Message no. 723[Branch from no. 720] Posted by Thomas Culhane (1311520071) on Wednesday, March 28, 2007 5:04pm Subject: Dust devils
Pat, I was just at an exhibit at the German Science Museum in Munich today that talked about glass making and new environmental safeguards to prevent toxic dust used in glass from getting into the air. They use an electrostatic process here.
There are websites that give a better description of the process than I can give. Here is an industrial site: http://www.elex.ch/E/html/elektrofilter.html Basically they use electrons to give dust particles a negative charge and then the dust sticks to a positively charged wire or surface for wash down.
Home HEPA filters do the same thing, though there is controversy over which perform best http://www.stretcher.com/stories/00/000117b.cfm
Interestingly, the International Energy Conversion Conference (which I presented at last summer in San Diego) had a paper about using this technique for Martian dust back in 1997, so there is work in this area. The abstract can be found here:
Mars dust removal technology Landis, G.A. Energy Conversion Engineering Conference, 1997. IECEC-97. Proceedings of the 32nd Intersociety Volume 1, Issue , 27 Jul-1 Aug 1997 Page(s):764 - 767 vol.1 Digital Object Identifier 10.1109/IECEC.1997.659288
Summary:The Mars atmosphere contains a significant load of suspended dust. Settling of atmospheric dust onto the surface of the solar array is potentially a lifetime limiting factor for a power system on any Mars mission. For long-term operation of arrays on Mars, it may be necessary to develop techniques to remove deposited dust. Dust is expected to adhere to the array by Van der Waals adhesive forces. These forces are quite strong at the dust particle sizes expected. If the array surface is insulating, it is possible that they may also be subject to electrostatic adhesion, which may be extremely strong. Dust removal methods must overcome this force. Dust removal methods can be categorized briefly into four categories: natural, mechanical, electromechanical, and electrostatic. The environment of Mars is expected to be an ideal one for use of electrostatic dust removal techniques.
Hope that helps!
Message no. 724[Branch from no. 694] Posted by Thomas Culhane (1311520071) on Wednesday, March 28, 2007 5:28pm Subject: Re: Adrienne Relational Summary
Nice summary Adrienne! Seems you have had a lot of experience with extreme weather environments!
One good thing about strong winds, of course, is that they can be captured, as you have pointed out, and used as a source of energy. The most interesting aspect of future urban design for me is the deliberate use of the wind tunnel (venturi) effect that the book mentions, to generate electricity. We know that buildings and city streets concentrate the winds power, but now some great engineers are looking at ways to turn this from a hazard into a blessing.
There are even competitions now for the constructions of do it yourself urban and rural home windmills. http://www.gotwind.org/index.htm http://www.gotwind.org/Entrants.htm
I installed a small Air403 (http://nooutage.com/air403.htm) on the roof of a friends apartment in the slums of Guatemala and put another one up at the Wadi Environmental Science Center in Egypt. They work great.
You can learn all about building integrated wind generators here
Here is what they would look like in a city building;
As for worrying global warming -- you must see Al Gore's film "An Inconvenient Truth". It is the most informative explanation of the crisis yet.
By the way, don't confuse the depletion of the ozone layer with global warming from carbon dioxide! They are different phenomena! The ozone layer is a layer of special oxygen (03, not 02) in the stratosphere that protects us from cosmic radiation by attacking like a shield. The hole in the ozone layer does contribute to global warming but is not the cause. The ozone hole is most dangerous because of the risk of skin cancer and blindness (not just among us, but all animals) which would most horribly prevent bees and other insects from pollinating crops leading to a collapse of our agricultural system (we can wear sunglasses, they can´t!). Global warming by CO2 is a condition where our pollutants trap heat IN the earth (ozone keeps radiation OUT). So while both contribute to warming, they act in opposite ways!