Friday 27 November 2015

Wireless energy transmission

Wireless energy generation in space is one step closer to becoming a feasible delivery source of power following a new experiment that transmitted electricity through microwaves.
The Japan Aerospace Exploration Agency (Jaxa) conducted the research, which sent 1.8 kilowatts of electricity 170 feet through the air, in the form of microwave radiation. The beam was transmitted with a great degree of accuracy, showing the technique may be used on a larger scale.
Solar energy might, one day, be collected by massive solar panels in space, and the energy generated from the systems could be sent to Earth in the form of microwaves. Such networks for generating electricity in space would have some advantages over ground-based systems. Solar collectors in space would not be subject to the cycles of day or night, or cloudy conditions.
"This was the first time anyone has managed to send a high output of nearly 2 kilowatts of electric power via microwaves to a small target, using a delicate directivity control device," a Jaxa spokesman said.
Engineers at Jaxa have spent years researching new technologies to deliver energy from space-based solar collectors down to our home planet. Solar cells commonly power satellites, space probes, and the International Space Station. However, delivering that power to Earth in an economical manner is still a challenge facing developers.
Current plans to develop an orbiting energy generation system involve sending satellites into geostationary orbits more than 22,000 miles above the Earth. The satellites would require large solar panels. Challenges facing engineers include launching these massive solar collectors that high above the Earth, and maintaining them once they are in space. Because of these issues, Jaxa engineers believe that a full network to generate electricity in space will not be available until sometime in the 2040's.
Japan is dependent on imports for near all of its energy needs, feeding a desire to develop their own systems. The nation had utilized nuclear reactors to generate electricity, but those plants shut down in the wake of the 2011 Fukushima disaster.
Mitsubishi Heavy Industries recently announced its researchers have successfully transmitted around 10 kilowatts of electricity to a receiver located more than 1,600 feet.
The idea of producing energy in space and sending it to Earth for use has been studied by American researchers for more than 50 years.
Additional uses for the transmitters could include charging electric cars, or sending electricity to remote regions in the wake of natural and man made disasters. Future development of the current system could produce a device capable of transmitting and receiving energy from ocean platforms, far from the nearest coast.

Thursday 26 November 2015

(Organic Photovoltaics)OPV Cell

This is a model of a generator being developed by the Georgia Institute of Technology that looks to take advantage of natural air movements in hot areas. When the sun’s heat hits the ground, a layer of hot air forms at ground level. If that ground-level air is hotter than the air above, it can create upwardly moving whirlwind. In nature, this columnar vortex phenomenon creates “dust devils,” or spinning whirlwinds that lift dirt off the ground. In the device, hot air rises through the turbine, generating electricity.
Features of OPV cell
The most unique aspect of the OPV cell devise is the transparent conductive electrode. This allows the light to react with the active materials inside and create the electricity. Now graphene/polymer sheets are used to create thick arrays of flexible OPV cells and they are used to convert solar radiation into electricity providing cheap solar power.
New OPV design:
Now a research team under the guidance of Chongwu Zhou, Professor of Electrical Engineering, USC Viterbi School of Engineering has put forward the theory that the graphene – in its form as atom-thick carbon atom sheets and then attached to very flexible polymer sheets with thermo-plastic layer protection will be incorporated into the OPV cells. By chemical vapour deposition, quality graphene can now be produced in sufficient quantities also.
Differences between silicon cells and graphene OPV cells:
The traditional silicon solar cells are more efficient as 14 watts of power will be generated from 1000 watts of sunlight where as only 1.3 watts of power can be generated from a graphene OPV cell. But these OPV cells more than compensate by having more advantages like physical flexibility and costing less.
More economical in the long run:
According to a team member, it may be one day possible to run printing presses with these economically priced OPVs covering extensive areas very much like printing newspapers. In Gomez’ words – “They could be hung as curtains in homes or even made into fabric and be worn as power generating clothing…. imagine people powering their cellular phone or music/video device while jogging in the sun.”
Advantages of OPVs:
The flexibility of OPVs gives these cells additional advantage by being operational after repeated bending unlike the Indium-Tin-Oxide cells. Low cost, conductivity, stability, electrode/organic film compatibility, and easy availability along with flexibility give graphene OPV cell a decidedly added advantage over other solar cells.

This is a model of a generator being developed by the Georgia Institute of Technology that looks to take advantage of natural air movements in hot areas. When the sun’s heat hits the ground, a layer of hot air forms at ground level. If that ground-level air is hotter than the air above, it can create upwardly moving whirlwind. In nature, this columnar vortex phenomenon creates “dust devils,” or spinning whirlwinds that lift dirt off the ground. In the device, hot air rises through the turbine, generating electricity.

Tuesday 24 November 2015

how power coal fired plant work


A power station is really a machine that extracts energy from a fuel. Some power stations burn fossil fuels such as coal, oil, or gas.Nuclear power stations produce energy by splitting apart atoms of heavy materials such as uranium and plutonium. The heatproduced is used to convert water into steam at high pressure. This steam turns a windmill-like device called a turbine connected to an electricity generator. Extracting heat from a fuel takes place over a number of stages and some energy is wasted at each stage. That means power plants are not very efficient: in a typical plant running on coal, oil, or gas, only about 30–40 percent of the energy locked inside the fuel is converted to electricity and the rest is wasted.
Left: Power plant transformers. Right: Power plant pylon transmission lines
Power station transformers                                    Transmission line
  1. Fuel: The energy that finds its way into your TV,computer, or toaster starts off as fuel loaded into a power plant. Some power plants run on coal, while others use oil, natural gas, or methane gas from decomposing rubbish.
  2. Furnace: The fuel is burned in a giant furnace to release heat energy.
  3. Boiler: In the boiler, heat from the furnace flows around pipes full of cold water. The heat boils the water and turns it into steam.
  4. Turbine: The steam flows at high-pressure around a wheel that's a bit like a windmill made of tightly packed metal blades. The blades start turning as the steam flows past. Known as a steam turbine, this device is designed to convert the steam's energy into kinetic energy (the energy of something moving). For the turbine to work efficiently, heat must enter it at a really high temperature and pressure and leave at as low a temperature and pressure as possible.
  5. Cooling tower: The giant, jug-shaped cooling towers you see at old power plants make the turbine more efficient. Boiling hot water from the steam turbine is cooled in a heat exchanger called a condenser. Then it's sprayed into the giant cooling towers and pumped back for reuse. Most of the water condenses on the walls of the towers and drips back down again. Only a small amount of the water used escapes as steam from the towers themselves, but huge amounts of heat and energy are lost.
  6. Generator: The turbine is linked by an axle to a generator, so the generator spins around with the turbine blades. As it spins, the generator uses the kinetic energy from the turbine to make electricity.
  7. Electricity cables: The electricity travels out of the generator to a transformer nearby.
  8. Step-up transformer: Electricity loses some of its energy as it travels down wire cables, but high-voltage electricity loses less energy than low-voltage electricity. So the electricity generated in the plant is stepped-up (boosted) to a very high voltage as it leaves the power plant.
  9. Pylons: Hugh metal towers carry electricity at extremely high voltages, along overhead cables, to wherever it is needed.
  10. Step-down transformer: Once the electricity reaches its destination, another transformer converts the electricity back to a lower voltage safe for homes to use.
  11. Homes: Electricity flows into homes through underground cables.
  12. Appliances: Electricity flows all round your home to outlets on the wall. When you plug in a television or other appliance, it could be making a very indirect connection to a piece of coal hundreds of miles away!

Saturday 21 November 2015

Diagram of a typical solar lighting kit



Diagram of a typical solar lighting kit

There are two approaches to seting up a solar lighting kit which can both be used at the same time or seprately. In the past, when inverters were less efficient and more expensive most solar lighting was 12v DC or low voltage. Current advances in inverter technology and mass production mean more solar lighting kits are basd around an inverter and use lower cost mains voltage lamps and components.

DC based solar lighting kits need thicker cables, special DC switches and new wiring. An AC solar lighting kit can use readily available switches and existing cabling. If you just want to run a couple of DC lamps in a garden shed/workshop then you're not going to have much problem but anything more that and you should start thinking about it a bit more. The diagram illustrates the DC Solar lighting connected directly to the Steca PR3030 solar charge controller. The PR303 controller has an output designed for a DC solar lighting circuit (or a similar low current load) and has a usefull push button switch and a sensor that will turn the output off if the battery voltage low (AKA LVD or low voltage disconnect) The switch is solid state which means it doesn't have any contacts which means it won't suffer from any arching problems commonly associated with low voltage high current circuits. It isn't for an inverter and must only be used for lower power devices!

The higher the voltage the less loss there is over longer lengths of wire. This means you can use thinner wire without loosing too much voltage. If is for that reason that the cables carrying mains electricity run at hundreds of thousand of volts. Transmitting 12 Volts over thin cables looses lots of voltage. The last thing you want to do is start wasting all that precious solar power that's been converted into electricity and stored in your solar battery.

12V or 24V DC has the advantage that it's relatively safe unlike 230V AC which is most definitely not. When choosing or designing your solar lighting kit make sure you consider above points. Think long term because once you've started using solar lighting with perhaps one or two bulbs we bet you a pound to a pinch of salt you'll want to illuminate the entire neighbourhood in the near future!

Types of source

  Ideal Voltage Source:  An ideal voltage source is capable to maintain the constant voltage across its terminals. The voltage across the vo...

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