Tapping the power of the sun

Solar power is essentially free as long as the sun shining on Earth continue to exist. Unless something catastrophic happens to our sun, it will definitely outlast fossil fuel. There are primarly 3 types of technology that uses solar power: photovoltaic cells, concentrating solar power technologies and low-temperature solar converters.

Photovoltaic cells convert sunlight directly into electricity and are made of semiconductors such as crystalline silicon or various thin-film materials. Photovoltaics can provide tiny amounts of power for watches, large amounts for the electric grid, and everything in between. Commonly known as solar cells, individual PV cells are electricity-producing devices made of semiconductor materials. PV cells come in many sizes and shapes from smaller than a postage stamp to several inches across. They are often connected together to form PV modules that may be up to several feet long and a few feet wide. Modules, in turn, can be combined and connected to form PV arrays of different sizes and power output. The photoelectric effect is the basic physical process by which a PV cell converts sunlight into electricity. When light shines on a PV cell, it may be reflected, absorbed, or pass right through. But only the absorbed light generates electricity.

The energy of the absorbed light is transferred to electrons in the atoms of the PV cell. With their newfound energy, these electrons escape from their normal positions in the atoms of the semiconductor PV material and become part of the electrical flow, or current, in an electrical circuit. A special electrical property of the PV cell what we call a "built-in electric field ”provides the force, or voltage, needed to drive the current through an external "load," such as a light bulb.

The size of an array depends on several factors, such as the amount of sunlight available in a particular location and the needs of the consumer. The modules of the array make up the major part of a PV system, which can also include electrical connections, mounting hardware, power-conditioning equipment, and batteries that store solar energy for use when the sun isn't shining.

Concentrating solar power technologies use reflective materials to concentrate the sun's heat energy, which ultimately drives a generator to produce electricity. These technologies include dish/engine systems, parabolic troughs, and central power towers. Concentrating Solar Thermal (CST) systems use lenses or mirrors and tracking systems to focus a large area of sunlight into a small beam. This is then used to generate electricity. Moreover, the high temperatures produced by CST systems can be used to provide process heat and steam for a variety of secondary commercial applications (cogeneration). However, CST technologies require direct insolation to function and are of limited use in locations with significant cloud cover. The main methods for producing a concentrated beam are the solar trough, solar power tower and parabolic dish; the solar bowl is more rarely used. Each concentration method is capable of producing high temperatures and high efficiencies, but they vary in the way they track the sun and focus light.

Low-temperature solar collectors also absorb the sun's heat energy, but the heat is used directly for hot water or space heating for residential, commercial, and industrial facilities.

Human Footprint

Human footprint is a documentary by National Geographic that reflects on the excesses of the human lifestyle. It documents and give insights to how much of the Earth's resources. It uses shocking statistics on the number of eggs we consumed, the number of diapers we use, the gallons of milk we drink, etc. It also tries to go beyond just the pure number by helping us understand that for every egg we eat, resources are used to transport the egg, refrigerate it, etc. It tries to give a sense of the amount of resources by laying out these resources in a visual way like laying out loafs of bread outside the house front yard. The team spent two years compiling statistics on the use of resources.

However, I cannot help feeling that the ironic piece of the communication involve some waste itself after viewing Behind the Scenes. For example, seeing thousands of eggs smashed on the ground when they could have been fed to the hungry is just pure waste. Doesnt the age of computer animation allow us to be more cost efficient to give us that visual representation?

Here are some vital stats from Telegraph.co.uk on the footprint in our lifetime:

2,327 kilograms of potatos consumed
4,239 rolls of toilet paper
120,000 litres of fuel used in our car
4.5 cows consumed
15 pigs consumed

Source:Telegraph.co.uk

The infinite power of the sun

The sun is a massive star in the solar system which pretty much supports all life on Earth. When the sun is shining on Earth, it generates about 1 Kilowatt per square meter. The natural process by which sunlight is converted to energy and stored as food is call photosynthesis. Even petroleum is derived from stored energy from photosynthesis eons ago. Absent of any major catastrophic event in our galaxy, the sun is expected to shine for billions of years which is many lifetimes of humans.

Therefore, in effect, it provides an infinite source of energy if humans learn how to tap the solar power provided by the sun. At 1 Kilowatt per square meter, if we can convert at a 100% efficiency, it can power sixteen 60 watt light bulbs. Currently, the most efficient solar panel can convert at about 45% efficiency though most commercial panels are between 9-15% efficiency. Unfortunately, the sun does not shine equally all the time. At night, the sun does not shine in most places and solar power is non-existent unless it is earlier stored. Also, the sun shines mostly and strongest at the equator which is why countries in those areas like Mexico and the Middle East can benefit most from solar power.