Solar Energy

By Vasco Batista, 11ºZi
Escola Secundária de Loulé

A solar cell or photovoltaic cell is a device that converts light energy into electrical energy. Sometimes the term solar cell is reserved for devices intended specifically to capture energy from sunlight, while the term photovoltaic cell is used when the light source is unspecified.

Fundamentally, the device needs to fulfil only two functions: photogeneration of charge carriers (electrons and holes) in a light-absorbing material, and separation of the charge carriers to a conductive contact that will transmit the electricity (simply put, carrying electrons off through a metal contact into a wire or other circuit). This conversion is called the photovoltaic effect.

Solar Power Plant in Serpa, Portugal
Image credit: The Sietch Blog

Since they use radiation from the Sun that is a renewable source photovoltaic cells are a good alternative for the production of electrical energy, particularly for areas with a high incidence of solar radiation.

However, the high cost of installation and low yield (which implies a huge surface to produce significant energy) are the biggest obstacle to the widespread use of this type of energy.

Due to the huge daily insulation period Portugal has made large investments in solar power, making it one of the biggest producers in a worldwide scale.

Acid Rain

By Vasco Batista, 11º Zi
Escola Secundária de Loulé

Described for the first time in 1872, acid rain is an unsolved problem of our time. What took nature millenniums to build has been quickly destroyed.

Though nature also produces acid rains especially due to volcanic emissions, the gases that are responsible for acid rains are mostly anthropogenic.

Most of the acid rain is due to the emission of sulphur dioxide that in contact with water produces sulphuric acid and sulphurous acid. These emissions are mainly due to the combustion of fossil fuels and by the calcinations of metallic sulphides. Nitric oxides emitted by motorized vehicles, nitric acid and fertilizer factories, thermoelectric plants and steel factories, also give origin to acid rains.

When acid rains fall at ground level, its effect can be perceived immediately: marble and calcium materials are immediately solved by these rains, metallic structures have accelerated oxidation, forests are attacked, rivers and lakes have their pH lowered with consequences for the life forms that inhabit them.

What is Science?

By Vasco Batista, 11º Zi
Escola Secundária de Loulé

The science is an amazing thing, the hability of discovering (understanding) the strange things that happen in our world. Like how to "rebuild" the beginning of the universe just after the Big Bang.

The Science has brought many good things and bad to mankind (depending on who uses them).