City lights: New York City has to meet the ever-growing demand for energy without forsaking the environment.

YOU know what they say about New York – the city never sleeps. To keep the pulse of the city racing 24/7 calls for adequate and uninterrupted energy supply.

Later this month, the power needs of the megacity will be further met via the Hudson Transmission Project.

The additional electricity of 660 megawatt will be generated in New Jersey and then transmitted to Manhattan via a high-voltage overland and undersea cable. Conveying electricity through long distances mean losses in power but this will be curtailed in the Hudson project through the use of high-voltage direct current (HVDC) transmission.

The technological core of the project is a converter station located in Ridgefield, New Jersey. Using Siemens technology and equipment, the converter station will change alternating current (AC) power from a substation to direct current (DC) and then back to AC within the same site (called “back-to-back conversion”). The AC-DC-AC conversion means that power can be controlled precisely and reliably while cutting down losses, explains Hudson project manager Wilhelm Kropf.

Construction started in 2011 and the system is now doing trial runs, in time to start operating later this month.

Kropf says generating the power in New Jersey for transmission to New York will be cheaper than siting a power plant in the city. “There will be transmission losses but this is now minimised with the back-to-back conversion. HVDC transmission has typically 30% to 50% less transmission loss than alternating current overhead lines.”

He says Siemens HVDC technology will contribute toward stabilisation of the systems, thus reducing grid disturbance, power supply bottlenecks and blackouts. The project also includes significant upgrades and reinforcements to the transmission system in New Jersey, which will reduce transmission constraints and improve power flow there, especially during critical peak demand periods. The ultimate result of these upgrades will be increased reliability – a reinforced transmission system that is better able to withstand periods of peak demand and system disturbances.

Tim Dawidowsky, chief executive officer at business unit transmission solutions at Siemens Energy Sector, says HVDC transmission is ideal for offshore projects located far out at sea or when a power plant is not wanted or would not be profitable or when there is no suitable space.

The demand for this technology is increasing rapidly. In the last 40 years, HVDC transmission links with a total capacity of 100 gigawatts (equivalent to the capacity of 100 large power plants) were installed, while another 250 gigawatts will be added in this decade alone.

With a market share of more than one-third, Siemens is one of the two biggest suppliers in the HVDC transmission sector. It has completed about 40 HVDC transmission projects worldwide, one-quarter of which are in China.

In 2007, Siemens completed a HVDC link which provides a power link between New Jersey and Long Island.

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