The future for current energy sources
Solar Energy- Energy with a Future
Clean and abundant, solar energy use has soared since the turn of the century and is becoming more cost-effective. The three technologies used (photovoltaics,
low-temperature, and high-temperature thermal) are now available. More and more plants are being opened, capacity records are regularly broken and ever more ambitious projects are in the works.
Clean Energy...
Solar energy is clean, releases almost no greenhouse gases, and produces no waste. And every year the earth receives 8380 times the amount of energy spent annually by humankind - 11 billion tons of oil equivalent! However, solar energy on its own cannot replace fossil fuels.
While as yet underdeveloped, it offers an important opportunity to diversify the energy mix. For example, solar technologies used in houses are both efficient and proven. Low-temperature thermal solar energy uses thermal panels to convert light into hot water. This technology can be used alongside photovoltaic panels- that convert light into electricity which individuals can use themselves or sell to distributors.
Moreover, there are many photovoltaic power plants already operating or under construction. In France, the Chambery plant has been operational since 2005, the Reunion plant has been open since 2006 and the Saint-Charles plant near Perpignan opened in 2010. Switzerland, Germany, and the United States also have photovoltaic power plants; and in 2008 the huge Amareleja plant was opened in Southern Portugal. This plant has installed capacity of over 46 MW and can produce 93 million kW/h per year, enough to meet the energy needs of 30,000 homes.
So solar energy is being produced in all four corners of the planet. In industrialized countries, most photovoltaic power plants are hooked up to the grid, while stand-alone facilities are more common in developing countries.
Thus solar energy is starting to develop and is now reaching maturity, even if it remains much more expensive than conventional energy sources. However, to make a decisive transition in terms of improving yield, reducing costs and diversifying applications, the solar sector still needs significant human, technological, and financial investment.
...that Remains Expensive
While solar panels fitted with thermal collectors to produce domestic hot water are relatively cheap to install and operate, this is not the case with photovoltaics. One of the reasons for this is that the panels contain silicon, which is used to convert sunlight into electricity. This involves substantial initial investment that takes several years to pay off.
However, improvements in technology, increasing numbers of production areas and the industrialization of this field should lead to a significant drop in the cost of solar energy over the next 10 years.
Promising Progress
Concentrated solar power plants use high-temperature thermal solar technology, an alternative to photovoltaics. These operate in a similar way to conventional thermal power plants, concentrating the sun's energy to heat water to very high temperatures (400-1000°C). The steam obtained in this way drives turbines that generate electricity. These plants are called thermodynamic solar power plants.
These power plants have two major advantages over photovoltaic power plants:
• Firstly, they can store solar energy. This is key because solar energy is intermittent - it changes according to season and sunshine. By storing it, even for a few hours, it is easier to match electricity supply to demand, which is constant.
• Secondly, it is cheaper to build a concentrated solar power plant than a photovoltaic power plant because silicon is not required.
Many countries are interested in these advantages. For example, Spain has had the most powerful thermal solar power plant in Europe since 2009. It is called Andasol and will eventually comprise 3 units. The first two plants, Andasol 1 and 2, are already operational. Their 624 parabolic mirrors produce 50 MW supplying electricity to 45,000 homes.
The government of Abu Dhabi is pursuing the Shams 1 project, the largest concentrated solar power plant in the world. It will cover an area of 2.5 km2 and will have production capacity of over 100 MW thanks to its 768 parabolic mirrors. It will open in 2012 and will help Abu Dhabi reach its 7% renewable energy target by 2020.
The future of solar technology may also be in heliostats or adjustable mirrors. A heliostat tracks the course of the sun to collect as much of its energy as possible throughout the day. It concentrates this energy to a photovoltaic collector, increasing the intensity of the light and therefore electricity production. Of the many concentrated solar power projects currently being studied, the Victoria project in Australia is particularly ambitious. In this plant the solar flux will be beamed by 19,250 heliostats to 246 towers which have concentrated photovoltaic cells at the top. With capacity of 154 MW, it will produce 270,000 MWh per year, equivalent to the annual electricity needs of 45,000 homes. The Victoria plant will begin operating in 20141.
Another technology currently being studied is the solar chimney, whose operation is based on the principle of circulating air. A flat-plate collector with a greenhouse-like structure heats the air that rises naturally inside the central tower. The airflow drives turbines that are connected to generators. A chimney of this type was operational in Manzanares in Spain in the 1980s. Two new projects are being studied: a 40 MW plant with a 200m tower in Spain and a 200 MW plant with a 990m tower in Australia2.
[1] http://www.solarsystems.com.au & http://new.dpi.vic.gov.au/energy-future/what-is-government-doing/info-library/opportunities-for-solar-energy-in-victoria
[2] http://www.energies-renouvelables.org/f-solaire_thermique_ht.asp
