Monday, January 30, 2012

Interminable innumeracy: "renewables" versus nuclear

Back to the Future Delorean
Interestingly, Doc Brown's modified Delorean was also the
equivalent output of a modern nuclear plant. Heavy.
A confession - I listen to and read a fair amount of science stories. (Yes, self-outing as a nerd right out the gate). And whenever the topic of renewable energy sources comes up, invariably a spurious comparison to the generating capacity to nuclear plants will come up. For example, identified resources for say, offshore wind will be identified somewhere in the realm of tens of gigawatts, to which the guest will inevitably state, "That's the equivalent of dozens of nuclear plants!" (i.e., about 1 GW each). Naturally, no clarification is given to the important factors here - as in, just how many wind turbines / solar cells / magical crystal arrays (okay, so maybe I'm exagerating with the last one) are required to accomplish this task, much less the inherent capacity factor in such a generating system. (In other words, the sun doesn't shine and the wind doesn't blow all the time, meaning these generators sit idle for more time than they actually generate power).

A basic unfamiliarity with these concepts (i.e., the scale of individual energy generators and their respective availability factors) tends to produce a pervasive level of innumeracy, which in turn leads to genuinely terrible energy policy positions, such attempting to displace some or all of baseload capacity (including nuclear) with intermittent sources. In an effort to combat this epidemic (and inspired by the old Total cereal commercials which used to air back when I was growing up) I've put together an infographic to demonstrate just how many of these types of generators one needs to replace just one baseload unit.

Comparison of generating requirements of nuclear, solar PV, and wind

I've made high-resolution versions available for download and reuse as well (svg and pdf).

The next time someone claims that renewable energy sources can somehow "displace" nuclear sources for baseload (such as say, Germany is attempting to do), I invite you to ask just how many units (and at what assumed capacity) will be required to accomplish the task. Chances are very good the advocate either doesn't know or simply isn't being honest with the numbers.

An aside: Does this mean I don't think we should use renewable sources at at all? Not really - if sources which coincide with peak demand (such as solar) can shave off demand for "peak unit" power (typically provided by fast-response units like natural gas turbines) and do so at an economically competitive price, more power to them. But don't count on inherently diffuse sources of energy providing baseload power needs anytime soon.