Hi Jones, > In fact - it would seem from the experiments, that by just breaking this > bond in humid air, as much as 4,000 cal/mol of energy is released.
Absorbed you mean? Evaporating the (H2O)2 dimer into unbounded H2O's , like evaporating liquid water (combination of n-mers), should absorb energy rather than release some. You might want to reword your essay once you will have had that first latte :) Regarding capital cost of solar cell panels, Nanosolar and others are supposed to reduce it considerably by turning presently expensive solar panels into inexpensive roofing material but we don't really know to what extent, they haven't delivered yet. Michel ----- Original Message ----- From: "Jones Beene" <[EMAIL PROTECTED]> To: "vortex" <[email protected]> Sent: Monday, July 02, 2007 5:30 PM Subject: [Vo]:The H2O Dimer Free energy schemes are "a dime a dozen" these days .... Here's my 2 cents worth for near-Independence-Day (energy independence). Perhaps someone can raise the ante to a dime. The water dimer consists of two water molecules "loosely" bound by a hydrogen bond. It is the smallest water cluster found in water vapor or steam, but it does provide real structure to the gas phase, whereas the natural inclination is to assume that there is no structure at all in water vapor. The bond does have net extractable energy which can be replenished easily by exposure to sunlight. In fact - it would seem from the experiments, that by just breaking this bond in humid air, as much as 4,000 cal/mol of energy is released. The bond can be broken catalytically. This can provide "free energy" to the extent that the energy of recombination of the dimer occurs elsewhere than the point of energy release. IOW it might be possible to construct a Stirling-type engine where heat and cooling are both provided by water vapor structural changes, and the energy is recouped from sunlight by a simple translucent enclosure. Certain polymers (clear plastics) have enough heat resistance to be useful for this. Because it is the simplest model system for studying hydrogen bonding in water, the water dimer has been the target of many theoretical studies, the latest of which significant changes in the model. Paynter et al. conducted the first high-resolution laboratory measurements of infrared and microwave light absorption by water vapor. Their analysis indicates that dimers contribute greatly to radiation absorption by the atmosphere, significantly in excess of that predicted by other studies. For the purposes of global warming - this study and others indicates that the more water vapor which is held in the atmosphere, the more solar energy is absorbed and less is reflected. Many secondary implications follow from this. Title of paper: “Pure water vapor continuum measurements between 3100 and 4400 cm^-1:Evidence for water dimer absorption in near atmospheric conditions” Geophysical Research Letters (GRL) 2007 Structure and properties of the water dimer (partly from Wiki): The binding energy between the two water molecules is estimated to be 5-6 kcal/mol. The actual dissociation energy (including nuclear quantum effects) is most likely around 3.4 kcal/mol. The O-O distance of the vibrational ground-state is experimentally measured at ~2.98 angstrom; the hydrogen bond is almost linear, but the angle with the plane of the acceptor molecule is about 57°. (H2O)2 is thought to play a significant role in many atmospheric processes, including acid rain formation, absorption of excess solar radiation, condensation of water droplets, and chemical reactions. In addition, a complete understanding of the water dimer is thought to play a key role in a more thorough understanding of hydrogen bonding in liquid and solid forms of water. Commentary (green in more ways than one) which you won't find in Wiki: For the inventor or home power advocate, it 'might' be possible to provide simple rooftop solar collector which is a thousand times cheaper than solar cells per unit of area being covered (being similar to rooftop hot water heaters) and one tenth the net cost of the installation (per kw-hr) - where the only function of the collector is to "restructure" water vapor which has given up heat to a 2-3 kwhr Stirling engine located in the attic of the house- thus providing much of the daytime energy needs of the house (and some of the cooling), but at a fraction of the cost of solar panels. ... or nor. Since I haven't had that first Latte yet, this is just a passing thought for now. But one thing is true, at least in California - if you want a major "sticker shock" - just get a firm quotation, from an authorized contractor (not the BS seen on the internet) for an installed and guaranteed 3 kwhr rooftop solar panel system. Even if they come down in price by half, or two thirds in cost (unlikely), they will still be outrageous and not viable except for a small segment of the population. Jones
