Salam Sejahtera

Topics :


free counters>

Enter your email address:

Delivered by FeedBurner


Ads 468x60px

Social Icons

Featured Posts

Wednesday, November 26

The Oceans' Wave Power

  • For more than 200 years inventors worldwide have filed patents for wave-power technology of a dazzling variety of designs-bobbing objects ("ducks"), buoys, articulated rafts, floating bags, overspills, and many others. There has been no shortage of ideas. Many of these ideas are in fact technically feasible, so it seems a shame that this renewable energy resource has not been much used. The main challenge is building a system that is economically attractive when so many other forms of energy production (nuclear, fossil fuels) receive subsidies and already have infrastructure in place. There are some wave power systems in place around the globe: the Faroe Islands; Islay, Scotland; Oahu, Hawaii (providing power for the U.S. Marine Corps. base there); Santo, Spain; Portugal; and even the world's first commercial "wave farm" in England.
    The World Energy Council has estimated that wave power could produce as much energy in a year as 2,000 oil, gas, coal and nuclear power plants' twice the amount of electricity produced worldwide-by generating as much as 2 terawatts (that's 1 trillion watts).
    Not every place is a candidate for wave power generation. Prime locations identified are Scotland, northern Canada, southern Africa, and the Atlantic Northeast and Pacific Northwest of the United States. Experts have estimated that wave-power systems in the Pacific Northwest alone could generate up to 70 kW per meter of coastline.

Typical Designs

Wave-power systems can be located onshore or offshore, and come in a surprising range of designs. There are currently four basic "capture" methods: point absorbers (largely vertical, with a relatively small footprint on the surface); attenuators (horizontal footprint, arranged parallel to the waves to undulate with the flow); terminators (perpendicular to the waves); and overtopping (perpendicular to the waves, which break over the system). There are different power take-off systems including hydraulic ram (water hammer pumps water above the starting point); elastomeric hose pump (peristaltic, like your intestinal tract), pump-to-shore, hydroelectric turbine, air turbine, and linear electrical generator. Here are some systems already in operation, or close to it:

    1. The Salter "Duck"-In 1970 Stephen Salter ("the father of wave power"), a professor at the University of Edinburgh, designed a wave-power device that could both stop 90 percent of the wave motion and convert 90 percent of that into electricity, a standard that all other designed continue to be measured against. Ironically, the Duck itself never went into use. During the 1990s, a project based on the Duck and dubbed the OSPREY (Ocean Swell Powered Renewable Energy), commenced in the Clyde Estuary of the Scottish coast. Capable of generating 1 mW of power, the OSPREY was on its way to becoming an unqualified success until Hurricane Felix came along and sunk it (at great expense in terms of both money and confidence).
    2. The AquaBuOY wave energy device-AquaBuOYs (Finivera Renewables) really do look like navigational buoys, and this is no coincidence. Obviously, maximum output from a wave-power device should be during those times when the waves are at their highest, but if the technology can't withstand rough seas (as with the OSPREY, above), they aren't much good. Operating on the premise that since navigational buoys can survive for decades in all sorts of conditions, the AquaBuOYs were designed to ride the waves for an estimated 100 years. The vertical wave action drives a two-stroke hose pump that directs pressurized seawater into a turbine connected to a generator; the resulting power is sent via an underwater transmission line. While at least four projects are in the permitting process (including one in Makah Bay, WA), as of this writing.
    3. PowerBuoy "Like the AquaBuOY above, the PowerBuoy resembles a navigational buoy, although one with long cylinder extending far below that houses the mechanics of the system. These PowerBuoys (Ocean Power Technologies) are placed from one to five miles offshore in 100 to 200 feet of water, and can be ganged together to form a "wave-power farm" such as the one to be installed off the coast of Santo, Spain. That 1.39MW station will have one 40kW and nine 150kW PowerBuoys.

1. Pelamis - Ocean Power Delivery, Ltd., developed world's first commercial offshore wave-power facility using its Pelamis Wave Energy Converter, a string of steel cyclinders hinged to articulate. It lies half-submerged, like a 150-meter-long, bright red sea snake (pelamis is the genus for the sea snake), more or less facing into the waves. The cylinders contain hydraulic pumps activated by the wave action; the electricity comes as high-pressure oil gets pumped into generators. The first phase of the wave farm, located 5 km off the coast of Portugal, comprises three 750kW Pelamis "snakes" that combined to generate 2.25 MW; another 28 are expected to be added, bringing the total power generated to 22.5 MW'enough to provide electricity for more than 15,000 homes.

    1. Nearshore OWC-This is an offshore version of the Limpet, described below.

1. Wave Dragon-Overtopping systems work very much like hydroelectric dams, using the potential energy of water stored at an elevation higher than the turbines it drives. The Wave Dragon overtopping system funnels the waves into its own reservoir to create a head; the water is then released through channels that contain turbines. The Wave Dragon is moored 25 to 40 meters offshore in deep water, somewhat like a floating beach.

1. Limpet (Land Installed Marine Powered Energy Transformer)- This an oscillating water column (OWC) system to convert the waves' kinetic energy to electrical power. Picture a box with the open end submerged but slightly tilted toward the incoming waves, with air trapped inside the box. Now imagine there is a narrow outlet for this air, and inside this tube is a turbine. As the waves raise the level of the water inside the box, the air rushing in and out of the tube powers the turbine. A Limpet system (WaveGen) in Islay, Scotland, uses an inclined oscillating water column (OWC) system optimized for the area's anverage annial wave intensity, and feeds a pair of 250kW generators. The Limpet power station in the Faroes is very similar. WaveGen also designs a near-shore oscillating water-column system.
There are many companies designing wave-power systems using these and other designs (such as the tapered channel system, an onshore system, and the pedulor system, an offshore device), and new ones seem to come along frequently as more countries come to recognize the potential of wave power.

Wave Power Advantages
1. Wave energy is an abundant and renewable resource. 2. Even though not every country has coastline, the combined potential output of wave-power generation would meet all the electricity needs of the world. 3. Although the equipment represents a substantial investment, the "fuel" is free and not confined by geopolitical boundaries. 4. The effect on the environment is deemed to be minimal.

Wave Power Disadvantages
1. These are most effective near coastlines, of which there is a finite supply. 2. Large scale systems are still in the early stages.

Take charge of your energy use! Free ebooks that show you how! Visit the best Alternative Energy Source. Click over to Alternative Energy HQ to get your free ebooks and terrific resources on Alt Energy
Monday, November 17

Science discovery- used physics to build a flying machine

Some scientific developments, and the inventions resulting from them, are so important that they change people's lives all over the world. In 1903, two brothers from Dayton, Ohio, USA, managed to solve a problem that others had failed to conquer for hundreds of years. They were Wilbur and Orville Wright and the problem was how to build a flying machine. The Wrights made many scientific studies of the shapes of wings, the way propellers work, and how to control an aircraft in flight. They carried out the first true powered airplane flight on 17 December, 1903 at the coastal sand dune area of Kitty Hawk, North Carolina, USA. Their invention of the plane transformed our world.

Soon after the Wright's early flights, many other craft took to the skies. First to fly across the Channel between France and England was Louis Bleriot, in 1909. Soon people began to see the potential for planes as passenger-carriers, beginning the era of fast long-distance travel.

The Wright's first plane, the Flyer, was powered by a small petrol engine that the brothers had designed themselves. They knew that the
petrol engines of the time, built for the early motor cars, were too heavy for an aircraft. Over the following years they built improved
versions of the Flyer and made longer flights.

Sunday, November 16

History of Computer

A COMPUTER IS AN ELECTRONIC MACHINE that manipulates, changes and processes information, or data, of all kinds - not only numbers but also words, patterns, pictures, animations, sounds and so on. The data is processed called a program, which tells the computer what to do. Inside a computer, the program according to a sequence of instructions and data are in digital form, as patterns of tiny electrical signals that pass around the many circuits and microchips. Computers can deal with vast amounts of information in a very short time. For example, a supercomputer can work out all the consequences of more than 200 million chess moves every second.

Supercomputers A supercomputer must work so fast that its main processing and memory circuits are supercooled to many degrees below freezing. Supercooling reduces the resistance of the conductors in the electronic circuits.

In the 1830s English mathematician Charles Babbage (1792-1871) designed several kinds of programmable mechanical calculators. His machines used gearwheels to do the calculating and had more than 2,000 moving parts. Due to engineering and money problems, Babbage's machines were never finished at the time. But modern computers still use his basic ideas.
Thursday, November 13

Physics Teacher - Electricity Network

ELECTRICITY IS AN INVISIBLE form of energy. It is based on the tiny charged particles inside atoms. In an atom's nucleus, particles called protons have a positive charge. Whizzing around the atom's nucleus are electrons, which have a negative charge. Normally, the positive and negative charges balance. If they become unbalanced, an electrical force is produced. This may stay in one place, as static electricity, or move from place to
place, as a flowing current. Electricity is so useful to us because it can flow along wires to
wherever we need it, and be changed into other forms of energy such as light, heat and movement.

The electricity network

Power stations turn the energy of movement into electrical energy which is medium strength, or mid voltage. This is changed into more powerful, high-voltage electricity and sent along large cables or wires, high on pylons or buried underground. This network of cables and wires is called the electricity distribution grid. The electricity is changed back into lower-power forms, industrial and mains voltage, for use in factories, farms, offices and homes.

Electricity in atoms

Everything is made up of trillions of incredibly tiny particles, called atoms. An atom has a central nucleus containing protons, each with a positive charge, and neutrons, each with
no charge, or neutral. Going around the nucleus in empty space are much smaller particles, called electrons, each with a negative charge. When atoms or substances gain or lose electrons, they become electrically charged. Gaining electrons makes them negative. Losing electrons makes them positive.

Electricity at work

If there was a power cut in this city, people would have to manage without most of their lighting and heating, and the machines that make their lives so much easier. Daily routine would grind to a halt and the only sources of energy would be batteries, candles, wood, coal or gas. Yet people managed without electrical devices for thousands of years, and still do in many parts of the world. It is only in the last century or so that electricity has been put to work. One of its great advantages is that it is available at the flick of a switch.
Saturday, November 8

Physics Tips For SPM 2008

For All Students STEP 2008

Chapter 1 : Sub-topic - Measure instruments
Chapter 2: Sub-topic - Momentum, impulse / impulsive force and Forces in Equilibrium
Chapter 3 : Sub-topic- Gas Pressure -atmospheric pressure and Pascal's Principle
Chapter 4: Gas Law - Experiment Heat Capacity/ latent heat/ Thermometer
Chapter 5: Refraction of light/ understanding lenses

Chapter 6: Interferens of Waves
Chapter 7: Ohm law, Relationship between I and V
Chapter 8: Electromagnetic Induction/ Application
Chapter 9: LOgic gates and Semiconductor diodes
Chapter 10 : Radioactive and Isotop/ Nuclear Energy - Nuclear Fusion

Science Discovery

Amedio Avogadro (1776-1856) worked as a lawyer before taking up science and becoming professor of physics. In about 1811, he imagined a row of the same-sized containers. Each held a different gas, but at the same numbers of molecules in each container. This is now known as Avogadro’s law-equal volumes of all gase, when at the same temperatures and pressure, have the same numbers of atoms or molecules.
Tuesday, November 4


Materials science is a fast growing area of science, especially in engineering. It involves taking various raw or ingredient substances and making them mix, combine or react together in various ways, to produce a new material with specialised properties. Each of the ingredient substances has some useful features, and these all add together to produce the final material. One example is glass-reinforced plastic, GRP. This is made by embedding tiny fibres of glass into a type of plastic. The plastic gives overall bulk and flexibility, while the glass fibres provide extra strength, stiffness and resistance to wear. GRP is used to make boat vehicles, aeroplanes, and factory and office equipment.

Space tiles- the tiles on the undersides of space shuttles are made of heat-resistant ceramic composites. As the shuttle comes back from space into the Earth’s atmosphere, friction with the thickening air generates enormous heat. The tiles keep this heat out of the shuttle’s interior. They are checked and renewed as necessary after each mission.
Sunday, November 2

Strong as steel…most valuable metal

The world’s industriies use millions of tonnes of steels each year. Steel plate form the lrge panels in washing machines, car, trains and ships. The stainless steel used for making cutlery is an alloy with at least one-tenth of the extremely hard , shiny metal known as chromium. Steel with titanium in them form the light but stiff structure sheets in high-speed aircraft. Gold is a famous symbol of wealth. But rarer metals such as platinum and palladium command higher prices for specialised engineering and electronic uses.

Keyword : Physics Teacher's, Trial Exam

Random Template

Live Traffic