By Noel T. Braymer
At the December 5th RailPAC/NARP Conference in Los Angeles, one of the speakers was Dave Cook of Rail Propulsion Systems. His company now rebuilds old diesel locomotives to meet the latest Tier 4 emissions levels at a fraction of the cost of a new Tier 4 Locomotive. Mr. Cook also presented a proposal to rebuild old diesel locomotives into hybrid diesel-electric locomotives. These would have the acceleration of an electrified railroad at a fraction of the cost of electrification with much lower emissions of even today’s Tier 4 diesel locomotives. As Mr. Cook pointed out, rail passenger service with several station stops often can’t reach their top speed before stopping at their next station. The advantage of an electrified railroad is faster acceleration than with diesel locomotives which translates into shorter end to end times and higher average speeds. Electrification also is much cleaner, emitting far less than a diesel locomotive.
Pollution, particularly from diesel engines is being tolerated less and less. The scandal of the smog test cheating by Volkswagen’s diesel cars are just one part of this. Increasingly neighborhoods next to rail yards or trucking centers are complaining of the diesel emissions and possible health risks from them. There are regulations coming into effect to reduce diesel locomotive emissions. The new Tier 4 cleanest to date diesel locomotives cost around 6-7 million dollars a piece. By executive order, Governor Schwarzenegger set California on the goal by 2050 to reduce Greenhouse Gas Emissions to 80% below their level in 1990. California is on track now to reach 1990 emission levels by 2020. To accomplish this goal will require major reductions of fossil fuel use and emissions from all forms of transportation, but from particularly diesel trucks and locomotives. How can this be done? The most likely way will be by switching transportation from fuel to electricity.
The problem with electrification today is cost. It will be very expensive just to electrify the major railroads of California. This is particularly true of the rail lines with joint freight and passenger service. There are also limits to how much cleaner we can economically expect to make diesel engines. What Mr. Cook is proposing is to marry 2 rebuilt locomotives as a single unit. One locomotive would have a rebuilt clean diesel engine powered by compress natural gas (CNG).The other rebuilt locomotive would be all electrically powered using capacitors. A capacitor can be quickly charged with electricity and discharge it quickly as well. This would allow quick acceleration. A battery while it takes more time to charge and discharge, can hold more power for the same amount of weight as a capacitor.
Mr. Cook’s plan is to use the all electric locomotive for acceleration, which takes much more power than running at a constant cruising speed. The clean diesel locomotive running on CNG would provide the power for the lights and air conditioning of the train as well as for running the train at cruising speed. The electric locomotive would recharge its capacitors from regenerative braking, from power from the diesel locomotive and from wayside sources such as at stations and yards. The result of using these 2 locomotives would be much fewer emission than existing locomotives, faster acceleration giving average speeds on par with electrified railroads and consumption of much less fuel.
The question is, is this the way rail service will be run in the future? What is certain is the cost of producing electricity, as well as making capacitors and batteries will continue to go down. There is a great deal of research on going to improve the performance and reduce the weight and costs of batteries and capacitors. There is even research into hybrid battery/capacitors. With this ongoing research and development of electrical storage will come smaller, lighter and cheaper batteries and capacitors.
Just a few years ago, the railroads, particularly the BNSF were making plans to convert from diesel fuel to Liquefied Natural Gas (LNG). A major motivation for this was to save money on the high cost of fuel (LNG being cheaper than diesel fuel) and to comply with more stringent emission standards coming in the future. Since the coming of the current Oil Glut, very little has been heard of plans to convert the railroads to LNG. While LNG fuel would be cleaner and cheaper than diesel fuel, it would require expensive new infrastructure for transporting, storing and pumping LNG around the BNSF system. Also needed would be new locomotives and or rebuilt locomotives to run on LNG as well as a central tender which would hold enough LNG to power all the locomotives on a freight train. There is also the issue that LNG is not popular with many people. Since LNG would have a great deal of energy, it has the power for a massive explosion in the case of an accident. Also attempts by some trucking companies to convert their trucks to LNG were not as successful or as economical as predicted.
What is likely is we will be see hybrid locomotives in the future with better acceleration that are vastly cleaner and more economical than current locomotives for both passenger and freight. This could include wayside power to recharge batteries and capacitors, reducing the need to use the onboard generator and saving money and producing fewer emissions. This could be done with short stretches of catenary or use of wireless, also called inductive charging. This is already being used commercially to charge smart phones and computer tablets. The way wireless charging works is to transmit electromagnetic energy (such as radio waves) which is picked up by a receiver and converted into electricity. A better choice as a generator for future locomotives would be to use turbine engines. Turbine engines in the past on locomotives were uneconomical when run like a diesel locomotive without batteries to store power. Turbines are more efficient and cleaner than diesel engines when run at a constant speed. Turbines are also more reliable and require less maintenance because they have many fewer parts than a diesel engine.They also are much smaller and lighter for the same energy as a diesel engine. Used only as a generator to keep batteries and capacitors charged, turbines are more economical than using a diesel engine. To further save energy and reduce emissions turbine engines can by shut down and restarted quickly between charges of a locomotive’s batteries. Turbines can run on many clean renewable fuels. It could still be economical to use higher cost renewable fuels with a turbine hybrid if it uses less fuel than a traditional diesel locomotive.