Although it is sometimes mistakenly thought of as a monolith, the United State’s current “electric grid” is more or less an aggregate of two large and several smaller but distinct and, heretofore, separate grids. That may change soon with the planned billion-dollar Tres Amigas LLC project that aims to physically connect at least the two big networks and one of the smaller ones using a system of special ac to dc voltage converters and superconducting connectors.
The U.S. grid’s diffused structure is a remnant of how the nation’s electrical infrastructure was cobbled together during most of the late 19th and 20th Centuries. Physical and technical constraints shaped most of the existing structure of the national grid, and, for the past few decades, it has impeded energy producers and consumers from assisting or buying from a truly national marketplace. These limitations have been exacerbated as it hass dawned on our political and science leaders that many renewable energy generation opportunities (e.g., wind and solar) are going to be centered (or at least optimized) in specific geographical regions that are remote in comparison with where demand is the greatest.
Thus, forging one national grid from the current parts is a priority — and that’s where the Tres Amigas company and its “SuperStation” comes in. The company describes itself as “a merchant transmission entity composed of electric utility industry operational, technology and thought leaders.” The goal is to build a SuperStation hub near Clovis, N.M., one of the closest interfaces among the Eastern, Western and Texas “interconnects.” This will be one of the largest projects in the U.S. that includes high-temperature superconducting cables, and the architects of the project say the Superstation will be able to transfer thousands of megawatts of power (scalable to 30 GW) among the three asynchronous U.S. grids.
The plans of Tres Amigas aren’t totally altruistic. The investors realize that without connecting the three parts, it will be extremely difficult to create a market hub for renewable power.
Materials aficionados are probably most interested in the three technologies Tres Amigas intends to leverage. The first are voltage source converters, whose role is to process the ac power flowing grid feed lines feeding into dc power that can be routed through the SuperStation. Likewise, the VSCs transition the dc power back to ac power to flow out elsewhere in the grid.
The second is Xtreme Power’s Dynamic Power Resources energy storage systems. Similar units are also being integrated into Hawaii’s Kaheawa Wind Power II project on Maui, and in several solar energy projects, such as the SolarTAC faciity in Colorado. Xtreme Power describes the building blocks of the DPRs as:
“[A] dry-cell battery technology with a very innovative design. Metal-alloy-coated, ballistic-grade fibers are woven together to offer structural integrity, as well as multiple pathways for ultra-low impedance current to flow both in and out of the battery. Proprietary formulas of fundamental alloys, such as copper, lead and tellurium, are used to form bipolar plates that provide a massive surface area at the nano-scale for the chemical reaction to take place, resulting in an extremely low internal resistance.”
The third are the superconducting wires and cable system that compose much of the hub. The cables are at least partially manufactured by American Superconductor. AMSC announced in November 2010 that it had selected Korea’s LS Cable Ltd. and France’s Nexans as subcontractors for the Tres Amigas SuperStation. LS Cable and Nexans will both manufacture superconductor power cables utilizing AMSC’s Amperium second-generation superconducting high-temperature wire.
The cables and many other Tres Amigas components will be located underground. Tres Amigas says it has procured 22 square miles for the SuperStation, and the general design is to have three voltage conversion facilities located about 2 kilometers apart from each other.
The timeline for the Tres Amigas project seems a little unclear at this point. Company officials are not providing a completion date, but there seems to be general agreement that the construction will take about five years.