Climate change is one of the most preeminent challenges facing the world. Continued fossil fuel energy consumption at the current trajectory will result in a temperature rise of more than 3.5°C by the year 2050. Melting glaciers, rising sea levels, wildfires, floods, and extreme weather events such as heat waves and large storms, are likely to become more frequent or more intense. The Paris Agreement is a legally binding international treaty to reduce carbon emissions which led to keep the global temperature rise well below 2°C [1]. This target cannot be achieved without deeply decarbonized energy production which focuses on three main factors: 1) Reducing energy consumption through improved efficiency (optimize), 2) Shifting energy demand to electricity and away from combustion of fossil fuels (electrify everything), 3) Shifting entirely to zero-carbon technologies such as solar photovoltaic (PV), wind, hydrogen, etc. to generate electricity (decarbonize). According to the United States (U.S.) Environmental Protection Agency (EPA), the largest contributors to anthropogenic U.S. greenhouse gas emissions in the descending order are transportation (29%), electricity (25%), industry (23%), agriculture (10%), commercial (7%), and residential (6%) [2].

In our previous research, we focused on decarbonization pathways using utility solar, hydrogen consumption and production (electrolyzer, compressor, storage tank, and stationary fuel cells) for improved utilities operation without considering transportation sector demand [3]. Here the focus is on energy decarbonization for both power and hydrogen fueled transportation sector using hydrogen systems. To this end, a vertically integrated 33-node distribution network which is managed by distribution system operator (DSO) is optimized. The DSO manages all the assets in the network including natural gas power plants (combined cycle units and combustion turbine units), solar PV, distributed energy storage systems, hydrogen systems (including storage and refueling station) with the objective of cost minimization. Besides managing the aforementioned technologies, the DSO ensures safe and reliable operation of these assets by considering the technical and physical constraints of the network including voltage regulation, power flow and line congestion management, etc. The DSO in this study also manages the transportation sector hydrogen demand of fuel cell electric vehicles, medium- and heavy-duty vehicles.

Simulation results show that hydrogen demand from the transportation sector is the main driver in sizing of hydrogen system components. Additionally, for the 33-node distribution network to fully supply heavy-duty vehicles demand, natural gas power plants must be operated to supply the required electricity for the electrolyzers to supply hydrogen for these vehicles. Furthermore, different sensitivity analysis for various PV and hydrogen demand penetrations will be presented.