We Need More Investment In Medium-Voltage Direct Current

High-voltage direct current (HVDC) is a hot topic right now as we look for the most efficient ways to deliver enough decarbonized energy to meet the world’s fast-growing electrification needs. Yet HVDC is only part of the story. Medium-voltage direct current (MVDC) is the next chapter.

Two things are driving this urgent interest in MVDC: the growth in distributed energy resources and the need to integrate them into the grid, and the high electricity demands needed to power heavy industry, transportation, and data centers.

HVDC is the most efficient way to transfer bulk energy over long distances from the point of generation to the grid. Photovoltaics, which transform the sun’s rays into usable energy, also deliver direct current. Yet once these two energy sources reach the grid, they are transformed to less efficient alternating current (AC).

For industries that use large amounts of electricity avoiding the energy leakage associated with AC can amount to millions of dollars a year. While it’s more efficient to use DC, a direct HVDC connection delivers too much voltage. MVDC can bridge the gap by either stepping down HVDC for industrial use or stepping up AC wind power to DC so it can travel long distances.

MVDC is a breakthrough technology that is designed to enable these industries to make the most out of every electron. It will also help us to truly harness the power of solar energy, our most abundant and reliable renewable energy source, and wind power, which is a growing contributor to the energy mix. MVDC, by regulating voltage, has significant potential to power data centers, green hydrogen* gigaplants, and other electricity-intensive industries such as steel, metals and petrochemicals. It could transform transportation by electrifying rail grids and powering ship power distribution and propulsion. Our customers may realize savings by achieving greater energy efficiency and by eliminating costs for the equipment needed to switch between DC and AC.

To open this next chapter, we need to invest in more MVDC distribution infrastructure and surmount a few key technical challenges.

More distribution infrastructure would allow high-intensity industries to tap into the direct current line via a substation that steps down the voltage to a range that the industrial application can use – but without converting it to AC. These lower power rating tap-off points could enable more access to DC power for remote communities or a city infeed, as well as for industrial applications.

The technology should also allow for DC connections between the photovoltaics, storage and the grid without the loss of energy from the AC conversion, enabling better usage of solar energy.

The technical challenges for MVDC center on the ability to break current. Alternating current is easy to break as it approaches zero voltage, but direct current never dips to zero. GE Vernova is investing time, talent and research dollars into developing MVDC technology and a DC circuit breaker.

GE Vernova delivered Europe’s first MVDC link for Scottish Power Energy Networks Angle-DC project in 2017.

Our business is also working with a major US-based customer to understand the technical and economic benefits of a solar plus storage MVDC installation. We are also working with the GE Vernova Advanced Research Center to demonstrate elements of a solar MVDC system at their facility in Schenectady, NY.

*Green hydrogen is an industry-wide term for a fuel produced by splitting water into hydrogen and oxygen using electrolysis powered by renewable energy sources, a process which produces no carbon dioxide emissions.

This article was written by GE Vernova's Philippe Piron, Chief Executive Officer, Electrification Systems.