Van de Graaff generator

A simple Van de Graaff generator consists of a belt of silk, or a similar flexible dielectric material, running over two pulleys, one of which is surrounded by a hollow metal sphere. Two electrodes, E1 and E2, in the form of sharply pointed cones, are positioned respectively near to the bottom of the pulley and inside the sphere. E2 is connected to the sphere, and a high DC potential (with respect to earth) is applied to E1; a positive potential in this example.

The high voltage ionizes the air at the tip of E1, repelling (spraying) positive charges onto the belt, which then carries them up and inside the sphere. This positive charge induces a negative charge to the electrode E2 and a positive charge to the sphere (to which E2 is connected). The high potential difference ionizes the air inside the sphere, and negative charges are repelled from E2 and onto the belt, discharging it. As a result of the Faraday cage effect, positive charge on E2 migrates to the sphere regardless of the sphere's existing voltage. As the belt continues to move, a constant charging current travels via the belt, and the sphere continues to accumulate positive charge until the rate that charge is being lost (through leakage and corona discharges) equals the charging current. The larger the sphere and the farther it is from ground, the higher will be its final potential.

The other method for building Van de Graaff generators is to use the triboelectric effect. The two rollers for the belt are made of different materials, far from each other on the triboelectric series. When the belt comes into contact with one and is then separated, charge is transferred from the roller to the belt, and the roller becomes charged. When the belt comes into contact with the other roller and is then separated, charge is transferred from the belt to the roller, and that roller develops an opposite charge. The strong e-field from the rollers then induces a corona discharge at the tip of the pointed electrodes. The electrodes then "spray" a charge onto the belt which is opposite in polarity to the charge on the rollers. The remaining operation is otherwise the same as the voltage-injecting version above. This type of generator is easier to build for science fair or homemade projects, since it doesn't require a potentially dangerous high voltage source. The trade-off is that it cannot build up as high a voltage as the other type, and operation may become difficult under humid conditions (which can severely reduce triboelectric effects).

Since a Van de Graaff generator can supply the same small current at almost any level of electrical potential, it is an example of a nearly ideal current source. The maximum achievable potential is approximately equal to the sphere's radius multiplied by the e-field where corona discharges begin to form within the surrounding gas. For example, a polished spherical electrode 30 cm in diameter immersed in air at STP (which has a breakdown voltage of about 30 kV/cm) could be expected to develop a maximum voltage of about 450 kV.

Wind Genrator H6.5-5000W

Features:
Streamlined three-bladed glass fiber reinforced blades have the advantages of great intensity, fatigue resistance and high efficiency. The Hummer-patented generator characterizes its high efficiency and good low-speed-performance.
The speed regulating system adjusts automatically to wind speed. The whole system is easy to install and convenient to maintain. Controlling, inverting and discharging are integrated.
Main technical datas:
1.Rotor blade diameter:6.5
2.Numbers of blade:3
3.Start up wind speed:4m/s
4.Rated wind speed:10m/s
5.Rated output power:5000W
6.Output Voltage:AC 220V ?230V?340V ,DC 24V,36V,48V,etc
7.Height:10m
8.Generator Weight:70kg
Temperature of working surrounding::±45°C

British Wind Energy Association

The British Wind Energy Association (BWEA) is the trade and professional body for the wind power and marine renewable energy industries in the United Kingdom, and the UK's leading renewable energy trade association.

Originally founded in 1978 to promote wind power in the United Kingdom, in 2004 the British Wind Energy Association expanded its mission to champion wave and tidal energy and use the Association's experience to guide these technologies along the same path to commercialisation.

BWEA espouses the view that wind can provide for 8% of the UK's energy mix by 2010.

The primary purpose of the BWEA is to promote the use of wind power in and around the UK, both onshore and offshore. The association works to co-ordinate statistics and intelligence on wind power and marine renewables in the UK, and represents industry at home and abroad, to Government, regional bodies and to local authorities in the UK. They also act as a central point for information for members, and also carry out research and find solutions to current issues.

Wind energy has now started a major expansion in the UK and will be the single greatest contributor to the UK Government targets for 10% of electricity supplies to be met by renewables by 2010. Onshore wind alone could meet over half of this target, one of the conclusions of BWEA’s analysis of the sector conducted as part of the Government Energy Review.

Wind has been the world's fastest growing renewable energy source for the last seven years, and this trend is expected to continue with falling costs of wind energy and the urgent international need to tackle carbon emissions to prevent dangerous global warming.

Wind Generator H3.8-2000W

Features:
Streamlined three-bladed glass fiber reinforced blades have the advantages of great intensity, fatigue resistance and high efficiency. The Hummer-patented generator characterizes its high efficiency and good low-speed-performance.
The speed regulating system adjusts automatically to wind speed. The whole system is easy to install and convenient to maintain. Controlling, inverting and discharging are integrated.
Main technical datas:
1.Rotor blade diameter:3.8
2.Numbers of blade:3
3.Start up wind speed:3.5m/s
4.Rated wind speed:9m/s
5.Rated output power:2000W
6.Output Voltage:AC 220V ,30V,340V ,DC 24V,36V,48Vetc
7.Height:9m
8.Generator Weight:25kg
Temperature of working surrounding::±45°C
The product partial pictures demonstration are as follows:

Wind Genrator H6.5-5000W

Features:
Streamlined three-bladed glass fiber reinforced blades have the advantages of great intensity, fatigue resistance and high efficiency. The Hummer-patented generator characterizes its high efficiency and good low-speed-performance.
The speed regulating system adjusts automatically to wind speed. The whole system is easy to install and convenient to maintain. Controlling, inverting and discharging are integrated.
Main wind generator h6.6-50002 technical datas:
1.Rotor blade diameter:6.5
2.Numbers of blade:3
3.Start up wind speed:4m/s
4.Rated wind speed:10m/s
5.Rated output power:5000W
6.Output Voltage:AC 220V ?230V?340V ,DC 24V,36V,48V,etc
7.Height:10m
8.Generator Weight:70kg
Temperature of working surrounding::±45°C
The product partial pictures demonstration are as follows:

MHD generator

The MHD (magnetohydrodynamic) generator or dynamo transforms thermal energy or kinetic energy directly into electricity. MHD generators are different from traditional electric generators in that they can operate at high temperatures without moving parts. MHD was eagerly developed because the exhaust of a plasma MHD generator is a flame, still able to heat the boilers of a steam power plant. So high-temperature MHD was developed as a topping cycle to increase the efficiency of electric generation, especially when burning coal or natural gas. It has also been applied to pump liquid metals and for quiet submarine engines.

The basic concept underlying the mechanical and fluid dynamos is the same. The fluid dynamo, however, uses the motion of fluid or plasma to generate the currents which generate the electrical energy. The mechanical dynamo, in contrast, uses the motion of mechanical devices to accomplish this. The functional difference between an MHD generator and an MHD dynamo is the path the charged particles follow.

MHD generators are now practical for fossil fuels, but have been overtaken by other, less expensive technologies, such as combined cycles in which a gas turbine's or molten carbonate fuel cell's exhaust heats steam for steam turbine. The unique value of MHD is that it permits an older single-cycle fossil-fuel power plant to be upgraded to high efficiency.

Natural MHD dynamos are an active area of research in plasma physics and are of great interest to the geophysics and astrophysics communities. From their perspective the earth is a global MHD dynamo and with the aid of the particles on the solar wind produces the aurora borealis. The differently charged electromagnetic layers produced by the dynamo effect on the earth's geomagnetic field enable the appearance of the aurora borealis. As power is extracted from the plasma of the solar wind, the particles slow and are drawn down along the field lines in a brilliant display over the poles.

Model Grassland Well-off

The vast grassland in Northeast & North China is rich in wind power. The wind power density is normally at 200-300 W/m2, sometimes up to 500 W/m2; the valid annual time reaches as long as 6000~7000 hours.According to these regional features—“great density, high and rich wind speed and long valid hours? our Hummer company has specially developed the Model Grassland Well-off, able to drive freezers and pumps, to meet the consumers?needs. Fine quality as well as low price have obtianed many customers , the structure is small & exquisite and therefore is convenient for pastorals to carry about.

Model Plateau Fortune

In Tibetan Plateau and the northern part of Northwest, and Northeast China, the wind power density is normally at 150-200 W/m2, and up to 6500 hours yearly, the wind speed can reach above & equal to 3 m/s. Due to the high altitude and thin air density, the wind power density is comparatively weak. The air density at 4000m is only 67% of that of the sea-level. For example, the 8m/s wind can generate 313.6 W/m2 at sea-level whereas 209.3 W/m2 at 4000m

The wind speed in Tibetan Plateau is the highest, while the wind power is far below the coastal Southeast.

Anhui Hummer Dynamo Co., Ltd. Specially designs the Model Plateau Fortune to meet the regional features—“even annual wind speed, long valid hours, and low valid wind power density? It is really a great innovation.

Wind power Onshore

Onshore turbine installations in hilly or mountainous regions tend to be on ridgelines generally three kilometers or more inland from the nearest shoreline. This is done to exploit the so-called topographic acceleration. The hill or ridge causes the wind to accelerate as it is forced over it. The additional wind speeds gained in this way make large differences to the amount of energy that is produced. Great attention must be paid to the exact positions of the turbines (a process known as micro-siting) because a difference of 30 m can sometimes mean a doubling in output. Local winds are often monitored for a year or more with anemometers and detailed wind maps constructed before wind generators are installed.

For smaller installations where such data collection is too expensive or time consuming, the normal way of prospecting for wind-power sites is to directly look for trees or vegetation that are permanently "cast" or deformed by the prevailing winds. Another way is to use a wind-speed survey map, or historical data from a nearby meteorological station, although these methods are less reliable.

Wind farm siting can sometimes be highly controversial, particularly as the hilltop, often coastal sites preferred are often picturesque and environmentally sensitive (for instance, having substantial bird life). Local residents in a number of potential sites have strongly opposed the installation of wind farms, and political support has resulted in the blocking of construction of some installations.

Turbine placement

As a general rule, wind generators are practical where the average wind speed is 10 mph (16 km/h or 4.5 m/s) or greater. Usually sites are pre-selected on basis of a wind atlas, and validated with wind measurements. Obviously, meteorology plays an important part in determining possible locations for wind parks, though it has great accuracy limitations. Meteorological wind data is not usually sufficient for accurate siting of a large wind power project. Site Specific Meteorological Data is crucial to determining site potential. An 'ideal' location would have a near constant flow of non-turbulent wind throughout the year and would not suffer too many sudden powerful bursts of wind. An important turbine siting factor is access to local demand or transmission capacity.

The most crucial step in the development of a potential wind site is the collection of accurate and verifiable wind speed and direction data as well as other site parameters. To collect wind data a Meteorological Tower is installed at the potential site with instrumentation installed at various heights along the tower. All towers include anemometers to determine the wind speed and wind vanes to determine the direction. The towers generally vary in height from 30 to 60 meters. Some meteorological towers are much taller and more permanent like the Obninsk Meteorological Tower in Russia at 315 meters. The towers primarily used in determining site feasibility for potential wind farms are guyed steel-pipe structures which are left to collect data for one to two years and then usually disassembled. Data is collected by a data logging device which stores and transmits data to a server where it is analyzed

Wind power

Wind power is the conversion of wind energy into more useful forms, usually electricity, using wind turbines. At the end of 2006, worldwide capacity of wind-powered generators was 74,223 megawatts; although it currently produces just over 1% of world-wide electricity use, it accounts for approximately 20% of electricity use in Denmark, 9% in Spain, and 7% in Germany. Globally, wind power generation more than quadrupled between 2000 and 2006.

Most modern wind power is generated in the form of electricity by converting the rotation of turbine blades into electrical current by means of an electrical generator. In windmills (a much older technology), wind energy is used to turn mechanical machinery to do physical work, such as crushing grain or pumping water.

Wind power is used in large scale wind farms for national electrical grids as well as in small individual turbines for providing electricity to rural residences or grid-isolated locations.

Wind energy is plentiful, renewable, widely distributed, clean, and reduces toxic atmospheric and greenhouse gas emissions if used to replace fossil-fuel-derived electricity. The intermittency of wind seldom creates problems when using wind power at low to moderate penetration levels.

MagLev Wind Power Generator

The "MagLev generator" is said to be the world’s first (Ref) permanent magnetic levitation wind power generator. Magnetic levitation is an important new development to reduce stress from the mechanical load on the wind turbine.

It is being regarded as a key breakthrough in the evolution of global wind power technology, boosting generation capacity by as much as 20% over traditional wind turbines, and dropping operational costs by as much as 50%.

How it Works
The magnetic levitation that they use is between the rotating shaft and the fixed base of the machine, basically taking the place of ball bearings. Such magnetic bearings have been used for decades in smaller turbines and pumps by Ebara, Leybold, Seiko-Seiki, and others. However, they generally can't handle being bumped around much (the magnetic force isn't that strong), and they generally require actively controlled electromagnets (to keep the levitating magnets from crashing--play with some magnets for a minute or two and you'll see why). Making magnetic bearings beefy enough to handle the loads a wind turbine would put on them is hard, and would use prohibitive amounts of power just keeping the electromagnets running strongly enough. However, the Worldwatch article says the new Chinese device uses "full-permanent" magnets, meaning there are no electromagnets, only cleverly placed permanent ones, so it should use no power.
"Unfortunately there's not a shred of additional technical information in the article, nor is there any to be found elsewhere online (if you have any, please leave a comment!), so we can only speculate what their solution was. A little research made me conclude (and this is also suggested by a couple highly knowledgeable Treehugger readers who left comments) that they're probably using Halbach arrays in a system like the Inductrack invented at Lawrence Livermore Labs several years ago. Any permanent magnet system would doubtless need lots of Neodymium ("rare earth") magnets, which may have questionable sustainability when mined in large amounts, but as it happens China is rich in that element--in fact, energy.buzz points out that China owns 90% of the world's market of rare earth magnets."

wind power turbine

Wind machines were used for grinding grain in Persia as early as 200 B.C. This type of machine was introduced into the Roman Empire by 250 A.D. By the 14th century Dutch windmills were in use to drain areas of the Rhine River delta. In Denmark by 1900 there were about 2500 windmills for mechanical loads such as pumps and mills, producing an estimated combined peak power of about 30 MW. The first windmill for electricity production was built in Cleveland, Ohio by Charles F Brush in 1888, and in 1908 there were 72 wind-driven electric generators from 5 kW to 25 kW. The largest machines were on 24 m (79 ft) towers with four-bladed 23 m (75 ft) diameter rotors.

By the 1930s windmills were mainly used to generate electricity on farms, mostly in the United States where distribution systems had not yet been installed. In this period, high-tensile steel was cheap, and windmills were placed atop prefabricated open steel lattice towers. A forerunner of modern horizontal-axis wind generators was in service at Yalta, USSR in 1931. This was a 100 kW generator on a 30 m (100 ft) tower, connected to the local 6.3 kV distribution system. It was reported to have an annual load factor of 32 per cent, not much different from current wind machines.