Another scorching summer: What's ahead for the electric grid?
The air-conditioners are blasting, the electric generators are running full tilt, and the planetary thermometer is spiking. Average land and sea-surface temperature for the first six months of 2010 was 0.67 degrees C above the 20th century average. On land, temperature was 1.07 degrees C above average.
Electric consumption is rising for many reasons, but those scalding temperatures mean we'll be needing a lot more electricity to power air-conditioners. On a singeing summer afternoon in states like California, AC comprises the biggest single part of the peak load at electric utilities.
That makes us wonder where we are going to get the electricity. But the answer will not just concern generation, but also distribution -- moving current from the generator to the point of use.
Until somebody invents a big, affordable storage mechanism, electricity will need to be distributed as soon as it is generated. Electrons begin this journey on high-voltage transmission lines, which stretch an estimated 211,000 miles in the United States. At substations, they travel via lower-voltage distribution lines to houses and businesses.
Transmission and distribution lines, together with generators, switches, capacitors and transformers, comprise the electric grid, and the U.S. edition is astonishingly complex. Cobbled together over the decades, subdivided into regional and state jurisdictions, moving electricity generated at roughly 15,000 power plants, it has a capacity of roughly one trillion watts and supplies more than 100 million customers.
In 2000, the U.S. National Academy of Engineering, called the grid the greatest single engineering achievement of the twentieth century, as judged by the difference it makes in human lives.
Horrors! The Academy gave a reliable, affordable electric supply primacy over computers, the Internet, safe water, the telephone and even the automobile.
Take that, Detroit!
As the grid faces inevitable expansion, we hear about the advantages of a "smart grid," which will allow devices to communicate among themselves about load, pricing and voltage, allow the integration of alternative energy, and reduce energy costs.
The smart grid will not come cheap: In 2004, the Electric Power Research Institute (EPRI) estimated the cost at $165 billion. EPRI spokesman Don Kintner says the older number is "not credible" any longer; the group plans to issue a higher estimate soon.
In 2009, the smart grid got a $3.4 billion boost under President Obama's American Reinvestment and Recovery Act, to pay for newer technologies and set standards for smart-grid components.
Why worry about the electric grid?
People in developed countries tend to take electricity for granted, but many factors suggest that we'll be thinking more about the electric grid, and seeing more hefty cables, more steel towers and more proposals to use our generation and transmission capacity more intelligently:
Demand: Electricity consumption has risen 25 percent in the United States since 1990, and we'll need an estimated 50,000 more miles of high-voltage lines by 2025.
Reliability: The electronic explosion has raised the economic cost of blackouts, which according to the feds, cost the average American $500 a year. A single failure on Aug. 14, 2003 darkened 50 million homes in the Northeastern United States and Eastern Canada. The long build-up to that blackout is a perfect measure of the grid's complexity and sensitivity.
Conservation: A power grid that enables communication between producers and consumers may shift demand away from the peak period in late afternoon and early evening, cutting equipment and operating costs. "Peak-power" plants operate only a few hundred hours a year, generating power that costs five or 10 times more than customers pay for it.
Non-carbon energy: Reducing the global-warming impact of electricity depends on building big renewable power plants -- mainly wind and solar plants -- that release no carbon dioxide. Proposals for such plants are often limited by shortages in transmission capacity between remote, windy locations like the Great Plains, and cities with heavy demand for electricity.
Delivering green power
The grid has played a key role in several major renewable projects:
In five years, Portugal has boosted renewable electricity from 17 to 45 percent of consumption, with significant help from a grid-building project.
The existence of transmission lines has eased a proposal to locate solar electric generator on thousands of acres of farmland in California's San Joaquin Valley.
Even though the Dakotas have been called the "Saudi Arabia of wind," a lack of transmission lines to the Midwest and East Coast has stymied efforts to tap that wind. One proposed solution, called "Green Power Express," is a 3,000-mile, $10-billion-plus project to move green electricity to markets via an ultra-high-tension 765,000 volt powerline.
Despite the bottlenecks, powerlines are eventually built to move green electricity, says Brian Seal, a smart-grid expert at EPRI. "We certainly don't have the transmission infrastructure we need to enable us to tap the vast wind resources in the mid-section and move the electricity to the Northeast and Southeast, but from what I hear, we are succeeding in building these lines."
Plans for new powerlines often attract opposition, and many big projects can take a decade to get built, but that seems reasonable given the political and technical considerations, Seal says. "There are a lot of decisions about where to put them, to minimize the environmental impact and property-owner inconveniences. By and large, I think we have been successful so far in building at the rate we need to continue to bring in wind."
Cutting consumption with a smart grid?
In building tomorrow's grid, quality is just as important as quantity -- and that brings us to the smart grid, which Seal defines as "a marriage of intelligent infrastructure, a lot of it born in the computing and communication industries, sensors, processing, technology, and overlaying it on power system, from generation and transmission to end use."
Although consumers tend to be preoccupied with the familiar electric meter, the smart grid "also includes automation of substations, and the ability to centrally observe and manage various technologies," Seal adds.
All of which sounds rather mundane unless you understand the importance of voltage and phase -- timing -- in the alternating current that the electric system supplies. The current is called "alternating" because it goes through 60 complete waves of second. Hundredths of a second matter, because the phase of the voltage, or the instant at which the reversals occur at various locations, determine when power is flowing. If the current goes "out of phase," it may lead to reduced voltage and threaten to wreck motors and other electric equipment.
To prevent damage and blackouts, the smart grid will include automated phase detectors, and automated substations that can respond faster to storms and equipment failures.
The smart grid will even be brainy enough to inform utilities that the power is off: Most utilities now must wait to get the rumor from a customer who happens to be equipped with a cellphone or a wired land-line phone.
Quicker notification means quicker repairs.
Terry Devitt, editor; S.V. Medaris, designer/illustrator; Jenny Seifert, project assistant; David Tenenbaum, feature writer; Amy Toburen, content development executive