The Ergosphere
Sunday, October 11, 2015

Paranoid fixations of anti-nukes

Nothing suggests mental illness more than the tortured reasoning used by anti-nuclear activists to attempt to justify their positions.  Often they fixate on particular claims which turn out to be utterly ludicrous after even shallow examination.  One of these is the argon-41 chromosome-damage "theory" currently being flogged by BasG (Bas Gresnigt) over at Atomic Insights.  This short-lived isotope (half-life 106 minutes, beta-decaying to stable potassium) is a noble gas, and disperses rapidly in air by diffusion and turbulent mixing.  The "researchers" who tortured their data to make it confess the crimes of 41Ar got it to sign a statement amounting to this:
  1. Spent nuclear fuel emits neutrons due to spontaneous fission.
  2. The neutrons escape into the air and run into 40Ar atoms, forming radioactive 41Ar .
  3. 41Ar ionizes due to recoil from the neutron capture.
  4. The ion is attracted to dust and water particles, keeping it close to the ground after formation.
  5. Because of this, the effects of 41Ar are most strongly felt upwards of 20 km from its point of formation, rather than immediately next to it.
  6. The measurable effect is an increase in the male-female sex ratio at birth, because the X chromosome has more DNA than the Y chromosome and is more susceptible to damage.
Got that?  I lost 5 IQ points just from reading the crap required to write that summary, so I'm not going to repeat it.  Oh, the "researchers" conveniently left out the mechanism by which 41Ar singles out the sex chromosomes for damage, rather than causing mutations and consequent birth defects all over the genome.  It's just one of the ways that 41Ar is evil, I guess. 

Back in reality, things are just a little bit different.

Argon is only a trace constituent of air.  Nitrogen is 78% of air by volume, while all isotopes of argon are only 0.93%.  Further, each molecule of nitrogen has two atoms while argon has but one.  Last, the thermal neutron capture cross-section of nitrogen is 1.91 barns, while argon's is only 0.675 barns.  The upshot is that a free neutron in air is about 470 times as likely to be soaked up by a nitrogen atom (forming stable 15N 14C by the (n,p) reaction) than by 40Ar.  My understanding is that even that's not terribly likely, and the most common fate of neutrons in air is beta-decay to hydrogen (half-life ~11 minutes).

But let's follow this to the end.  40Ar plus a free neutron have a total mass of 40.9710480385 AMU.  41Ar masses 40.9645006 AMU, for a difference of 0.0065474385 AMU or on the order of 6 MeV.  This will be released as a gamma ray.  This is certainly enough to ionize an atom... but is it likely to stay that way?  The ionization energy of argon is 15.7 electron-volts (eV).  The ionization energies of both nitrogen and oxygen are less than that, so at the first collision with an oxygen or nitrogen molecule the newly-formed 41Ar+ ion is going to steal an electron and not be an ion any more.  That will take on the order of picoseconds.

Last is the issue of location of the decay.  The typical human contains enough potassium that the beta decay of 40K occurs around 4000 times per second; against this background of beta decays, you'd have to have a huge effect from 41Ar to measure something.  But even if an atom of 41Ar was able to stay ionized, attach to a dust particle or water droplet, and stick around near a human, what is the likelihood that it could be ingested and migrate to the gonads before it decayed?  Roughly zero.

The funniest thing about this 41Ar "theory" is that there are actually people who take it seriously.  So who's pushing this nonsense?  There are two basic possibilities here, not necessarily mutually exclusive:  either they are objectively deluded (crazy), or they want you to be.  The latter want to panic you into following their agenda, which you wouldn't do by pursuing your own interests.  And that, my friends, is evil.

Note:  Corrected the results of neutron capture in nitrogen, H/T rrmeyer.

Edit:  corrected notation. 
Sunday, October 04, 2015

How unreliable is wind?

Someone on The Energy Collective suggested that 24/7/365 facilities like data centers could run on "renewable energy" (meaning unreliable wind and solar) by taking the first pick of power from a wind farm or other facility and letting others take the surplus.  Specifically, he said this:
The wind farm that HP is drawing from is 300 MW. If they get first dibs on generation,it's not out of the question that 95 percent of the time it will generate more than 112 MW which would be a 37 percent CF.
Is that true?  I decided to find out.

Here's a plot of Texas wind generation over March of 2014, courtesy EIA:

I cut this down to a 143-by-489 area (69927 px²) of just the plot itself trimmed down to the production maximum, and used Gimp's histogram function to measure the red area.  It came to 32026 red pixels.  If we assume that the production peak was 100% of nameplate (unlikely, but it's favorable to the case) that's a capacity factor of 45.8% for the month.

45.8% of the 143 pixel height is 65.5 pixels.  Cutting the graph down to 65 pixels from the baseline yields this:

The curve never quite goes to zero, but it gets close to it several times; it stays very low for an entire day.  Even the wind across the entire state of Texas, cut down to its capacity factor for the windy month of March, is not reliable enough to keep data centers running; the net capacity factor for the entire state of Texas is just 73.9%, far less than the 95% assertion of "wind smith".  The infrastructure of an information economy needs reliability more like 99.99%.

But what's left over?  Here's what that curve looks like:

In the windy state of Texas, in March 2014, the "leftovers" from preferred loads taking everything up to 45.8% of the peak has a capacity factor of just 22.1%.  It's a very spiky curve that has gaps lasting days when there is little or no power available.  What sort of business or process could anyone operate using power that was so unreliable?  I can't think of one.  Maybe you could dump this power to heaters or some other extremely cheap load, but what you'd do with the heat I'm not sure.  At one point I had the idea of using surplus electricity to heat crushed concrete, with the goal of dehydrating the cement and converting it back to separate streams of cement, sand and aggregate for recycling into new concrete.  I don't know if this is chemically possible (does hot cement react with sand or otherwise become inseparable and unusable?), but at 22.1% capacity factor the kilns and sifters and whatnot would have to be very cheap to make this a workable proposition and you'd have to get the power for close to nothing.

"Renewables" fanatics (maybe I should start calling them "windbags")  like to say that the wind is always blowing somewhere.  At least for Texas in the month of March 2014, that much was true.  However, there were many periods even in that blustery month where it was certainly not blowing hard enough to keep essential 24/7 things running.  When it comes down to e.g. pumping stations filling up and backing raw sewage into homes and buildings because the unreliables are not there that day, even the most fanatic Green is likely to burn fossil fuel instead.

The unreliable sources of energy are simply not going to replace fossil fuels.  They can't; their characteristics make it an engineering impossibility.  This is why Greens need to drop their contrived objections to those sources of energy which actually can.

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