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Transmission Lines: An Interstate Highway for Energy

Oct. 21, 2011 | Northwest Public Radio
CONTRIBUTED BY:
Courtney Flatt

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Transmission lines work as an interstate highway, shipping energy from large-scale wind farms to where it’s most needed, in cities like Portland. | credit: Flicker Creative Commons: doug_wertman | rollover image for more

RICHLAND, Wash. – As more renewable energy projects come online, grid managers will need a way to transport that power from where it’s produced to where it’s most often consumed.

Enter transmission lines. They work as interstate highways, shipping energy from large-scale wind farms to where it’s most needed, in cities like Portland, Boise and Seattle.

But sometimes these lines can act as bottleneck to the entire system. It’s much faster to build renewable energy projects than transmission lines, said Cameron Yourkowski, senior policy manager with Renewable Northwest Project.

It can take years to build lines, with numerous permitting processes bogging down projects. To help speed up the process, the Obama administration recently announced the creation of a Rapid Response Team for Transmission. Officials say this will reduce red tape.

Some hope new lines will also help with more renewable energy generation. New lines provide access to wind and solar projects, Yourkowski said.

“Building new lines or adding segments of new line that go from existing lines to the renewable energy resources is just a critical component in getting them to market as a part of our energy future,” Yourkowski said.

Dig Deeper

Read how transmission works.

When contemplating new lines, grid managers try to envision these factors 10 years down the road. A lot of that picture depends on how states will meet renewable energy standards. More often than not, requests for transmission are driven by wind power, said Wally Gibson, manager of system analysis and generation for the Northwest Power and Conservation Council.

“It’s a little tricky because traditionally transmission is built to connect generation to load,” Gibson said. “But if the generation can show up faster than the transmission line, it kind of turns around the traditional planning process from 20 or 30 years ago, when the choices were coal plants or large gas plants.”

FASTER PERMITTING

The three proposed Rapid Response lines in the Pacific Northwest include:

Cascade Crossing Project:

Boardman to Hemingway:

Gateway West:

Rapid Response Team for Transmission detail

New transmission lines are driven by two main factors: how many power generators are asking for service (Think of all the wind farm construction.), and forecasted energy demand, or load.

REINFORCING POWER

The new projects are all about reinforcing areas that don’t have enough energy flow, said Doug Johnson, a Bonneville Power Administration spokesman.

“You have to be able to move the energy along a system and deal with the way it flows because it’ll hit the path of least resistance,” Johnson said. “You’ve gotta make sure that you’ve got sufficient space on that network to deliver power to all those points. The utilities and independent power producers and all of those individuals rely on you to make sure that their energy can travel across your network to where it’s going. You’ve gotta be able to meet those needs.”

When needs can’t be met – because there is too much energy for the network to handle – transmission lines become congested. That’s when unplanned power outages can occur.

Johnson said BPA operates 15,000 miles of transmission lines (PDF) across the Pacific Northwest. The utility also recently started construction on a transmission line, unrelated to the Rapid Response Team:

Big Eddy-Knight project:

Big Eddy-Knight Project Map

The Big Eddy-Knight line will add reinforcement for east to west transmission, Johnson said. That means more power available to Portland, especially during cold winter months.

Adding new transmission lines helps make grid management easier, Yourkowski said. It’s sort of like insurance, to make the system more reliable.

“It just helps create more flexibility and more options for the grid managers,” Yourkowski said. “The issue last spring – there was an oversupply of hydro energy. It would have given the grid operators more flexibility in how to dispose of that energy.”

ENVIRONMENTAL CONCERNS

But transmission projects come with a cost (PDF). Many environmentalists worry about habitat disruption from construction and line maintenance. Nesting trees for endangered or threatened birds could be cut down. Neighbors worry what lines will look like from their backyards. Utilities say they can mitigate these factors by finding alternate routes or creating large right-of-ways.

The new projects will build mostly 500-kilovolt towers (graphic). This allows for larger amounts of energy to be transported, which mean fewer lines need to be built.

New technology at these lines will also make the system more efficient, Yourkowski said. That includes more efficient conductors in the lines, new substation technologies and new monitoring and communication technology for grid managers.

© 2011 Northwest Public Radio
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