Solar
In energy terms, the term "solar energy" refers to the energy released by the sun that reaches the earth in the form of electromagnetic radiation.
Solar energy is the most widespread source of energy, found in abundance everywhere and, at least in theory, far exceeding our actual energy needs.
In order to transform this solar energy into electricity, we use either photovoltaic plants or solar thermal generation systems.
Photovoltaic conversion relies on the capacity of certain semiconductor materials, such as silicon, to generate electricity directly when exposed to solar radiation.
There are now a great many applications of photovoltaic technology throughout the world, with significant growth in recent years (out of the total 9,162 MW of power generation capacity at the end of 2007, 32% was added during the last year, and capacity is expected to reach at least 21,600 MW by the end of 2010).
This technology is modular, reliable and requires a limited amount of maintenance. Accordingly, investment is being concentrated in this area in order to maximize our ability to take advantage of solar energy.
Solar thermal conversion is based on the transformation of solar radiation into heat.
Using a series of parabolic mirrors, solar radiation is focused onto a heat-absorbing fluid, which is then used to produce the high-temperature steam needed in conventional thermal power generation.
This technology has already been used to build plants with a capacity of a few megawatts.
One particularly innovative effort is the Archimede Project, which is currently being developed at Enel's Priolo Gargallo (Syracuse) plant. The project envisages the construction of a 5 MW solar plant comprised of 576 parabolic mirrors, which will focus sunlight onto pipes carrying a mixture of fused salts capable of storing the heat accumulated throughout the day. The thermal energy produced and stored in this manner will then be used to generate high-pressure steam, which is sent to the turbines in the adjacent Enel combined-cycle plant in order to boost power generation. This large-scale solar plant will enable us to generate additional power using solar energy that can meet the annual power needs of 4,500 households, with a savings of some 2,400 metric tons of oil equivalent per year and a reduction in CO2 emissions of about 7,300 metric tons per year.
There is currently a great deal of research being conducted internationally, and constant progress in being made in the development of more efficient and less costly technologies.
