Giving the grid some backbone
By Scientific American
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The U.S. has vast quantities of renewable electricity sources waiting to be tapped in these regions, but what it does not have there are power lines — big power lines that can carry the bountiful energy to distant cities and industries where it is needed.
The same is true beyond the windswept high plains and the sun-baked Mojave Desert: renewable supply and electricity demand are seldom in the same place, and too often the transmission lines needed to connect them are missing. The disparity exists even in New England, where hundreds of miles of high-tension wires supported by thousands of steel towers run neatly through dense areas of settlement.
When Gordon Van Wiele, chief executive of ISO New England — in charge of transmission in the six-state region — unfurls a map of the land there, large ovals show the location of the best wind sites: Vermont near the Quebec border and eastern Maine spilling over into New Brunswick. But sure enough, no transmission lines transect them.
The U.S. has the natural resources, the technology and the capital to make a massive shift to renewable energy, a step that would lower emissions of greenhouse gases and smog-forming pollutants from coal-fired power plants while also freeing up natural gas for better uses. Missing is a high-voltage transmission backbone to make that future a reality.
In some places, wind power, still in its infancy, is already running up against the gridÂ’s limits.
“Most of the potential for renewable resources tends to be in places where we don’t have robust existing transmission infrastructure,” Van Wiele says. Instead, for decades electric companies have built coal, nuclear, natural gas and oil-fired generators close to customers.
That strategy worked reasonably well until recently, when 28 state governments set “renewable portfolio standards” requiring their utilities to supply a certain portion of their electricity using renewables, such as 20 percent by 2020 or even sooner.
But as Kurt E. Yeager, former president of the Electric Power Research Institute in Palo Alto, Calif., points out, such standards “aren’t worth the paper they’re written on until we have a power system, a grid, that is capable of assimilating that intermittent energy without having to build large quantities of backup power, fossil-fueled, to enable it.”
In Colorado the utility that serves most of the state, Xcel Energy, is now building a megawatt of natural gas capacity for every megawatt of wind so that it is ready to come online quickly to provide power when the wind tails off. That plan is a carbon improvement but not really a carbon solution.
The U.S. needs a new transmission backbone that crisscrosses the country, knitting together many large wind farms, solar-energy fields, geothermal pools, hydroelectric generators and other alternative sources.
One utility company has already unveiled a grand plan for the U.S., and other experts are charting their own backbone schemes. But whichever one might prevail will require a lot of money and a lot of coordination across what are now independent areas of technological and political control.
Even before the emphasis on climate change, reasons were mounting to remake the grid. Chief among them are bottlenecks that stifle the flow of power.
North America is actually covered by four regional grids (three of which serve the U.S.). The largest is the Eastern Interconnection, an extensive complex of transmission lines that stretches from Halifax to New Orleans, with substations that step down the high-voltage electricity to lower levels so that it can be distributed locally along smaller wires.
West of the Rockies is the Western Interconnection, from British Columbia to San Diego and a small slice of Mexico. Texas, in an echo of its history as an independent republic, comprises its own grid, now called the Electric Reliability Council of Texas. And Quebec, with its separatist undercurrent, also has its own grid.
The high-voltage transmission systems in the four regions comprise about 200,000 miles of power lines, divided among a staggering 500 owners, that carry current from more than 10,000 power plants run by about 6,000 investor-owned utilities, public power systems and co-ops.
The four interconnections are linked by short, high-voltage lines, but they do not provide nearly enough capacity to move sufficient power back and forth, much less to handle the additional burden of thousands of renewable sources with output that is intermittent and sometimes hard to predict. Transmission lines within the interconnections are similarly inadequate, strained by the ever-increasing demand for electricity. As a result, the entire grid is more prone to blackouts.
“The transmission system is being used closer to its limits more of the time than at any time in the past,” says Rick Sergel, president of the North American Electric Reliability Corporation, which sets operating standards for the system in the U.S. and parts of Canada. Restructuring of the electric industry has also created many more dispersed buyers and sellers, but the conduit to connect them has barely changed.
Transmission is not faring well even within the footprint of a single large utility. Take American Electric Power (AEP), which serves a broad swath of the nationÂ’s midsection.
Throughout the 1980s a key high-voltage link near the center of its system operated like an occluded artery. The bottleneck ran between two places most electricity users have never heard of: Kanawha, Virginia, and Matt Funk, West Virginia. At times the line hobbled the entire system, limiting transfer of abundant, cheap electricity from dozens of coal plants in Illinois, Indiana, Kentucky and Ohio to the hungry markets of the East Coast, which had to rely instead on local generators fueled by more expensive natural gas or oil.
The line was rated as high as the industry goes — a 765-kilovolt leviathan with towers 13 stories high, straddling a right-of-way 200 feet wide. But it was usually limited to carrying less than half of its capacity because of the grid’s design.
The electric system always has to be operated so that no single line failure will start a cascade of failures that would lead to a blackout. If the Kanawha–Matt Funk line tripped out of service at full load, it could send a wave of power flowing to a parallel but smaller line rated at only 345 kilovolts. That line would be knocked out, and a cascade might follow.
The occlusion started in the 1980s, when for a few hours every year limits on the line prevented interregional transfers of power that would have saved consumers money. Instead new power plants had to be built or existing plants that were expensive to run were kept on when, economically speaking, they should have been shut. By 1990 the hours ran into the hundreds, and AEP reached for the obvious cure: it decided to erect a parallel line, also rated at 765 kilovolts.
On paper the project was straightforward. The company already had decades of experience operating about 2,000 miles of such lines. And construction took a modest 30 months. The new line, which cost $306 million, finally entered service in June 2006. But that came after 14 years of work to get the permits from all kinds of jurisdictions that ruled part of the route, including two states and the U.S. Forest Service.
It is even more numbing to consider that in this case the entity that wanted to build the line was the same one that wanted to send power across it. Now consider the more typical situation — in which a power producer is trying to persuade another company to build transmission — and the prospect becomes even more complicated.
During the past two decades very little transmission capacity has been built. Seventy percent of the existing high-voltage system is consequently 25 years old or more, according to the U.S. Department of Energy.
The electric system undergirds nearly every aspect of modern life, from water supplies and steel mills to traffic lights and the Internet. Although we think of it as a national institution, it is virtually a feudal system among those 500 owners. Control of the power flow is also balkanized among dozens of jurisdictions, an artifact of the gridÂ’s history; it grew together from many small systems and local regulators that to this day are not melded.
Frustrated by internal complications such as the Kanawha–Matt Funk line, AEP last year teamed up with the DOE to rethink the grid for the whole country. The result — part of the DOE’s exploration of how to get 20 percent of U.S. electricity from wind by 2030 — was a plan for a national, high-voltage transmission backbone. The 22,000-mile system would be to electricity what the interstate highway system is to transportation, enabling a different kind of energy economy suited for a carbon-conscious era.
The plan would not extend todayÂ’s transmission system, which often operates at no higher than 345 kilovolts. Rather it would be superimposed over it, with various on- and off-ramps. The backbone would move power across the continent at the extreme high-voltage rating: 765 kilovolts, which would reduce typical system losses of 3 to 8 percent to around 1 percent. The higher voltage would also require fewer lines than any lower-voltage option, meaning less real estate for rights-of-way.
To further decrease losses, some long stretches would use direct current, instead of the usual alternating current that most of the system — and virtually all households and businesses — run on. Although direct-current lines are highly efficient, the equipment that converts alternating current into direct current and back again is not, so the advantage accrues on long spans — such as those from the windy high plains and the sunny Southwest.
Those spans only make sense if they traverse sparsely populated areas, however. If the line was going from Wyoming to Chicago, notes Michael Heyeck, senior vice president of transmission at AEP, “I’m sure Iowa or other states would want to tap into it.” Otherwise the line becomes like an interstate without an interchange, hardly welcome anyplace.
High-voltage lines of both varieties have long proved reliable. And there is now reason to believe that a national backbone could be effectively controlled.
AEP recently opened a state-of-the-art transmission control center in New Albany, Ohio, near Columbus, that could serve as a model for nationwide operation. The center sits far back from a local highway, surrounded by a moat, with an unmarked gatehouse in front.
Inside, giant floor-to-ceiling computer-driven displays show all the power lines and electricity flows across AEPÂ’s entire system. The displays can show details down to the level of transformers at individual substations and circuit breakers across thousands of square miles. The wall-size monitors also generate foglike clouds over large parts of the maps of entire states to indicate general voltage trends: white is good, orange is not, and red is worse.
AEPÂ’s primary motivation for the center, through better real-time monitoring of every line, better organization of all the data and better presentation of diagnostics to the operators, is to prevent another great blackout such as the one of August 2003.
Back then, a neighboring utility, First Energy, lost track of what was running and what wasnÂ’t, which allowed a cascade to begin. In a few seconds the blackout raced across Ohio, propagated to Detroit, up through Ontario and back down into New York.
But beyond preventing such blackouts, the level of sophisticated control the center provides would also make operating a national backbone possible.
The concept of a national energy grid is not far-fetched. Indeed, the U.S. already has one that is highly successful in moving resources vast distances, notably from the Gulf of Mexico to New York and New England. But it is for natural gas, not electricity.
And it exists because in the 1940s Congress created a system of national regulation for natural gas. Electricity was left to be regulated state-by-state and sometimes town by town.
As a result, says Andrew Karsner, a former assistant secretary of energy for renewables and efficiency, the country has “Btu liquidity” but not “electron liquidity.” Scrapping feudal transmission regulations for similar national rules would require forceful leadership from Washington.
The first step, Karsner notes, is making transmission reform a priority. “Stop the blah-blah” dithering among elected officials, he says.
A regulatory lever might already exist.
The 2005 Energy Act gave the DOE “backup authority” to approve new power lines over state objections, by designating “national interest electric transmission corridors.” But some utility executives think the department has been too hesitant to use the authority.
Bureaucrats at the DOE are moving carefully, because in the two locations they have tried, one in the Northeast and one in the Southwest, they have provoked fierce reaction.
In the Northeast case, for example, Senator Robert P. Casey, Jr., a Democrat from Pennsylvania, quickly rounded up 13 other senators to ask for hearings about how the authority was being used. He said the exercise of such power showed “a level of arrogance on the part of the federal government that undermines confidence in government.”
Translation: even where the legal authority may exist to erect transmission lines, the political consensus may not.
Another issue, of course, is cost. The DOE’s wind report put the price tag for a national backbone at $60 billion — a staggering sum, at least until various federal bailouts started to come along last autumn after the stock market plummeted.
Whether a better grid would be considered an infrastructure investment worthy of stimulus spending by the Obama administration is not clear; the work would not produce legions of jobs and would create economic benefits only slowly.
But even very large investments can be modest compared with the cost of having to use expensive local generation rather than cheaper renewables from remote locations. In Connecticut, for example, Northeast Utilities recently completed a 20-mile line from Bethel to Norwalk that cost $336 million but in its first year saved nearly $150 million. The line will operate for decades. According to the DOE, the national electric bill is about $247 billion a year, meaning that a small percentage drop in costs could finance tens of billions of dollars in investments.
Implementing such broader thinking would require a true national energy strategy, not a state-by-state energy strategy. A similar problem is repeated to varying extents across the globe. Lester Brown, president of the Earth Policy Institute, says the world must replace the 40 percent of its electricity that comes from coal with a like amount from wind, with 1.5 million wind turbines rated at two megawatts each. But transmission, he acknowledges, is a “gnarled-up situation.”
Clearly, a construction of a national transmission system is within America’s capabilities. “The interstate highway system was not designed by individual states and glued together,” Brown points out. “One way or another, if it became important enough, we would do it.”
