Vincent Phalip, Philippe Debeire and Jean-Marc Jeltsch

University of Strasbourg France

1. Introduction

1.1 General needs for energy

General needs for energy are still increasing. In 2000, the energy provided worldwide was 10 Gt of oil equivalent (Gtoe) and the demand is forecasted to be around 15 Gtoe for 2020 (source: Energy Information Administration [EIA], 2002, as cited in Scragg, 2005). During the 20th century, coal proportion in energy supply decreased whereas oil and gas increased drastically. First after the 1973 oil crisis and afterwards periodically depending on oil prices, developments for producing energy by new ways were considered. In the last decade, the depletion of fossil energy sources appeared as a reality although exhaustion time remains highly controversial. Currently, it is clear that considerable efforts to promote alternative sources of energy are driven by both environmental concern (limiting fuel by-products emissions) and economic necessity linked to the fossil fuel depletion.