(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.

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.

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!

TOP 10 POWER GENERATING STATION IN THE WORLD

 

 

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Parts of a power line

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!

What if hot air could become electricity? That is the goal of clean technology startup company, Alphabet Energy, based in California. It has a new so-called thermoelectric material which it says can turn waste heat – such as that from car exhausts and industry – into usable electric power more cheaply and efficiently than ever before, saving both money and the environment. 

The company, which was founded in 2009 and has raised over $30m in investment, released its first product which uses the material last October. The E1 thermoelectric generator, which comes in a shipping container, is designed to help make remote-location mining and oil and gas extraction operations more efficient by capturing waste heat from the exhaust of the small, diesel-fuelled power plants they use. Fuel consumption and greenhouse emissions for a one-megawatt power plant can be cut by up to 2.5% – the equivalent of saving 52,500 litres of fuel a year. There has never been a larger thermoelectric generator, Scullin says, adding it is more than 20 times bigger than existing ones. He won’t disclose sales figures but says it is getting “very good early traction” and he expects to see sales ramp up further in 2015, with improvements continuing to be made to the core technology.

The company is prototyping other products, with the possibility that some could be ready to launch in 2015. “The E1 is simply our market entry point,” says Scullin. The company is working on more industrial applications – such as a generator to attach to a factory furnace – and is also working with car manufacturers to harness heat from vehicle exhaust. “From huge mining trucks all the way down to passenger cars we are actively pursuing products,” says Scullin. There are no thermoelectric generators on car exhausts, although a few prototypes have been built and tested in the past, he says.

Thermoelectric materials can generate electricity from heat because electrons flow from warmer areas to cooler ones. But only a few known materials have the rare combination of properties that make them effective. They have to be good electrical conductors but also poor thermal conductors so the temperature difference across the material doesn’t disappear too quickly. Commercial manufacture is difficult because the materials can be rare, expensive, toxic or complex to synthesise. Thus far they have only really found niche applications. For example, their reliability – they are solid materials that don’t require maintenance – has led to their use on space probes, where the steady decay of radioactive material warms the thermoelectric material to create electricity.

The company puts the cost of tetrahedrite at about $4 per kilo compared to between $24 and $146 for other thermoelectric materials. Scullin says a thermoelectric system in cars today based on it could lead to net fuel and greenhouse emissions savings of up to 5%. That is double the saving other car prototypes have achieved to date, he says.However, Alphabet Energy’s material – based on the mineral tetrahedrite – amply satisfies requirements. First developed by researchers at Michigan State University but exclusively licensed to the company, the raw ore is abundant, environmentally friendly and easy to manufacture into the material on a large scale, says Scullin. It is also more efficient than existing thermoelectric materials.

Jeff Snyder, a thermoelectrics expert at the California Institute of Technology, says little information is available publicly about the company’s tetrahedrite technology so it is hard to know if it is onto a breakthrough. But he added it was good to see a product like the E1 thermoelectric generator finally coming to market, though the cheap cost of fuel might make it hard to win traction. “Thermoelectric materials are great in principle,” he says. “The real reason it doesn’t get done is simply economics.”

He added that the technology was difficult to apply to car exhausts because the engine temperatures change as we stop and start. Thermoelectric materials work best when the heat is constant. Payback times would also be longer than for a continually operating machine like a power plant because we don’t drive all the time.

Eventually Scullin sees applications of Alphabet Energy’s technology to consumer devices. Maybe the dryer could power the alarm clock, he suggests. “The coolest thing about what we are doing is making people recognise that this thing that’s all around them, waste heat, is actually valuable.”