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An employee looks through a Zeiss Ni2 Automatic Level optic, manfactured by Carl Zeiss Meditec AG, to measure the stator frame of a hydropower generator in the workshop at the Voith GmbH factory, in Heidenheim, Germany, on Thursday, Aug. 14, 2014. Voith, a German engineering company, is targeting Angola's next major hydro-electric power project as it seeks to increase growth in Africa.MARTIN LEISSL

It's easy to feel optimistic about the future of global energy these days. New technology is tapping vast amounts of North American oil and natural gas, and solar and wind power is gaining traction. Energy transmission is driving its share of optimism as well, although it's encumbered by a name that's far from catchy: high-voltage direct current, or HVDC. While it doesn't exactly roll off the tongue, HVDC does promise to open up remote sources of renewable energy in China, Brazil, India, Canada and even the Sahara Desert.

The battle over direct current/alternating current–or AC/DC–dates back to the 19th century and Thomas Edison and Nikola Tesla. Edison championed direct current, but it was Tesla's cheaper technology that won the day. This despite the fact that A/C leads to high transmission losses, especially problematic when you're conveying power over long distances. "Direct current solves a number of the hot topics in the world today," says Anders Hultberg, senior vice-president at ABB, the Zurich-based power and automation technologies company that has constructed Canadian HVDC systems in Quebec, Manitoba and British Columbia.

Among the hot topics: connecting remote wind parks, solar farms and hydroelectric stations, and providing a more efficient way to send energy between provinces or export it abroad. The Desertec Foundation, a global sustainability initiative, is even hoping to use the technology one day to power the world by sending solar energy along lines from sun-baked North Africa.

The HVDC systems being built today aren't quite on that scale, but they're ambitious. The 7,100-megawatt Rio Madeira system will deliver hydroelectric power generated in Brazil's Amazon Basin to the economic hub of São Paulo, 2,375 kilometres away, boosting the country's generating capacity by about 6 per cent. An 8,000-megawatt system being built in India will transmit electricity generated near the mountainous Nepal border 1,700 kilometres to Agra, serving the energy needs of an estimated 90 million people.

In Canada, some of the existing HVDC systems allow Quebec to send its excess hydroelectric power to where it's needed, in Ontario, New York state and Boston– making renewables a bigger part of North America's energy output.