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Wind Power Plant

Sunday, May 8, 2011 | | 9 comments

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Wind Power

Wind is a form of solar energy. Wind power all starts with the sun. When the sun heats up a certain area of land, the air around that land mass absorbs some of that heat. At a certain temperature, that hotter air begins to rise very quickly because a given volume of hot air is lighter than an equal volume of cooler air. 

Air Circulation

Faster-moving (hotter) air particles exert more pressure than slower-moving particles, so it takes fewer of them to maintain the normal air pressure at a given elevation When that lighter hot air suddenly rises, cooler air flows quickly in to fill the gap the hot air leaves behind. That air rushing in to fill the gap is wind.

If you place an object like a rotor blade in the path of that wind, the wind will push on it, transferring some of its own energy of motion to the blade. This is how a wind turbine captures energy from the wind.

Principles of Wind Power Plant
The terms wind energy or wind power describe the process by which the wind is used to generate mechanical power or electricity. Wind turbines convert the kinetic energy in the wind into mechanical power. This mechanical power can be used for specific tasks (such as grinding grain or pumping water) or a generator can convert this mechanical power into electricity.

So how do wind turbines make electricity? Simply stated, a wind turbine works the opposite of a fan. Instead of using electricity to make wind, like a fan, wind turbines use wind to make electricity. The wind turns the blades, which spin a shaft, which connects to a generator and makes electricity. Take a look inside a wind turbine to see the various parts.

Inside The Wind Turbine

Inside The Wind Turbine

Measures the wind speed and transmits wind speed data to the controller.

Most turbines have either two or three blades. Wind blowing over the blades causes the blades to "lift" and rotate.
A disc brake, which can be applied mechanically, electrically, or hydraulically to stop the rotor in emergencies.

The controller starts up the machine at wind speeds of about 8 to 16 miles per hour (mph) and shuts off the machine at about 55 mph. Turbines do not operate at wind speeds above about 55 mph because they might be damaged by the high winds.
Wind Farm

Gear box:
Gears connect the low-speed shaft to the high-speed shaft and increase the rotational speeds from about 30 to 60 rotations per minute (rpm) to about 1000 to 1800 rpm, the rotational speed required by most generators to produce electricity. The gear box is a costly (and heavy) part of the wind turbine and engineers are exploring "direct-drive" generators that operate at lower rotational speeds and don't need gear boxes.

Usually an off-the-shelf induction generator that produces 60-cycle AC electricity.
High-speed shaft:
Drives the generator.

Low-speed shaft:
The rotor turns the low-speed shaft at about 30 to 60 rotations per minute.

The nacelle sits atop the tower and contains the gear box, low- and high-speed shafts, generator, controller, and brake. Some nacelles are large enough for a helicopter to land on.

Blades are turned, or pitched, out of the wind to control the rotor speed and keep the rotor from turning in winds that are too high or too low to produce electricity.

Wind Turbines Offshore
The blades and the hub together are called the rotor.

Towers are made from tubular steel (shown here), concrete, or steel lattice. Because wind speed increases with height, taller towers enable turbines to capture more energy and generate more electricity.

Wind direction:
This is an "upwind" turbine, so-called because it operates facing into the wind. Other turbines are designed to run "downwind," facing away from the wind.

Wind vane:
Measures wind direction and communicates with the yaw drive to orient the turbine properly with respect to the wind.

Yaw drive:
Upwind turbines face into the wind; the yaw drive is used to keep the rotor facing into the wind as the wind direction changes. Downwind turbines don't require a yaw drive, the wind blows the rotor downwind.

Yaw motor:
Powers the yaw drive.

Types of Wind Turbines

Modern wind turbines fall into two basic groups: the horizontal-axis variety, as shown in the photo above, and the vertical-axis design, like the eggbeater-style Darrieus model, named after its French inventor. 

Horizontal-axis wind turbines (HAWT) typically either have two or three blades. These three-bladed wind turbines are operated "upwind," with the blades facing into the wind.

Vertical-axis wind turbines (VAWTs)
Vertical-axis wind turbines (VAWTs) are pretty rare. The only one currently in commercial production is the Darrieus turbine.  

In a VAWT, the shaft is mounted on a vertical axis, perpendicular to the ground. VAWTs are always aligned with the wind, unlike their horizontal-axis counterparts, so there's no adjustment necessary when the wind direction changes; but a VAWT can't start moving all by itself -- it needs a boost from its electrical system to get started. 

Instead of a tower, it typically uses guy wires for support, so the rotor elevation is lower. Lower elevation means slower wind due to ground interference, so VAWTs are generally less efficient than HAWTs. On the upside, all equipment is at ground level for easy installation and servicing; but that means a larger footprint for the turbine, which is a big negative in farming areas.

Size of Wind Turbines

3.6 MW Wind Power Plant
Utility-scale turbines range in size from 100 kilowatts to as large as several megawatts. Larger turbines are grouped together into wind farms, which provide bulk power to the electrical grid.

Single small turbines, below 100 kilowatts, are used for homes, telecommunications dishes, or water pumping. Small turbines are sometimes used in connection with diesel generators, batteries, and photovoltaic systems. These systems are called hybrid wind systems and are typically used in remote, off-grid locations, where a connection to the utility grid is not available.
Wind Turbine Size Compared with a Man

Solar Wind Bridge Consept

The hybrid system (combining solar and wind power) proposed allows for a continuous production of Energy. The project is based on the idea of utilizing the space between the pillars of the existing viaducts to house a system of wind-powered turbines which will be integrated into the structure.

The solar park is conceived as a green “promenade”, along which there alternate panoramic viewing points and entirely self-sufficient solar greenhouses. As with city farms, visitors to the park will be able to stop and buy the local produce grow in these greenhouses.

The asphalt will be substituted with a technological road surface of a kind already in use in the USA (“solar roadways”). The road surface itself will, therefore, collect energy as a part of a power-generating system composed of a dense grid of solar cells coated with a transparent ad highly resistant form of plastic.

The entire system is capable of producing around 40 million kWh per annum – enough energy to provide power for approximately 15.000 families.

This Solar Wind concept is the brainchild of designers Francesco Colarossi, Giovanna Saracino and Luisa Saracino, who came second in a competition to dream up a bridge spanning the Italian areas of Bagnara and Scilla.

Solar Roadways

Reference Books: Wind Power

Wind Turbine Technology: Fundamental Concepts in Wind Turbine Engineering, Second EditionWind-Diesel and Wind Autonomous Energy SystemsReaping the Wind: How Mechanical Wizards, Visionaries, and Profiteers Helped Shape Our Energy Future
Wind Turbine Technology: Fundamental Concep...
by David A. Spera

Wind-Diesel and Wind Autonomous Energy Syst...

Reaping the Wind: How Mechanical Wizards, V...
by Peter Asmus

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Hydrogen Fuel Cell Applications

Tuesday, April 5, 2011 | | 1 comments

There are many uses for fuel cells — right now, all of the major automakers are working to commercialize a fuel cell car. Fuel cells are powering buses, boats, trains, planes, scooters, forklifts, even bicycles. There are fuel cell-powered vending machines, vacuum cleaners and highway road signs. Miniature fuel cells for cellular phones, laptop computers and portable electronics are on their way to market. Hospitals, credit card centers, police stations, and banks are all using fuel cells to provide power to their facilities. Wastewater treatment plants and landfills are using fuel cells to convert the methane gas they produce into electricity. Telecommunications companies are installing fuel cells at cell phone and radio. The possibilities are endless. 

Fuel Cell as Power Source in Remote Location

Fuel cells are very useful as power sources in remote locations, such as spacecraft, remote weather stations, large parks, rural locations, and in certain military applications. A fuel cell system running on hydrogen can be compact and lightweight, and have no major moving parts. Because fuel cells have no moving parts and do not involve combustion, in ideal conditions they can achieve up to 99.9999% reliability. This equates to around one minute of down time in a two year period.

Since electrolyzer systems do not store fuel in themselves, but rather rely on external storage units, they can be successfully applied in large-scale energy storage, rural areas being one example. In this application, batteries would have to be largely oversized to meet the storage demand, but fuel cells only need a larger storage unit (typically cheaper than an electrochemical device).

One such pilot program is operating on Stuart Island in Washington State. There the Stuart Island Energy Initiative has built a complete, closed-loop system: Solar panels power an electrolyzer which makes hydrogen. The hydrogen is stored in a 500 gallon tank at 200 PSI, and runs a Reli On fuel cell to provide full electric back-up to the off-the-grid residence.

Fuel Cell in Residential Applications

In residential applications, small fuel cell power plants could be installed for the production of both electricity and heat or hot water for the home. 

In addition to homes in developed countries, where the market may first develop, an ideal application for fuel cells is to provide power to remote residential entities that have limited or no access to primary grid power, thereby delaying, if not eliminating, the necessity of expensive, maintenance intensive transmission line installations. These applications will be more common in developing countries, where fuel cells can provide electricity in regions gradually as development warrants and allows.

Fuel Cell in Data Centers

The propagation of  Data Centers through out the U.S. and the developed world, is a sign of continued growth in the digital age and also a significant burden on grid generation and transmission capacity. The power use density for these facilities can be in excess of 100 watts per square foot resulting in very high electrical demands for a relatively small facility. These same facilities are extremely dependent on premium quality and highly reliability power.

The potential for cogeneration at these facilities is low, however the development of the Data Center Campus concept allows cogeneration to be implements beyond the confines of the Data Center in surrounding process, office, or hospitality relate buildings. The waste heat of a fuel cell can be converted to chilled air through the absopbtion chilling process, a definite need for such a data center facility.

In 1999, the First National Bank of Omaha (FNBO) - the nation's largest privately owned bank-installed a 800-kw fuel-cell system as the primary power source for its new 200,000 square foot Technology Center's critical loads. This bank is the nation's seventh largest credit card transaction processor, handling over three million transactions per day, 365 days a year. According to officials at the bank, a single one-hour blackout could cost FNBO's credit card operation as much as $6 million in lost business.

Fuel Cell in Transportation

There are numerous prototype or production cars and buses based on fuel cell technology being researched or manufactured by motor car manufacturers.

The GM 1966 Electrovan was the automotive industry's first attempt at an automobile powered by a hydrogen fuel cell. The Electrovan, which weighed more than twice as much as a normal van, could travel up to 70 mph for 30 seconds.

The 2001 Chrysler Natrium used its own on-board hydrogen processor. It produces hydrogen for the fuel cell by reacting sodium borohydride fuel with Borax, both of which Chrysler claimed were naturally occurring in great quantity in the United States. The hydrogen produces electric power in the fuel cell for near-silent operation and a range of 300 miles without impinging on passenger space. Chrysler also developed vehicles which separated hydrogen from gasoline in the vehicle, the purpose being to reduce emissions without relying on a nonexistent hydrogen infrastructure and to avoid large storage tanks.

In 2005 the British firm Intelligent Energy produced the first ever working hydrogen run motorcycle called the ENV (Emission Neutral Vehicle). The motorcycle holds enough fuel to run for four hours, and to travel 100 miles in an urban area, at a top speed of 50 miles per hour. In 2004 Honda developed a fuel-cell motorcycle which utilized the Honda FC Stack.

In 2007, the Revolve Eco-Rally (launched by HRH Prince of Wales) demonstrated several fuel cell vehicles on British roads for the first time, driven by celebrities and dignitaries from Brighton to London's Trafalgar Square. Fuel cell powered race vehicles, designed and built by university students from around the world, competed in the world's first hydrogen race series called the 2008 Formula Zero Championship, which began on August 22, 2008 in Rotterdam, the Netherlands.

After this first race, Greenchoice Forze from the university of Delft (The Netherlands) became leader in the competition. Other competing teams are Element One (Detroit), HerUCLAs (LA), EUPLAtecH2 (Spain), Imperial Racing Green (London) and Zero Emission Racing Team (Leuven).

In 2008, Honda released a hydrogen vehicle, the FCX Clarity. Meanwhile there exist also other examples of bikes and bicycles with a hydrogen fuel cell engine.

A few companies are conducting hydrogen fuel cell research and practical fuel cell bus trials. Daimler AG, with thirty-six experimental units powered by Ballard Power Systems fuel cells completing a successful three-year trial, in eleven cities, in January 2007. There are also fuel cell powered buses currently active or in production, such as a fleet of Thor buses with UTC Power fuel cells in California, operated by SunLine Transit Agency. The Fuel Cell Bus Club is a global cooperative effort in trial fuel cell buses.

The first Brazilian hydrogen fuel cell bus prototype began operation in São Paulo during the first semester of 2009. The hydrogen bus was manufactured in Caxias do Sul and the hydrogen fuel will be produced in São Bernardo do Campo from water through electrolysis. The program, called "Ônibus Brasileiro a Hidrogênio" (Brazilian Hydrogen Autobus), includes three additional buses.

The Type 212 submarines of the German and Italian navies use fuel cells to remain submerged for weeks without the need to surface.


Fuel Cell Fueling stations

The first public hydrogen refueling station was opened in Reykjavík, Iceland in April 2003. This station serves three buses built by Daimler Chrysler that are in service in the public transport net of Reykjavík. The station produces the hydrogen it needs by itself, with an electrolyzing unit (produced by Norsk Hydro), and does not need refilling: all that enters is electricity and water. Royal Dutch Shell is also a partner in the project. The station has no roof, in order to allow any leaked hydrogen to escape to the atmosphere.

The California Hydrogen Highway is an initiative by the California Governor to implement a series of hydrogen refueling stations along that state. These stations are used to refuel hydrogen vehicles such as fuel cell vehicles and hydrogen combustion vehicles. As of July 2007 California had 179 fuel cell vehicles and twenty five stations in operation, and ten more stations have been planned for assembly in California. However, there have already been three hydrogen fueling stations decommissioned.

South Carolina also has a hydrogen freeway in the works. There are currently two hydrogen fueling stations, both in Aiken and Columbia, SC. Additional stations are expected in places around South Carolina such as Charleston, Myrtle Beach, Greenville, and Florence. According to the South Carolina Hydrogen & Fuel Cell Alliance, the Columbia station has a current capacity of 120 kg a day, with future plans to develop on-site hydrogen production from electrolysis and reformation. The Aiken station has a current capacity of 80 kg. There is extensive funding for Hydrogen fuel cell research and infrastructure in South Carolina. The University of South Carolina, a founding member of the South Carolina Hydrogen & Fuel Cell Alliance, received 12.5 million dollars from the United States Department of Energy for its Future Fuels Program.

Japan also has a hydrogen highway, as part of the Japan hydrogen fuel cell project. Twelve fueling stations have been built in 11 cities in Japan. Canada, Sweden and Norway also have hydrogenhydrogen highways implemented.

Reference Books

Modern Electric, Hybrid Electric, and Fuel Cell Vehicles

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