Next-Gen Motive Power

Written by William C. Vantuono, Editor-in-Chief
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Left to right: Progress Rail EMD® GT38H hybrid, SD40JR Joule battery-electric, and GT38JC Joule. Progress Rail photo

RAILWAY AGE, MARCH 2023 ISSUE: Transitioning from steam to diesel took more than 20 years. Moving to zero emissions will probably take much longer.

Be it battery-electric, hybrid, biofuel, hydrogen fuel cells, or improvements to the tried-and-true diesel-electric, the motive power market is glowing with clean, green technologies. The most widely used terms are “decarbonization” and “zero emissions.”

“Railroads are working diligently to develop lower and ultimately zero-emission technologies that deliver an even more sustainable future,” the Association of American Railroads notes. “Railroads are taking active steps to further reduce emissions associated with current locomotive technology and move toward lower and zero-emission technologies that are still in research, development and demonstration phases. Numerous railroads have active demonstration programs for alternative fuel locomotives that hold great promise as tomorrow’s lower or even zero-emission solutions.”

All of this will take time—lots of it. The railroad industry has been around for nearly 200 years (167 of them documented in the pages, print or electronic, of Railway Age). The diesel-electric locomotive, which will remain the industry’s primary source of motive power for many years to come, first appeared in 1920. Will railroad historians in the 22nd century consider 2023 (or thereabouts) a milestone year, the beginning of a major move away from the diesel-electric? Or will another 10 to 20 years of development and testing, followed by 10 to 20 transitional years, push back that date in history? 

We’ve talked with Progress Rail, Wabtec and Cummins about the evolving market for alternative propulsion. In a companion article, three professional engineers from HDR offer their perspective. Also, veteran railroad locomotive specialist and Railway Age Contributing Editor Mike Iden offers his views (including the benefits of electrification), based on decades of experience.

Progress Rail

Progress Rail, a Caterpillar company, is embracing all forms of alternative propulsion technologies. The brand that got its start as Electro-Motive Corporation in 1922, and as EMD (Electro-Motive Division of General Motors), jump-started dieselization in 1941 with the FT. Today, Progress Rail sees an evolving market for its EMD® product line, including battery-electric, hybrid and HFC (hydrogen fuel cell) propulsion, as well as diesel-electric locomotives fueled with bio-diesel blends, renewable diesel, a hydrogen/diesel blend, or even straight hydrogen. The possibilities are vast, and there is no “one size fits all” solution.

“We are proactively developing cutting edge solutions—focusing on our customers’ interests and their ability to obtain funding for additional investments,” says Senior Vice President of International Sales, Technology & Marketing Paul Denton. “There are several options along the path of emissions reduction that are emissions-friendly and do not require railroads to replace their investment in diesel engines.”

The crown jewel of Progress Rail’s alternative propulsion initiatives is aptly named the EMD® Joule. Available in five configurations, new or repowered (“R” nomenclature)—SD70J (6 axles, 8.0 MWh maximum battery capacity); SD70J-BB (8 axles, 14.5 MWh); SD40JR (6 axles, 4.0 MWh); GT38JB (4 axles, 4.0 MWh); GT38JC (6 axles, 4.0 MWh)—these units all feature regenerative braking for battery recharging (see chart, above, for additional technical specifications). Customers can specify what they desire in MWh, up to the maximum rating. The modular EMD® Joule Charging Station provides stationary charging in 700- and 1,400-kW configurations.

In Southern California, BNSF will be taking delivery next year of up to four SD70Js with charging stations for continuous operation. Their 8 MWh of storage capacity will make them “the most powerful battery-electric locomotives in North America.” BNSF’s acquisition is funded in part by CARB (California Air Resources Board) and EPA grant funding.

At 14.5 MWh, the SD70J-BB offers the largest known battery capacity in the industry. BHP Western Australia Iron Ore will be testing two beginning early next year. The test will include regenerative braking (also called “energy capture”) charging using the rail network’s natural topography to reduce overall power demand. On the downhill run to BHP’s Port Hedland export facility from the mine in the Pilbara, the locomotives will capture energy from regenerative braking and use it to help power empty trains back to the mine. FMG/FFI (Fortescue Metals Group) will take delivery this year of two units for its Australian iron ore mining operations, which are currently under manufacture at the Progress Rail facility in Sete Lagoas, Brazil.

Brazil’s Vale S.A., a metallurgical and mining firm, was among Progress Rail’s initial partners for its first battery-electric locomotive. “In conjunction with Caterpillar, our engineering teams designed a locomotive for that application,” says Senior Vice President of Engineering Mike Ramm. “That project, which resulted in the GT38J, a meter-gauge/low clearance version of the SD40JR, started our journey into battery-electric,” he adds.

The newest iteration of the Joule line is a standard-gauge unit for Pacific Harbor Line, currently testing at MxV Rail in Pueblo, Colo. “Battery locomotives are ideal for certain railway applications,” notes Ramm. “Yard service is a perfect example, which is why PHL expressed interest to acquire the SD40JR for its operations.”

Progress Rail selected LiFePO4 (lithium iron phosphate) batteries. “When you look at battery locomotives in the industry, much of it comes down to battery chemistry and how it is being used,” says Ramm. “Do you want faster discharging/charging for highly cyclic applications, or something that is more stable? Batteries have a finite life, like in cell phones. When you repeatedly charge and discharge them, battery life goes down, which is also true for locomotives.”

Hybrid propulsion, which uses a combination of diesel engines and battery, is another solution from Progress Rail. Brazilian logistics/transportation firm Rumo Logística will take delivery early this year of two EMD® GT38H intermediate-power locomotives, the first hybrid locomotives in revenue freight service. These use modular architecture to accommodate various energy sources, retain the capability of their diesel counterparts, and are capable of both regenerative and external battery charging. “We see hybrid locomotives as one of the bridge technologies to helping customers conserve fuel and reduce emissions,” says Ramm.

Joule charging station. Progress Rail illustration

For longer-distance line-haul, high-power applications, HFC shows promise, provided its limitations can be managed. “A hydrogen fuel cell vehicle is, at its core, an electric vehicle with electric traction motors and a battery system,” explains Director of Advanced Energy Michael Cleveland. “The battery system is recharged or supplemented by the fuel cell, which takes in hydrogen from onboard storage and extracts oxygen out of the air. It is analogous to a battery. One of the limitations of fuel cells is they do not perform well with load fluctuations. A freight locomotive can go from Notch 8 to idle in a couple of minutes, for example. The way to mitigate that is to couple the fuel cell with a battery system that can manage load fluctuations.”

“We are taking what we are learning with batteries and incorporating it with fuel cells. Hydrogen contains about 20% of the energy by volume of diesel fuel, so an external hydrogen tank, a tender, will be needed to support long-haul operations, which is essential to the Class I’s,” notes Cleveland. “Hydrogen has some challenges, but the fact that the only ‘exhaust’ is water makes it an attractive option.”

In December 2021, BNSF, Chevron U.S.A. Inc., and Progress Rail entered a memorandum of understanding (MOU) to demonstrate an HFC locomotive. The goal is “to confirm the feasibility and performance of hydrogen fuel for use as a viable alternative to traditional fuels for line-haul rail,” Progress Rail said. “Hydrogen has the potential to play a significant role as a lower-carbon alternative to diesel fuel for transportation, with hydrogen fuel cells becoming a means to reduce emissions.”

“As a division of Caterpillar, we are deeply involved in the energy transition across our entire business. Our investments in technology—from hydrogen, to battery, to electric, and even hybrid locomotives—are being jointly developed with our parent company,” comments Denton. “When we couple our powertrain innovations to our existing technology stack for fuel savings, such as Talos energy management and our Nitro Suite of yard and network optimization decision support tools, we contribute significantly to our customers’ ability to operate more efficiently and safely, while helping them achieve their ESG goals.” 


Wabtec first-generation FLXdrive. William C. Vantuono photo

“We’re trying to create options for our customers,” says Wabtec Executive Vice President and Chief Technology Officer Eric Gebhardt. “We’re looking at biofuels and renewable fuels. We have our FLXdrive battery locomotive, and also hydrogen. On top of that, we’re driving more efficiency through diesel engine modifications—5% lower fuel consumption, 5% less carbon, etc.”

Wabtec currently has more than 40 locomotives operating with various blends of fuels, for example, 20% biodiesel and 80% renewable diesel. What’s the difference between biodiesel and renewable diesel? “Biodiesel is close to diesel, but with more waxes and paraffins and other elements,” Gebhardt explains. “It’s chemically different. Renewable diesel is hydrogenated, so it’s a pure form of the diesel molecule. In fact, it’s actually a little too pure, so it requires additives to improve viscosity. We’ve approved up to 5% biodiesel and up to 30% renewable diesel for our locomotives, and we’re trying to get to 20% biodiesel and up to 100% renewable diesel. Both types come from the same feedstocks.”

FAME (Fatty Acid Methyl Ester) is the generic chemical term for biodiesel derived from renewable sources. It is used to extend or replace mineral diesel and gas oil used to fuel on- and off-road vehicles and static engines. FAME consists of acids created during the transesterification of vegetable oils and animal fats to create biodiesel. These high molecular weight oils and fats react with short chain alcohol in the presence of a catalyst, usually potassium hydroxide, to produce lower molecular weight esters.

“We need to understand what engine parts would have to be changed out burning these different types of fuels—things like hoses and seals,” explains Gebhardt. “We want to understand the deterioration factors, the impact on fuel injection systems, for example, to stay within current emissions compliance standards. Fuel injectors have very precise passages. We need to make sure we can reach the NOx and particulate matter requirements. We’re working with our customers through field tests, inspecting these units to make sure we know what the maintenance intervals need to be. We’re less concerned about the metals (internals). We don’t think any of those would be a large concern, with the right lubricity (the measure of friction reduction) and viscosity (the measure of a fluid’s resistance to flow) additives. We’re paying close attention to how elastomers and hoses, the rubber components, will interact. We have a program with the Class I’s, and we don’t see any reasons why we won’t be successful with this. Longer term, it’s going to be important for our customers to understand the availability and cost of these fuels. Some parts of the U.S. have significant subsidies—California, for example. The price points might vary in different parts of the U.S.”

The FLXdrive program is progressing to the next level. The 2.4 MWH “version 1.0” successfully tested with BNSF between Barstow to Stockton, Calif., registering an 11% fuel savings operating in a consist with two diesel-electrics, vs. a three-unit diesel-electric. “We now have two new iterations,” says Gebhardt. “The first is what we call the FLXdrive 2.0, with 7 MWh, the first two of which are shipping at the end of this year to Australia for a trial with BHP Western Australia Iron Ore (in the same trial as Progress Rail’s SD70J-BB).”

This will be followed by the FLXdrive 2.5, which replaces the NMC (nickel-manganese-cobalt) batteries with GM’s Ultium NCMA (nickel-cobalt-manganese-aluminum) technology manufactured by Ultium Cells LLC, a joint venture of GM and LG Energy Solution. “We’re utilizing the Ultium designed for the Hummer truck,” says Gebhardt. “We’ll ruggedize it. The batteries have individual cells; a module consists of a stack of cells. Several modules create a pack. One weighs more than a ton, but they have a lot of energy capacity. We’ll take the Hummer pack and stack 42 inside the locomotive, and that gets us to 8-plus MWh.”

“It’s not how much power you have when you start or end the route,” says Gebhardt. “It’s the fact that you’re regenerating the electricity. There are parts of the route that have high standard deviation, in terms of grade. You can generate a lot of energy with a train that might have 10,000, 20,000 or 30,000 trailing tons. If you think about the 2.4 MWh hour version that one saves about 11%, with an 8 MWh unit we could save 20% or 30% on fuel usage, depending on track standard deviation.”

Wabtec Hydro Locomotive concept with hydrogen fuel tender.

Wabtec’s venture into hydrogen includes HFC as well as burning hydrogen inside an internal combustion engine. The company is working with GM to utilize its Hydrotec fuel cell technology in a hybrid unit, with batteries supplying traction power. The fuel cells would be trickle charging the batteries. “The game-changing part of fuel cells is efficiency,” says Gebhardt. “We’ll be working toward 65% efficiency, compared to 40%-42% with an internal combustion engine. Fuel cells have that significant advantage, which should be achievable over the next decade or so. We have to make sure that we understand how to provide enough fuel for those fuel cells. Right now, the energy density, volumetric energy, of hydrogen is low. If we’re going to offer a main line solution, it will have a tender car. Our locomotives carry about 5,000 gallons of diesel. One kilogram of hydrogen is equivalent to one gallon of diesel, roughly, in energy content (expressed as DGE, diesel gallon-equivalent). To get that same amount would require a tender car with about 7,000 kilograms of hydrogen. That amount provides more range than 5,000 gallons of diesel. Because of the volume, we’ll need a tender. But we are operating with LNG tenders in Florida and Mexico, so we understand how to work with them, and with liquid and gaseous fuels.”

Burning hydrogen in an internal combustion engine will be similar to LNG. “We’re working with Argon and Oak Ridge National Labs on this as part of a Department of Energy grant,” explains Gebhardt. “We’re looking at different configurations to see how much of a blend of hydrogen with diesel for energy content we can get to. Our goal is to get into the 90%-plus range, to stay with compression ignition, avoiding spark plugs. Part of that has to do with what our customers are looking for. Spark ignition has shorter maintenance intervals. Compression ignition is more robust, with longer maintenance intervals. Spark ignition with hydrogen or LNG is maybe an easier solution, but it does require more maintenance.”


Cummins X Series Fuel-Agnostic 15-litre engine lineup

Among the world’s largest diesel engine manufacturers, Cummins has established a major presence in the North American diesel-electric locomotive market in partnership with Siemens, whose Charger series of passenger locomotives utilize the Cummins Tier 4 QSK95 high-speed engine. Smaller variants of the QSK series are used in DMUs and freight switcher locomotives. Long-term, the company’s official decarbonization strategy is called Destination Zero, “which is about achieving net-zero emissions by reducing greenhouse gas (GHG) emissions and supporting customer transitions to decarbonized power,” says Innovation Lead, Industrial Markets Brian Olson.

Cummins’ alternative fuel initiatives took flight after it purchased, for $290 million, Canada-based Hydrogenics in 2019. The company intends to become a major player in HFC, battery-hybrid and “fuel-agnostic” (hydrogen, natural gas, diesel and biofuels including HVO) heavy-equipment engine technology.

“We’ve looked across our rail engine portfolio, and we think there will be unique adoption times for alternative fuels and different types of propulsion, whether it’s full electrification, fuel cells, dual-fuel engines, hydrogen fuel combustion or a diesel alternative equivalent,” says Freight Rail Business Manager Tyler Hodge. “Each market is going to have a different adoption curve associated, based largely on the infrastructure to support it, as well as the maturity and energy density of the technology. With respect to rail in general, we still see a long runway for the internal combustion engine, or ICE—a nickname that has become quite popular.”

“Even broader than rail, we’re seeing different markets adopt at different rates,” adds Olson. “For example, the passenger car market is adopting at a certain rate vs. some of our industrial markets. Shorter, captive systems like transit routes are going to adopt technologies faster because the infrastructure challenges are easier to overcome, whether it’s battery charging or fuel cells, or even installing overhead catenary lines. In rail and some of the other industrial markets, the longer routes, especially in areas with low population, may not make sense to build out the infrastructure, and we see that evolving slower.

“Our near-term focus is making sure that products can meet the railroads’ decarbonization goals. That includes alternative fuels like HVO (hydrogenated vegetable oils, used to make renewable diesel). We recently completed a multi-year test with 100% HVO on the QSK95—a big breakthrough. We plan to roll that out on the rest of our high-horsepower engines in the rail market.

“We’re currently testing higher biodiesel blends of up to 20% on our T4 products. That seems to be where the industry is moving. Next is a B20 blend, maybe part HVO/part diesel. We’re investing today in our current products to understand the life cycle and maintenance implications. We want to make sure that, with the repower trend in the freight market, whether it’s line haul locomotives or switchers, and the regulatory pressures that are coming from states like California, we have products that are easy to change out. It will take years for the rail infrastructure to meet the needs of hydrogen or methanol or battery, because the network is vast and disparate.”

“To replace all diesel locomotives between now and 2050, you’d really have to start tomorrow, based on their life cycle,” says Olson. “This is why we are investing in technologies and solutions that can allow customers to buy our QSK95 today, but still have a path to a carbon-neutral fuel in the future.”

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