The natural resources available to man are not unlimited. On the contrary, according to various studies, we may run out of all the stocks of oil, coal and methane very soon. Moreover, there is a growing awareness that the costs of oil, coal and methane pollution are too high. Just think of the fact that they are responsible for acid rain and the greenhouse effect. For all these reasons, alternatives such as green energies are being studied. These are renewable energy sources, which are cheaper if exploited on a large scale and, above all, less harmful to the environment. However, some of them may have disadvantages in their implementation. Let’s find out together which ones.
Green Energies: Biomass and Geothermal Energy
Biomass is defined as all organic materials of plant or animal origin, which can be used as or transformed into fuels. This may be forest residues, waste from the wood processing industry or animal slurry from the livestock holdings. The biomass category also includes the so-called “biofuels”, i.e. fuels obtained from certain plants, such as soya, wheat, maize, beet and sugar cane.
Biomass is one of the largest renewable resources available. The production of biofuels, however, is problematic. In fact, it involves the allocation (worldwide) of large agricultural areas to the cultivation of the plants used to obtain them. As arable land is a scarce resource, this risks depriving a huge part of the world’s population of livelihoods. In addition, land prices could rise, impoverishing small farmers in favour of large multinational soil-buying companies.
Geothermal energy, on the other hand, uses the heat from the subsoil to produce electricity – but also to power heating systems and provide heat to greenhouses. This energy source is inexhaustible, low-pollution and economical. However, only certain areas of the Earth allow the use of thermal energy.
Wind, Water and Solar Energy
Wind energy is one of the first forms of renewable energy discovered by man together with water. It is based on the exploitation of wind to produce motive power – just think of windmills or sailboats. Wind energy has the advantage of being free, inexhaustible, does not produce residues and does not pollute. Unfortunately, only a few locations are suitable for the use of wind energy. In addition, the plants are still very expensive and require large areas.
Solar or photovoltaic panels, on the other hand, allow us to exploit the energy of the sun and transform it into heat and electricity. Unfortunately, solar energy is a discontinuous source, primarily because it disappears at night and when it is cloudy. In addition, solar power plants are still expensive. Finally, to produce good amounts of electricity you need to cover large areas with solar panels.
Among the renewable energy sources there is also water. However, hydroelectric power is only available where there are natural or artificial rivers and reservoirs. Reservoirs can have a significant environmental impact by changing the hydrogeological balance and ecosystems. In the event of accidents at dams, serious damage can also affect the populations.
Other Renewable Sources
Another source of green energies comes from hydrogen, an odourless, colourless, non-toxic and very light gas. Extremely widespread in nature, especially in water, it has a high energy content – more than twice as much as methane and three times as much as gasoline. As a result, in the next few years hydrogen shall replace petrol and diesel in means of transport.
We also try to obtain energy from the tides building mobile dams. These are opened when the high tide phase begins, which allows the basin to be filled in. From here the water is drained off during the low tide phase. Unfortunately, the use of this energy source is advantageous only where the difference in height is greater than at least 6 meters and such conditions are very rare.