This review describes the renewable energies trends and developments in the world, in Europe and in Italy. The text highlights the role of the biomass use in the EU, following the commitments undertaken after the Kyoto Protocol with the Directive 2009/28/EC of the European Parliament and of the Council, known as 20-20-20. In the frame of agroenergy chains and biomass characteristics, the most suitable bioconversion processes and biofuel development (first, second and third generation) are taken into account. In the review, the role of 'first generation' energy crops, borrowed from the food industry, such as sugar cane and oil palm in tropical countries, maize, rapeseed, soybean in temperate zones are considered. The text also depicts the exceptions raised on the convenience of using these crops for the production of energy (low biomass and energetic yields, high input requirement, environmental and ethical issues) and new orientations looking for an ideotype of biomass crop, no-food, of lignocellulosic raw material, suitable for cultivation in the so-called marginal lands. Lignocellulosic crops suitable for cultivation in Italy, identified among those already widely spread (giant reed and Saccharum spontaneum), or coming from other environments (Miscanthus spp.), also formerly grown for other purposes (switchgrass, cardoon, Brassica carinata, woody crops), are depicted in terms of agronomical, environmental and energy issues, also in relation to the main agroenergy chain: biodiesel, bioethanol, heat and electricity. Comparison among biomass species lead to the conclusion that there are strong differences in terms of energy efficiency and environmental impact.
Keywords: world energy demand, renewable energy, first generation crops, lignocellulosic crops, energy efficiency, Life Cycle Assessment