Environmentally Friendly Power for New Delhi

2007-Mar-22 | Siemens will soon supply environmentally friendly electricity to the energy-hungry region surrounding India’s capital city of New Delhi. In cooperation with its Indian partner BHEL, Siemens is currently building a high-voltage direct current (HVDC) transmission line that is considerably more efficient than conventional power transmission systems and will therefore reduce emissions of the greenhouse gas carbon dioxide by 688,000 tons per year.

Around 17 million people live in the New Delhi metropolitan area, where energy is a scarce resource and power failures frequently affect entire districts, particularly in summer. The new transmission line is designed to improve the region’s energy supply without requiring the construction of any new power plants in the vicinity. Once the new line goes into operation in November 2009, it will transport 2500 megawatts of power over a distance of about 800 kilometers, from Ballia in eastern Uttar Pradesh to a location near New Delhi. The contract has a total volume of €235 million, of which €170 million have been awarded to Siemens, which, as the consortium leader, has overall responsibility for the project.

HVDC transmission is economic for above-ground lines more than 600 kilometers long, as the transmission losses over such distances are lower than with alternating current. A special feature of the system are its light-triggered thyristors, which are semiconductor modules that transform alternating current into direct current at the beginning and end of the line. The thyristors developed by Siemens use laser flashes that last for ten microseconds and attain peak intensities of 40 milliwatts.

Siemens is the only HVDC supplier that utilizes such laser-controlled converters. Conventional technology uses electrically-triggered thyristors, which require a pulse of several watts. Such powerful electronics are not required with direct light pulse systems, however, which is why the electronic control systems of light-triggered thyristor valves have about 80 percent fewer components. Not only does the technology take up less space as a result, it is also more reliable. Another advantage of HVDC systems is that the flow of energy can be controlled as desired. This enables the facilities to stabilize other connected networks and help prevent disruptions.

According to experts, this transmission technology will grow in importance as energy demand increases worldwide. In the future, HVDC systems could help exploit energy reserves, whose sources (power plants using wind, water or solar energy, for example) are located far from the consumers.