The North Carolina Department of Transportation, Rail Division (NCDOT) is responsible for the Piedmont passenger train that connects Raleigh and Charlotte. The benchmark locomotive-hauled trains comprise a diesel-electric locomotive, intermediate passenger cars, and a cab control unit. Diesel combustion results in exhaust containing air pollutants and greenhouse gas emissions.
The Rail Division desires to reduce emissions. Battery and hydrogen fuel cell technologies applied to railways offer the opportunity to eliminate harmful exhaust emissions with potential for a low- or zero-emission energy supply chain.
Technical feasibility of diesel, hydrogen and hybrid options with batteries for the Piedmont service were assessed. Modeling of various train and powertrain configurations was conducted, and energy and emission impacts estimated on a well-to-wheel basis. Single train simulation was utilized for feasibility assessment of powertrains while GREET was employed to estimate well-to-wheel emissions and energy. 25 train configurations and powertrain options were modelled, and nine hydrogen supply options were evaluated in addition to the diesel and electricity supply.
Results show that diesel and hydrogen hybrid options as well as a hydrogen only option would be feasible for the Piedmont and that a low- or zero-carbon hydrogen supply chain could likely be possible. Energy reduction from operations ranged from 14% for a two locomotive diesel and battery option to 48% for a single locomotive fuel cell hybrid plugin powertrain. Hydrogen production from electrolysis where electricity is provided from renewables offers the highest well-to-wheel (WTW) energy savings without emissions in the supply chain if produced at the refueling site. Hydrogen delivery from a central location with the same method results in a small amount of emissions. Electrolysis with electricity from the SERC grid would result in energy and emission increases for some criteria pollutants and greenhouse gas emissions on a WTW basis compared to the diesel-electric. Production from natural gas or biomass would reduce emissions and energy consumption.
Based on the results of this study, energy and emission reductions could be achieved with a diesel hybrid configuration. Significant further WTW reductions could be realized with a hydrogen rail (hydrail) option. Most significantly, the results indicate that hydrail technology is feasible for the Piedmont service.
