The vast expansion of wind and solar power planned by the Obama administration and congressional leaders is fraught with challenges for the nation's aged electricity network, grid monitors with the North American Electric Reliability Corp. say.
But a NERC report released today does not call for a slowdown in deployment of renewable energy. Officials expressed confidence that technology solutions will arrive in time.
"I am extremely confident we will be successful," said Mark Lauby, a NERC director of reliability assessments who briefed reporters yesterday. If there is a limiting factor in renewable power growth, it will be the inability to add enough transmission lines to accommodate new wind, solar and other renewable generation resources, he said.
The NERC report is a response to policy proposals now before Congress. Non-hydro renewable power now supplies less than 2 percent of the nation's electricity. A Senate Energy and Natural Resources Committee bill would require utilities to deliver 20 percent of their power from renewable sources by 2021, starting with a 4 percent target in 2012.
The House Energy and Commerce Committee's version starts at 6 percent in 2012 and climbs to 25 percent in 2025. A portion of the targets could be satisfied through increased energy efficiencies.
No one knows the 'magic number' of renewable capacity
The Joint Coordinated System Plan issued by grid officials this year modeled a 20 percent renewable energy target in 2024, which would require 229,000 megawatts of new wind capacity east of the Rockies. Renewable policy will "fundamentally change how the system is planned, operated and used, from grid operators to the average customer," Lauby said.
Denise Bode, CEO of the American Wind Energy Association, called the report "an excellent road map for the grid planning and operations changes needed for America's future electric generation portfolio."
Revis James, who directs energy technology assessment for the Electric Power Research Institute, said that a critical question hangs over the push to increase renewable energy output. "How much renewable energy can you have before [you] have to have systemic improvements to the system to handle the variability of renewables?" he said. "Is 10 percent too high? No one knows what the magic number is."
He added: "Are we moving too fast? On the policymakers' side, there's a lot that is not still understood about the implications of a large share of renewables." On the other hand, renewable generation standards will be phased in over more than a decade, and research is being done on many of the systems and technologies that will be required. The question is whether they will be given enough priority, he added.
NERC said that integrating renewable power will require complex new computer models to anticipate, monitor and respond to the vagaries of weather that can suddenly alter electricity output from wind or solar units. Sophisticated new power flow monitors and controls will be needed.
New regulatory and political questions raised
Wind power generators typically experience steep up or down "ramps" in output compared to traditional generators. This characteristic figured in a 2008 grid emergency situation in Texas -- a center of wind energy -- NERC's report says, when 1,000 megawatts of wind energy was not available when needed.
Advances in battery storage and the use of flywheel storage could make wind and solar units easier to manage on the grid, NERC said. Increasing use of solar and wind generators on homes and offices must be tied properly into the network, it added.
New wind turbine technology makes wind generators more flexible, NERC said. Modern turbine blades can be feathered to "dump wind" suddenly when needed. The report mentions only briefly the daunting political challenge of deciding who pays for the upgrading of the power grid required to handle more renewable power.
Growing amounts of wind and solar power, currently subsidized by Congress, will displace energy from older conventional generators in patterns that are still unclear, experts said. At the same time, other generators may be called on more frequently to fill in gaps when the wind dies and night falls.
Regulations or workable market plans must be forthcoming to ensure those resources are ready when needed, the NERC report says. "That's an equity issue that is basically a political question, not a technical question," said James.