Clean Energy from Freight Trains and Gravity

Freight Rail's Downhill EnergyAll over the western United States, and to a lesser extent across the whole country, there are mountain grades crossed by railroad tracks.  The surface topology and the maximum rail slope limit of about 3% is a challenge to the trains that travel these tracks everyday.  It is common to see trains with four locomotives moving over 100 cars and 15 million pounds of weight.  15 million pounds moving downhill could be converted to clean renewable energy instead of heat lost in braking – These trains rely on a safety air brake system that uses friction brake pads and shoes to slow the downhill speed.

This is one example. Along the I-15 highway between San Bernardino and Barstow, California, through the Cajon Pass a double track rail line transcends a summit 2735 feet above the switch yard in San Bernardino 18 miles below.  On the average a train travels down the grade every half hour, 24 hours a day, 365 days a year.  If only 40% of the energy now used to heat the air could be recovered, it would supply enough power for 32,000 homes.  Alternatively, if the energy could be used to assist trains traveling uphill, over 1 million gallons of fuel would be saved every year.

How could this be done?  A hybrid-electric or electric train?  Or a power station?  There are developed technologies that would need refinement, but are available today.

Dual mode locomotives are in daily operation today along the East Coast where they run on either diesel fuel or electricity supplied from a third rail or overhead catenary.  Electric commuter rail cars are operating all over the world.  Linear motors technology used in Mag Lev trains are another way to transfer power and energy between the ground and a moving train.  To supply and collect power would require a connection to the power grid along the entire 18 miles.  Is it that much different than a wind or solar energy farm?  Power stations have an estimated life of about 50 years.  The cost of electrifying 18 miles of track could easily be paid back in less than 10 years with 40 years left of almost pure profits because there is no fuel consumption.  It would operate similar to a hydroelectric generator at a dam.

A hybrid electric train wouldn’t require an electric grid infrastructure, but would require energy storage on board the train.  It would take 4 or 5 energy storage cars (battery box cars) per train to generate and capture the braking energy, and supply propulsion assist to the locomotives.  The cost breakeven point is estimated at 4 years, just in time to replace the original batteries.  The profit picture looks better from there on out to the estimated rail car life of 35 years.

There are many passes with railroad track grades.  As exciting as this potential seems, it won’t happen without a large dose of government money and will power.

If downhill grades were operated like power stations, the power companies would have to partner with a railroad and not completely own the plant and facilities, a new type of business venture.  Almost all of the Western slope tracks with grades are owned by either Union Pacific (UP) or Burlington Northern Santa Fe (BNSF) railroads who are already spending $Billions (with a B) just to maintain and improve the current track infrastructure including enlarging switchyards with the latest controls in Southern California.  UP has deployed hybrid-electric Green Goat switch yard locomotives and more efficient diesel-electric switchers that use 700 hp Cummins gensets instead of 2300 hp engines.

Typically, the introduction of new technology in the railroad business takes decades to accomplish.  New “risky” technology will need immediate money or safety payback especially at a time when freight traffic is down.  However, rail electrification precedents exist all over Europe and light rail electric commuter rail exists in most urban areas of the US.  The East Coast even includes some third rail heavy rail electrically driven locomotives.  The US Army has built a hydrogen fuel cell electric locomotive and GE was reportedly working on a heavy rail hybrid-electric locomotive with energy storage.  The heavy equipment used in the rail business offers unique opportunities.  A 4 year breakeven on 35 year rolling stock life argues for action.

Tom Bartley has been writing about battery pack and ultracapacitor energy storage systems for over four years.  He has co-authored papers on the use of energy storage systems with braking regeneration for commuter railcar applications.  Tom Bartley has a BSEE and MSEE from Stanford University.  He is a life member of the IEEE and a member of SAE.  He is a director on the board of the San Diego Clean Fuel Coalition and is on three different committees of the San Diego Regional Chamber of Commerce.  He is currently an independent business analyst known as Tom Bartley Ideas.  Tom can be reached at:

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About Author: Tom Bartley

Tom Bartley is an expert about vehicles, drive systems, and energy storage. Tom Bartley has a BSEE and MSEE from Stanford University. He is a life member of the IEEE and a member of SAE. He is a director on the board of the San Diego Clean Fuel Coalition and is working with Transpower of the development of heavy-duty electric drive systems.

4 thoughts on “Clean Energy from Freight Trains and Gravity

  1. tombartley
    June 12, 2009 at 12:38 am

    I have stopped at a roadside rest along side a railroad track just east of Logan and watched several downhill trains. It would make an excellent application!


  2. perk
    June 11, 2009 at 6:00 am

    “points east” should read “points west”

  3. perk
    June 11, 2009 at 5:58 am

    At first read I thought this idea was too expensive to implement to be practical. However, remembering my drives through Helper, UT, I see the possibilities. Helper sits at the base of a steep pass that is very highly trafficked with coal trains destined for points east. The pass is so steep than up that up to 12 locomotives have to be added to trains just to make the crossing. Interestingly, a small coal fired power plant feeds the grid from that pass.

    It would be quite practical to install the (15 miles?) of conductors needed for electric locomotives (well they are all electric, but you get my point), the power grid is in place, the local power plant can provide the uphill energy and the grid captures the downhill energy.

    Nice thought!

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