Date: Jan 23, 2013 5:27 PM
Author: Rich Delaney
Subject: Re: honeycombs

On Jan 22, Salmon Egg <Salmon...@sbcglobal.net> wrote:
> > > I saw a news item about a new technique to draw CO2 from
> > > the atmosphere.  It's a chemical process, using amines,
> > > which binds with the molecule, coated on a large structure,
> > > in the shape of a honeycomb.

>
> > > According to the story, this maximizes surface area.
> > > ok, mathematicians, which function gets optimized by a
> > > honeycomb?  What are the constraints and assumptions?

>
> > 2D problem to *minimise* the surface area to occupy a given volume. Bees
> > use it to make honeycomb with the least amount of wax.

>
> > It is not difficult to show that the angle between sides must be 120
> > degrees and that equal lengths minimise total length/area occupied.

>
> > They have the structure just about as wrong as it is possible to be
> > unless the stuff they are making it out of is extremely precious.

>
> > The 3D problem to occupy volume with a foam of minimum surface area is
> > far more interesting and gives rise to Plateau's laws of soap films. The
> > Kelvin foam structure was optimal until fairly recently when
> > Weare-Phelan discovered a 3% better solution using a pair of shapes. A
> > whole new family has been found but as yet a proof of optimality eludes.

>
> This concept of honeycomb is crazy. True, the area of the honeycomb is a
> relativity efficient way of getting large reactive area to convert CO2
> to something that can be safely sequestered.
>
> How are you going to get the zillions of tons of amines the OP thought
> would be a suitable reactant? How much CO2 is sent into the atmosphere
> to prepare the amines? The honeycomb math problem is a red or even
> infrared herring.


The chemistry, I don't know. I was asking about
the optimization problem.

Anyhow, the inventor, Global Thermostat, has funding,
and a working prototype.

--
Rich