United States: Mixed views on superhub plan - Tall order to unite power grids

A new US company has a grand vision to unite North America's three major electricity grids in an effort to ease the transfer of renewable energy between distant markets. The idea is drawing interest for its creativity, but critics say it ignores political and market realities.

Tres Amigas plans to unite North America's three electricity grids

The company, called Tres Amigas, was founded this summer by Phil Harris, former chief executive of transmission system operator PJM Interconnection. PJM manages the world's largest electricity grid and wholesale market, with over 240 GW of power across 14 states in the eastern US.

Currently, there is only minimal trading of power between the three grids that cover nearly all of the US and most of populated Canada. No system links all three. Tres Amigas is looking to create that three-way link, stating that each link would have a capacity of 5 GW. While not all of this electricity is guaranteed to be from renewables, the company expects that the connections will encourage development of power from wind and other clean energy sources.

Key to this strategy are three existing substations, facilities that reduce the voltage of electricity transmitted between distant points. The three are located within a 58-square-kilometre area in eastern New Mexico, near the town of Clovis. An agreement signed in September gives Tres Amigas two years to evaluate the suitability of the area as part of project planning, according to the New Mexico State Land Office.

Surveys and studies

The Land Office confirmed that Tres Amigas paid $30,803 for the two year agreement. During that period, it will conduct environmental analyses, geology, soil and archaeological surveys, and study the impact on wildlife habitat. It will also pursue PPAs and sales agreements and interconnect agreements with various electric utilities in several states.

The three grids involved are: the Western Interconnection, representing US states between the Pacific Coast and the Great Plains, as well as two Canadian provinces; the Eastern Interconnection, comprising a swath of land from Central Canada and the Rocky Mountains eastward to the Atlantic coast; and the Electric Reliability Council of Texas (Ercot), which covers most of Texas (see map, right).

Tres Amigas' technology partner is Massachusetts-based American Superconductor (AMSC), which owns several power generation technologies, including designs for wind turbines. Tres Amigas will use its superconductor technology to enable high-temperature, high-voltage transmission between the substations. Three direct-current (DC) cables roughly 45 centimetres in diameter would be buried underground and encased in liquid nitrogen for cooling, to connect the three points. Tres Amigas says it would install three high-voltage DC converters to connect the three alternating current (AC) power grids. Tres Amigas has not presented a timetable for construction or other benchmarks.

A commercial first

Due to their complexity and high cost, superconductors have never been put to commercial use. The technology envisioned by Tres Amigas and AMSC, though, is promising, says Craig Cox, executive director of the Interwest Renewable Energy Council, a regional trade organisation that partners with the American Wind Energy Association.

The main question, according to Cox, is whether the three markets can create mechanisms that will allow fluid, contract-based power sales between them. "You need liquid markets if you're going to start wheeling power from three different grids to one another, and you need proper market signals," Cox says.

Parochial danger

A particularly big challenge will be to integrate the Texas Ercot grid, which effectively operates independently from the rest of the US. Its regulators are reluctant to strike power-sharing agreements with neighbouring states. "Whether Ercot wants to play ball with the other grids could be a real question," Cox says. "It's going to be a test of the willingness of states and regions to compete across regions and the country. There's great potential. I just hope it doesn't get sidetracked by parochialism."

One transmission expert, who prefers to remain unnamed, believes that the necessary trading hubs for flexible sales of electricity in the Western Interconnection region currently do not exist. He says that a western state such as New Mexico would be unlikely to welcome intrusion into its marketplace by states outside its region, such as Kansas and Texas.

Another transmission expert, who also requests anonymity, questions how energy from distant points can efficiently cross the three substations, given the lack of transmission capacity at the edge of each grid. "It's like putting Atlantis in the middle of the Atlantic Ocean and saying it will be the commercial hub that brings all the Atlantic continents together - you still need a boat to get there," he says. "I should think there would be better places to apply the technology, like along existing, well built-up yet congested hubs."