Microwave zapping kills invasive species before the invasion
May 12, 2008
Scientists have developed a microwave heating system for ballast water treatment that could help rid waterways of invasive species, such as the zebra mussel (above), that annually cause billions of dollars of infrastructure damage. Courtesy of the U.S. Fish & Wildlife Service
Scientists in Louisiana are reporting development and successful testing of a new cost-effective system to kill unwanted plants and animals that hitch a ride to the United States in the ballast water of merchant ships.
These so-called “invasive species,” such as the notorious zebra mussel, devastate native organisms and infrastructure and cost taxpayers billions of dollars annually. The study is scheduled for the June 1 issue of ACS’ Environmental Science & Technology.
In the study, Dorin Boldor and colleagues point out that invasive species often travel in ballast tanks of international cargo ships. Ships pump sea water into these tanks for stability when a vessel leaves port with little or no cargo. They dump the water at their destination — along with zebra mussels, Asian clams and other organisms that may pose environmental risks.
The new study describes development and laboratory-scale tests of a continuous microwave system which, much like a kitchen microwave oven, used heat to inactivate zooplankton, algae, and oyster larvae in salt water.
Researchers found that a 30-second zap, followed by a 200-second holding period, removed all marine life. Boldor noted that the high heating rates, low operating costs, and effectiveness in hazy water distinguish it from conventional heating methods.
Source: ACS
16 hours ago |
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To heat 100.000t of water (normal cargo ship or small tanker) by 50K, you need 20TJ, which are the full 1400MW output of a big nuclear plant during 4 hours.
Plus the losses when producing the field from electric power - usually 50%, neglected in the paper. 80% is the fraction of the field power coupled into water. That is, you need to cool down another 1400MW of magnetron losses as well.
If you put a heat exchanger to reduce consumption, then you can just as well burn natural gas in this exchanger - no need for a RF field.
And the best is: these figures about energy consumption are in the paper - only not fully developed.
This is more energy than the whole travel consumes, and probably more than building a new boat consumes.
What do they mean by further progress on efficiency and costs? Do they plan to invent a better sea water?
Complete CRAP. I can't imagine how ACS accepts to publish this kind of things. Offer them a pocket calculator.
http://pubs.acs.o...752.html
even when thermal effects are minimal, will interfere with organism's ability to reproduce properly - thus reducing that specie.