From Edison’s Trunk, Direct Current Gets Another Look
source: http://www.nytimes.com/2011/11/18/business/energy-environment/direct-current-technology-gets...
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Thomas Edison’s direct current technology is gaining popularity as engineers are finding that it can carry electricity over long distances with less loss of power than alternating current.
The revival of DC for long-distance power transmission began in 1954 when the Swedish company ASEA, a predecessor of ABB, the Swiss maker of power and automation equipment, linked the island of Gotland to mainland Sweden with high-voltage DC lines.
Now, more than 145 projects using high-voltage DC, known as HVDC, are under way worldwide.
While HVDC equipment remains expensive, it becomes economical for high-voltage, high-capacity runs over long distances, said Anders Sjoelin, president of power systems for North America at ABB.
Over a distance of a thousand miles, an HVDC line carrying thousands of megawatts might lose 6 to 8 percent of its power, ABB said. A similar AC line might lose 12 to 25 percent.
Direct-current transmission is also better suited to handle the electricity produced by solar and wind farms, which starts out as direct current.
In most situations, solar or wind energy has to be converted, and sometimes reconverted, into AC before it can be used. With HVDC, conversions can be reduced. DC grids can also more easily manage the variable output that occurs, say, when a storm hits or the wind dies.
http://www.siemens.com/about/pool/business/energy/e_hvdc_458px.jpg
The revival of DC for long-distance power transmission began in 1954 when the Swedish company ASEA, a predecessor of ABB, the Swiss maker of power and automation equipment, linked the island of Gotland to mainland Sweden with high-voltage DC lines.
Now, more than 145 projects using high-voltage DC, known as HVDC, are under way worldwide.
While HVDC equipment remains expensive, it becomes economical for high-voltage, high-capacity runs over long distances, said Anders Sjoelin, president of power systems for North America at ABB.
Over a distance of a thousand miles, an HVDC line carrying thousands of megawatts might lose 6 to 8 percent of its power, ABB said. A similar AC line might lose 12 to 25 percent.
Direct-current transmission is also better suited to handle the electricity produced by solar and wind farms, which starts out as direct current.
In most situations, solar or wind energy has to be converted, and sometimes reconverted, into AC before it can be used. With HVDC, conversions can be reduced. DC grids can also more easily manage the variable output that occurs, say, when a storm hits or the wind dies.
http://www.siemens.com/about/pool/business/energy/e_hvdc_458px.jpg
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Dagum
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wow. Looks impressive.
- 1 year ago
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Dagum
