The battle to resurrect DC power transmission scored a point this week as Swiss firm ABB announced that it had developed a new circuit breaker that would enable the transmission of DC current over long distances. DC lines are more efficient than AC lines over long distances, and electricity produced from renewable power generation like solar and wind power is produced as direct current.
The problem with DC current has always been that stopping its flow—breaking the circuit—is very difficult. And without a circuit breaker, for emergencies and to control electricity flow, long haul DC transmission of electrons isn’t possible.
ABB has installed a 2,000 km line in China and has an even bigger line is in development in Brazil. Clearly the company is betting that DC transmission will be a key part of locating renewable power generation in geographic locations where it is most easily produced. This opens up the possibility of electricity transportation, which, aside from storing energy, is perhaps the second holy grail of energy development.