Washington hand-wringing over the future of renewable energy tax credits has not dampened a private company's plans to build a new network of high-voltage transmission lines that could efficiently move tens of thousands of megawatts of clean energy to load centers across the country.

Houston-based Clean Line Energy Partners is staking billions of dollars on the development of four transmission corridors that will rely on high-voltage direct current technology (HVDC) to move electricity mostly from wind farms in the Midwest and Great Plains to points east. Another line in the early stages of development would carry renewable energy from northwest New Mexico to Southern California.

Two of the four projects -- the Rock Island Clean Line, running 500 miles from northwest Iowa to a power substation in the Chicago exurbs, and the Plains and Eastern Clean Line, linking Oklahoma and Texas Panhandle wind farms to the Tennessee Valley Authority grid near Memphis -- have received approval from the Federal Regulatory Energy Commission to begin negotiating service agreements with potential users of the lines.

If built, the two 600-kilovolt lines will have the capacity to move 7,000 megawatts of wind energy to power-hungry markets in the East and South, where a combination of economic, regulatory and demand pressures are driving rate-based utilities to add more renewables to their electricity mix.

"When we started the company, the mindset was that if wind power is going to be an important electricity resource going forward, we wanted to find a way to move the best wind power we could find to market in the most efficient way possible," said Jimmy Glotfelty, a Clean Line Energy Partners co-founder and executive vice president. "Experts told us that the middle of the country -- from Iowa to Texas -- is where the highest-class winds were. So that's where we set our sights."

With financial backing from New York-based Ziff Brothers Investments and the Zilkha family of Houston, whose investments in conventional and renewable energy in Texas are well-known, Clean Line Energy Partners set out to fill a gaping hole in the nation's transmission grid, and it would do that by resurrecting a tried-but-true technology that dates to the earliest days of electricity -- direct current.

Direct current makes a belated comeback

Direct current (DC), championed in the late 19th century by Thomas Edison, relies on a one-way flow of electricity from generation source to load source via a system of conductors. While popular in the early 20th century and still used for specific power applications, direct current runs a distant second to alternating current (AC) for most electricity transmission today.

AC, which powers almost all homes and businesses in the United States, can flow in opposite directions and is often preferred by transmission developers because its voltage can be stepped up or stepped down using a transformer.

But AC transmission comes with some distinct disadvantages, experts say, including a higher rate of energy loss as the alternating current travels over hundreds of miles. One way to reduce such load losses is to convert AC electricity to direct current at a central distribution point, then send it hundreds of miles to a distant substation, where the power can be offloaded and converted back to AC for use on regional and local power grids.

Clean Line and other proponents of HVDC lines say the technology is vastly superior to move large amounts of "stranded electricity" from wind power generation sites in the nation's rural quarters to load centers as far away as New York, Philadelphia, Washington and Atlanta.

Furthest along in the development pipeline is the Rock Island Clean Line, which will provide transmission on-ramps for hundreds of wind farms in western Iowa, southwest Minnesota and eastern Nebraska and South Dakota.

It would carry that electricity to a Commonwealth Edison substation near Joliet, Ill., about 50 miles southwest of Chicago, officials say. From there, the power would cross a critical transmission boundary and become available for use in the PJM Interconnect, the primary grid operator for 13 Eastern states and the District of Columbia.

Cary Kottler, project director for the $1.7 billion project, which draws its name from the historic Chicago, Rock Island and Pacific Railroad, said the use of HVDC technology will significantly reduce the amount of electricity lost in transmission -- from roughly 15 percent on a 500-mile-long high-voltage AC line to as little as 5 percent on an HVDC line.

At the same time, HVDC allows for smaller towers and a narrower transmission corridor, an important consideration in farm states like Iowa and Illinois.

Kottler said officials with Clean Line and engineering and design partner Kiewit Corp., of Omaha, Neb., have stressed the technology's benefits in dozens of meetings with landowners and elected officials in the two Corn Belt states. It will continue to do so in hearings before the Iowa Utilities Board and the Illinois Commerce Commission, which must approve new transmission projects to ensure they do not harm the states' rate-based utilities and their ratepayers.

At least one major rate-based utility in the region, Alliant Energy Corp., which distributes electricity and natural gas to much of eastern and central Iowa through its Interstate Power & Light subsidiary in Cedar Rapids, has asked the Iowa Utilities Board to carefully review the Rock Island Clean Line proposal.

Specifically, IPL wants to make sure the cost of the Rock Island line's construction will not fall on IPL's customers and that the operation of the HVDC line won't compromise reliability on Iowa's larger power grid.

Scott Drzycimski, an Alliant Energy spokesman in Cedar Rapids, said that so long as such concerns are fully addressed, the company is open to having Clean Line Energy Partners build a transmission line through its service territory. "In general, we're supportive of anything that helps grow the wind industry in the state of Iowa. We have customers who are heavily involved in that," he said.

Some farmers remain unimpressed

A tougher sell may involve Midwestern farmers, some of whom view transmission lines as impediments to farming and eyesores on the landscape. Clean Line officials have worked hard to assuage such concerns, and insist that the Rock Island Clean Line will be routed in the most sensitive way possible to preserve high-quality farmland.

"The way we do that is to route the project in straight lines that aren't crisscrossing fields left and right," said Kottler, the Rock Island line project manager. "It's hiring an independent agricultural inspector as we go along and having an agricultural impact mitigation agreement that governs how we treat their lands so nobody drives a machine through a muddy field."

But in Corn Belt communities like Illinois' LaSalle and Bureau counties west of Chicago, opponents have started mobilizing and public discourse in the local papers has grown more pointed with claims of thousands of acres of cropland being converted to right of way for the new line.

"Placing towers and lines across some of the best farmland in the world will forever prevent and/or alter normal farming operations," Paul Litow, a former resident of Earlville, Ill., wrote recently to the Bureau County Republican. "These are economic and operational burdens that farmers -- and ultimately consumers -- will have to bear."

Critics are particularly concerned about Clean Line's petition to receive public utility status in the two states, which would effectively extend eminent domain rights to the project if negotiations between the developer and private landowners along the Rock Island line's route were to reach a stalemate.

Others, like Steve Barlow of Princeton, Ill., argue the project will generate significant new revenue for farmers through land leases and "play a part in leaving this world a better, cleaner, safer place for our grandchildren and future generations," according to a Sept. 19 letter in the same newspaper.

High-wire act with multiple players

An equally important constituency for merchant developers like Clean Line is the regional transmission organizations (RTOs) that govern the nation's power grid with an eye toward protecting electric reliability within broad geographic regions and ensuring that power flows smoothly to sections of the country that need it the most.

Rock Island project officials say they have spent considerable time and resources addressing concerns from two regional entities -- the Midwest Independent Transmission System Operator (MISO), which oversees the grid in 11 Midwestern states and the Canadian province of Manitoba, and PJM Interconnection, the grid operator for 13 Eastern states and the District of Columbia.

While the project's buildout will occur mostly in MISO's territory, Clean Line officials say the more critical relationship is with PJM because virtually all of the Rock Island line's 3,500 megawatts will be offloaded onto the more eastern grid, which extends from New Jersey to North Carolina and west to Illinois. As part of its planning process, Clean Line acquired a number of interconnection queue positions at the Illinois substation to expedite its eventual link to the PJM grid.

Officials at PJM Interconnection, based in Norristown, Pa., outside Philadelphia, say they have had constructive discussions with Clean Line Energy Partners for several years and that the Rock Island proposal is undergoing a series of studies to evaluate its feasibility, potential impacts on PJM's grid and resource requirements.

Paul McGlynn, PJM's director of system planning, said the transmission organization does not endorse particular projects, though he said an HVDC line the size of the Rock Island Clean Line "certainly is something that our system could accommodate."

Looking for 'anchor tenants'

To date, PJM has worked with Clean Line officials to help identify various issues and challenges related to the linking of a major new generation or transmission source to the PJM grid. Ultimately, McGlynn said, the decision about linking to PJM's grid will lie with Clean Line after it considers the full range of costs and logistical hurdles at hand.

Officials with Clean Line Energy Partners say they are confident that Rock Island Clean Line and the other proposed HVDC projects will attract sufficient customer interest to make them financially and operationally viable. "There's been numerous wind studies that show we can fill up the [Rock Island] line pretty fast," said Kottler.

Under a FERC order issued last May, the company can sell up to 75 percent (2,850 MW) of the Rock Island line's capacity to "anchor tenants," primarily wind developers, while the remaining 25 percent would be subject to open bidding by all energy firms.

Beth Soholt, executive director of the nonprofit group Wind on the Wires, which does technical and policy work on wind and transmission, said Clean Line Energy Partners' strategy will be important to developing a robust amount of wind farms in the Midwest. She said that development of HVDC transmission projects like the Rock Island line would be beneficial to wind developers whose ability to sell wind energy is limited by insufficient transmission capacity.

But she said transmission planning involves many moving pieces, and that the construction of both AC and large merchant projects like Clean Line's is essential to maintaining a robust grid that can move renewable energy to the right places at the right times. "In general, the Midwest region is going to produce way more than its share [of renewable energy] because of the size of the resource we have and the demand for that clean energy in other parts of the country," she said.