This is the tag cloud generated from the abstracts of my first four published journal papers. I hope to add a submitted paper to it soon. The word cloud was generated by Wordle.
Washing treatment of automotive shredder residue (ASR)
37 minutes ago
The non-random ramblings of an environmental engineering graduate student. Topics cover science, engineering, policy and other miscellaneous garbage.
Webb will find the first galaxies that formed in the early Universe, connecting the Big Bang to our own Milky Way Galaxy. Webb will peer through dusty clouds to see stars forming planetary systems, connecting the Milky Way to our own Solar System.
First, the author, James Lewis,[sic] leads the reader to believe that since a biobased material will quickly biodegrade under aerobic conditions, such as composting, that it will also do so under the anaerobic conditions found in landfills.Firstly, all publicity is good publicity IF they spell your name right. Secondly, this statement is not at all based in fact. Our results for the methane generation from PHBO were based on anaerobic reactor studies of PHBO published in Biomacromolecules in 2002 (Federle et al, 2002). We spend 400 words describing exactly how this was done in the section of the paper entitled Modeling of Individual Waste Components.
Firstly, our calculations were performed on a per mass basis, which means we calculated the amount of greenhouse gas emissions per ton of waste discarded in a landfill. Therefore, it makes no difference that other waste materials are landfilled in greater amounts. Secondly, it's irrelevant from a planning perspective because we can't substitute biodegradable plastics for food waste or yard waste or paper, which constitute traditional biodegradable materials. The fact that some of those materials may emit more methane (which we quantify and discuss in the paper), is completely irrelevant since those materials perform completely different functions. People can't substitute food for bioplastics, so it doesn't matter from a decision standpoint that food waste may lead to more emissions.---
There are bio-based, non-biodegradable bioplastics -- such as bio-based versions of PET and polyethylene -- that do not produce methane because they are not biodegradable, explained the association. They, however, constitute a significant proportion of the current bioplastics production.Firstly, it should go without saying that “non-biodegradable plastics” are not biodegradable, and therefore not being referenced in the title of the manuscript. Secondly, our study's only mention of bio-based non-biodegradable products was to say that they would lead to the least greenhouse gas emissions in a landfill.
These results suggest that for a national average landfill, in which not all gas is collected and converted to energy, optimal performance would be achieved for biogenic materials that are recalcitrant under anaerobic conditions.So, these materials are out of the scope of the question asked in the title of paper, and we still addressed the fact that they are preferable from a greenhouse gas emission standpoint. Perhaps, instead of criticizing our work they should be highlighting the fact that we have shown the benefits of bio-based, non-biodegradable plastics which "constitute a significant proportion of the current bioplastics production".
In addition, biodegradable and bio-based materials do not all behave the same way under landfill conditions.... In sanitary landfill the moisture level is low and not conducive for biodegradation as shown by some studies.Once again we have a problem of definitions. The U.S. FTC states that claims of "biodegradable or photodegradable should be substantiated by competent and reliable scientific evidence that the entire product or package will completely break down and return to nature, i.e., decompose into elements found in nature within a reasonably short period of time after customary disposal". I do not see how a compelling case can be made that a material that is in a landfill is "not conducive for biodegradation" degrades "within a reasonably short period of time after customary disposal". Landfills may not be considered customary disposal of these materials in Europe, but that is certainly not the case in the U.S.
|Greenhouse gas flows in a landfill.|
|Greenhouse gas emissions from materials disposed in national average and state-of-the-art landfills. (Units and colors have changed for readability).|
|Greenhouse gas emissions from hypothetical biodegradable materials versus decay rate. (Units and colors have changed for readability).|
Rationally, we should all fear climate change. It threatens our occupation of this planet within a century. This, rather than nuclear power, is what keeps me awake at night.
The biggest contributor to climate change is coal. Renewables alone cannot displace coal quickly enough. But nuclear power plus renewables can, with minuscule risk. The only rational response is to be open to the further deployment of nuclear power, in partnership with growth in renewables.
By contrast, we do not have to worry about terrorists stealing wind turbine blades or earthquakes shattering solar panels. It is quite rational to see nuclear energy as a high-risk approach.Things may be different in Australia, but I disagree with this because the real comparison is between nuclear and coal. Nuclear and coal both provide baseload power, and a shift away from nuclear, especially in this political climate is a shift towards coal. And, I haven't seen anyone make the case that the risks associated with coal are less than those associated with nuclear. According to the Clean Air Task Force:
Specifically, Abt Associate’s analysis finds that fine particle pollution from existing coal plants is expected to cause nearly 13,200 deaths in 2010. Additional impacts include an estimated 9,700 hospitalizations and more than 20,000 heart attacks per year. The total monetized value of these adverse health impacts adds up to more than $100 billion per year.And this doesn't even include the climate impacts associated with coal use or the damage done by mountaintop removal, or the risks that coal miners face everyday. It was only a year ago this week that 29 coal miners died in the Upper Big Branch Mine in West Virginia, and that certainly lead to an international discussion about whether we need to shutter global coal plants. It's also been well documented that living near a coal plant will lead to higher radiation doses than living next to a nuclear plant operating under U.S. regulations.
Experts will identify opportunities for improvement, and conclude that the best option for clean, industrial strength base-load power remains nuclear energy.Finally, the last commenter is Beverley Raphael, who is a psychiatrist and international expert on the impact of disasters on mental health. She focuses mostly on understanding the psychological and sociological foundations of Japan's nuclear fears. She also rightly points out that people don't tend to quantitatively evaluate risk. We assess risk on a very emotional level. I don't really disagree with what she says, and her viewpoint is interesting, but it avoids the real question in my mind about what the future of nuclear power should be and how acceptable the risks actually are.
We all live with risk. We pursue risk as "thrill". Life involves the balancing of risks for the present and the future. This is part of our resilience, as individuals, as nations. We feel for, and with, the people of Japan, for whom such threat is so painfully evocative of their history.