Renewable energy refers to forms of energy produced by energy transfer of the energy resulted from renewable natural processes. Thus, the energy of sunlight, the wind, flowing water, biological processes and geothermal heat can be captured by people using different processes. Sources of non-renewable energy include nuclear power and energy generated by burning fossil fuels, such as oil, coal and natural gas. These resources are, obviously, limited to the existence of deposits and are generally considered non-renewable. Among renewable energy sources are:
• Wind energy;
• Solar energy;
• Water energy:
• Hydraulic energy ;
• Tide energy;
• Geothermal energy ;
• Energy derived from biomass:
• biogas .
All these forms of energy are used to generate electricity, hot water, etc..
Annual global investment in renewable energy has increased in recent years from 39 billion dollars in 2005, to 55 billion dollars in 2006. Investments for 2007 will reach a level of 100 billion dollars.
Under a directive of the European Union, Member States should gradually mix traditional fuel used in transport with biofuel, so that, by 2010, biodiesel will represent 5.75% of the diesel fuel on the market, following that in 2020, it’s percentage to increase to 20%.