Latest from: CleanTechnica
Posted: 28 Apr 2012 07:27 AM PDT
The experience of residents living near the Puna Geothermal Venture (PGV), about 20 miles south of Hilo on Hawaii?s ?Big Island?, raises serious questions about the environmental health and safety of geothermal energy and power plants. Longstanding residents of area around PGV?s geothermal plant? now being expanded? were given a long overdue public hearing on geothermal energy recently at a special session of the Hawaii County Council in Pahoa.
Their well-documented, well-presented testimony provides details of the history of what?s now the PGV geothermal energy plant?s development and operations over the decades since it first began producing electricity. It?s not a pretty picture. In fact, it?s very disturbing.
Open venting of geothermal gases and liquids rife with toxic chemicals and heavy metals, poor environmental monitoring, control and reporting, corporate lies, lax oversight and a particularly troubling, even seemingly nonchalant disregard for residents? repeated requests to local government and state authorities to investigate their concerns and claims command attention and raise very serious environmental health and safety questions regarding geothermal energy?s credentials as a ?clean, green? energy source.
Hawaiian government and electric utility HECO (Hawaii Electric Light Co.) are looking to significantly exapnd geothermal energy production. Hawaii, as well as other states and countries around the world, have very substantial geothermal energy resources, and they are looking to develop them as sources of clean, stable, long-lasting electrical power. The benefits of doing so need to be comprehensively, honestly and openly assessed and considered, however, against the costs, and I?m talking here not about the financial costs, but about the long-term, possibly irreparable threats and damage to human and other forms of life, as well as land, water and air.
Geothermal energy technology has come a long way since the 1970s, but if the experience described by residents living near the PGV plant is a reliable indication? and it seems to be? geothermal energy developers such as Ormat Technologies, which operates PGV, along with utilities and local authorities need to respond truthfully, comprehensively and quickly to Hawaiian residents? legitimate concerns if they care to preserve their own credibility and legitimacy.
Watch the Big Island Video News video of the PGV geothermal plant resident group?s presentation via this hyperlink. Thanks to Oahu News for posting this. And thanks to this determined, civic-minded group of residents who have fought so long to have their voices heard and their legitimate concerns addressed.
The issues they raise need to be addressed, and they stand to benefit not only themselves, but residents living near geothermal plants everywhere, as well as the geothermal, clean energy and clean tech industries in the US and worldwide. That?s if their voices and actions are given the consideration they deserve.
Posted: 28 Apr 2012 05:58 AM PDT
princeton teams with air force and navy on biomimicry solar cell researchA team of scientists headed up by Princeton University has achieved a whopping 47 percent increase in electricity generation from flexible plastic solar cells, simply by texturing the surface to mimic the wrinkles of a typical leaf. The biomimicry approach has resulted in a low cost, elegant solution for polymer-based solar cells, which are relatively cheap to manufacture but don?t pack the efficiency punch of typical silicon solar cells.
Navy and Air Force support solar research
By now it should come as no surprise that the U.S. Navy and the U.S. Air Force have provided funding in support of the Princeton biomimicry research, as the Department of Defense aggressively transitions to solar energy and other low cost, reliable alternatives to fossil fuel. The National Science Foundation also chipped in, and the University of Pennsylvania contributed to the research.
Plastic solar cell efficiency on the rise
Polymer (aka plastic) solar cells are notoriously inefficient compared to silicon solar cells, but what they lack in punch they make up for in flexibility, durability light weight and above all, low manufacturing costs.
Lately the efficiency of polymer solar cells has been creeping closer to the commercial viability level. In one new development, a team from UCLA achieved a 10.6 percent efficiency, putting it just within the desired range of 10-15 percent. One more tweak and the technology could just about make it ? and according to the Princeton team, their biomimicry solution could be applied to almost any kind of plastic solar cell.
The biomimicry solar cell solution
In a report from Princeton University, the principal investigator on the research team, Yueh-Lin Loo, explains the simple principle behind the biomimicry solution. The surface was manipulated to create channels similar to those found in leaves:
?On a flat surface, the light either is absorbed or it bounces back. By adding these curves, we create a kind of wave guide. And that leads to a greater chance of the light?s being absorbed.?
Mimicking nature to make light channels
In practice, the folding technique involved a complicated mathematical exercise. The team used an aerospace engineering lab to develop a technique for introducing different levels of stress to a layer of liquid photographic adhesive. Depending on the rate at which the liquid was allowed to dry, shallow wrinkles and deeper channels or folds were formed.
The team found that a mix of wrinkles and folds performed better than texturing the surface with only one or the other. In fact, the textured surface performed even better than the researchers predicted for the long (red) end of the light spectrum. Absorption at this end is a particular challenge for conventional solar cells, and the textured surface increased it by about 600 percent.
According to Loo, despite the fancy mathwork the actual fabrication process is fairly practical as applied to commercial development, especially for portable solar power applications such as solar powered backpacks and other wearable items, which are of increasing interest to the U.S. military.
Image: Frank Wojciechowski (via Princeton University).
Follow Tina Casey on Twitter: @TinaMCasey.