The three-year project, says the company, will involve the development and demonstration of a super-fast DC circuit breaker that is essential for enabling next-generation medium-voltage direct current (MVDC) grids. The project is part of a broader interest by ARPA-E to upgrade existing alternating current (AC) distribution grids and expand opportunities for congested areas to access remote clean energy sources to meet their future power needs.
“Many big urban cities today are facing higher electricity demands because of growing applications such as electric vehicle charging, with limited options for tapping into new energy sources,” says Timothy Sommerer, Principal Scientist at GE Research and Principal Investigator on the MVDC program. “By upgrading existing AC distributions grids to MVDC grids, it would allow these cities to cast a much wider net in securing new clean renewable energy sources.”
The new DC circuit breaker, says the company, is essential for enabling the upgrade of the distribution grid from AC to MVDC. Because DC doesn’t inherently contain natural breaks like AC that help manage faults, a switch with an extremely fast response time is needed that can create these breaks.
GE Research will leverage its gas discharge tube technology (pictured above) to develop the MVDC circuit breaker. Gas discharge tubes switch without mechanical motion by transitioning the internal gas between its ordinary insulating state and a highly conductive gas plasma, allowing for the much faster response times required to handle DC currents.
The envisioned MVDC distribution lines will support up to 100,000 volts and more than 100 megawatts of power to meet the needs of large cities. With the land area required to power a city by renewable sources like wind, solar, and hydro being three to ten times larger than the city itself, it is usually located some distance from the city. At the same time, electric urban power demand is increasing as vehicles and other fuel-burning power users go electric.
In general, says the company, the increasing use of DC instead of AC in electricity transmission has the potential to greatly expand where utilities can draw power from to meet their energy needs in two important ways: First, electric power can move more efficiently over long distances on high-voltage DC lines versus AC lines; and second, an MVDC distribution grid can then take that HVDC power and distribute it more efficiently and effectively into a large urban area.
“The development of DC grid technologies could vastly increase the flexibility utilities have in addressing future power needs,” says Sommerer. “Imagine the day when cities like New York, Chicago, or Los Angeles have the option of accessing electricity from multiple wind installations in the Midwest to meet electric vehicle charging needs.”
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