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