This article focuses on hydrogen energy strategies and discusses the key role of hydrogen as an energy carrier in this century and beyond. Two important empirical relations that describe the effects of fossil fuels on world peace and global unrest are developed. These relations incorporate predicted utilization ratios for hydrogen energy from non-fossil fuels, and are used to investigate whether hydrogen utilization can reduce the negative global effects related to fossil fuel use, eliminate or reduce the possibilities of global energy conflicts, and contribute to achieving world peace and stability. Consequently, the highest levels of global peace and global unrest can be estimated. If hydrogen use from non-fossil fuels increases, for a fixed usage of petroleum, coal and natural gas, the level of global unrest decreases. However, if the utilization ratio of hydrogen energy from non-fossil fuels is lower than 100%, the level of global peace decreases as the symptoms of global unrest increase. Thus, to reduce the causes of global unrest and increase the likelihood of global peace in the future, it is suggested that hydrogen energy be widely and efficiently used as part of sustainable technologies and systems. It is expected that the results of this study will be of use to decision makers and scholars who want to develop and promote the use of hydrogen-based technologies and solve future energy and environment related problems globally. (C) 2004 Elsevier Ltd. All rights reserved.