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Earth Talk
EarthTalk®
Written by the Editors of E/The Environmental Magazine   
Wednesday, 08 September 2010 08:05

Dear EarthTalk: Is there any way to harness volcanic energy to meet our electricity and other power needs? -- Antonio Lopez, Chino, CA

The short answer is yes: Heat generated by underground volcanic activity can and has been harnessed for electricity for over 100 years around the world. Utilities can capture the steam from underground water heated by magma and use it to drive the turbines in geothermal power plants to produce significant amounts of electricity. Getting at the sources is not so easy or cheap, though, as it requires drilling into unstable sections of the Earth’s crust and then harnessing the heat energy miles below the surface.

Despite these difficulties, volcanic geothermal energy reserves account for about a quarter of Iceland’s energy consumption (with the rest taken up by another clean renewable resource, hydropower dams). According to statistics from the Geothermal Energy Association, the Philippines is also a big user of geothermal power: About 18 percent of that country’s electricity comes from underground volcanic sources. And in New Zealand, geothermal accounts for about 10 percent of total electricity consumption.

 
EarthTalk®
Written by the Editors of E/The Environmental Magazine   
Monday, 30 August 2010 13:47

Dear EarthTalk: What are the differences between farmed versus wild salmon when it comes to human and environmental health?     -- Greg Diamond, Nashville, TN

Salmon farming, which involves raising salmon in containers placed under water near shore, began in

EarthTalkSalmonFarming

"Ocean advocates would like to end fish farming and instead put resources into reviving wild fish populations. Pictured: a salmon farming operation in Chile. Credit this image to "Sam Beebe, EcoTrust."

 Norway about 50 years ago and has since caught on in the U.S., Ireland, Canada, Chile and the United Kingdom. Due to the large decline in wild fish from overfishing, many experts see the farming of salmon and other fish as the future of the industry. On the flip side, many marine biologists and ocean advocates fear such a future, citing serious health and ecological implications with so-called “aquaculture.”

 
EarthTalk®
Written by the Editors of E/The Environmental Magazine   
Monday, 23 August 2010 13:40

Dear EarthTalk: Should I fear radiation exposure associated with medical scans such as CT scans,

EarthTalkCTScans
"Critics of the health care industry
postulate that our society's quickness
to test for disease may in fact be
causing more of it, especially in the
case of medical scans. The radiation
dose from a typical CT scan is 600
times more powerful than the average
chest x-ray."I
mage courtesy of"Getty
Images."

 mammograms and the like?       -- Shelly Johansen, Fairbanks, AK

The short answer is…maybe. Critics of the health care industry postulate that our society’s quickness to test for disease may in fact be causing more of it, especially in the case of medical scans. To wit, the radiation dose from a typical CT scan (short for computed tomography and commonly known as a “cat scan”) is 600 times more powerful than the average chest x-ray.

A 2007 study by Dr. Amy Berrington de González of the National Cancer Institute projected that the 72 million CT scans conducted yearly in the U.S. (not including scans conducted after a cancer diagnosis or performed at the end of life) will likely cause some 29,000 cancers resulting in 15,000 deaths two to three decades later. Scans of the abdomen, pelvis, chest and head were deemed most likely to cause cancer, and patients aged 35 to 54 were more likely to develop cancer as a result of CT scans than other age group.

Another study found that, among Americans who received CT scans, upwards of 20 percent had a false positive after one scan and 33 percent after two, meaning that such patients were getting huge doses of radiation without cause. And about seven percent of those patients underwent unnecessary invasive medical procedures following their misleading scans. CT scans are much more common today than in earlier decades, exacerbating the potential damage from false positives and excessive radiation exposure.

 
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