Biological Fuel Cells

There's a lot of promise behind the biological fuel cells, which normally use an organic fuel, like methanol or ethanol. In these cases, it is the enzymes, instead of conventional chemical catalysts like platinum, that help speed up the electrode reactions. These Fuel Cells attempt to copy nature in a way that energy is obtained from organic fuels. However, these fuel cells are not anywhere near to becoming commercial applications.

Reference:

LARMINIE, James; DICKS, Andrew. Fuel Cell Systems Explained. 2. ed. West Sussex, England: Wiley & Sons Ltd., 2003. 418 p.

Comments

Photovoltaics: Band Diagram

In the previous post we discussed silicon, which is the most used material in photovoltaics. In this post, we introduce the band diagram, for which we will use silicon as an example. We will start our discussion of the band diagram with the Bohr model of the silicon atom. In semiconductor materials the outer shell of the atom, which is called the valence shell, is not completely filled. The outer shell of silicon contains 4 out of the possible 8 electrons, which we call valence electrons. As we discussed in the previous post, each silicon atom in a crystalline structure is bonded to four other silicon atoms. The bonds between the silicon atoms are called covalent bonds. These bonds actually consist of two valence electrons that are shared by two silicon atoms. All valence electrons are fixed in the lattice, forming covalent bonds, and are therefore immobile. However, at a temperature above absolute zero, thermal energy is supplied to these miconductor and some of the vale...

Photovoltaics: Doping

In the previous post, we explained that semiconductors do not conduct electricity very well. One way to manipulate electrical conductivity in semiconductors is to manipulate the concentration of electrically charged carriers. We can do this by using doping. In this post, we will first introduce what doping is. Then we will discuss how doping changes important material properties in semiconductors. The concentration of charge carriers in a semiconductor can be manipulated by doping the material. Doping means that we add impurities in a controlled way to the material. Let’s take the example of silicon. Silicon has four valence electrons. In a silicon lattice, each atom is bonded, covalently, to four other silicon atoms. We can take that silicon lattice and substitute a small amount of silicon atoms with different atoms. This is commonly done with atoms of two different elements: Boron and Phosphorus. Boron atom has three valence electrons, while phosphorus atom has five val...

Environmental conservation must be a commitment of all

In the midst of the presidential race, historically, we have followed guidelines linked to environmental conservation placed in the background. The result of this stance are inoperative mandates regarding the gradual and uninterrupted degradation of our forests and natural resources. We need the elected candidates, both in the Executive and in the Legislative, to make real commitments to the preservation of our biodiversity, even though promises related to the environment do not attract so many votes. In view of the election of the National Electoral Council last month, the people's choices cannot depend on environmental issues alone, but also on the protection of our natural resources, the health of our environment and its environment, of our environment with respect to the people. Our objective is to create a culture of conservation, of environmental awareness, and of respecting the environment. Environmental awareness is a cornerstone of our campaign and is linked to envi...

The Environmental Engineering Hub

Search This Blog