In the case of a “wind turbine generator”, the wind pushes directly against the blades of the turbine, which converts the linear motion of the wind into the rotary motion necessary to spin the generators rotor and the harder the wind pushes, the more electrical energy can be generated. Then it is important to have a good wind turbine blade design to extract as much energy out of the wind as possible.
Marine energy (also sometimes referred to as ocean energy) refers to the energy carried by ocean waves, tides, salinity, and ocean temperature differences. The movement of water in the world's oceans creates a vast store of kinetic energy, or energy in motion. This energy can be harnessed to generate electricity to power homes, transport and industries. The term marine energy encompasses both wave power – power from surface waves, and tidal power – obtained from the kinetic energy of large bodies of moving water. Reverse electrodialysis (RED) is a technology for generating electricity by mixing fresh river water and salty sea water in large power cells designed for this purpose; as of 2016 it is being tested at a small scale (50 kW). Offshore wind power is not a form of marine energy, as wind power is derived from the wind, even if the wind turbines are placed over water. The oceans have a tremendous amount of energy and are close to many if not most concentrated populations. Ocean energy has the potential of providing a substantial amount of new renewable energy around the world.[165]
The New Zealand Parliamentary Commissioner for the Environment found that the solar PV would have little impact on the country's greenhouse gas emissions. The country already generates 80 percent of its electricity from renewable resources (primarily hydroelectricity and geothermal) and national electricity usage peaks on winter evenings whereas solar generation peaks on summer afternoons, meaning a large uptake of solar PV would end up displacing other renewable generators before fossil-fueled power plants.[127]
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 largest machines were on 24-meter (79 ft) towers with four-bladed 23-meter (75 ft) diameter rotors. By 1908 there were 72 wind-driven electric generators operating in the United States from 5 kW to 25 kW. Around the time of World War I, American windmill makers were producing 100,000 farm windmills each year, mostly for water-pumping.[9]
Wind power - Air flow on the earth's surface can be used to push turbines, with stronger winds producing more energy. High-altitude sites and areas just offshore tend to provide the best conditions for capturing the strongest winds. According to a 2009 study, a network of land-based, 2.5-megawatt wind turbines in rural areas operating at just 20% of their rated capacity could supply 40 times the current worldwide consumption of energy.
Above this rated speed, the wind loads on the rotor blades will be approaching the maximum strength of the electrical machine, and the generator will be producing its maximum or rated power output as the rated wind speed window will have been reached. If the wind speed continues to increase, the wind turbine generator would stop at its cut-out point to prevent mechanical and electrical damage, resulting in zero electrical generation. The application of a brake to stop the generator for damaging itself can be either a mechanical governor or electrical speed sensor.
In a twist that has some Republicans in this oil- and gas-rich state whistling Dixie, Ross is now friends with Al Gore, who featured Ross in An Inconvenient Sequel, the 2017 follow-up to An Inconvenient Truth, his Oscar-winning documentary about global warming. “We bonded right away,” Ross recalls. “I said, ‘Mr. Vice President, we’ve got a lot in common. You invented the internet. I invented green energy.’” Trained as an accountant, Ross still works as one—being mayor of Georgetown is a part-time job—and there’s no mistaking his zeal for the other kind of green. When conservatives complain about his energy politics, he is quick to remind them that the city has the lowest effective tax rate in Central Texas.
A report by the United States Geological Survey estimated the projected materials requirement in order to fulfill the US commitment to supplying 20% of its electricity from wind power by 2030. They did not address requirements for small turbines or offshore turbines since those were not widely deployed in 2008, when the study was created. They found that there are increases in common materials such as cast iron, steel and concrete that represent 2–3% of the material consumption in 2008. Between 110,000 and 115,000 metric tons of fiber glass would be required annually, equivalent to 14% of consumption in 2008. They did not see a high increase in demand for rare metals compared to available supply, however rare metals that are also being used for other technologies such as batteries which are increasing its global demand need to be taken into account. Land, whbich might not be considered a material, is an important resource in deploying wind technologies. Reaching the 2030 goal would require 50,000 square kilometers of onshore land area and 11,000 square kilometers of offshore. This is not considered a problem in the US due to its vast area and the ability to use land for farming and grazing. A greater limitation for the technology would be the variability and transmission infrastructure to areas of higher demand.[54]
Besides getting a working product, the one measure you are after as a small wind turbine owner is how much electrical energy it will produce for your location. Hopefully by now you know the annual average wind speed for the height that you are planning to put your turbine at, and you have selected a site with little turbulence. Forget about the manufacturer’s claims; it turns out that the best predictors for turbine energy production are the diameter and average wind speed. Here is an equation that will calculate approximate annual average energy production for a grid-tie horizontal axis turbine of reasonable efficiency:
A solar cell, or photovoltaic cell (PV), is a device that converts light into electric current using the photovoltaic effect. The first solar cell was constructed by Charles Fritts in the 1880s.[5] The German industrialist Ernst Werner von Siemens was among those who recognized the importance of this discovery.[6] In 1931, the German engineer Bruno Lange developed a photo cell using silver selenide in place of copper oxide,[7] although the prototype selenium cells converted less than 1% of incident light into electricity. Following the work of Russell Ohl in the 1940s, researchers Gerald Pearson, Calvin Fuller and Daryl Chapin created the silicon solar cell in 1954.[8] These early solar cells cost 286 USD/watt and reached efficiencies of 4.5–6%.[9]
×