Evaluation of hydrogen production cost in a real case of smart cities applications

Both the production and the use of hydrogen have attracted highest attention while the practical aspects of a hydrogen economy, are rarely addressed. In this work the cost of hydrogen was studied through the design, realization and validation of a solar-powered hydrogen fueling station in smart cities applications. CNR-ITAE together with other industrial partners has developed, under the Italian research project called i-NEXT (innovation for greeN Energy and eXchange in Transportation), the on-site hydrogen production plant. The plant is fed by a microgrid able to receive energy from solar radiation by a 100 kW rooftop photovoltaic plant and connected with a battery energy storage of 300 kWh (composed by 16 sodium nickel chloride high temperature batteries) in this way the plant is able to deliver hydrogen and electricity for an electric and hydrogen vehicles fleet. The hydrogen fueling station consists of four subsystems: hydrogen production by electrolysis, compression system, high-pressure storage system and hydrogen dispenser for automotive applications and it is able to generate in the hydrogen production subsystem, through alkaline electrolyzer of 30 kWh: 6,64 Nm3/h of H2 with a gas purity of 99,995% (O2 < 5ppm and dew point < -60°C). The compression subsystem consisted of three stage compressor with gas flow rate of 5,2 Nm3/h and a delivery pressure of 360 bar. After that, the compressed H2 gas is stored in high-pressure tanks with a total capacity of 350 liters allowing, in this way, a supply through dispenser system of two automotive's tanks of 150 liters @ 350 bar in less than thirty minutes. This work, in particular, compare through three case studies coming from a first test campaign, the real cost of hydrogen obtained by the electricity for the electrolysis and compression process coming from the main grid (thermoelectric power plants), with the support of photovoltaic plant and with the integration of the battery energy storage in support of photovoltaics plant.