Articles to 2013-08-17

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First the link to this week's complete list as HTML and as PDF.


Park & Brannon's result is not about approximate mental math, as I first thought, but about eyeballing, so their result is not as obvious as it first seems and reveals something deeper and more meaningful.


Forwood is a healthy reminder of unrecognized confounders. Of course the smaller the effect you’re studying, and those in the social sciences tend not to rise much above the noise anyway, the more relevant confounders become.


As it is well known that catalysts can move thermodynamic equilibria to any place you want them to be and as hydrogen is an inexhaustible fuel source, the world's seas are full of it, it seems that Wesselbaum et al. have finally solved the world's energy and hydrocarbon resource problems. Or else they've found a nice little earner for themselves by bamboozling law and economics graduates in civil service and defrauding the tax payer.


For Jensen, Henrich, and Proctor also see the list of 2013-02-11.


Opie et al. use a cogent approach for deciding between conflicting hypotheses objectively and quantitatively. I'm not convinced by their conclusion though: “These phylogenetic analyses support a key role for infanticide in the social evolution of primates, and potentially, humans.”. While other primate infants cling to their mothers' fur unaided and impede them very little, quite the opposite is true for humans. A human mother of a newborn will find it very hard to survive without the undivided attention of a male caring for them both. This peculiarity will have developed very early on the road to bipedalism and hair loss and have caused a strong selection advantage for caring, bonded fathers. This is supported by one of their findings being wrong for humans: “This finding hints at one mechanism by which social monogamy may reduce infanticide risk: social monogamy facilitates a shorter lactation period compared with gestation, thereby reducing infanticide risk. [...] In primates, paternal care is associated with a shortening of interbirth intervals and an increase in reproductive rates similar to that seen in birds and other mammals.” Also by their own measures, the human is the one line where monogamy could not have appeared through strongly counteracting conditions: “However, a switch to social monogamy may only be possible where ecological conditions permit. Other factors play a role in determining optimal grouping patterns: predation pressure drives up group size and resource distribution and habitat use also impact on group size and structure. Hanuman langurs and gorillas incur high levels of mortality from infanticide but also live in a habitat with high predation risk. The pressure to maintain cohesive social groups as an antipredator defense may render social monogamy a nonstarter.” Predation risk and group living were two main characteristics of savannah life centred on high quality nutrients and scavenging.


Reading them closely von der Assen et al. are quite open about the facts: Using CO2 as a chemical feedstock saves CO2 emissions overall if and only if the energy used comes from renewable or otherwise CO2-free sources. (Actually the wind power involved is fifteen times the power – that's sixty times in nominal power – of the one plant they are helping to decarbonize.) This means that any environmental or climate advantages of those power plants are already used up. They themselves can no longer have those assigned to them, thus no more subsidies or preferred treatment. That and the price for it must all be accounted for by the production claiming the benefits, which, unsurprisingly, is of course never done. Honest accounting, which is also done in another scenario of theirs, leads to a tripling of overall CO2 emission for the process compared to the conventional one. But it's all still well worth a pork barrel of subsidies from the ministry of science and education, isn't it?

Addendum (2019)

Originally I had only posted the assertion above and only given the derivation in a personal mail to friends. For the sake of completeness and verifiability I've now appended it here.

Dafür ist von der Assen um so aufschlußreicher, besonders gut zu sehen in seiner Abbildung 4b: Ein Braunkohlekraftwerk läßt sich immer dann CO2-arm betreiben, wenn man den Strom stattdessen aus Windkraft bezieht. Wie er in Tabelle 1(iv) klar auflistet und auf derselben Seite (scenario iv) auch deutlich ausspricht, führt die tatsächliche Methanolproduktion aus CO2 zur mehr als der dreifachen Kohlendioxidemission verglichen mit dem Standardprozess.

Ich habe mir das dort gezeigte Reaktionsschema noch einmal vorgenommen. Der ganze komplexe Ablauf entspricht in der Summe einem Braunkohlekraftwerk mit 14 kg-CO2 pro 1273 kWh. Über Preise reden wir nicht. Das Windrad ist dabei ein störender Fremdkörper. Wo Strom gebraucht wird, da nehmen wir doch gleich den, den wir haben. (N.B: Es fällt auf, daß Wasserstoff aus Elektrolyse mit billigem Strom nicht gemacht wird, also wohl ungünstig ist. Jetzt wird er hier kommentarlos aus teurem Windstrom erzeugt. Es ist damit klar, daß genau hier die Leiche versteckt sein sein muß.) Über die Größe des Windrades wird nichts gesagt. Für Wasserspaltung finde ich 570 MJ/kmol also rund 80 kWh/kg. Die Elektrolyse soll bis zu 80 % Wirkungsgrad haben, macht dann 100 kWh/kg. Der Prozess braucht 188 kg H2, also 18800 kWh, leider etwas mehr als die 1273 zur Verfügung stehenden. Wir brauchen also 14.8 Braunkohlekraftwerke, um netto keinen Strom zu erzeugen. Die 13.8 zusätzlichen haben keinen Abnehmer, emittieren also 13.8 mal 1090 kg CO2. Die 14 kg des letzten können wir getrost unter den Tisch fallen lassen, brauchen aber noch ein Kraftwerk mehr, damit netto Strom ensteht. Das sind dann 14.8*1090 kg für 1273 kWh oder ganz glatt das 14.8-fache des Standardprozesses.

Man kann die Sache auf eine zweite Art vereinfachen. Wir lassen das Braunkohlekraftwerk, zweimal den Methanolprozess und die Elektrolyse weg und übrig bleiben 188 kg CO2 für 18800 kWh, das sind 13 kg CO2 pro 1273 kWh. Mit anderen Worten das ganze Geraffel um das Windrad drumherum ist nichts als teure, überflüssige Augenwischerei, deren einziger Effekt es ist, die Summenbilanz minimal zu verschlechtern und 93 % des teuer gewonnenen Windstroms sinnlos zu vernichten.

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