Crashworthiness for Alternative Fuel Powered Locomotives

[mahatmakanejeeves]

Which the authors refer to as "vehicles." Go figure.

August 08, 2023 | Locomotives

Crashworthiness for Alternative Fuel Powered Vehicles

Written by Przemyslaw Rakoczy, Senior Research Engineer, ENSCO, Inc., and Matthew Dick, P.E., Chief of Strategy & Development, ENSCO, Inc.



TTC Operated by ENSCO, RAILWAY AGE, AUGUST 2023 ISSUE: Following the global movement to reduce emissions and, ideally, use renewable energy instead of diesel fuel, the rail industry is looking for alternative means to propel future trains.

One of the major current areas of development and research in the rail industry is alternative fuels, such as hydrogen, Renewable Natural Gas (RNG), and other means to store energy, such as Battery Energy Storage Systems (BESS). This shift to new fuels and energy storage systems brings the necessity to review and, in some cases, update current crashworthiness requirements and test protocols to ensure safe operation and reduce the consequences of extreme events, such as derailments and collisions.

Alternative fuels

Several alternative fuels are currently being evaluated to replace diesel, each with the advantage of lower or zero emissions. However, they also have important characteristics that must be addressed. Liquefied Natural Gas (LNG) is one of the first alternative fuels considered by the rail industry. Natural gas burns significantly cleaner and produces lower emissions of sulfur, nitrogen, and carbon dioxide into the atmosphere as compared to diesel.

The volume energy density of LNG is 40% of diesel and therefore requires an LNG tender for the same train range. Moreover, LNG needs to be stored in cryogenic tanks. To avoid the cryogenic storage challenges, Compressed Natural Gas (CNG) is also considered. The volume energy density of CNG is lower than diesel, which requires the use of fuel tenders for long-haul operations. RNG is biogas that is manufactured to have similar performance to fossil natural gas but has further lowered emissions.

A very promising alternative fuel considered is hydrogen, which can be produced in the electrolysis from water and turned back into water in fuel cells to produce electricity. This makes hydrogen powered rail vehicles virtually emission-free if the hydrogen is produced using renewable energy sources, such as photovoltaic or wind power plants. Like natural gas, the volume energy density of cryogenic liquid and compressed gas hydrogen is lower than diesel, which requires the use of fuel tenders for long-haul operations.

Another solution to propel the trains is BESS (Battery Energy Storage System), which typically uses lithium-based battery packs. The benefit of the BESS is that there are no emissions from the vehicles. The disadvantage is the limited range and time necessary to charge the batteries. However, it is a valuable alternative that could be advantageous in certain applications.

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[hunter]

1. Dimethyl Ether (DME) seems much less of a hassle than either LNG or Hydrogen.

DME has got about the same energy content "by gallon" as LNG without all the cryogenic nonsense.

Hydrogen fuels will always be the exciting "new" idea introduced with great fanfare until it's quietly abandoned later. It's been that way for fifty years at least.

The future of no-fossil-fuel railroads is electrification and synthetic diesel fuels made from atmospheric or oceanic carbon dioxide using nuclear power.

I see little reason to complicate our transportation infrastructure with exotic and potentially dangerous synthetic fuels or batteries.