ALTERNATIVE SOURCES OF ENERGY By Cesare Rollo and Alessandro Manieri

What ASOE are? ASOE (Alternative sources of energy) are sourses based on renewable energy. It involves natural phenomena such as sunlight, wind, tides, plan growth, and geothermal heat. They could power the world without using raw materials up and polluting water, atmosphere and soil.

What are the most common kind of ASOE? There are a lot of different kinds of ASOE, but some of them are the most widespread. That’s due to economical and pratical reasons, in fact some of them are much easier to exploit and don’t need huge investiments or are very profitable (usually with the economical aids of the countries). They are :

Solar Energy Nevertheless its production is very changable (day/night, summer/winter), it can be used everywhere in the world and It can be exploited in different ways: With photovoltaic cells or with solar towers to produce eletricity; With boilers to produce hot water. The first way is the most spread because of the very low cost and the chance to use it for little needs. New materials such as CIGS alloy (copper, gallium, indium and selenium) make this sistem very productive so more profitable. Usually photovoltaic sytems are installed together with solar systems for hot water, in order to reduce the power dependence. The second one instead is quite rare, because it needs big investiments and installations even thought it produces a higher amount of electrical energy.

Wind Energy Though wind energy is now affordable, easly available, and pollution-free, it does have some drawbacks. The fact that it is a "very diffuse source" means that a large number of wind generators (so large land areas) is required to produce useful amounts of heat or electricity. But wind turbines can’t be erected everywhere simply because many places are not windy enough. When an appropriate place is found, building and maintaining a wind farm can be expensive. Anyway in good condition it can be much more profitable than solar energy so much more attractive for investitors.

Hidropower Energy in water can be used quite easly. Since water is about 800 times denser than air, even a slow flowing stream of water, can produce considerable amounts of energy. Hydroelectric energy is a term usually reserved for large-scale hydroelectric installations. Micro hydro systems are hydroelectric power installations, which typically produce up to 100 kW of power, aren’t as unusal as it can seems to be, and they of course don’t need a dam. These systems are very productive but of course they are limited to little fluvial areas.

Geothermal Geothermal energy is thermal energy generated and stored in the Earth. Earth's geothermal energy originates from the original formation of the planet (20%) and from radioactive decay of minerals (80%). This energy can be used to produce electrical energy with big installations. The high cost of these systems and the lack of suitable places makes this sourse rare. Anyway in the few places where it can be exploited it may be very productive.

Emerging renewable energy technologies There are a lot of new kinds of techonologies in the energy field. Some of them seem to be very interesting and could become really important. For example Tidal Power is the generation of electrical power through the harnessing of the ebb and flow of the tides. A barrage, which is in fact a huge dam, is built across a river estuary or bay. This barrage has gates in it which allow the water to flow into the barrage with the incoming tide. These gates are then closed when the tide begins to go back out. There are other gates within the barrage which are now opened; these gates contain hydro-electric generators, very similar to the ones used in Hydropower. The main downfall of tidal power generation is the capital needed at the beginning of the project to construct the barrages. Some scientists substain they can use cold nuclear fusion reactions to produce energy. This could be a great innovation but probably it will take years to become reality. Biomass (plant material) is a renewable energy source because the energy it contains comes from the sun. Through the process of photosynthesis, plants capture the sun's energy. When the plants are burnt, they release the sun's energy they contain. In this way, biomass functions as a sort of natural battery for storing solar energy. As long as biomass is produced sustainably, with only as much used as is grown, the battery will last indefinitely. In general there are two main approaches to using plants for energy production: growing plants specifically for energy use (known as first and third-generation biomass), and using the residues (known as second-generation biomass) from plants that are used for other things. See biobased economy. The best approaches vary from region to region according to climate, soils and geography.