April 17, 2013

The Reliability of the Sun and the Wind

The following is reposted from the Environmental Law Prof Blog.

The electric utility industry often complains that renewable energy proponents don’t pay enough attention to the intermittency of renewable resources.  A common refrain is “the sun doesn’t always shine and the wind doesn’t always blow.”  The industry then reminds us that, for a reliable electricity grid, supply and demand must be in balance at all times. The implication is that this will be impossible if we rely heavily on renewable energy.

A new report published by the Civil Society Institute models a year 2050 scenario in which renewable energy is used to generate about half of all electricity in the US, and the lights still reliably come on.  In the scenario, about 22% of demand is met by solar (almost all PV), 16% by wind, 8% by hydro, and 5% by biomass. The rest is supplied primarily by natural gas and nuclear energy.  The scenario includes no coal-fired generation.

The authors explain that the intermittency problem of solar and wind is greatly reduced when you consider generation on a regional rather than local scale. Also, weatherpeople are actually pretty good at forecasting available solar resources (i.e. cloud cover) and wind resources (i.e. wind speed) on the time scale that’s needed for sophisticated grid operators to balance supply and demand – namely, several hours ahead of time.  It also helps that as a general matter, solar electricity is most plentiful and reliable when we most use electricity: during daylight hours. To the extent that disparities between energy supply and demand occur in the 2050 scenario, the report shows that reliability can be achieved using interregional transfers of electricity, energy storage, demand response, and other available approaches.

So it seems we can build electric power systems that bank on the reliability of the sun and the wind.  A new refrain could be “the sun’ll come out tomorrow, bet your bottom dollar that tomorrow, there’ll be sun!” and we can recall that our forebears didn’t name places Windy Mountain, Windy Plains, and the Windy City for nothing. 


Lesley McAllister, CPR Member Scholar; Professor of Law, University of San Diego School of Law. Bio.

  • Read Comments (0)
  • + Add a Comment
Be the first to comment on this entry.

First Name:
Last Name:
Email:
We ask for your email address so that we may follow up with you, ask you to clarify your comment in some way, or perhaps alert you to someone else's response. Only the name you supply and your comment will be displayed on the site to the public. Our blog is a forum for the exchange of ideas, and we hope to foster intelligent, interesting and respectful discussion. We do not apply an ideological screen, however, we reserve the right to remove blog posts we deem inappropriate for any reason, but particularly for language that we deem to be in the nature of a personal attack or otherwise offensive. If we remove a comment you've posted, and you want to know why, ask us (info@progressivereform.org) and we will tell you. If you see a post you regard as offensive, please let us know.