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Smart Grid Technologies: First-Ever Linkage of America’s Three Big Grids
By SGN Staff
Oct 13, 2009 - 1:48:11 PM

America's three power grids will be united for the first time, a giant step forward for Smart Grid technology and renewable energy transmission.

New Mexico Governor Bill Richardson announced the Tres Amigas project, which will be built on 22.5 square miles of land in Clovis, NM. It will be the country's first renewable energy market hub and will utilize underground Superconductor Electricity Pipelines from American Superconductor (AMSC).

The concept was originally developed by Phil Harris, Tres Amigas CEO. The superstation will allow wind, solar, hydro and geothermal energy sources that have no access to transmission lines and/or customers to take advantage of multiple markets through the superstation.

"To truly open up the market for electricity generated from renewable sources of energy, we must enhance transmission in the United States. Tres Amigas will serve as a renewable energy market hub by connecting all three of America's power grids to enable the transfer of green power from region to region," Harris said. He added that the superstation also will augment the reliability and security of the country's power supplies.

The project will comprise a triangular electricity pathway of Superconductor Electricity Pipelines capable of balancing and transferring several GWs of renewable energy between the three U.S. electric grids, commonly referred to as "interconnections." The three are known as the Eastern Interconnection, the Western Interconnection and the Texas Interconnection (also referred to as the Eastern Reliability Council of Texas, or ERCOT).

Now, power transmission between grids is performed primarily by utilizing alternating current (AC) electricity transmission lines. But, power transfer between any two of the grids can only be done through special power electronic conversion stations. The process is typically achieved by converting AC power in one grid to direct current (DC) as an intermediate form of power at a substation, and reconverted back to AC before it reaches the adjacent grid, all of which synchronizes the flows of power. There are small bilateral "DC links" in existence between two grids today, but all three have never been interconnected by one system.

Tres Amigas is asking FERC for a declaratory order that the transmission lines that connect to Tres Amigas from ERCOT will not come under the agency's jurisdiction and that Tres Amigas can operate as a merchant transmission entity.

Following approval, AMSC is expected to provide transmission planning, superconductor wire and cable systems for the project.

The Superconductor Electricity Pipelines appear to resolve the most stubborn challenges inherent in transmission and delivery of electricity from renewable energy sources such as wind, solar and geothermal. The pipelines bring together conventional pipeline construction with innovative high-capacity superconductor cables and multi-terminal DC-AC power electronic converters ready to transmit power from those renewables through high-capacity transmission lines. The underground pipelines also resolve numerous siting problems. They can carry all those GWs within a narrow 25-foot wide corridor (as opposed to several hundred feet required for overhead lines) and can be routed in existing railroad and highway rights of way.

Also, the underground pipelines enhance transmission security because they are unaffected by ice storms, hurricanes, tornadoes and other frequently unpredictable forces of nature that play havoc with lines suspended more than 100 feet off the ground. Another benefit is that transmission loss is reduced by two to three times over that of a conventional system.

The system also simplifies cost allocation and is considered cost effective. Because it is a merchant transmission system, Tres Amigas will charge a fee for use of the hub.

Quick Take: Other countries, particularly China and increasingly those in Europe, are getting ahead of the U.S. with regard to high-voltage interconnections. It’s good to see progress at home.