Future trend: Solar battery charger

In our modern life nowadays, electric devices like laptop, handphone or iPod are widely used all over the world and play an important part in our work, entertainment and many other things.

As we know, all these devices depend on electricity supply, which means if you forget to charge the battery, all these devices become useless. It is really irritating that when you need to use your handphone, for example, urgently, you find that it has run out of battery.

That’s why scientists have come up with the idea of solar battery charger. This device, built up from solar cells (photovoltaic cells), basically function by the physics principle of harnessing energy from sunlight and convert it to electricity. ( For the details of this principle, you can refer to old posts in this blog on photovoltaic cells.)  

Nobody can deny the environmental-friendly value of this device. With it, our electric devices will consume electricity generated from solar energy instead of normal elctricity which is partly from fossil fuel. At a time when the fossil fuel resources are going to be empty as now and are an element of environmental distress, it is very important to use renewable energy, particularly solar energy as a wonderful replacement.

The environmental-friendly advantage of solar battery charger is very meaningful. Beside this, solar battery charger is also very convenient to use. Users will not have to care about the case when they pick up their hand-phone in hurry in the morning only to realise the empty battery indicator and have to look for an electricity source to plug in the battery charger . All they need to do is to take the solar battery charger going out with them, hang it on their bag like an accessory and let it generate electricity from sunlight automatically. It is free and convenient, they will never worry that their laptop, iPod… run out of battery when they need.

The disadvantage of solar battery charger, as any other solar device, is that it cannot be charged at night or in rainy weather. However, the battery charger is made to be chargeable by normal AC also, so this will not be a problem.

This product is still very new, but in the near future, its great effectiveness and usefulness will help people a lot in saving unrenewable resources and protect our environment.

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Lan – just back from Viet Nam (

http://internetsiao.com/?s=solar+charger

http://www.strapya-world.com/products/25095.html

 

 

 

 

More on pros and cons of Solar Energy: case study – SOLAR CARS :D

This is Lien

Thanks to Sylvia’s previous entry I have come up with some possible pros and cons of a solar car

Pros:

A solar car is absolutely environment-friendly! All the exhaust it gives out is already converted to harmless materials, unlike normal diesel/petrol fumes which contain chemicals that can destroy the ozone layer (e.g. CFCs)

Little or no petrol/diesel is needed to run a solar car. This is a wonderful advantage as the world oil price is rising with each hour:-s. Moreover it helps to save this non-renewable natural resource.

Cons:

Even though the use of solar cars helps to protect the environment, the production process of these may harm the environment instead. However, the same problem occurs to the making of normal cars. Hence, overall, a solar car is still a lot more environment-friendly compared to the cars we are commonly using.

A solar car faces the typical challenge of all such devices: they depend largely on the supply of sunlight, which, sadly, is unstable and unpredictable. L This is perhaps the most serious disadvantage as cars are supposed to be readily used even in emergencies.

Solar cells are installed on the roof of cars to capture sunlight. Thus the size and weight of these cells do matter. Problematically, at the same time, they must be large enough to capture and store energy for the car to run. (It is said that “the more likely place for solar cells will generally be on the roofs of buildings, where they are always exposed to the sky and weight is largely irrelevant” – Wikipedia)

 

All in one, solar cars are a wonderful solution to the current polution situation. Unfortunately, they also suffer from the common disadvantages of solar-energy-based devices; and even worse, these disadvantages matter a lot to them as a means of transportation. More work needs to be done on the solar car before they can really become the revolutionary vehicle of this era!!!

Pros and Cons of Solar Energy

Hello! Sylvia here!!!

Pros:

Solar energy is a renewable resource. Although we cannot utilize the power of the sun at night or on stormy, cloudy days, etc., we can count on the sun being there the next day, ready to give us more energy and light. As long as we have the sun, we can have solar energy (and on the day that we no longer have the sun, you can believe that we will no longer have ourselves, either).

Oil, on the other hand, is not renewable. Once it is gone, it is gone. Yes, we may find another source to tap, but that source may run out, as well.

Solar energy is non-polluting. Of all advantages of solar energy over that of oil, this is, perhaps, the most important. The burning of oil releases carbon dioxide and other greenhouse gases and carcinogens into the air.

Solar powered lights and other solar powered products are also very easy to install. You do not even need to worry about wires.

 

Cons:

 A solar energy installation requires a large area for the system to be efficient in providing a source of electricity. This may be a disadvantage in areas where space is short, or expensive (such as inner cities).

Solar energy is only useful when the sun is shining. During the night, your expensive solar equipment will be useless; however the use of solar battery chargers can help to reduce the effects of this disadvantage.

Although the negative points above may put the majority of people off, the advantages can be greater incentive over the above points.

 

 

 

 

 

 

 

 

Concentrated Solar Power-more beneficial?

Hello! Sylvia here!:)

As we know, solar power is something that is being researched in our world as fossil fuel is becoming not only costly but also a factor of environmental distress.

Placing panels that are made from treated silicone onto a home provides solar power. Photons are absorbed in these panels from the sun and then convert them into energy, like how the batteries work. This energy is then used to supply electricity to a home. This can be a beneficial and productive way to use a natural resource to provide electricity as it will not caused environmental distress. Some companies have already began to look into ways to provide concentrated solar power to larger communities.  This process may be the forerunner of changing the way that we use energy.

So how does concentrated solar power work?

Firstly, there must be a discussion on the best location to place the concentrated solar power plant before contemplating using the concentrated solar power . The best place that is suggested to locate the concentrated solar power plant is a place where it can get a steady stream of sunlight that can be captured and used. The sunlight that is captured will be converted into energy. This energy then will be used to supply electricity. We are not suppose to locate the concentrated solar power plant at places where there is not enough sunlight.

A concentrated solar power plant is constructed in Naveda recently. The ideas of constructing the concentrated solar power plant is that by using mirrors to absorb  the energy, then taking in the energy. Later, it is used to produce steam. The homes that are in the nearby area can use the combination of steam to run an energy plant, hence it is energy efficient. 

Also, in Mojave Desert, the similar type of power plant has been constructed and it has worked extremely efficiently. It uses a combination of resources to provide local areas with energy. By combining steam, sunlight and even fossil fuel, a concentrated solar power plant can provide customers with a broad range of energy alternatives that are affordable and cleaner for the environment.

Not everything is perfect, the most useful things also have their bad points. For solar energy, it definitely has it’s cons. however, we think that the pros of solar energy greatly outweigh its cons.

There are many advantages of solar energy. Just consider the advantages of solar energy over that of oil:

· Solar energy is a renewable resource. Although we cannot utilize the power of the sun at night or on stormy, cloudy days, etc., we can count on the sun being there the next day, ready to give us more energy and light. As long as we have the sun, we can have solar energy ; Oil, on the other hand, is a fossil fuel, it is not renewable. Once used, it can never be replaced again, until thousands of years later. Other sources can be fournd, but they may eventually be used up as well.

· Solar cells are totally silent. They can extract energy from the sun without making a sound. Oil drills and pumps however, make a lot of noise and contribute to noise pollution.

· Solar energy is non-polluting. Of all advantages of solar energy over that of oil, this is, perhaps, the most important. The burning of oil releases carbon dioxide and other greenhouse gases and carcinogens into the air. The usage of solar energy does not release harmful gases into the air, thus it is environmentally friendly.

· Solar cells require very little maintenance (they have no moving parts that will need to be fixed), and they last a long time.

· Although solar panels or solar lights, etc., may be expensive to buy at the onset, you can save money in the long run. After all, you do not have to pay for energy from the sun. Also, with the rising cost of oil, solar energy would be a much cheaper and wiser alternative in the long run.

· Solar powered lights and other solar powered products are also very easy to install. You do not even need to worry about wires.

As you can see, there are many advantages of solar energy. The advantages of solar energy range from benefiting your pocketbook to benefiting the environment. There are actually only a few features of solar energy that can be considered disadvantages.

Here are the disadvantages of solar energy:

· Solar cells/panels, etc. can be very expensive.

· Solar power cannot be created at night because of the absence of sunlight.

As you can see the advantages of solar energy create a much longer list that the disadvantages, and the disadvantages are things that can be improved as technology improves. Thus we can say that the pros of solar energy greatly outweigh the cons.

 http://ezinearticles.com/?Solar-Power:-Advantages-and-Disadvantages&id=260246

- Rachel(:

to be continued… solar cookers…

The three most common types of solar cookers are heat-trap boxes, curved concentrators (parabolics) and panel cookers. Scientists have also developed large-scale solar cooking system to meet the needs of institutions worldwide.

Box cookers are the most common type of solar cookers as they cook food at moderate to relatively high temperature and can accommodate multiple pots at the same time.

Curved concentrators cookers, also known as parabolics, are especially useful for large-scale cooking but need frequent supervision and adjustment as it cook food at very high temperatures.

Panel cookers, incorporating the elements of the two above, are simple and quite inexpensive to use as well as produce.

With people like us, we choose solar cooking because it helps protect the environment as it consumes no fossil fuel. We do not care much about the economic benefit because with us, money spent on cooking fuel have become too normal and we even ignore it. However, hundreds of millions of peoples around the world who cook over fire fueled by wood or dung, and who walk for miles to collect wood or spend much of their meager incomes on  cooking fuel, solar cooking is more than a choice – it is a blessing.

Solar cookers bring benefits to:

Your health:

Moderate cooking temperatures in simple solar cookers help preserve nutrients.

Solar cookers are smoke-free and fire-free à Your eyes and lungs will not get affected by smoke and no dangerous fire get out of control unexpectedly.

With good sunlight, solar cookers can be used to pasteurize water (a process to kill disease-causing organism in water by exposure to heat) during emergencies when other fuels and power sources may not be available. Many solar cookers can be used to disinfect dry medical supplies such as medical instruments, bandages and other cloth materials, as well as to heat compresses

Economics

Many poverty-stricken families worldwide spend 25% or more of their income on cooking fuel. Sunlight — solar cooker “fuel” — is free and abundant.

Solar cooker businesses can provide extra income. Opportunities include cooker manufacturing, sales and repair, as well as solar food businesses like restaurants and bakeries.

Environment:

1/3 of the world’s population rely on wood and charcoal for cooking fuel as they are to poor to afford biogas or electricity. Solar cooking alleviates the conflict between their basic needs and the need to preserve earth’s dwindling forests, hence help to protect the environment.

Convenience:

At moderate solar cooking temperature, food can be left unattended for several hours without burning. It is great to put your solar cooker out in the morning with a pan containing some materials, and return home in the late afternoon to a hot meal ready to eat, isn’t it?

…And many more benefits that you may visit http://www.solarcookers.org/basics/why.html#envir to find out yourself!

Now you know how significant the invention of solar cookers is, right? That’s great that we can use solar energy in such a normal and daily activity like cooking. Looking around us, can we see any other things/works consuming fossil fuel that can be replace by solar energy? Going on, maybe we will make a change to the world J.

Thanks!

Bibliography:

http://www.solarcookers.org/basics/how.html

http://en.wikipedia.org/wiki/Solar_cooker

The Sun will cook for you !!!

The Sun will cook for you !!!

 

Hi, Lan’s here!

 

How do you (or rather, your mother ) start cooking a meal? Turn on the oven or cooker, put materials in the pan and put it on the flame, right? Even if you use the oldest kind of cooker which is a piece of woodJ, or the newer one using gas, or even the modern one using electricity, it will still consume fossil fuel and that contributes to global warming.

 

Nowadays, you can think of cooking with no fossil fuel at all. It is the era of SOLAR COOKERS!!! Since cooking is an essential part of our daily life, solar cookers will help save large amount of fuel spent and more than that……

 

Let’s explore J

Most solar cookers work on basic principles: sunlight is converted to heat energy that is retained for cooking.

o       Fuel: Of course, solar cookers need an outdoor spot which is sunny for several hours and protected from strong wind. They do not work at night or cloudy days. (It is quite a disadvantage but inevitable with any solar device. Furthermore, this limitation is negligible compared to many benefits that solar cookers bring.)

o       Convert sunlight to heat energy: Black pans and pots are always used in solar cooking because they absorb almost all of the sunlight and turn it into heat, while light-color pans reflect the sunlight.

o       Retain heat: A transparent heat trap around the dark pot lets in sunlight, but keeps in the heat. It is a clear, heat-resistant plastic bag or large inverted glass bowl or an insulated box with a glass or plastic window. Curved concentrator cookers typically do not require a heat trap.

o       Capture extra sunlight: One or more shiny surfaces reflect extra sunlight onto the pot, increasing its heat potential.

Do you see that these principles are not too complicated? But yet when they are applied creatively, they actually became so useful.

The great benefits of solar cookers will be brought to you in my next post

Wait for me ……

Blocking convection currents – Why not?

Hi Lien there  

Preamble

In this post I am going to continue with the solar thermal technologies ^^. In a nutshell, at the first step of solar thermal technologies, a large amount of solar energy is harnessed using different methods.

… And then?

In certain cases, since it may not be feasible to make use of all the heat collected by the collectors efficiently at once, there is a need to store this excess energy for further use. Also, due to the unpredictability of the sun, it will also be more useful to store more energy than needed if possible, so that we can still use it in case of bad weather or at night. 

Nowadays, the most commonly-used devices for heat storage (known as the thermal reservoirs) include: the solar pond, the molten salt tank and the multi drum heat storage vault. Let’s zoom in how these particular devices work.

 

Main  

1/ A solar pond is simply a pond of salt water, which has levels of increasing concentration of salt (hence increasing density) from the top to bottom, until a certain depth. Below this depth, the bottom layer have uniform and highest salt concentration.

 Naturally in a normal water pond, in the bottom (and hottest) layer of water, the particles are furthest apart compared to other layers. Thus the layer has lowest density, and will travel upwards to float on others in convection currents. Such convection currents will continuously be formed until the whole body of water reaches a uniform temperature. To achieve this state, a lot of heat energy will be lost to the surroundings through the water surface (as the water exposed to the air is constantly renewed)

 However, in the case of the solar pond, the bottom and the hottest layer has previously had the highest density. Thanks to this density gradient, there will be no convection currents of the liquid in the pond, and hence heat will be trapped in this salty layer.

As a matter of fact, the temperate of a solar pond’s bottom layer can rise to up to 90^oC.

 2/ A detailed animated illustration of the structure of the multi drum heat storage vault can be found at http://www.jc-solarhomes.com/drum.htm

I will continue with the drum and some other thermal reservoirs in another post! See you then! 

Learning points:

Through the study of the solar pond, I have understood much better about convection of liquids. I know now that we can stop the seemingly-inevitable convection currents just by changing the density of different layers of water. This is really useful in energy storage.

 

Bibliography:

http://en.wikipedia.org/wiki/Solar_pond

 

From SUNLIGHT to ELECTRICITY – UNLIMITED SUPPLY!!!

I.                    Definition 

Photovoltaics, or PV for short, is a technology that converts light directly into electricity. It is best known as a method for generating solar power by using solar cells packaged in photovoltaic modules.     

II.        PV system 

A photovoltaic system consists of 4 main components: _ Photovoltaic modules/solar panels which are packaged solar cells: Solar cells are made primarily of silicon, a semiconductor. When sunlight strikes the solar cells, or photovoltaic modules, a relatively high percentage of sun’s rays is absorbed into the silicon material. This energy activates and loosens electrons, allowing them to flow freely. Incorporated into the solar cells are electrodes, a networked grid that forces the freed electrons to flow in the designated direction, creating an electrical current. _The inverter: changes the Direct Current (DC) received from the modules into Alternating Current (AC) to power TVs, appliances and other household equipment. _Solar power monitor: displays immediate and cumulative readouts on electricity generation, power consumption and C02 reduction level. _Electric meter: The solar electric system connects to the utility grid thru a standard breaker. The utility meter tracks the net power usage and spins backward when you create more electricity than you use. 

III.               PV applications 

PV has worldwide applications. The first practical application of PV was to power orbiting satellites and other spacecraft and pocket calculators, but today the majority of PV modules are used for grid connected power generation. As electricity is always one of the most necessary energy in daily life as well as industry, PV has been applied in various fields of life and has proved high efficiency. 

PV in buildings

PV solar panels on a house’s roof Building-integrated photovoltaics (BIPV) are increasingly incorporated into new domestic and industrial buildings as a principal or ancillary source of electrical power, and are one of the fastest growing segments of the PV industry. Typically, an array is incorporated into the roofs or walls of a building. Alternatively, an array can be located separately from the building but connected by cable to supply power for the building. Where a building is at a considerable distance from the public electricity supply (or grid) – in remote or mountainous areas – PV may be the preferred possibility for generating electricity, or PV maybe used together with wind, diesel generators and/or hydroelectric power. 

PV in transport

PV on the International Space Station  Nuna 3 PV powered car PV is being used increasingly to provide auxiliary power in boats and cars. Recent advances in solar cell technology have shown the cell’s ability to administer significant hydrogen production, making it one of the top prospects for alternative energy for automobiles. 3.      PV in standalone devices  Solar powered parking meter PV has been used for many years to power calculators and novelty devices. Solar power remote fixed devices have seen increasing use recently, due to increasing cost of labour for connection of mains electricity or a regular maintenance programme. In particular, some common uses are parking meters, emergency telephones and temporary traffic signs. à Nowadays, electricity generated using PV method is still more expensive than usual electricity; therefore it has not become popular in household life. However, in the situation that the Earth’s environment is getting worse and worse, human has to thoroughly control any kind of pollutions; a pollution-free power like solar power will soon find its position in daily life as well as industry.        

IV.     Bibliography:
 http://en.wikipedia.org/wiki/Photovoltaics_in_transport http://en.wikipedia.org/wiki/Photovoltaic_system http://en.wikipedia.org/wiki/Photovoltaics#Applications_of_PV http://solar.sharpusa.com/files/popup3d.asp?title=Solar&file=/files/solar.swf&type=1&height=500&width=700 

 

Photovoltaic cells

Hello! Sylvia here:) 

Solar photovoltaic energy conversion is a one-step conversion process which generates electrical energy from light energy. The explanation relies on ideas from quantum theory. Light is made up of packets of energy called photons, whose energy only depends upon the frequency, or colour of the light. The energy of visible photons is sufficient to excite electrons, bound to solids, up to higher energy levels where they are more free to move. Normally when light is absorbed by matter, photons are given up to excite electrons to higher energy states within the materials, but the excited electrons quickly relax back to their ground state.

In a photovoltaic device, however, there is some built-in-asymmetry which pulls the excited electrons away before they can relax, and feeds them to an external circuit. The extra energy of the excited electrons generate a potential difference, or electromotive force(e.m.f). This force drives the electrons through a load in the external circuit to do electrical work.

The effectiveness of a photovoltaic device depends upon the choice of light absorbing materials and the way in which they are connected to the external circuit.

The solar cell is the basic building block of solar photovoltaics. The cell can be considered as a two terminal device which conducts like a diode in the dark and generates a photovoltage when charged by the sun. Usually it is a thin slice of semi conductor material. The surace is used to reflect as little visible light as possible and appears dark blue or black. A pattern of metal contacts is imprinted on the surface to make electrical contact.