By Michael Mariotte

Average hourly load over a one-week period in January, April and July 2009. Credit B. Posner.

This post first appeared on Power for the People, a blog focused on energy issues in Virginia, the home base of Dominion Resources–a company that is an industry laggard when it comes to renewable energy issues, and is still pursuing the possibility of building a third nuclear reactor at its North Anna site despite its costs projection of around $19 Billion, which would make it the most expensive nuclear project ever undertaken in the U.S. Those projections are not far off the costs anticipated for the UK’s highly controversial Hinkley Point reactor and, given the near-certainty of cost overruns and schedule delays, could go far higher if construction is attempted.

In this piece, Ivy Main explains–I think much more clearly than I have to date–exactly how deployment of expensive nuclear power (and baseload power generally) prevents the growth of cleaner, safer and cheaper renewable energy sources. And it’s not true only in Virginia; while that state has a higher percentage of nuclear than many, meaning that it is closer to the point where nuclear blocks out renewables, the problem is real in every nuclear-powered state–and nation–to one degree or another. This is the key reason why nuclear power is counterproductive in the battle to forestall global warming: renewables are faster to deploy and can provide low-carbon power more cheaply than nuclear–both necessities if we are to prevent the worst of climate change’s impacts.

Michael Mariotte

Dominion Resources CEO Tom Farrell is famously bullish on nuclear energy as a clean solution in a carbon-constrained economy, but he’s got it wrong. Nuclear is a barrier to a clean-energy future, not a piece of it. That’s only partly because new nuclear is so expensive that there’s little room left in a utility budget to build wind and solar. A more fundamental problem is that when nuclear is part of the energy mix, high levels of wind and solar become harder to achieve.

To understand why, consider the typical demand curve for electricity in the Mid-Atlantic, including Virginia. Demand can be almost twice as high at 5 p.m. as it is at 5 a.m., especially on a hot summer day with air conditioners running.

The supply of electricity delivered by the grid at any moment has to exactly match the demand: no more and no less. More than any other kind of generating plant, though, the standard nuclear reactor is inflexible in its output. It generates the same amount of electricity day in and day out. This means nuclear can’t be used to supply more than the minimum demand level, known as baseload. In the absence of energy storage, other fuel sources that can be ramped up or down as needed have to fill in above baseload.

Wind and solar have the opposite problem: instead of producing the same amount of electricity 24/7, their output varies with the weather and time of day. If you build a lot of wind turbines and …read more

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