2015-08-07 13:36:00
The fuel of the stars.
Hydrogen is the chemical element that lies at the origin of all things. When this universe that surrounds us began its existence, just a fraction of a second after the Big Bang, the first hydrogen nuclei (protons) began to populate it. A single proton and an electron around it is the simplest model of an atom that we can imagine, that is hydrogen. However, its simplicity is only apparent because without it the stars would not exist and since they do not exist, given that they are the factories of the other chemical elements, there would also be no carbon, oxygen, nitrogen and the rest of the atoms that, conveniently arranged, they give us life.
As an energy source, hydrogen is a true gem that nuclear fusion energy experts strive to master. Under the devilish conditions of pressure and temperature that exist inside stars, the hydrogen nuclei join together in a process called “nuclear fusion” and form a larger nucleus, that of a Helium atom. Helium is a heavier element than a hydrogen nucleus but has less mass than the sum of the initial hydrogen nuclei, a difference in mass that becomes the energy that powers the hearts of stars.
Energy vector.
The conditions that occur inside stars do not exist on Earth, except in the few places where attempts are made to build a nuclear fusion reactor. On our planet the pressure and temperature conditions are much more benign, ideal for the realm of chemistry, a realm in which atoms combine with each other without losing their identity. Under these conditions hydrogen does not even exist in its pure state. Hydrogen gas is made up of molecules of two atoms chemically linked together, a formation that quickly disappears when it combines chemically with other elements, especially oxygen. Hydrogen gas is so light that, if it were not combined with other elements, the Earth’s gravity would be unable to capture it and it would be lost in interplanetary space. However, thanks to the ease of joining with others, hydrogen exists in abundance on Earth, forming part of the molecules of water, hydrocarbons, ammonia and countless chemical compounds, including most of those that make up bodies. of all living beings.
When hydrogen combines with oxygen, it burns, releasing energy. As a result of the reaction, water is obtained, a very reassuring waste for all of us who are concerned about the increase in greenhouse effect pollutants. On the contrary, if we want to obtain hydrogen from water we must supply it with energy to break the molecule and separate it from oxygen. It’s that simple. So, based on this basic principle, it is not possible to obtain chemical energy from water and therefore the water engine is an impossible dream.
Now, this game of energy exchange between the molecule that is broken and the one that is formed can be very useful in a society in which the availability of energy is a matter of survival. Maybe we cannot obtain energy directly from water, but we can use its creation-destruction cycle of molecules and use hydrogen as an “energy vector.” The principle is easy to understand: if we have a source that provides us with energy that we do not need to consume immediately, that produced by a wind turbine or a photovoltaic plant are good examples because they depend on the presence of wind or sun and their production many times. They do not coincide with the peaks of demand in consumption, in that case we can use the excess energy to decompose the water and obtain hydrogen, a fuel that can be stored for later use. This way the excess energy is saved for the future.
Hydrogen is not only obtained from water, it is also obtained from hydrocarbons; in fact, the largest production in the world is based on these compounds. A molecule of methane, to give the simplest example of a hydrocarbon, contains a carbon atom linked to four hydrogen atoms, a molecule of ethane has 2 carbons and 6 hydrogens and thus we could list a good number of compounds that, like those They form natural gas, oil or coal, they come from the transformation of organic matter. The high hydrogen content makes natural gas and other organic compounds an important source of this element, although in this case, the process is not as clean as would be desirable.
The challenges posed by the use of hydrogen have been the topic developed during the UCLM summer course entitled: “Hydrogen: production, transportation and applications”, directed by our guest today: Antonio F. Antiñolo García , Professor of Inorganic Chemistry at the Faculty of Chemical Sciences and Technologies of the University of Castilla La Mancha.
During the course, experts in different fields related to hydrogen research and the hydrogen industry have made efforts to promote knowledge of technologies linked to hydrogen and to publicize their application in the industrial and commercial field. Obtaining hydrogen from hydrocarbons, the electrolytic production of hydrogen and the use of solar and wind energy, the storage of hydrogen and its use in electrical microgrids are some of the topics covered during the course.
We invite you to listen to Antonio F. Antiñolo García.
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