United States

United States

Transmission there but access blocked

While construction of major new power lines cannot be put off for ever, better management of existing transmission capacity and some modest line improvements would free the way for thousands of megawatts of wind development across the United States

From Texas to Tehachapi, wind-rich areas in the US are increasingly finding their plentiful resources potentially stranded by regulatory and physical transmission constraints. But steady work by industry groups is beginning to show some progress in creating a transmission system that is conducive to wind energy growth.

"Our goals for the transmission planners are to make better use of the transmission that's already there with improvements like curtailable firm [tariffs]," says Mike Jacobs of the American Wind Energy Association (AWEA), referring to flexible contracts, including the option for curtailment of power output. "Step two is modest investments to upgrade the known bottlenecks. Then we can talk about the grand transmission plans like building lines from the Dakotas to Chicago or Wyoming to the West Coast."

Toward step one, AWEA has been working in the Northwest to develop "conditional firm" transmission tariffs as the Bonneville Power Administration (BPA) gears up for another rate case, when such a tariff change could be approved by the US transmission system's governing body, the Federal Energy Regulatory Commission (FERC).


Currently, BPA's transmission tariff requires generators to reserve capacity in advance. The problem with that arrangement is that while transmission capacity may be fully subscribed, generators may not be using all their reserved capacity. So capacity is physically available, but inaccessible to unsubscribed generators because it has been reserved. One recent study of a fully reserved line found unused capacity about 80% of the time.

Wind generators face the added challenge of having to reserve transmission for their nameplate capacity even though the project is likely to only produce a third of that, assuming they can get it at all. Most firm transmission capacity in the West is already locked up in long term power contracts.

"Conditional firm" agreements would in essence allow a transmission customer to reserve in advance, but the reservation is conditional upon capacity being available. In the rare instances where a system is at physical capacity, the system operator may have to curtail a generator, but generators would have some idea of how often that curtailment would take place.

Elsewhere, modest improvements in the physical system would provide welcome relief. At the Tehachapi wind resource area, about 35 miles east of Bakersfield, California, and home of one of the largest concentrations of wind turbines in the world, transmission lines are at full capacity, according to Charles Adamson of Southern California Edison (SCE), which operates the grid in the region.

The area has an estimated 4000-4500 MW of additional wind generation potential, but the question of how to fund new transmission lines to move the power is at issue. SCE applied to FERC for approval to collect money for part of the line from ratepayers. FERC disallowed the request, forcing SCE to go back to the drawing board to reconfigure the line to fit with FERC requirements that it provide a network benefit, or back to the California Public Utility Commission for a funding mechanism.

A network benefit would benefit multiple transmission customers and so the cost is borne by that group. If the line does not provide a transmission benefit, and is instead a "tie-in" line between the generator and the transmission grid, the generator pays for construction.

With so much wind energy trapped at Tehachapi, the project "is hugely important," says Nancy Rader of the California Wind Energy Association. Rader's group has been advocating for SCE to designate the new line as a network benefit, which now seems to be in the offing. The utility has reconfigured the design slightly so that it provides the critical benefit to the transmission network. That should allow it to collect from transmission customers to pay for the line.

Needs investors

Progress is also being made in the western Rocky Mountains, where the Wyoming Infrastructure Authority recently announced that it is partnering with the private Trans-Elect Inc to develop the so-called TOT 3 transmission line between Wyoming and Colorado. Specific construction plans and benefits have not been determined, pending investor interest. "This is all being driven by the supply interests," says Jacobs. "The project needs willing buyers."

The decision to focus on the TOT 3 line was based on work by the Rocky Mountain Area Transmission Study, a group of regional stakeholders charged with finding ways to break transmission bottlenecks in the region. The study identified 12,000 MW of wind that could be tapped by 2013 in Wyoming, Montana, Colorado, Utah and Idaho.

In the East, regulatory improvements made in the late 1990s demonstrate how such changes can create benefits. Transmission in the east mostly uses a "standard market design" that gives priority to the lowest cost generators for each hour. Any problems, according to AWEA's Mike Jacobs, are comparatively minor. In New York State, if multiple wind farms get built in the same area, they may end up competing against each other for limited physical transmission as happened in Minnesota's Buffalo Ridge area. Because of the experience at Buffalo Ridge, developers in New York have begun to spread projects around the state. New York estimates it can easily accommodate 5000 MW of wind on the existing transmission system. "By adopting standard market design," says Jacobs, "New York has made better use of its transmission system and that's why most of these problems don't exist in New York."

Texas transmission zones

In Texas, the wind-rich western region of the state has seen nearly 2000 MW of new wind built since a government mandate for renewable energy was adopted in 1999. That has put the region's transmission grid nearly at capacity. So when legislators increased the renewables mandate in the summer -- starting at 2280 MW by 2007 and increasing to 10,000 MW by 2025 -- they added a requirement to figure out how to overcome the transmission bottlenecks.

"Constraint was a big topic of discussion -- how to incorporate [new levels of renewables] given that transmission is not sufficient to fully integrate 5000 plus megawatt of wind generation," says Bill Bojorquez, director of transmission for the Electric Reliability Council of Texas, which administers the Texas power grid covering about 85% of the state's electricity load.

The legislation setting the new mandate also requires the Public Utility Commission of Texas (PUCT) to investigate and report on "competitive renewable energy zones" -- wind-rich areas where transmission capacity will be added first. That gives developers assurance that if they build within the zone, transmission will be available to move generation to where the demand is heavy in East Texas.

First report

The PUCT report must include the estimated cost of transmission service improvements needed for each competitive renewable energy zone and an evaluation of the effects that additional renewable generation has on system reliability and on the cost of alternatives to mitigate the effects. The first report is due in December 2006.

While much of the discussion focuses on West Texas, Bojorquez says transmission capacity is currently available for 300-900 MW of wind or other energy along the Texas Gulf Coast. "And there are more customers near those areas," he adds, "So you don't need as much transmission."

With US wind poised for another record year, Jacobs says work with all types of power generators on finding space on the wires grows increasingly important. "What we'd like to see the power industry do is make better use of its [existing] transmission assets," says Jacobs. "They're so hard to build, they're so highly demanded and there are so many institutional changes like modernising control areas, making use of off-use capacity" that would provide benefits without the enormous cost of construction. "Those are not new topics," he says, "But the inertia is what we've been trying to point to and ask why are we all stuck here."

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