Ecology/Enviornmental
Wind Energy: 31
We have been harnessing the wind's energy for hundreds of years. From old Holland to farms in the United States, windmills have been used for pumping water or grinding grain. Today, the windmill's modern equivalent—a wind turbine—can use the wind's energy to generate electricity.
Wind turbines, like windmills, are mounted on a tower to capture the most energy. At 100 feet (30 meters) or more aboveground, they can take advantage of the faster and less turbulent wind. Turbines catch the wind's energy with their propeller-like blades. Usually, two or three blades are mounted on a shaft to form a rotor.
A blade acts much like an airplane wing. When the wind blows, a pocket of low-pressure air forms on the downwind side of the blade. The low-pressure air pocket then pulls the blade toward it, causing the rotor to turn. This is called lift. The force of the lift is actually much stronger than the wind's force against the front side of the blade, which is called drag. The combination of lift and drag causes the rotor to spin like a propeller, and the turning shaft spins a generator to make electricity.Wind turbines can be used as stand-alone applications, or they can be connected to a utility power grid or even combined with a photovoltaic (solar cell) system. For utility-scale (megawatt-sized) sources of wind energy, a large number of wind turbines are usually built close together to form a wind plant. Several electricity providers today use wind plants to supply power to their customers.
Stand-alone wind turbines are typically used for water pumping or communications. However, homeowners, farmers, and ranchers in windy areas can also use wind turbines as a way to cut their electric bills.
Small wind systems also have potential as distributed energy resources. Distributed energy resources refer to a variety of small, modular power-generating technologies that can be combined to improve the operation of the electricity delivery system. (cited reproduction)
Wind is such a simple and basic force and the thought that something so simple can be transformed into energy so powerful that entire cities can be powered by it. Just some simple wind can create energy that us modern day human civilizations are craving for. Wind energy is a clear example of how the simplest thing like energy can be transformed or go through an alchemical process to be used as energy.
We have been harnessing the wind's energy for hundreds of years. From old Holland to farms in the United States, windmills have been used for pumping water or grinding grain. Today, the windmill's modern equivalent—a wind turbine—can use the wind's energy to generate electricity.
Wind turbines, like windmills, are mounted on a tower to capture the most energy. At 100 feet (30 meters) or more aboveground, they can take advantage of the faster and less turbulent wind. Turbines catch the wind's energy with their propeller-like blades. Usually, two or three blades are mounted on a shaft to form a rotor.
A blade acts much like an airplane wing. When the wind blows, a pocket of low-pressure air forms on the downwind side of the blade. The low-pressure air pocket then pulls the blade toward it, causing the rotor to turn. This is called lift. The force of the lift is actually much stronger than the wind's force against the front side of the blade, which is called drag. The combination of lift and drag causes the rotor to spin like a propeller, and the turning shaft spins a generator to make electricity.Wind turbines can be used as stand-alone applications, or they can be connected to a utility power grid or even combined with a photovoltaic (solar cell) system. For utility-scale (megawatt-sized) sources of wind energy, a large number of wind turbines are usually built close together to form a wind plant. Several electricity providers today use wind plants to supply power to their customers.
Stand-alone wind turbines are typically used for water pumping or communications. However, homeowners, farmers, and ranchers in windy areas can also use wind turbines as a way to cut their electric bills.
Small wind systems also have potential as distributed energy resources. Distributed energy resources refer to a variety of small, modular power-generating technologies that can be combined to improve the operation of the electricity delivery system. (cited reproduction)
Wind is such a simple and basic force and the thought that something so simple can be transformed into energy so powerful that entire cities can be powered by it. Just some simple wind can create energy that us modern day human civilizations are craving for. Wind energy is a clear example of how the simplest thing like energy can be transformed or go through an alchemical process to be used as energy.
Solar Energy: 32
Plants have been using the energy from the sun for billions of years. Until recently, however, this energy has been available only indirectly to humans via the energy we harvest in the form of everything from fossil fuels to plants to wind power (all solar energy derivatives).Today, as environmental awareness and rising oil prices put pressure on society, the potential of emerging solar energy technologies that directly harness the nearly limitless energy of the sun is increasingly desirable and economically feasible.
Harnessing solar energy involves both the direct use of the radiated heat as well as its conversion to electricity in the most efficient way possible. There are three categories that define every type of solar energy technology.
First, passive solar collection begins with the design of the building and includes optimal location, windows facing south, walls that absorb heat and light, and plenty of insulation. The heat and light that is collected is used in its original form of heat or light such as in a greenhouse. For example, the chapel on the Massachusetts Institute of Technology campus has no windows, but has been designed such that natural light reflects off the surrounding moat and into the room. Passive collection is much easier to include in new construction because retrofitting an existing building can be difficult and costly. Active solar collection implies converting solar energy to a more usable form of heat or electricity.
A second distinction is the type of energy an active solar system creates. Thermal applications include heat collection and heat-driven mechanisms, such as converting water to steam to power a steam engine that generates electricity. Electric processes use photovoltaic cells that create a moving electric charge that produces a direct electric current. PV panels have been used successfully on satellites and have a life expectancy of thirty years, making them an economically viable option for commercial use.
Finally, a third distinction in solar energy concerns the degree of concentration used in harnessing the suns energy. Concentrating systems engage mirrors and lenses to direct the sunlight to the area of collection. In some systems, parabolic trough-shaped structures of photovoltaic cells can even be powered to follow the motion of the sun allow for increased electricity generation. Non-concentrating systems are often simple flat panel collectors that are most commonly found as rooftop PV or as solar pool heaters.
In 2005, the amount of electricity generated by photovoltaic systems increased by 56% and resulted in 1,445 megawatts (MW) of PV being installed in the United States, Germany, Japan, among others. At the average of $8.00 per watt, this is a worldwide $12 billion investment in the solar energy markets in 2005 alone. Due to this market growth and increased capital for research and development, production costs for solar electricity are decreasing by five to seven percent per year.
Japan and Germany support the two largest solar markets due to targeted government subsidies designed to stimulate their growth. Japanese companies produced 47% of the PV cells manufactured globally in 2005, while Germany represented half of the installations. The US, once a leader in this technology represented less than 10% of both production and installations globally in 2005.
Worldwide, solar currently provides less than one percent of electricity demand but is projected to supply 26% of the worlds consumption by 2040. This industrial transition will occur as solar generated electricity becomes cost effective throughout the United States and much of the world.(cited reproduction)
Using the sun's energy is no longer wishful thinking from idealists of environmental sustainability; it is the solution to the world's approaching energy crisis and an economic inevitability. We are rapidly moving toward a dramatic and dominant role for solar energy - a trend that should be encouraged by both policy makers and capital markets because, in the end, it benefits everyone.
The sun and its heat energy has been present longer than this experimental project has been. Solar energy was the first form of energy in the universe. The thought that this simple energy force is now able to be transferred and used in ways which amaze people. Solar energy can be used to power entire cities and it is quite astonishing that such a simple power can be used to do so much.
