On a New Track

With tougher federal emissions standards on the horizon and an aging fleet of diesel-electric locomotives, could the ethanol-hybrid locomotive become the next American railroad workhorse?
By Michael Shirek | March 27, 2007
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Tom Mack has heard the question before: Isn't biodiesel the obvious renewable fuel for the railroad industry? Not necessarily, says the president and CEO of Milford, Ohio-based Alternative Hybrid Locomotive Technologies (AHL-Tech). Biodiesel might look like a winner in the race to reduce dependence on foreign petroleum and lower greenhouse gas emissions, but Mack says ethanol is the better bet for his business. Although biodiesel can be used in diesel blends with today's diesel-electric locomotives, Mack is convinced that tomorrow's locomotives will have to take a different approach in order to meet U.S. EPA emissions standards.

AHL-Tech is in the process of developing an ethanol-hybrid locomotive to capitalize on the growing ethanol market in the United States, and to replace the railroad industry's aging diesel-electric locomotive fleet. Combine that with the federal emissions standards being phased in over the next decade, and an alternative to the diesel-electric locomotive starts to look even more promising. Now is the time; economics and environmental protection have created an opportunity, the likes of which may never come along again, Mack says.

The EPA adopted its first emissions regulations for railroad locomotives in 1997—a three-tier standard to be phased in on newly manufactured and remanufactured locomotives built after 1973. The tier 0-2 emissions standards targeted nitrogen oxides (NOx), hydrocarbons, carbon monoxide, particulate matter and smoke produced by the U.S. locomotive fleet—a fleet dominated by the diesel-electric locomotive.

This was the first time the railroads had faced such regulation. When railroads transitioned from steam-powered locomotives to diesel and later diesel-electric locomotives in the 1940s and 1950s, it wasn't a reaction to environmental regulations—it was pure economics. This time the change was, and will continue to be, brought on by legislation. "They weren't under government regulation to switch over," Mack says. "Now, suddenly, it's not an option to continue using an older, dirtier emissions locomotive. We now have the air quality standards and we have to meet those." Meeting those standards, means either re-engineering the current locomotive or coming up with something new.

The Nuts and Bolts
The current diesel-electric locomotives that form the backbone of the railroad fleet range from 1,000 to 5,000 horsepower. The diesel engines are connected to large generators that drive electric motors that are directly attached to the locomotive's axels. While some consider the diesel-electric to be a hybrid vehicle, Mack says that's not the case. The electric generator aboard the locomotive acts as a transmission, not a power source.

AHL-Tech's ethanol-hybrid locomotive is designed to replace some of the smaller locomotives in the fleet, generally the 1,000 to 2,000 horsepower models. The ethanol-hybrid has two power sources driving the axels. Much like in diesel-electric locomotives, an ethanol-fueled engine powers a generator connected to the locomotive's axels. Unlike the diesel-electrics, the ethanol-hybrid also has a battery component. Instead of a direct correlation between the speed of the engine and the power transmitted by the generator, AHL-Tech's design features a capacity to store electricity when the generator produces more power than is being used to move the locomotive. This gives the operator the option of powering the axels by running the engine or using power stored in the battery. It also allows for regenerative braking—capturing the energy lost when a locomotive is brought to a halt.

Regenerative braking could also be used in an electro-mechanical battery (EMB), a pressure-gradient-driven system used to store energy and release it when needed to boost power in the short term. The EMB system complements the batteries, allowing for a short-term surge in power to ease the load on the main battery component during acceleration at start-up. While the locomotive's main batteries are designed to expend their energy at a measured pace over time, the EMB is designed to expend its energy quickly and recharge when not in use.

Another feature expected to be utilized by AHL-Tech's proposed locomotive is predictive power management control (PPMC). The idea behind this technology is to have a database of track routes on which a locomotive will operate and tune the engine's performance to maximize efficiency along each trip. This technology can also be used to manage emissions, running on electric power in more environmentally sensitive areas and on ethanol power in less sensitive areas.
The biggest difference between the diesel-electric and ethanol-hybrid locomotives, however, is what goes in the tank and what comes out as exhaust.

Making the Grade
The lifecycle of a diesel-electric locomotive can be extended greatly through maintenance, Mack says. However, that becomes tougher as the rebuilt locomotives must meet the emissions standards of a new engine.

"It's true a locomotive in theory could last for 40 or 50 years," Mack says. "There are some out there that are that old. But for a locomotive that's really seen heavy service for 20 or 30 years, at that point in time, the railroads were looking to replace them." Mack says that railroads bought newer locomotives with more horsepower for use on their main lines and moved the older locomotives to local and yard use. Over the course of time, however, the amount of aging locomotives has started to add up.

"So all of the sudden they've got to do something—either buy new or rebuild what they have," Mack says. "The problem with rebuilding what they have, is again going back to the number one problem—emissions. You're not allowed to just take that locomotive and rebuild it to the old, dirty standards." The opportunity for AHL-Tech, according to Mack, is that a new technology in ethanol would not only meet current tier 2 standards, but also meet tier 3 and 4 standards, which aren't likely to be imposed for decades.

Tier 0 standards apply to locomotives manufactured between 1973 and 2001. These vehicles are allowed the highest levels of emissions among regulated engines. Tier 1 standards apply to locomotives manufactured between 2002 and 2004, while tier 2 standards apply to locomotives manufactured in 2005 or later. The EPA is considering a tier 3 standard for engines manufactured as early as 2011. Each successive level of regulations tightens the amount of NOx, hydrocarbons, carbon monoxide, particulate matter and smoke a locomotive can produce.

Why Not Biodiesel?
Mack says there are still some NOx emissions issues that have kept biodiesel from becoming the renewable fuel of choice in the railroad industry, but those issues pale in comparison to the biofuel's biggest limitation—availability. With the railroad industry consuming billions of gallons of fuel each year, biodiesel production won't be able to match the demand in the near future.

"We're looking at several billion gallons a year—about 11 [billion] to 12 billion gallons a year of ethanol here shortly versus maybe 1 [billion] or 1.2 billion gallons of biodiesel," Mack says. "In the railroad industry, we're talking about an industry that uses 6 billion gallons of diesel a year, and that number will potentially increase. If we're going to put any major dent in that, then ethanol certainly makes more sense from the supply side."

An ancillary benefit, Mack says, is that ethanol plants would actually be able to invest in ethanol-powered locomotives for local rail use at their facilities and produce their own fuel in-house.

AHL-Tech is hoping to have its prototype ethanol-hybrid locomotive released in the coming year. From there, Mack says the demonstrated abilities of the ethanol engines and the state of the market will dictate what happens with the locomotive.
"There is enough of a market, we believe—starting with the locomotives—to justify the [research and development] that it would take to actually build an ethanol-optimized, high-horsepower engine," Mack says. "It's really never been done before, or if it has, it's never really been documented. Everything we know about ethanol as a fuel [and] everything we're seeing with the way the industry is going indicated to us, and then to the partners that got involved with this, that [ethanol] was the way to go."

With the lower emissions levels produced by and the ready availability of ethanol fuel, now is the time to take action, Mack says. Using a fuel that can be produced domestically just happens to be a positive side effect of the ecological benefits.

Michael Shirek is an Ethanol Producer Magazine staff writer. Reach him at mshirek@bbibiofuels.com or (701) 746-8385.