Understanding Solar Energy
Light (particularly sunlight) can be used to create heat or generate electrical power. This is referred to as solar energy.
It is a clean form of energy production, which doesn't pollute the environment as some other forms of energy production do.
Solar Thermal Conversion
Solar thermal conversion systems use reflectors or mirrors to concentrate sunlight to extremely intense levels of heat. (Solar means "of the sun," thermal means "of heat" and conversion means "changing something from one form to another.")
You can understand this better if you consider the example of using a magnifying glass to start a fire. You may have heard of this or even tried it before. You can hold a magnifying glass under the sun, and concentrate the light on a small pile of flammable materials. The magnifying glass will make the sun's heat much stronger, and will light the materials on fire. It has been said that a magnifying glass one meter in diameter, held under the sun, will create a ray hot enough to melt stone.
If you want to experiment, hold a magnifying glass flat under the sun and put your hand under it. Very soon you will need to move your hand away - don't burn yourself.
Solar thermal conversion systems use mirrors or reflectors to concentrate sunlight onto containers full of liquid. Sometimes water is used. Sometimes other liquids are used, which retain heat better than water.
The liquids are heated up to high temperatures, and this produces steam. The steam is used to turn a turbine. The turning motion of the turbine is used to create electricity.
How does a rotating motion create electricity? When you set up a coiled wire or similar device to rotate between two magnets, it generates an electric current. This is how electric generators work, as well as windmills, nuclear power plants, and other energy plants which use such things as coal, gas, or petroleum.
Windmills use the wind to create the turning motion. Nuclear power or fossil fuels are used to heat water up, thus creating steam to turn the turbines.
Solar heating is another form of solar thermal conversion. In solar heating, an absorber is used to take in sunlight and convert it to heat. The absorber could be something simple, like black paint, or it could be a special ceramic material. A heat absorber is considered to a be good one when it collects at least 95 percent of the sun's radiation.
The absorbers are then used to heat a fluid, which is then circulated to warm up buildings or to create hot-water supplies.
Photovoltaic Conversion
As covered above, photo means "light." It comes from the Greek word “phos,” which means "light."
“Voltaic” means, "producing electric current." The word comes from the name of Alessandro Volta, an Italian physicist who was a pioneer in the field of electricity during the 1700's. (His name is also where the word "volt" comes from.)
Photovoltaic means, "creating electrical energy when exposed to light."
A “cell” is a device that produces electricity. An example of an electrical cell is a flashlight battery.
Photovoltaic cells produce electricity when they are exposed to light. They usually consist of panels. The panels contain two layers of different materials.
When light hits these two layers, one of the layers becomes positively charged, and the other becomes negatively charged.
This works similarly to a regular flashlight battery, which has a positive end and a negative end. When a wire connects the two ends, they produce an electric current.
When the two layers of material in a solar cell are exposed to light, they create an electric current.
The AMOUNT of electricity generated by a solar power cell depends on several factors. Mainly:
-How big is the solar power device, and how much surface is exposed to the sun?
-How strong is the sun? (This depends on time of day, weather, latitude, etc.)
-How long is the solar power device exposed?
-How much impediment is there to the light? (Clouds, mist, dust, dirt, etc.)
In other words, a solar power cell generates electricity faster when the sun (or light) is brighter. A device with larger solar panels will produce more electricity than one with smaller panels. Exposing the cell for a longer period of time will create more electricity than exposing it for a shorter period of time. A panel near the equator will be more effective than one in an arctic region. A solar panel in misty or dusty conditions does not create as much electricity as it would in full, unobstructed sun.
Some solar cells produce only enough current to power small electronic devices, but can be "daisy-chained" (connected together) in order to create more electricity for other items.
Solar cells which produce enough electricity to run larger equipment (such as laptops) may be larger, more expensive, or heavier than the others.
But there are many varieties available. Individuals and companies are consistently striving to create lighter and more efficient portable solar cells.
Solar Energy and the Future
An advantage to solar power is that it can reduce expenses. It can also be portable. When one is backpacking in the wilderness or traveling far from power grids, solar power can provide a means of powering electronic equipment.
Another advantage is, of course, the lack of pollution created by solar energy production. In fact, if all of our electrical energy were produced by such means, we might not be worrying about global warming and the other destructive effects of pollution on our environment.
These threats to our environment also pose a threat to mankind. Solar power could be developed to a point where it, along with other forms of renewable energy, would replace harmful means of electricity production.
It isn't necessarily impossible to have a clean and safe Earth. We just have to work on it.
About the author: Anna Stone is an educator and a student in photography. She is the webmaster of the website, http://www.findportablesolarpower.com, which has the purpose of helping photographers and travelers find portable solar power devices to run their equipment when they are far from main power supplies.
No generator is 100% efficient, and kinetic energy that is not converted to electric energy usually ___.?
a-stays electric energy
b-becomes thermal energy
c-becomes light energy
d-disappears
What are three types of atomic or radioisotope batteries?
Are thermal converters atomic or radioisotope batteries? Ex: Thermionic converter, Radioisotope thermoelectric generator, Alkali-metal thermal to electric converter, etc.
If not, what are some types of atomic or radioisotope batteries?
Thanks
This answer may confuse you even more. The US Government uses batteries powered by Pu-238.
Power units, called “space batteries,” “Radioisotope Thermoelectric Generators,” or “RTGs,” have been in use since the 1960s. The United States uses RTGs to power things that need a reliable source of power in remote locations. Other countries have used them to power things like lighthouses, radio beacons, and weather stations.
In simple terms, a heat source.
Long-life nuclear batteries are expected to power Voyager 1 until at least 2020, when it will be more than 13 billion miles from Earth. Solar panels would be ineffective in the total dark of space.
What is the temprerature of the Voyagers 1 & 2?
In the void of the universe, some 10 or so billion miles away, what is the temperature of the Voyagers? What is the temperature of their environment? Does the on-board radioisotope thermal electric generators (RTGs) keep them warm? In what temperature range do the electronics function?
b
What circuit can I use for a voltage source from variable input current?
I’m designing the electrical system for a thermal electric generator from sunlight that will output different currents depending on the heat differential between the thermoelectric plates. I’m trying to find a way to power my electronics using this current source which require 24 and 12 V inputs. I need an efficient way to use this current to output a CONSTANT voltage of 24 and 12V.
When the system is off or there is not enough sunlight for the system to produce efficient power it will be run of Li-ion rechargeable battery packs. It would also be nice to switch between powering the system and charging the batteries when there is no high power requirements of the step motors or MCU(ie. when we don’t have to move the fresnel lens).
Also, is there an easy way to read the current flowing from the thermoelectric generators that could be sent to my MCU (TI MSP430) and saved to monitor the power production. Any ideas about circuits or websites to refer to would be much appretitated.
Why don’t we utilize the heating power of volcanoes to make thermal electric power stations?
Turning the generator makes electricity, generator is turned by turbine, and turbine is turned by force: the force is either water from waterfalls or steam. Boiling water creates steam. Water is boiled by coal, natural gas or atomic power. Why don’t we use the heat form volcanoes? This question is for scientists, who can think of a way utilize that wasted heat.
geothermal energy is well developed in places like Iceland. It doe cause large hot minerally laden lakes; but these have been turned into tourist attractions/spas
the question is not for scientists but economists and politicians. who do not add the cost of pollution and use of non-renewables into the cost of oil and nuclear.
The main problem is access to geothermal energy near to users, or the loss of long transmission lines.
They’re both beyond the orbit of Pluto, whose temperature is about 35 kelvins.
Using an energy balance with the Stefan-Boltzmann radiation law http://en.wikipedia.org/wiki/Stefan-Boltzmann_Law , and assuming a power dissipation of 10W and emissivity of 0.3, the equilibrium temperature of a 3ft diameter object would be 122 kelvins, which is warm enough for satellite electronics to still work.
The logical approach is to run your equipment off the battery system, so it has continuous power. The thermo electric generator (TEG) probably needs a voltage converter of some kind to charge the battery. This inverter would convert the voltage from whatever the nominal TEG voltage is to a voltage suitable to charge the battery. It is a critical part of the system. There could be two batteries for your 12 and 24V or a single battery with another DC to DC converter to get the second voltage. Depends on the relative power levels of these two loads. If you are really after efficiency you would have an efficient single voltage load, and the TEG is close to the battery.
The generator output can be monitored by a simple comparator that determines whether it is operating or not, and this status (a logic level signal) is used to control the switching of the load as you may require, using a series mosfet power switch. The MCU can monitor generator voltage and charge current and manage the load accordingly.
Briefly the MCU has a voltage input for analogue measurements, maybe 3 or 5V full scale. To measure a current you need to convert to voltage. You could monitor the battery charging current and the load currents separately. A resistor in series with the power lead drops a few 10s of milli-volts at full load. This voltage is ground referenced and amplified using an op amp circuit as shown in the first link below. High side current monitors are often more suitable. The magnetic field can be used with a “DC clamp meter” using hall effect devices. These are not very effective at low currents below a few amps though.
The battery charger..
If you are lucky you won’t need an inverter type, just a switch. You need to characterise the generator to find what it does (see the third link).
Without knowing details of the TEG I cannot help much, but a voltage converter needs to be efficient and convert the voltage correctly to charge the battery. The TEG probably has a significant source resistance, so the load presented by the inverter when charging should match the source resistance to get the maximum power transfer (efficiency). Half the voltage is dropped in the load, half in the source resistance.
The second link below shows some historical TEG systems that are interesting.
The third is quite similar to your needs, and even has a basic circuit as a starting point. The maximum power point tracking is a good idea.