Alternative Energy

By João Araújo, 11º Zi
Escola Secundária de Loulé

Everyday new organic fuels that have not a fossil origin are developed for commercial proposes. Among these, the most promising for a close future are ethyl alcohol (ethanol), bioalcohol (which is a mixture of ethanol and methanol) and biogas (methane).

These organic fuels, as well as hydrogen, are the most promising fuels of the future.

The research in fuel chemistry has a straightforward goal of taking advantage of the use of these raw materials.

Ethanol (CH₃CH₂OH) is produced by biological fermentation of starches from cereals, particularly maize or from the sugar derived from sugar cane. This bioalcohol can then be purified to be almost entirely ethanol. Ethanol and methanol have oxygen in their molecular composition which reduces the energy released in the combustion of each molecule. However, they have a great tendency to burn without formation of secondary products which gives them better fuel characteristics concerning environmental protection. Since its combustion is total there is not a big energetic deficit when compared to hydrocarbons of similar molecular weight. The ethanol is denser that the methane will also carry greater weight in the same volume.

Cereals can be used do produce bioalcohol (Image credit: Wikipedia)

Methane (CH₄) is also obtained from biological materials, but through anaerobic digestion, that is, by processes that occur in the absence of oxygen. Because it produces less energy than the ethanol per unit of volume, methane is less suitable as a fuel for vehicles of heavy transportation. However, it can be used in all applications where natural gas is used. For instance in many farms, suinicultures or herding, the biogas produced from the solid waste is used to feed electrically to the farm.

Another alternative fuel is biodiesel that can be produced from vegetable oils, such as peanut oil or soybean oil.
Hydrogen is the most abundant element in the universe. This makes scientists believe it will be the fuel of the future because it could hold the key to ongoing energy demands. Relatively new technologies (such as fuel cells) can be used to efficiently harness the chemical energy stored in diatomic hydrogen (H₂). However, there is no accessible natural reserve of uncombined hydrogen, since what little there is resides in Earth's outer atmosphere (exosphere). Hydrogen for use as fuel must first be produced using another energy source; hydrogen would thus actually be a means to transport energy, rather than an energy source, just as common rechargeable batteries are. One existing method of hydrogen production is steam methane reformation; however, the most common source of methane is natural gas, which is in short supply. Another method of hydrogen production is through electrolysis of water which uses electricity generated from any source like renewable energy sources (solar, eolic, etc). If molecular hydrogen could be obtained from the water in an economically viable way it would be a virtually inexhaustible source because its combustion regenerates it back to water.

If we can obtain it from water, hydrogen would be an inexhaustible fuel (Image credit: seujhorg)

Water’s physical properties

By João Araújo and Ruben Silva, 11º Zi
Escola Secundária de Loulé

Due to its molecular structure and its hydrogen bonds water presents some special properties. An unusual feature of water is its anomalous expansion. It contracts with the drop in temperature, but at 4°C begins to expand, returning to his contract after solidification.

Life under frozen water. Credit: Wikipedia(http://pt.wikipedia.org/wiki/Imagem:H2O.jpg)

That explains why the water first freezes on the surface because the water that reaches a temperature of 0ºC becomes less dense than water at 4°C, which mean it stays at the surface. This phenomenon is also important for the maintenance of life in cold water, because makes the water at 4°C is at the bottom and holds more heat for the creatures that live there. The lower density is due to the holes in the three-dimensional hexagonal structure due to hydrogen bonds typical of ice.

Ice three-dimensional structure. Credit:NYU (http://www.nyu.edu/pages/mathmol/textbook/hbond_ice.gif))

What is Science?

By João Araújo, 11º Zi
Escola Secundária de Loulé

I do not know for sure what science is, but science has been given to the world by many people that known by almost everybody in the world.

Science has good and bad applications. If it wasn’t for science, today there would be no computers, vehicles, mobile phones, clothing or footwear as we know them, vaccines and so on. All these things are essential in our daily life. But bad things also "appear”, as the ozone layer problems, the Ebola virus, terrorist attacks and so on. But it is known, all that is good also has, most of the time, undesirable strike backs.

But let’s see, what is science? I don’t know how to answer in concrete way, because science is studying various things of the world, such as light, sound and more phenomena that can be explained (though not by me…).