jeudi 23 novembre 2017

Solar energy advantages and disadvantages

Solar power technologies pros and cons

Controversy over alternative energy  (part 2)

Voltaic cells production 

   From an electric point of view, a photo-voltaic cell is the equivalent of a power generator to which a diode has been added. In a photo-voltaic cell, a semiconductor is exposed to the light, a photon with a sufficient energy pulls off an electron from the matrix of the semiconductor, creating a hole. The principle of the voltaic cell is to force the electrons and the holes to go toward the opposite side of the material and created a difference of potential, a voltage in between the two faces like in a battery.
   A semiconductor is generally made of silicon because of its properties, cheap price and its abundance in nature. In the semiconductor's production, the introduction of small impurities into the intrinsic semiconductor is made for the purpose of modulating its electrical properties. The dope material is referred to as extrinsic semiconductor.
  In the superior layer of a semiconductor doped N voltaic cell exists a larger quantity of free electrons compared to the intrinsic material (non-doped), hence the name superconductor doping N, for electron negative. The doping N production consisted of increasing the density of electrons in the semiconductor. The atoms or the elements needed generally have 5 valence electrons to participate in the chemical bond, and they are usually in the IV column of the periodic table chart: P, As, Sb, are commonly used in the production… Those atoms embedded in the crystal lattice will present 4 covalent bonds and a free electron. This electron who's weakly bound to the atom can easily be excited toward the conductive band. When the doping N is sufficient, the number of electrons surpass by far the number of holes, and they become majority carriers. 
   The doped P semiconductors production consists of creating a deficit of electrons and to increase the density of holes in the matrix. And then the semiconductor will be considered positively charged, hence its name superconductor doped P for positive charge. To do this, we include a certain number of atoms low in electrons in the semiconductor. For silicon semiconductors, trivalent atoms will be embedded in the intrinsic (pure) matrix and it is boron atoms that are used most often in the fabrication of the P semiconductors. This atom: boron with his 3 valence electrons can only produce 3 covalent bonds with his 4 neighbours, creating holes in the structure. Holes who will be filled with electrons from silicon neighbours; thus displacing the holes. When the doping P is sufficient, holes surpass by far the number of electrons, and holes become majority carriers.

mercredi 22 novembre 2017

Hydroelectricity pros and cons

Hydroelectricity pros and cons

Controversy over alternative energy  (part 1)

  Hydroelectricity is a good alternative energy source to fossil fuel (wood, coal, natural gas, and oil) for the environment. Hydro-power produces a 100 times fewer greenhouse gases than coal-fired power plants. It's called hydroelectricity and it's the most popular clean energy source in the world and it counts for 16% of the world's production, but well behind fuel fossil energy production. It's an affordable energy source and it's easy to stock electricity, compared to solar panels or wind power turbines. Those technologies need batteries to stock electricity, hydroelectricity not, it's a water reservoir and you just open the van when you need to have electricity. It's a renewable energy source as long as you have the water supply. 

Hydroelectricity and evaporation water supply

  One of the major problems of hydroelectric water retaining dams in hot countries like Egypt and Namibia in Africa is the stagnation of water and its evaporation. In Egypt 10 cubic kilometers of water is lost to evaporation each year: that's 12% to 18% of the Nil water. The champion in Africa is in Namibia whose one of its dams dispense 14 millions cubic kilometers of water and loose 45 millions cubic of water each year due to evaporation, no question it's for sure more than its production of electricity. 
  Hydro-power Greenhouse gases debate Some say hydro-power doesn't emit carbon dioxide or just a few. At Hydro-Quebec their numbers say that it's a clean energy source and it produces the same quantity of green-gases in kWh than wind power turbines and 4 times less than solar panels technology at their fabrication. In fact in 2009 in Quebec, thanks to hydro-power, the electricity sector accounts for only 0,6% of GHG emissions. The transportation sector accounts for the most with 44%.  
   But others say the opposite, hydro-power plants are emitting GHG indirectly. Their point is that when they have built the hydro dams they usually completely flood large areas of lands, full of trees, biomass and other variety of organic stuff. After the flood, the soil organic vegetation and sediments start to decompose, rut and emit methane. This decomposition produces methane which is at least 34 times more potent as other greenhouse gases. Some experts say that hydroelectricity contributes to 4% of greenhouse gases pollution emitted every year in the world. It's also said that hydroelectricity pollutes more than the aviation industry on this planet.
Hydroelectricity and the environmental impact

Hydroelectricity is also linked to disrupting aquatic ecosystems. It interferes with aquatic life and results in huge scale devastation. With that, also it leads to water stagnation. Stagnant water is when water stops to flow and it can be a major environmental hazard, a breeding ground for mosquitoes and parasites, an incubator for many kinds of bacteria and diseases and illnesses like malaria and dengue fever in hot countries where the temperature is ideal for it. Hydro-power plant dams are usually built across rivers to stock large bodies of water in a basin. The water loses is good proprieties, lose oxygen, sediments start to build, water stagnated and that's very bad for the ecosystems and the environment. It had been found that a lot of individuals, fishes, and others aquatic animals will perish in there by the lack of oxygen and impossibility to reproduce in their native habitats. There is a huge probability also that the fish and other aquatic creatures will find a way into the penstock pipes then to the turbines and get exterminated.

Renewable energy debate

Hydroelectricity may not be the perfect alternative energy source and the answer to all of our environmental problems. If greenhouse gases are our big concern and the control of global warming our first priority today, hydroelectricity is maybe not the final solution for to save the environment and the planet.

lundi 20 novembre 2017

Controversy over alternative energies

  Controversy over alternative energy


    Nothing is easy and simple here. We will always be confronted with difficulties and problems with the environment every time we try to make use of many forms of energies just for trying to make our life a bit easier.
  The resulting way we calculate, and we use energy for driving our fuel gas vehicles to work, for cooking or for heating our house will not necessarily be in terms the best for us and for the environment. 
  Problems will rise, and they are part of the equation. With new technologies, we cannot escape our responsibility when we face environmental problems. With respect to nature, we must preserve the Earth, our flora, and fauna, because it's important for our survival. By the fact, we want to stay in a clean place, with breathable air and eat healthy food; it's where we want to be.
  Nature is an entropy, in chaos you may say, but with the Sun it's our Universe. The Earth here around is a unique place and it's like nowhere else with ecosystems whose life takes place and gets created like by magic. It's where every part of it is important. You'll find also by the fact that you are not God, and you can't replicate or create life on Earth and you better take care of it.
  I would like to talk about laws of physic to try to make you understand who we are and where we live. A good definition of Earth and the thermodynamic laws that govern it is very important for our comprehension. Our place the Earth with the Sun is a closed system in equilibrium. Our Sun has created a thermodynamic machine on Earth. The particle's entropy is at the maximum in a physical static environment with temperature, pressure, and other parameters very well-defined. The Earth is by definition obeying the laws of physic and it cannot be violated.
  When we're referring to alternative energies we are talking about an alternative energy to a previous form of energy like fossil fuel, wood, even whale oil, and nuclear. And that, for the biggest part we would prefer an alternative source of energy to the fossil fuel responsible for the poisonous greenhouse gases, health diseases, and global warming. It could be also an alternative to the scarcity of wood and the destruction of forests and the preservation of nature. It could be also that we would like to get rid of the danger of the nuclear and its nuclear wastes. All of this has many objectives and many goals like saving the trees or just to clean up the atmosphere for world health problem issues.
  When we think of alternative energies, renewable energies or clean energies, we may think of them as perfect alternative solutions to fossil fuel, but it's not the case. Even those technologies have many direct and indirect effects on the environment. Some pollute also, some make noises, and they are not by far magic solutions that will solve all our problems.