Year: 2014
Type: dissertation
Abstract: Hydrogen as an energy carrier is a promising candidate to store green energy and it has a\npotential to solve various critical energy challenges. Although, hydrogen is a clean\nenergy carrier, the possible negative impacts during its production cannot be disregarded.\nTherefore life cycle analyses for various scenarios have been investigated in this study.\nIn this thesis, a comparative environmental assessment is presented for different\nhydrogen production methods. The methods are categorized on the basis of various\nenergy sources such as renewables and fossil fuel. For the fossil fuel based hydrogen\nproduction, steam methane reforming (SMR) of natural gas is studied. Renewable based\nhydrogen production includes electrolysis using sodium chlorine cycle. Electrolytic\nhydrogen production is also compared using different cells such as membrane cell,\ndiaphragm cell and mercury cell. Wind and solar based electricity is also used in\nelectrolytic hydrogen production. Furthermore, vehicle cycle is studied on the basis of\navailable literature to compare the hydrogen vehicle with gasoline vehicle.\nThe investigation uses life cycle assessment (LCA), which is an analytical tool to\nidentify and quantify environmentally critical phases during the life cycle of a system or a\nproduct and/or to evaluate and decrease the overall environmental impact of the system or\nproduct. The LCA results of the hydrogen production processes indicate that SMR of\nnatural gas has the highest environmental impacts in terms of abiotic depletion, global\nwarming potential, and in other impact categories. The abiotic depletion for SMR is\nfound to be 0.131 kg Sb eq. which is the highest among all methods. The second highest\nabiotic depletion value comes under electrolysis using mercury cell which is 0.00786 kg\nSb eq. However, thermodynamic results suggested that SMR is the efficient method of\nhydrogen production because the amount of hydrogen energy produced as output in the\nsystem is larger than any other method. The energy efficiency of the system in this\nmethod is about 76.8% and the exergy efficiency is about 72.4%. In terms of vehicle\ncycle comparison, it is found that the gasoline vehicle appears to be the largest\ncontributor in energy consumption and GHGs emissions. The energy consumption of\ngasoline vehicle is three times higher than hydrogen vehicle. Moreover, GHGs emissions\nof the hydrogen vehicle are 8% of the gasoline vehicle.
Author: F. Suleman
Language: English
Subfield: Energy Engineering and Power Technology
Field: Energy
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W2751989160