Plug-in and Hybrid Locomotives; Another Sweet Spot for Axion Power

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John Petersen

I’m a cynic and a heretic when it comes to plug-in vehicle schemes because most defy the laws of economic gravity and violate a cardinal rule that Ford engineers developed for the EcoStar light delivery vehicle program in the early ’90s:

– The unloaded weight of a plug-in vehicle should never exceed 70% of its loaded weight.

Investors who pay attention to this simple rule can easily distinguish between pipe-dream vehicle electrification schemes that are nothing more than feel-good eco-bling and realistic vehicle electrification projects that make economic sense.

For the last few weeks I’ve been studying a technology partnership between Norfolk Southern (NSC) and Axion Power International (AXPW.OB) that is developing cost effective battery and hybrid electric drive retrofit systems for railroad locomotives. After extensive research I’ve decided that battery and hybrid electric locomotives are applications that even a heretic can love because:

  • Vehicle weight to cargo weight ratios range from good to extraordinary;
  • Expected payback periods are in the three to four year range;
  • Electric retrofits can avoid emissions abatement costs mandated by EPA regulations; and
  • Axion’s PbC technology appears likely to overcome the battery problems that plagued earlier efforts.

Like e-bikes, stop-start idle elimination and hybrid electric vehicles, battery and hybrid electric locomotives are clean fuel efficiency technologies that just make sense.

The Green Goat

The first hybrid electric switching locomotive was introduced in 2004 by Railpower Technology and called the “Green Goat.” It replaced the 1,750 hp diesel engine in a General Motors EMD GP9 locomotive with a 290 hp diesel generator and 60,000 pounds of lead-acid batteries that offered a combined power output of 2,000 horsepower. The Green Goat’s core strengths were a $750,000 price tag that compared favorably with the $1.5 million price of a new switching unit and a battery dominant hybrid electric drive promised fuel savings of 40% to 60%. Subsequently, Railpower launched a smaller version called the “Green Kid” that offered a combined power output of 1,000 horsepower.

6.1.11 Green Kid.png

In a year long field trial by IDC Distribution Services, the operator of an inter-modal port facility in British Columbia, the Green Kid logged 3.6 million feet of switching operations over 2,347 hours, saved 10,450 gallons of diesel fuel, and reduced CO2, CH4 and N2O emissions by 53% compared to a conventional switching locomotive.

Initially, the Green Goat was well received and railroads including BNSF, Union Pacific (UNP) and Canadian Pacific (CP) ordered a combined total of 175 units. Despite the initial marketing successes, the Green Goat had significant battery problems and only 55 units were delivered before Canadian Pacific returned four units and canceled the balance of a 35-unit order citing unsatisfactory performance. The company went bankrupt in 2009 and emerged as a subsidiary of the RJ Coleman Co. that no longer builds the Green Goat.

The NS 999

In 2009, Norfolk Southern unveiled an experimental electric switching locomotive that it built in cooperation with the Department of Energy, the Federal Railroad Administration and Penn State University with the aid of a $1.3 million Federal grant. Unlike the Green Goat, the NS 999 draws all its power from an array of 1,080 lead-acid batteries that provide a power output of 1,500 horsepower. The project’s goal was to demonstrate the feasibility of a plug-in battery powered locomotive that would eliminate direct rail yard emissions and save up to 50,000 gallons of diesel fuel per year.

6.1.11 NS 999.jpg

During initial trials with 80% of its batteries connected, the NS 999 “operated a full switcher shift, at one point pulling 2,200 tons of rail cars on an uphill track – without using a sanding system, which helps locomotives gain traction. After the shift, the four-axle locomotive had enough juice in its 12-volt batteries to run two more eight-hour shifts.” Like the Green Goat, however, the NS 999 ran into battery performance issues that had Norfolk Southern evaluating lithium-ion batteries, nickel-based batteries and advanced lead-acid batteries in a matter of weeks. In June of 2010 Norfolk made its battery technology selection and recruited Axion Power to develop a new battery management system and integrate its disruptive PbC battery technology into the NS 999. The project is scheduled for completion later this year.

In addition to the NS 999 project, Norfolk Southern is working with Axion to develop a retrofit hybrid drive system for multi-purpose locomotives that will use 1,600 to 1,700 PbC batteries to improve fuel economy in long distance freight transportation. A prototype is expected by next spring.

The Battery Problem

The fundamental battery problem encountered by both the Green Goat and the NS 999 is a chemical process known as negative electrode sulfation. During discharge, a lead-acid battery’s electrodes are partially dissolved and lead sulfate is created. During charging, the bulk of the lead sulfate gets dissociated and redeposited on the electrodes. In practice complete dissociation of lead sulfate never happens. Instead, a portion of the lead sulfate is deposited on the negative electrode in the form of hard crystals. As the number of cycles increases so does the level of crystallization. When the crystal build up is extreme, the battery fails. The following electron micrographs show how sulfation increases over time in a shallow-cycle partial state of charge environment.

6.1.11 Sulfation.png

The PbC Solution

Axion’s patented PbC battery is a hybrid device that uses conventional lead plates for the positive electrodes and carbon electrode assemblies for the negative electrodes. The PbC is technically classified as an asymmetric ultracapacitor. Due to its unique architecture, the PbC does not experience negative electrode sulfation. It also offers significantly higher charge and discharge currents than a conventional lead-acid battery. In a shallow cycling environment like the Green Goat, prototype PbC batteries have demonstrated the ability to withstand tens of thousands of cycles without degradation. In a deep cycling environment like the NS 999, prototype PbC batteries have demonstrated the ability to withstand up to 2,000 cycles at a 100% depth of discharge without battery damag

After several years of working with alpha and beta prototypes of its PbC electrodes and electrode fabrication processes, Axion is just now completing the installation, optimization and certification of its first commercial electrode fabrication line. While it has not launched a commercial product yet, that launch is expected later this year.

The Business Opportunity

North America’s Class I Railroads operate a combined fleet of approximately 1,500 switcher units that each burn about 50,000 gallons of diesel fuel per year. The average switching locomotive is 30 to 40 years old and was manufactured during an era when emissions control regulations were far less stringent than they are today. As a result of new EPA regulations and a variety of state air quality initiatives, the railroads are under intense pressure to reduce N2O and particulate emissions in their switching yards, which are often located in heavily populated urban areas.

Based on a recent report to the California Air Resources Board, it appears that the cost of bringing an old locomotive up to current standards is roughly equivalent to the cost of converting an old locomotive from diesel-electric to battery powered electric. While an emissions abatement upgrade will improve fuel economy through the application of newer technology, a battery retrofit can eliminate all direct emissions and fuel consumption. Based on a current off-road diesel price of $3 per gallon and an estimated fuel consumption of 50,000 gallons per year, a battery retrofit should offer a payback period in the three to four year range. In comparison, the payback period for an emissions abatement upgrade will be closer to ten years. The long-term revenue potential of retrofitting a portion of the switcher fleet to run on batteries isn’t a company maker, but it’s a darned good start.

The Voting Machine

Over the last year Axion’s stock price has stagnated in the $0.50 to $0.75 range as shares that were sold in December 2009 moved from relatively weak hands to stronger hands. While I’ve responded to countless comments and questions from readers, many have missed the crucial fact that Axion is focused on completing the development of its technology, rather than marketing a fully developed product. It’s never had a marketing team and except for the odd technical presentation at industry events, its selling efforts have been non-existent.

Despite a lack of marketing for a development-stage product that wasn’t ready for commercial use, Norfolk Southern found the path to New Castle because it was looking for a cost-effective solution to a critical performance problem that could not be solved with conventional lead-acid batteries. Based on its own technical evaluation of the prototype PbC batteries Axion was able to make in 2009, Norfolk Southern hired Axion to design and build a new battery management system that would facilitate the integration of PbC batteries into the NS 999. After about eighteen months of working with the technology, the refurbishing project for the NS 999 continues apace. If there was any substantial reason to believe the PbC would not stand up to the rigors of the NS 999, Norfolk Southern would have terminated its relationship with Axion long ago. The same can be said for BMW which also found the path to New Castle because it was looking for a cost-effective solution to a crucial performance problem that could not be solved with conventional lead-acid batteries.

In its last quarterly report, Axion disclosed that it had received notification from the Department of Energy that a grant application under the Vehicles Technology Program had passed the first round of criteria testing and advanced to the final round of review. In its last conference call, management told participants that the grant application identified Axion as the prime contractor, and included a top-three US automaker, a research university and a national laboratory as subcontractors. While details of the application will remain confidential until a funding decision is made, it appears that this time around a first tier US automaker has found the path to New Castle because it was looking for a cost-effective solution to a critical performance problem that could not be solved with conventional lead-acid or lithium-ion batteries.

Given the mainstream media’s infatuation with lithium-ion batteries, the voting machine that is the market does not want to believe the PbC will be a disruptive energy storage technology. When I consider the growing parade of world-class companies that found the path to New Castle before Axion even had a product to sell, I have to believe there is more substance to the PbC than even I understand.

Disclosure: Author is a former director of Axion Power International (AXPW.OB) and holds a substantial long position in its common stock.


  1. Great writeup. Couple this with your earlier article on the Class 1 locomotive companies and you can see why both Axion & those companies will be great investments in the future. They will be the kings of efficiency.

  2. It certainly seems to be shaping up that way. The railroads are certain to prosper. Axion’s future will depend more on whether the PbC can continue to offer the same performance in commercial devices that it offered in the pre-commercial prototypes. So far all the signs are positive, but it really is up to the battery at this point.


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