Monday, August 18, 2014

It Takes More Than Turbines

The Telegraph ran a brief story earlier this month about UK regulators paying wind farms in Scotland nearly £3.0M to not generate so much electricity for one day.  High winds due to the remnants of Hurricane Bertha coincided with a period with low local demand for electricity, and the grid lacked capacity to carry the available power elsewhere.  Such situations are neither new, nor confined to the UK: in both 2011 and 2012, the Bonneville Power Administration ordered wind generators in Oregon shut down to avoid oversupply problems.  The problems in both cases are not that the grid isn't smart enough to handle the intermittent nature of wind; the problem is that the grid lacks sheer bulk transport capability to move the excess wind power to someplace it could be used.

The map to the left is a portion of a graphic from an NPR story about the US power grid, showing the US portion of the Western Interconnect.  The bold orange lines represent a proposal by the American Wind Energy Association for an overlay high-level grid that would allow full use of wind when it is available in a geographically diverse set of sites.  This overlay grid passes "close" [1] to all of the major population centers in the West, as well as the best of the wind resources.

Building a reliable grid from intermittent renewable sources requires not just geographic diversity, but source diversity as well.  The AWEA overlay also happens to pass close to excellent solar resources in the desert Southwest, undeveloped hydro resources in the Northwest, geothermal resources in the Great Basin, and sites suitable for pumped hydro energy storage.  Balancing all of those resources against demand across eleven states (plus western Canada and a bit of Mexico) is a complex but doable task, given enough bulk transport.  Speaking broadly, the situation in Oregon with too much supply and not enough demand shouldn't happen.  If there really are no consumers for it, it ought to be pumping water uphill against future need.

The AWEA isn't the only group that draws proposals for overlay super grids [2].  In the Western Interconnect, they all tend to look similar.  As I've noted in other posts, geography plays a big role.  The people are concentrated in a small number of areas; the easy routes for transportation or transmission are few and obvious; the energy resources are where they are, many of them either close to one or more demand centers, or along one of the routes between those demand centers.  This is a good part of the reason that people can draw up nuts-and-bolts sorts of plans for a heavily-renewable power grid in the Western Interconnect.  The other parts of the country present a much more difficult challenge.  And as always, I raise the question of whether those other parts of the country will demand a single national energy policy that makes the West's efforts difficult or impossible.

[1] "Close" in the West can be rather different than close in other parts of the country.  As in, "it's only a hundred miles", or "it only has to cross one mountain range".

[2] The AWEA map does get used a lot, though.  Part of that is probably that it shows up in Wikipedia's Wikimedia Commons, unencumbered by copyright.  An interesting feature of the full national map is that it doesn't show any additions in the Southeast part of the country, where wind resources are rather poor.

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