International Journal of Hydrogen Energy 32 (2007) 3183 – 3193 www.elsevier.com/locate/ijhydene Multi-criteria evaluation of hydrogen system options Naim H. Afgan a , ∗ , Ayfer Veziroglu b , Maria G. Carvalho a a Instituto Superior Tecnico, Av. Rovisco Pais, 1094 Lisbon, Portugal b International Association for Hydrogen Energy, Coral Gables, FL 33146, USA Received 17 April 2007; accepted 17 April 2007 Available online 28 August 2007 Abstract The paper gives an overview of the potential of multi-criteria assessment of hydrogen systems. With respective selection of the criteria that comprise the performance, environment and market indicators, the assessment procedure is adapted for the assessment of the selected options of the hydrogen energy systems and their comparison with new and renewable energy systems. The multi-criteria procedure is based on the sustainability index (SI) rating that is composed of a linear aggregative function of indicators, of which all have respective weight functions. The hydrogen fuel cell systems have three options, natural gas reforming, photovoltaic and wind energy systems, from which the latter two represent the renewable options. These options are evaluated with a multi-criteria method comprising the following indicators: the performance indicator, the market indicator, the environment indicator and the social indicator. An example of a multi-criteria procedure for the assessment of hydrogen systems proves that the sustainability general index (SGI) rating is an effective tool for decision making compared to single indicators evaluation.  2007 Published by Elsevier Ltd on behalf of the International Association for Hydrogen Energy. Keywords: Multi-criteria assessment; Hydrogen energy; Hydrogen energy systems 1. Introduction Sustainable development is a strategic goal of a modern society reflecting contemporary demand for economic, social, political and environmental development. It is of fundamental importance for the world to join this movement and promote future strategy in the economic development, based on the vi- sion of sustainability criteria. The energy strategy in this re- spect plays the most important role in the design of the sustain- ability concept development. Access to affordable and reliable energy that is drawn from environmentally acceptable sources of supply is an important feature of sustainable development. The present dilemma, which reflects different approaches to the potential utilization of hydrogen, greatly attracts the sci- entists, the engineers and the academic society to discuss the potentiality of the options under consideration. Fossil fuels, nuclear energy, geothermal energy, hydro-potential and solar energy have all been the essential resources of energy. The conversion of primary energy resources to final energy is a ∗ Corresponding author. Tel.: +351 21 8418082; fax: +351 21 8475545. E-mail address: nafgan@navier.ist.utl.pt (N.H. Afgan). 0360-3199/$ - see front matter  2007 Published by Elsevier Ltd on behalf of the International Association for Hydrogen Energy. doi:10.1016/j.ijhydene.2007.04.045 chain of processes leading to usable form of energy. Electricity is the widely used form of energy. Today’s technology for elec- tricity production basically consists of burning a fuel in order to heat up water to get steam, and turning a turbine to obtain mechanical energy, the form of energy which is then converted to electricity through an induction mechanism. The electricity can be used to produce hydrogen which is then used as a fuel in fuel cells, so that hydrogen becomes the novel energy carrier. There are two major objections to the hydrogen route for the development of future energy strategies. One is based on the insufficiency of hydrogen as a fuel compared to other energy resources. Oil can be directly pumped out from underground and fortunately it has a huge net energy, which is usually more than 200 times the amount of the energy that is required for its extraction. However, hydrogen has a negative net energy, which means that its production requires more energy than the energy it can actually provide for the same volumes at the same pressure conditions. Moreover, even if hydrogen is the most abundant element in the universe, its production is relatively difficult. Oil is the most concentrated form of hydrogen that is available for human consumption, and contains more hydrogen by volume than the pure hydrogen itself, since the configuration