P10: Pujada de Sant Feliu. La Carbonera
Pujada de Sant Feliu. La Carbonera
It is not difficult to understand how they work if we understood how an LED makes light. The principle is very similar; in fact it could be said that it works the other way around. In a photovoltaic cell, two materials are put in contact: one rich in electrons and the other deficient. They are closed between two conductive plates. When light hits, it causes electron movement that is ultimately responsible for the electrical current (like we saw at stop 3). The basic material used to make photovoltaic cells is very abundant on Earth: silicon. Beach sand contains it in large quantities. The problem of the price of the cells is not so much in the raw material as in the technology required to manufacture them.
Therefore, energy is required to break the water molecule. Once broken, it is as if the hydrogen stored that energy, because when combined with oxygen, it will come out. That’s why it is sometimes said that hydrogen is like a battery. When hydrogen comes into contact with the oxygen in the air in a special cell, the two combine to produce water and generate an electrical current. It is like the hydrolysis reaction, but in reverse. This current runs an electric motor.
Coal is no longer seen at “la Carbonera.” The stoves have been changed out for more modern ones, cleaner ones.
Did you know?
Sulfur compounds contained in some fossil fuels are the main reason behind acid rain. Their combustion and subsequent reaction with the water in clouds transforms these compounds into acid. This precipitation is then very damaging to the environment.
This reaction is not strange: onions make us cry for a similar reason. When we cut an onion, cells are broken and certain substances are released. The substances at play here are enzymes and sulfoxides which, when they come into contact, give rise to a molecule (a propanethial derivative) that contains sulfur. This molecule causes us to cry because when it reacts with the moisture of our eyes it produces sulfuric acid, among other things. This is a very strong acid, and our eyes react by sending water to dilute it and make it less concentrated. This water comes in the form of tears. That’s why onions make us cry.