Why railroads are against running locomotives on natural gas

Since oil is finite, natural gas was seen as a fuel that could extend how long oil lasted by being a “bridge” fuel.  Since natural gas is finite also, and would lead to dependence on unstable foreign nations, the plan was that this would “bridge” us to hydrogen fuel cells. Needless to say, that’s never going to happen.

Railroads are adamantly against being pushed towards using natural gas driven locomotives.  Here are a few of the reasons why:

  1. Railroads have experimented with alternative fuels since 1935 and they haven’t worked out
  2. Natural gas emissions are much worse than emissions from a diesel locomotive
  3. LNG locomotives are more expensive than diesel equipment to operate, and a completely new fueling infrastructure would be needed.
  4. Since only one locomotive is sold for every 211 Class 8 trucks, manufacturers are unlikely to do the necessary research required to build an LNG locomotive
  5. Line-haul locomotives need a tremendous amount of fuel – 10 times more than the switch locomotives that re-arrange rail cars in yards.  LNG line-haul locomotives would not go as far, not have enough power, and require a huge amount of on-board fuel storage, which is very impractical and expensive.
  6. In a derailment or accident, LNG is likely to be far more dangerous than diesel

Building LNG locomotives would be really stupid given that fracked natural gas production in America will peak roughly 2016-2020 and decline at an alarming rate, given the 60% per year decline rate of fracked natural gas wells (conventional natural gas reserves have been declining for over a decade), and we have few LNG import terminals.

If railroads stopped running, within a month or two coal electric power plants would shut down, due to lack of coal deliveries, since trains deliver over two-thirds of coal, and refineries would be impacted by trains unable to deliver 759,000 barrels per day (Chase 2014), 8% of USA oil production.

I’ve got two documents below about why railroads do not want to use natural gas fueled locomotives.

Alice Friedemann   www.energyskeptic.com  author of “When Trucks Stop Running: Energy and the Future of Transportation, 2015, Springer

BNSF, et al. 2007. An Evaluation of Natural Gas-fueled Locomotives. BNSF & Union Pacific RR, Assoc of American railroads, California Env  Assoc.  94 pages.

New locomotives must meet a wide range of railroad company, customer, and community requirements, including:

  • safety
  • exhaust emissions performance
  • extensive range
  • high horsepower
  • high tractive effort
  • fuel economy
  • reliability

The principal line-haul locomotive builders, General Electric (GE) and Electro-Motive Diesel, Inc. (EMD), continue to meet these requirements through clean diesel engine enhancements, not through the commercialization of natural gas-fueled locomotives.

The Railroads’ position on natural gas

Some members of the regulatory, engine supply, and fuel supply communities believe the railroads have an opportunity to use natural gas as a locomotive fuel to help meet emissions and performance goals. Except for some potential niche applications, the Railroads disagree. Decades of research and development activities and over-the-rail locomotive prototype demonstrations have given the Railroads a great deal of information about the practicality of using natural gas-fueled locomotives.

Locomotives use a diesel-electric drive system where the output from a combustion engine is used to generate electric power. That electric power is then used to drive an electric motor to provide the high torque required for the locomotive. Locomotives are rated based on tractive horsepower available to drive the wheels of the locomotive.

The emission standards are based on the brake horsepower developed by the combustion engine on the locomotive. Unless stated otherwise, all references in this report to horsepower refer to the tractive horsepower of the locomotive.

A “gen-set” is a self-contained modular package of power generating equipment consisting of a diesel or gas engine coupled to an electrical generator.

Green Goats for both Railroads have been returned to the manufacturer for modification to resolve an equipment malfunction that causes engine fires. One Green Goat for UP is already back in limited service, and the remaining UP Green Goats should be back by the end of the year. BNSF’s Green Goats are still with the manufacturer.

Figure 1 timeline of railroad research activities

Figure 1: Timeline of Railroad Research Activities

The Railroads currently know of one commercially available, proven and tested natural gas-fueled line-haul locomotive product available for the North American locomotive market. It is available only as a retrofit or conversion product. It would convert an approximately 25-year-old, EMD645-E3 3,000 hp diesel locomotive to run on natural gas. Comparing the exhaust emissions of this converted locomotive with those of EPA certified Tier 2 compliant diesel locomotives shows that the new diesel locomotives outperform the natural gas-fueled locomotive on emissions (see Table 1).

Table 1 comparing natural gas-fueled line-haul locomotive converstion and certified tier 2 diesel






Table 1– Comparing Natural Gas-fueled Line-haul Locomotive Conversion and Certified Tier 2 Diesel Line-haul Locomotives

There is no NOx benefit from using this natural gas-fueled locomotive, and all other criteria pollutant emissions are higher—including particulates, which are four to five times greater.

Compared to the operation of the same locomotive on diesel fuel, natural gas is less energy efficient and produces more greenhouse gas emissions (CO2 equivalent). Also, a locomotive using this natural gas conversion kit will likely have higher emissions of some toxic air contaminants, especially formaldehyde.

Niche opportunities may exist There may be niche opportunities to use natural gas in certain locomotive applications, such as the liquefied natural gas (LNG) rail yard switch locomotives in service in Los Angeles

However, because of the relatively small amount of fuel consumed by yard switchers and the possible use of diesel particulate filters on gen sets, there may be little improvement in emissions by using natural gas as a fuel in these engines, and it begs the question as to what advantage there would be in using natural gas given the requisite infrastructure costs that accompany it.

Cost Savings Claims

Claims that natural gas-fueled locomotives will be less expensive to operate than diesel equipment are unfounded.

Moreover, support of natural gas-fueled locomotives will require significant investments in new fueling infrastructure that are duplicative to established diesel based infrastructure. These infrastructure investments and their associated operating costs must be accounted for in any evaluation of cost effectiveness.

Given the small size of the locomotive market (approximately one locomotive is sold for every 211 Class 8 trucks) and given manufacturers’ personnel and financial constraints, it is highly doubtful the builders can simultaneously pursue further improvements in diesel locomotive technology and natural gas-fueled locomotive development.

The following factors should be considered when evaluating natural gas-fueled locomotives:

Locomotive Type. There are significant differences between switch and line-haul locomotives. The differences include: the size and horsepower of the engine that powers the locomotive, the amount of tractive effort the locomotive produces, the duty cycle of the locomotive, the fueling infrastructure requirements, and the range of operations. Switch locomotives spend their time in one location (such as a rail yard), whereas line-haul locomotives crisscross North America and often operate interchangeably on different rail company lines. Due to its greater power rating and higher load factor, a line-haul locomotive will burn up to ten times the fuel compared to a switch locomotive.

What is sensible for one locomotive type may not be for another. For example, spark ignited LNG-fueled locomotives are inhibited by low fuel storage capacity, range, and power density, thus making them impractical for line-haul use, but they could be potentially practical for switch duty if the locomotive can stay close to a fueling source and if high power output is less important.

High locomotive utilization is critical to ensure that the locomotive asset provides an adequate economic return. To achieve this requirement, high horsepower line-haul locomotives must be interchangeable with other railroad fleets (other railroads must be able to fuel, maintain, and operate these locomotives); be highly reliable so as to minimize maintenance requirements and avoid breakdown events; and have the ability to operate over a long range to minimize refueling events. With the possible exception of switch locomotives, creating captive fleets of unique locomotives serving small geographic regions works against these requirements and will decrease locomotive asset utilization and greatly impair the economic competitiveness of the rail industry. This in turn would alter the competitive landscape within the goods movement system, drive additional cargo to heavy-duty trucks, and worsen air quality.

The duty cycle of the locomotive refers to the percentage of time it is operated at different power settings. Locomotives have eight power settings called “notches”. There are also settings for idling and dynamic braking.

The growing practice of run through trains where locomotives interchange from one company’s system to another increases locomotive asset utilization. UPRR, for example, reports that up to 12% of the locomotives operating on its system at any given time are locomotives owned by other railroad companies. This level and frequency of interchange and degree of interoperability keeps the nation’s railroads operating efficiently. New engine and locomotive technology that cannot integrate into this operations paradigm will drive up costs, create emissions inefficiencies, and impair goods movement on rail.

This fact increases the importance of uniformly applied federal emission standards. The devolution of locomotive emissions standards into separate regional or state programs would most certainly lead to higher costs and program inefficiencies to the extent that they presume static and increasingly outdated assumptions about locomotive asset ownership and operational patterns.

A run through train is a train that travels from one company’s track to another without changing locomotives.

When the Tier 3 and Tier 4 standards are adopted, the railroads expect this will make LNG locomotive technologies less favorable to new clean diesel locomotives, not more.

Care must also be taken in reviewing emission benefits for specific projects using natural gas locomotives where the benefits do not come from the fuel change, but come from switching freight to rail. For example, railroads have consistently noted the environmental benefits of replacing truck freight by rail freight. Here the appropriate comparison is the difference between two scenarios: 1) the emissions from truck freight, and 2) the emissions from carrying the same amount of freight by rail. Statements from a California consortium evaluating the use of natural gas-fueled locomotives to replace diesel-fueled trucks provides an example where this type of scenario comparison is both useful and, at the same time, potentially misleading. The consortium’s website indicates that the planned conversion of four EMD SD40-2 locomotive engines to natural gas using the ECI 1SDT dual-fuel, low pressure injection conversion package result in emission reductions of 68.7 tons of NOx and 3,434 pounds of PM annually.” According to materials on file with the SCAQMD, the cause of this reduction appears to be both the replacement of truck freight by rail freight and the potential use of natural gas-fueled locomotives.

As shown in Figure 2, the locomotive builders sell a total of around 1,000 new locomotives to the North American market per year.

Can the natural gas engine technology be packaged into the space constraints of a modern locomotive? (See Figure 3)

  • Can the natural gas engine technology “scale” to meet broad operational requirements?25
  • Can a locomotive with the natural gas engine match the power delivery requirements of newer diesel engine locomotives?
  • Is the natural gas-fueled locomotive sufficiently reliable and durable?
  • What is the fuel economy? How is this measured? How does this fuel economy compare to diesel?
  • Are there fuel supply reliability considerations?


  • Is the natural gas engine technology applicable to new locomotives, existing locomotives, or both?
  • What is the expected use (e.g., switch, local service, passenger, or freight line-haul) and how does the application-specific duty cycle affect emissions?
  • Are there safety-related issues associated with the natural gas engine locomotives, the fueling stations and infrastructure, or with the fuel delivery process?

Scale relates to how the technology is deployed in practice versus how it performs in limited test or demonstration modes. An example is the current method of fueling the LNG switch locomotives operating in the Los Angeles area. These locomotives are fueled by tanker trucks dispatched from an Arizona processing facility. This fueling method would not reasonably scale to meet broad operational requirements because the volume of fuel required would be too great. There could be similar issues around track and facility space requirements where scaling to meet broad operational requirements is impossible.

The existence of natural gas engines in a variety of stationary and on-road applications identified [by the report authors] does not, however, mean that LNG technology: (a) can be transferred to a variety of locomotive classes operating in all types of service conditions, (b) can meet NOx and other criteria pollutant emission reduction requirements and (c) can meet the railroads’ operating requirements for high horsepower, reliability, and overall fuel efficiency.

This section explains the basic approach to using natural gas as a locomotive fuel. The 1995 EF&EE Report correctly pointed out that there are three methods of burning natural gas in large-bore, heavy-duty engines: spark-ignited, low pressure, and high-pressure injection with diesel pilot ignition (where the fuel is ignited by compression ignition of a small quantity of diesel fuel introduced into the cylinder).

Burlington Northern CNG Effort (1983-1987) In 1983, the Burlington Northern Railroad tested a modified EMD GP-9 locomotive (a 1954-era 1,750 HP switch-sized locomotive with a two-stroke, 16-cylinder 567C model engine) to run the locomotive diesel engine on CNG in a spark-ignited mode. The CNG fuel was stored in compressed gas cylinders mounted on an over-the-road truck trailer placed on a flat car coupled to the experimental GP9 locomotive. The Burlington Northern performed on-the-rail tests for two years in the upper Midwest. It concluded that the low energy density of the CNG made it impractical for wide scale railroad use because of its low range between fueling events.

This effort showed that the energy content of CNG vs. LNG vs. diesel is an important consideration in the evaluation of each fuel. Because of the differences in energy content for each fuel, locomotives utilizing these fuels will have different ranges for a given volume of fuel storage.

For a given fuel volume. an LNG-fueled locomotive will have 2.4 times the range of a CNG-fueled locomotive. Assuming equal engine efficiencies, the diesel-fueled locomotive will have 4.3 times the range as a CNG-fueled locomotive and 1.75 times the range of the LNG-fueled locomotive for equivalent volumes of fuel storage.

Figure 7: Fuel Energy Densities. Energy Content – Btu/gal: CNG 30,100    LNG 73,100    Diesel No. 2 128,100

In addition to the requirement for a new fueling infrastructure, the lower CNG or LNG energy densities would require new fueling infrastructure and operational strategies for locomotives. This includes the use of fuel tender cars and the creation of captive locomotive fleets whose operational ranges are restricted to specific geographic regions. The use of tender cars reduces the number of revenue freight cars and increases the train weight, thus increasing the cost of moving freight. Also, fuel tenders and the locomotives they supply must be kept coupled together increasing equipment asset utilization and difficulties. An LNG locomotive consist (i.e. several locomotives coupled and controlled as a unit) would require one to two LNG tenders at approximately $1 million each.

Other important questions that should be considered for this and other similar projects in the future include:

  • How reliable are the locomotives? For example, should the locomotives experience an in-route break down, diesel locomotives will have to be dispatched to help complete the train movement and bring the non-functioning locomotive to a repair shop. This would impact emissions.
  • Where will the locomotives be maintained and by whom?
  • Where will the locomotives be inspected for Federal Railroad Administration safety inspections?
  • What company will provide the train crews?
  • Over whose tracks will the locomotives operate?
  • Will these locomotives and the revenue service contribute towards the upkeep of the rail infrastructure?
  • How will safety issues be addressed in the event of a derailment?

Answers to these questions and others go to the heart of understanding the Railroads’ arguments about the critical importance of maintaining locomotive interoperability throughout the North American rail network system. While a technology may be effective in a pilot program or small scale, it must be able to be “scaled up” to operate seamlessly within the existing national rail system to maintain operating efficiencies. The Class I railroad companies cannot be competitive operating small fleets of locomotives that are captive to specific regions.

The comparative costs of natural gas and diesel fuel play a large role in determining the potential feasibility of deploying natural gas-fueled locomotives and the cost-effectiveness of any resulting air quality emission reductions. All else being equal (i.e. emissions, thermal efficiency, reliability, etc.), the delivered cost of natural gas would have to be much less expensive than diesel fuel to justify a conversion to its use due to the significant investment required in new and/or retrofit locomotives, duplicative fueling infrastructure, and related operational support costs.

Presently the four LNG switch locomotives that the BNSF leases and operates in Southern California are fueled by LNG that is refined and liquefied in Arizona and is delivered to the locomotive along the right-of-way by truck. According to a BNSF representative, the fuel is delivered “every few days” and each locomotive’s 1,300 gallon fuel tanks are topped off during each refueling. While this is practical for these four locomotives, any appreciable sized fleet of locomotives that use LNG would require a nearby, sizeable, and reliable source of LNG.108 By the end of 2005, California had 40 LNG fueling facilities scattered throughout the state and primarily located near major thoroughfares and serving on-the-road vehicle operators.109 These facilities are not sized or located to support Railroad operations. Furthermore, how this infrastructure might be expanded is unknown.

Decades of research and development activities and over-the-rail locomotive prototype demonstrations have given the Railroads a great deal of information about the practicality of using natural gas-fueled locomotives. Figure 16 below highlights the main Western Class I Railroad research efforts since 1935.

Below is from http://www.siliconinvestor.com/readmsg.aspx?msgid=29524960

  • Freight railroads and the basic economics of fuel choice Major U.S. railroads, known commonly as Class 1 railroads, are defined as line-haul freight railroads with certain minimum annual operating revenue. Currently, that classification is based on 2011 operating revenue of $433.2 million or more [1]. While there are 561 freight railroads operating in the United States, only seven are defined as Class 1 railroads. The Class 1 railroads account for 94% of total freight rail revenue [2]. They haul large amounts of tonnage over long distances, and in the process they consume significant quantities of diesel fuel. In 2012, the seven Class 1 railroads consumed more than 3.6 billion gallons (gal) of diesel fuel [3], amounting to 10 million gal/day and representing 7% of all diesel fuel consumed in the United States. The two largest consumers of diesel fuel among the Class 1 railroads—Burlington Northern Santa Fe (BNSF) and Union Pacific—consumed more than 1 billion gal each in 2012. The cost to Class 1 railroads of consuming such large quantities of diesel fuel was more than $11 billion in 2012, representing 23% of their total operating expense (Table IF3-1).Table IF3-1. Class 1 railroad diesel fuel consumption, fuel cost, and fuel cost share of operating expense, 2012column 1 Class 1 railroad (2012)
  • column 2 Diesel fuel consumption (gallons)
  • column 3 Fuel cost thousand 2012 dollars)
  • column 4 Percent fuel cost share of total operating expense
Burlington Northern Santa Fe 1,335,417,552 $4,273,779 29%
Union Pacific 1,108,029,359 $3,505,671 24%
CSX Transportation 490,902,017 $1,542,747 18%
Norfolk Southern 462,466,433 $1,437,178 18%
Canadian National Grand Trunk 101,555,124 $326,303 16%
Canadian Pacific Soo 71,575,774 $231,211 16%
Kansas City Southern 64,078,412 $195,428 22%
Total 3,634,024,671 $11,512,317 23%
Source: Class 1 Railroad diesel fuel consumption, fuel cost, and fuel cost share of operating expense, 2012: U.S. Departmentof Transportation, Surface Transportation Board, “Annual Report Financial Data,” stb.dot.gov.


Challenges for liquefied natural gas (LNG) as a freight rail fuel (Chase 2014)

While simple economic calculations involving the comparison of fuel cost savings to additional upfront cost are relatively straightforward, other factors, including operational, financial, regulatory, and mechanical challenges, also affect fuel choices by railroads. One of the most challenging factors raised by the switch to LNG locomotives by Class 1 railroads is the effect on operations. Switching from diesel fuel to LNG would require a new delivery infrastructure for locomotive fuel. Natural gas would need to be delivered to fuel depots, either by truck in smaller quantities, as LNG [4],or perhaps by pipeline. Larger quantities of natural gas would require liquefaction before delivery to tender cars for use in locomotives. Building the new infrastructure would require a large financial investment in addition to the large investments made in locomotives and tender cars.

The building of LNG refueling infrastructure could also complicate the inter-operability of the rail network, depending on how quickly modifications could be made to accommodate refueling at multiple points around the nation. Impeding the ability of the rail network system to move goods because of a lack of fuel availability could drive up costs and lead to reductions in network flexibility and operational efficiency [5]. In addition, operations could be further affected by fuel switching because of the cost of training staff at refueling depots and in maintenance shops, updating maintenance facilities to handle LNG locomotives and tenders, and managing more extensive logistics [6]. Further, LNG locomotives and tender cars could require more maintenance than their diesel counterparts. All of these operational changes would create a duplicative infrastructure [7], because many diesel-fueled locomotives still would be in service at least for some significant period, and compression-ignited LNG locomotives still require at least some diesel fuel for combustion ignition.

Replacing the current stock of diesel locomotives with LNG locomotives and tender cars would represent a significant financial investment by Class 1 railroads. In 2012, there were 25,174 locomotives in the service of Class 1 railroads, the vast majority of which were line-haul locomotives [8]. A new diesel line-haul locomotive costs about $2 million [9], and rebuilt locomotives cost about half that amount. With a new LNG locomotive and tender costing about $1 million more than a diesel counterpart, the cost to replace the entire diesel locomotive stock with LNG locomotives and tenders would be tens of billions of dollars, not including additional infrastructure, training, logistics, and a potential increase in maintenance costs. Moreover, much of the cost of the transition, such as purchases of locomotives and tender cars, potentially would occur over a much shorter time period than a fuel payback period.

The financing requirement of large capital expenditures complicates the rather straightforward calculation of locomotive fuel economics. The amount of capital available to Class 1 railroads, either on hand or raised in capital markets, is an important factor in determining whether, or to what extent, railroads can take advantage of fuel cost savings over time. The decision to switch from diesel fuel to LNG is also influenced by the facts that railroads are a highly capital-intensive industry [10] with complete responsibility for maintaining the physical rail network, that they face many competing needs for financial investment, and that they must ensure adequate return on investment for their shareholders.

On the regulatory side, LNG rail cargos currently are not permitted without a waiver from the Federal Railroad Administration (FRA) under Federal Emergency Management Agency (FEMA) rules. The development of standard LNG tenders and regulations is underway, with issues related to safety, crashworthiness, and environmental impact, including methane leakage, under consideration [11].

Finally, LNG locomotives currently are undergoing extensive testing and demonstration to determine their fuel consumption, emissions, operational performance, and range under real-world conditions. Locomotives and tenders will be evaluated to ensure mechanical performance of such components as connections between tender and locomotive. Several Class 1 railroads are planning to start LNG locomotive demonstration projects to provide better understanding of the obstacles to an LNG fuel switch.

Chase, N. April 14, 2014. Potential of liquefied natural gas use as a railroad fuel. United States Energy Information Administration.

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2 Responses to Why railroads are against running locomotives on natural gas

  1. david johnson says:

    Conversion to natural gas seems impractical but I’d like to see a study of electrification. Advantages include zero emissions at point of use, ease of distribution and recapture of energy from descents via regen braking. Current diesel-electric locos must waste all such energy.

    • energyskeptic says:

      In when trucks stop running I discuss electrified locomotives via catenary or battery. An older version is here:

      Electrifying freight trains in the U.S. is a really bad idea

      What is most energy efficient mass transit mode: bus, rail, or auto?

      Challenges facing California’s high-speed rail. House Hearing 2014.

      From my book:

      Batteries for regenerative braking? Locomotives have very little room to accommodate regenerative braking batteries. Instead, a battery tender car coupled-and-connected to the real locomotive, or a separate locomotive devoted only to energy storage would need to be built (Iden 2014).

      It is hard to capture regenerative braking energy, because much of the time the train isn’t using the brakes because the ground is flat or slightly undulating. Centuries of railroad engineers have sought out and purchased the flattest routes, and invested a lot in building them. Only a small minority of tracks known as “hogbacks” can capture regenerative braking, which are steeper uphill and downhill grades about the length of the train. And a mile-long train can be going downhill, uphill, and level at the same time, requiring train engineer to play the two types of braking system used on trains like a concert pianist.

      The 80 trains going down California’s steep 25-mile Cajon pass grade every day, one of the few grades this steep in America, could generate as much as 1200 kWh per train with regenerative braking. The downside is that this would require 525 tons of lead–acid batteries. That’s a lot of deadweight to haul when the train returns uphill to the Cajon pass, and is not economically viable because it would only save 70 gallons of fuel (Painter 2006). If you tried to haul fewer batteries to save on weight and cost, complex systems to monitor the batteries to prevent them from overcharging would be required.

      Iden, M.E. 2014. Battery storage of propulsion-energy for locomotives. Proceedings of the 2014 Joint Rail Conference.

      Painter, T. 2006. Prospects for dynamic brake energy recovery on north american freight locomotives. JRC2006-94051, ASME Joint Rail Conference.