The world's energy supply is largely based on conventional energy sources. Most of these sources of energy, however, will not last forever and have proven to be one of the main causes of our environmental problems. Environmental impacts of energy use are not new but they are increasingly well known. They range from deforestation to local and global pollution.
It is clear therefore, that in due time renewable energies1 will dominate the world's energy supply system, due to their inherent advantages such as mitigation of climate change, generation of employment and reduction of poverty, as well as increased energy security and supply. Renewable energy technologies are well suited to respond to the limitations of current energy patterns and contribute to the further modernisation of the energy sector.
Renewable sources of energy are in line with an overall strategy of sustainable development. They help reduce the dependence on energy imports, or do not create a dependence on energy imports in countries with
1 Any energy resource naturally regenerated over a short time scale that is derived directly from the sun (such as thermal, photochemical and photoelectric), indirectly from the sun (such as wind, hydropower and photosynthetic energy stored in biomass), or from other natural movements and mechanisms of the environment (such as geothermal and tidal energy).
E.J. Moniz (ed.), Climate Change and Energy Pathways for the Mediterranean, 89-100.
© 2008 Springer.
increasing energy needs, thereby ensuring a sustainable security of supply. Furthermore, renewable energy sources can help improve the competitiveness of industries and have a positive impact on regional development and employment. Renewable energy technologies are suitable for off-grid services, serving those in remote areas of the world without having to build or extend expensive and complicated grid infrastructure.
The earth receives solar energy as radiation from the sun, in a quantity far exceeding mankind's use. By heating the planet, the sun generates wind. Wind creates waves. The sun also powers the evapotranspiration cycle, which allows water to generate power in hydro schemes — currently the largest source of renewable electricity in use today. Plant photosynthesis, which is essentially a chemical storage of solar energy, creates a wide variety of so-called biomass products ranging from wood fuel to ra-peseed, which can be used to generate heat, electricity and liquid fuels. Inter-actions with the moon produce tidal flows, which can be intercepted and used to produce electricity. Renewable energy sources (RES) are based on the natural and interconnected flows of energy of our planet Earth.
Though humans have been tapping into all renewable energy sources (wood, solar, wind, geothermal and water) for thousands of years for their needs (such as cooking and heating), so far only a tiny fraction of the tech-nical2 and economic potential of renewable energy has been captured and exploited for energy usage. Yet, with existing and proven technologies, renewable energy offers safe, reliable, clean, local and increasingly cost-effective alternatives for all our energy needs.
• Heating and cooling — Solar water heating, solar passive and biomass-based space heating for buildings, geothermal heat and geothermal heat pumps are entering the market as mainstream technologies. Active solar space heating and cooling for buildings and industry are under development.
• Electricity — Electricity from wind power, small-scale hydro and biomass are a market reality. Geothermal electricity has existed for
2 A study shows that the total available global wind resource technically recoverable is more than twice as large as the projection for the world's entire electricity demand in 2020. Similarly, theoretical solar energy potential corresponds to almost 90,000,000 Mtoe per year, which is almost 10,000 times the World Total Primary Energy Supply (IEA 2003).
decades and supplies electricity for 30 million people worldwide. Photovoltaics are already cost-effective in niche markets worldwide, while tidal and wave power as well as concentrated solar power will need further research and development before they can be commercialised.
• Transport fuels — Liquid biofuels, like bioethanol and biodiesel produced from agricultural crops, will require better recognition of their low-carbon benefits and their rate of progress will be influenced by decisions taken in other areas of policy such as taxation policy and agricultural policy.
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