Analyzing the levelized cost of hydrogen in refueling stations with on-site hydrogen production via water electrolysis
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Date
2024-03-21
Authors
Στούπα, Μαρία
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Abstract
Conventional modes of transportation, that are long-established in the market, utilize fuels such as natural gas, gasoline and diesel, that are derived from crude oil, a nonrenewable resource. The overconsumption of fossil fuels has led to the depletion of their reserves, which, in conjunction with the negative effects to earth’s climate has made the transition to renewable alternatives resources urgent. That is why there is a shift towards renewable energy sources that are perpetual, and their utilization has a minimal environmental impact.
In accordance with this approach, hydrogen seems to be an optimal option to deal with the problem of the climate crisis that has surfaced since years ago and has escalated in the recent years. Hydrogen, as a transportation fuel has been the subject of research from both academia and industry, and Fuel Cell Electric Vehicles (FCEVs) have matured and compete with other technologies for a place in the market in the years to come.
The current diploma thesis is a techno-economic study of green hydrogen production via water electrolysis, which occurs in the Hydrogen Refueling Station (on-site HRS) and utilizes renewable electrical energy, retrieved from wind turbines. The research is looking into the modelling of the PEM electrolyzers and the optimal determination of model parameters (the exchange current density, the transfer coefficient and the correction of the ohmic resistance). For model validation purposes, experimental data were collected from the open literature. To this end, 19 case studies from the literature were examined, that are extensively analyzed in Chapter 4. The model adequacy is tested based on the ability of the proposed model to reproduce the experimentally derived polarization curve, which is a representation that illustrates the influence of current density on voltage. Important to this study are two more performance curves: the specific (per kg of H2 produced) electrical energy consumption of the PEM electrolyzer as a function of current density and the efficiency of the PEM electrolyzer versus the current density. The results have shown that the proposed model fits the experimental data accurately when its parameters are optimized. Furthermore, research has shown that that the required energy value to produce 1 kg of H2 is around to 50 kWh and according to the model’s result, the current density required for this quantity of energy is in the range of ~(0.5-2) A⁄cm^2 .
The main purpose of Chapter 5 is to calculate the levelized cost of (energy and) hydrogen (LCOE & LCOH), which is a measure of estimating the cost to produce, electricity and subsequently, hydrogen from wind energy. A case study of a wind turbine, with rated power at 1000 kW, is examined. A model was built, that connects the electrical power and green hydrogen produced as a function of the average wind speed under the assumption that wind speed follows the Weibull distribution. The aim is to directly connect the wind potential with the LCOH and to give a guidance on deciding of what is a realistic LCOH when a realistic performance of the electrolyzer is assumed. LCOH is taking into consideration the purchasing and installations costs of wind turbine, electrolyzer, as well as their maintenance and operations costs for the project’s lifespan. The graphs that were extracted, has shown that the cost to produce 1 kg of hydrogen ranges between 10 $ and 3 $ for average windspeed values (3-7) m/s. This is in agreement with results from the open literature and shows that green hydrogen can be a competitive transportation fuel that can offer a sustainable solution to some of our socioeconomic problems in the near future.
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Keywords
Hydrogen refueling station, Fuel cell electric vehicle, Electrolysis, Hydrogen, Proton exchange membrane (PEM) electrolyzer, Wind turbine, Wind energy, Levelized cost of hydrogen (LCOH), Levelized cost of energy (LCOE)