by John Fialka: High-voltage, direct-current lines could become the backbone of a U.S. supergrid…

 

A deal that would create the largest clean-energy transmission project in the United States was announced yesterday, a $2.5 billion effort to build a high-voltage, direct-current (HVDC) power line that would take wind energy produced in Oklahoma’s windy Panhandle region to the Memphis, Tenn., area.

From there it would be distributed by the Tennessee Valley Authority to other major power distribution systems in the South and Southeast.

The project will be the nation’s first to take relatively cheap wind-generated electricity from a region where wind is abundant and carry it for 720 miles into a region where wind power is relatively scarce, explained Michael Skelly, president of Clean Line Energy Partners, a Houston-based company that has four other HVDC projects in the works.

This one, called the Plains & Eastern Clean Line, will be built with private funds and has already received permits for its route from the Department of Energy and regulators in the three states it will pass through.

“We have 50 rights-of-way agents in the field right now” to buy land needed for the project, Skelly said.

HVDC technology involves transmission systems built to convert alternating current to direct current. The lines can carry more electricity over longer distances, and then the power is converted back to AC. Technology for the Oklahoma to Tennessee line will be provided by GE Energy Connections, where Russell Stokes, president and CEO of the GE subsidiary, called the project “transformational.”

When the line is fully operating, sometime in 2020, it would carry electricity that would cut power plant emissions by 13 million tons of carbon dioxide and reduce the need for 3.4 billion gallons of water that would ordinarily be used to cool nuclear and fossil fuel-fired power plants in the South and Southeast. These units would no longer produce as much of the region’s power load.

The imported wind power, coming from a DC conversion point in Guymon, Okla., will be enough to serve 1 million homes. It is 4,000 megawatts, the equivalent of the output of four large nuclear power plants.

Some U.S. power experts predict that long HVDC lines could become the backbone of a new “supergrid” in the United States that would carry wind- and solar-generated power from places where it is plentiful to places where it would not be cost-effective to produce.

NEXT STOP FOR OKLA. WIND: THE SOUTH?

The Plains & Eastern project is one of several HVDC wind projects under preparation in the United States.

Clean Line, which was formed by veterans of U.S. wind companies, is also proposing a slightly longer project called the Grain Belt Express Clean Line. It is a 780-mile line that would bring wind power from near Dodge City in western Kansas across northern Missouri and Illinois to a point in eastern Illinois, where its power would be converted to AC and flow into the PJM Interconnection, a wholesale electricity market that would feed the power as far as the East Coast (ClimateWire, Sept. 7).

HVDC transmission was pioneered in Europe, where a subsidiary of one of the companies involved, Alstom, a French multinational firm, was bought last year by GE, which will build the big conversion stations needed to transform the power from AC to DC and back to AC. Two earlier HVDC lines have been built in the United States, one in California to bring coal-fired electricity from Utah and one constructed in the 1970s to bring hydroelectric power from the state of Washington to the Los Angeles area.

The technology is also being used extensively by China to feed clean energy from its north and west to population centers along its coastline.

Skelly said that other major electric power generators in the South are also interested in importing the Clean Line wind power into their regions via the connection through TVA’s extensive distribution system. They include Southern Co. and Entergy. The power would come from new wind turbine farms ready to be developed in Oklahoma, but some may also come from wind farms in Texas and western Kansas, he noted. A midway distribution point to be built in Pope County, Ark., would also make some of the line’s power available there.

“We are excited to see GE, the world’s premier digital industrial company, working with Clean Line Energy on a transmission line that will harness and export Oklahoma’s great wind resource,” commented Oklahoma’s Republican governor, Mary Fallin. Construction of the line is expected to begin in the second half of 2017.

Source: Scientific America