road load, both through improved rolling resistance tires and especially aerodynamic improvements. Aero improvements to the tractor and trailer are critical to achieving the types of gains we anticipate.”
Schaeffer says almost never are the truck and trailer thought of as a single unit—until now. “They’re owned by different people,” he says. “Trailers are a fungible commodity. We’re not that far into the regulatory rule for trailers, but it’ll be interesting to see how that plays out.” Matching the truck and trailer can produce what Schaeffer says is a “super-optimal, highly efficient outcome.” He references Daimler Trucks North America LLC’s Freightliner SuperTruck, unveiled last year at the Mid-America Trucking Show.

“By incorporating a mix of available technologies with future innovations, we were able to use the SuperTruck program to take the first steps in seeing what may be technically possible and commercially viable,” said Derek Rotz, principal investigator for SuperTruck, DTNA. The U.S. DOE’s SuperTruck program was a five-year research and development initiative to improve freight efficiency by at least 50 percent, brake thermal efficiency by 50 percent, and reduce fuel consumption and GHG of Class 8 trucks. One key initiative of Daimler’s SuperTruck was exploring how the tractor and trailer should be designed and optimized as a single system, not separate units. Closing the gap vastly improves aerodynamics.

Though Schaeffer notes engines will continue to get more efficient, it’s not from where the bulk of the benefits are to come. “Because we’ve been working on optimizing the diesel combustion process for so long, we’ll have less gains there than from areas that have not been dealt with before,” he says. These new areas include, for instance, deliberately lightweighting trucks and trailers by using aluminum instead of steel wheels, or by use of super single tires. “Instead of having a tractor with dual wheels on twin rear axles, now we’re looking at replacing them with one large tire, which will maintain the needed footprint on the road, but cut down on inherent inefficiencies on two wheels running together, while also losing weight, given no extra hub assemblies.” 

With Phase 1 and 2, there is a direct monetary payback that far surpasses the costs associated with implementation. According to EPA, the buyer of a new long-haul truck in 2027 would recoup the extra cost of the technology in less than two years through fuel savings. Phase 2 will save vehicle owners about $170 billion in fuel costs over the lifetime of the vehicles sold in the regulatory time frame. Furthermore, the standards will result in approximately $230 billion in net benefits over the lifetime of the vehicles sold in the regulatory timeframe, while costing the affected industry less than one-tenth that amount (about $25 billion over the same period).

The consensus is that similar GHG emissions and fuel economy standards will not be implemented for locomotive and marine sectors in the U.S. “It’s too complicated to do at this point,” Schaeffer says. And developing an international GHG reduction strategy would be an even more tremendous feat to accomplish. “We need standards that govern international freight, but the detailed process to work that out is beyond my expertise,” Martin says. “The climate doesn’t care which jurisdiction the CO2 came from. It has the same effect of warming the climate, so as we move into considering international shipping, it’s big enough that we can’t ignore it.”

Rail and marine transport per ton of cargo is quite efficient compared to over-the-road trucking. As a sector, Schaeffer says, marine emissions are low on the pecking order for GHG emissions. “For energy use, ships and boats only account for 3 percent in 2014, according to EPA, while heavy-duty trucks and buses account for 20 percent,” he says. However, in a scientific research study titled, Potential Greenhouse Gas Benefits of Transatlantic Wood Pellet Trade, by Puneet Dwivedi, Madhu Khanna, Robert Bailis and Adrian Ghilardi, the authors indicate that while GHG emissions from transportation of feedstock is relatively small (3 percent) of the overall GHG emissions for wood pellets, the GHG emissions from the transatlantic shipment of pellets are second only to the manufacturing process itself, meaning there is significant room for improvement. The actual burning of the wood pellets comes in a distant third.

“Transportation is absolutely part of the life-cycle analysis,” Martin says. “But we’ve got some pretty dirty fuels as part of the mix. You’re not going to get any deep reductions without addressing all sectors.”

Fuels
“When we talk about the diesels of the future, the idea of getting to clean and near zero, it’s the ticket just to get in the door for future discussion,” Schaeffer says. “We have to think about how diesel can improve efficiency, reduce its carbon footprint, reduce barriers. Just envision, what if in 10 years diesels are not even running on diesel fuel? That’s happening today. With some of the renewable diesel fuels out there, like from Neste, that whole area of producing lower carbon fuels from renewable sources is a major lifeline to the future as we like to think of it.”

Biodiesel, renewable diesel, synthetic diesel from biomass—they all can contribute significantly to reducing GHG emissions and criteria pollutants like PM from legacy heavy-duty vehicles, marine vessels and locomotives. “That’s definitely important,” Martin says. “As this administration moves toward heavy-duty efficiency standards, cleaning up those fuels is definitely relevant. We could make a significant difference cleaning up the fuel supply chain.”

More than 78 percent of the diesel vehicles coming off U.S. production lines today are approved for use with 20 percent biodiesel (B20), according to the National Biodiesel Board. Notably, all of Detroit’s Big Three Automakers—Ford, General Motors and Fiat Chrysler—have supported high biodiesel blends for nearly a decade. Among U.S. heavy-duty truck segments, which account for more than 87 percent of actual diesel fuel usage, every major engine manufacturer supports B20 in their new engines, except for Daimler’s Detroit Diesel, which remains at B5. Furthermore, ISO 8217, the prevailing marine fuel specification, recently passed an allowance of 7 percent biodiesel.

As fuel economy standards and concerns increase, it is fair game to question where biodiesel and renewable diesel stand in this context. “B100 biodiesel contains about 10 percent less energy per gallon than conventional diesel fuel, such that a B20 blend contains 2 percent less energy,” says Robert McCormick, principal engineer at National Renewable Energy Laboratory in Golden, Colorado. “To a first approximation, mpg fuel economy is proportional to fuel energy content. In my opinion, a 2 percent reduction in fuel energy content is too small for a consumer to measure or notice, given all of the other factors that affect fuel economy and the variation in energy density of conventional diesel fuels.” McCormick says renewable diesel has about 5 percent lower energy content per gallon than conventional diesel.

Scott Fenwick, technical director for NBB, says while B100 has a slightly lower energy content than petroleum diesel, he doesn’t believe this necessarily translates to lower fuel economy. “A study performed by Purdue University concluded that there was no difference in fuel economy when comparing trucks after an entire calendar year operating on ULSD vs. B20,” Fenwick says. “Engine oil analysis, along with the service and maintenance were also found to be similar for the two fleets analyzed.” He says many additional vehicle and engine manufacturers are just now investigating the qualities of renewable diesel. “Some have approved its use while other applications, such as the railroad industry, are just beginning to evaluate its performance,” Fenwick says.

How biodiesel and renewable diesel perform in new diesel technologies is also an area of concern. Since biodiesel first got its ASTM fuel quality specification in 2002, it has gone through 21 revisions, many of which were adaptations to concerns from OEMs over changing diesel technologies, such as implementation of aftertreatment systems. “Our industry prides itself on being responsive to the concerns of OEMs,” Fenwick says.

“With support from NBB, NREL has done research on how B20 blends affect the performance of diesel emission control systems for more than eight years now,” McCormick says. “The main concern has been the very low levels of sodium, potassium, calcium and magnesium that can be present in B100 as residues from the manufacturing process. These are limited in the ASTM standard for B100 (D 6751) to 5 parts per million (ppm) of sodium plus potassium, and 5 ppm of calcium plus magnesium—although quality surveys show that actual levels are usually well below these limits. Calcium and magnesium are present in engine lubricant, and so are not expected to impact the performance of diesel oxidation catalysts or selective catalytic NOx reduction catalysts. For heavy-duty trucks, full useful life is over 400,000 miles. We have conducted tests simulating 435,000-mile exposure of emission control systems to engine exhaust from B20 blended from B100 at the metals specification limit. In these tests, we have not observed significant loss of catalyst activity. Questions remain about the potential for these ash-forming metals to increase the frequency of diesel particulate filter clean out, although this seems unlikely given the very low, below-specification limit levels observed in the field.” 

Cooke adds, “As we look out to 2030 and beyond, we know that fuel switching will need to play a greater and greater role to continue to drive down emissions. And investments in those technologies will need to be incentivized over the next decade to bring them to market in sufficient capacity.”


Author: Ron Kotrba
Senior Editor, Biomass Magazine
218-745-8347
rkotrba@bbiinternational.com