Striding across the countryside like metallic cartoon characters, transmission towers grasp in their stiff, unwieldy arms the wires that enabled me to write this and enable you to read it.
The long-distance lines don't care where the electricity that they're carrying comes from. For the record, half the electrons that they shunt around America are generated by burning coal, which comes with steamer trunks of environmental baggage - billions of tons of heat-trapping carbon pollution, particulate matter that sears lungs, toxic mercury that sears brains, and disfigured landscapes in the Appalachians.
Many greens would like to replace much of that coal with wind and solar energy. Both have a long way to go; wind and solar combined account for less than 3 percent of U.S. generating capacity. The rub is that the best wind resources in the nation are in the short-grass country of the Great Plains and the best solar is in the sun-blasted expanses of the Southwest - in both cases, far from where people expect electricity to light their homes, power their businesses, and energize their plethora of electronic toys 24/7/365.
Without transmission lines, there is no way to move electrons from where they're supplied to where they're demanded. Thousands of megawatts worth of proposed wind and solar projects cannot hook up because sufficient transmission is lacking.
A 2008 report published by the Department of Energy took a look at what it would take to generate 20 percent of U.S. electricity with wind by 2030. The report concluded that 20 percent is feasible, but one of the conditions for making it so is building more high-voltage transmission capacity. Like water pressure, voltage is the force necessary for pushing electricity across long distances.
One of the complications attending transmission is that ownership and operation are fragmented. In the transportation world, it is possible to pull out of a driveway in Boston and pull into Seattle days later thanks to interstate highways. There is no comparable superhighway system for electricity, however. It is not practical for a wind farm in Montana to send its juice to Chicago, nor could a concentrated solar plant in Arizona easily light up the New Orleans Superdome. U.S. transmission is divided into three "interconnections" - Western, Eastern, and Texas - which have limited links among each other.
American Electric Power (AEP), which serves 11 states in the Midwest and South and owns more transmission than any other utility, has proposed an interstate electricity highway, a $60 billion "backbone" made up of 19,000 miles of lines pushing electrons at 765,000 volts, the upper level of voltage used in the U.S. today. AEP today operates some 2,000 miles of such heavy-duty lines in its service area.
One of the benefits of supersizing voltage is energy and land use efficiency - for moving power longer than 100 miles, one 765,000-volt line on a 200-foot-wide right-of-way can carry as much juice as five 345,000-volt lines consuming a 750-foot right-of-way. The extra high-voltage lines cost twice as much per mile to build, but looked at another way, they're more economical. For each megawatt that such lines are capable of moving, their per-mile cost is half that of lower voltage lines.
Complications arise, however, when figuring out how such lines would be permitted and who would pay. AEP, along with wind and solar developers, contend that permitting lines today is a laborious, state-by-state process that takes years and delays lines needed to integrate renewables into the grid and to ease transmission congestion that threatens reliability of service. They want the feds to take over permitting for backbone, extra high-voltage lines. States, however, jealously guard their siting authority and would mightily resist a federal takeover.
How costs would be divvied up is another source of contention. So are the environmental issues - no one likes transmission in their backyards or in places they like to visit. Many are concerned that transmission corridors designated on Western public lands in 2008 are too close for comfort to parks and wilderness areas.
Look for those arguments to remain difficult to resolve. In the meantime, a backlog of wind and solar projects will remain backed up on the transmission on-ramp, waiting for the highway to come through.
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