PDS APES 5th Period 2009-10

Hey guys, I’m stumped. Question 7g on the study guide talks about how coal can be turned into a gas or liquid fuel (synfuels). First of all, it never explains how this is done. And second, this seems pointless to me because why would we want to coal to different forms if it costs more and requires more mining? Lastly, the book says that gas and liquid coal fuels produce less air pollution than solid coal when burned but more CO2 emissions. That is contradicting!  Any help would be nice.

Hey guys,

Looking over my study guide, I’m confused about the difference between net energy and efficiency. Is there a difference? As I understand it:

Net energy is the amount of energy available minus energy needed to extract/process/etc.

Efficiency is input= output/percent efficient.

Aren’t these definitions basically two different ways of saying the same thing–that the second law of thermodynamics ensures that heat will be lost in all reactions, thus input will never equal output, yet the degree to which energy is lost in the reaction varies?

Thanks!

Hey guys, so on the study guide, number 7 asks the four R’s of waste reduction and also notes that they need to be prioritized.  The order gave in the book didn’t seem like what we went over in class…and also Mr. Willard has been talking about redesign the past few days, and that was completely left out.  Mr. Willard…or someone else, if you could just please clarify the order…and where redesign fits in to the list? Thanks!

Okay, so I had a question on waste-to-energy incinerators.  Are all incinerators waste-to-energy? Do they all produce excess energy that can be used as electricity or for other uses?  I just didn’t know if there were special incinerators that were waste-to-energy or if they were all like that.  Also, in the book it says that these incinerators “boil water to make steam,” so does that mean after the waste has been burned there is water left over?  I’m just a little confused on the process, and the diagram 16-10 isn’t helping me much.

So in class, we’ve discussed how landfills are now the norm over incinerators due to the fact they are more convenient, less expensive and don’t release as many toxins into the air. So I guess my question is, why are incinerators still being built and used if the landfill is overall better for the environment? Is it a matter of convienience or cost? Thanks to anyone that can help!

Hi everyone! Ok so I have been looking at figure 16-10 for a while and need some explaining. So the trash is burned into ash, and then the heat from burning it boils water for energy, and then the ash is disposed of, but what is the Electrostatic precipitator? I guess I just don’t see where that fits in and what it does….and same with the fly ash? Any comments just clarifying would be great!

Hey guys. I was having trouble figuring out exactly how hazardous waste is treated PHYSICALLY and CHEMICALLY (question 17 on the study guide). I know that bioremediation and phytoremediation are both biological methods used to absorb and eliminate toxic wastes, but what else is there? Also, does physical treatment include placing hazardous waste in surface impoundments, deep-wells, and secure landfills? Any help here would be lovely.

Hey APES class!

Question 43 on the study guide asks for alternatives to synthetic pesticides. The book lists “natural enemies/biological controls” and explains that introducing a natural predator could help reduce the numbers of the pests. Granted, later in the paragraph the text qualifies this statement by acknowledging that sometimes introducing foreign species is disruptive to ecosystems. Nevertheless, I’m having a hard time reconciling this statement after watching Cane Toads.  Is this actually a legitimate solution, or is it sort of hit or miss? Are there any examples of this strategy working without the predator totally invading the habitat like in Cane Toads?

Thanks! -Coco

Number 3 on the study guide asks that if “we, humanity, produces more than enough food to meet the basic nutritional needs of every person on earth, why do one in six people in developing countries not get enough to eat?”  Food insecurity, or living with chronic hunger and malnutrition that threatens the ability to lead healthy and productive lives is one of the main topics the book brings up about this subject.  Poverty, war, and corruption also are reasons people have poor access to food.  Did we ever discuss why the US or other developed nations don’t take part in helping these poorer countries have food to survive?  I think we might have discussed this in class, but I thought since I was questioning myself on it, I would see if anyone else remembered what we said…thanks!

Question 32 on the study guide asks what is the most sustainable form of meat production/consumption, and I wrote down that shifting from animal protein (like beef or pork) to poultry or herbivorous farmed fish would be the most sustainable form, but I don’t really understand why.  Is it because less grain is used to feed the animals, which will help the environment by reducing the large-scale agriculture?  

Also, question 35 asks about bycatch. We learned about that from the movie, but I wrote down that because it isn’t profitable, it is chopped up and pumped back into the ocean, which we didn’t see in the movie.  The bycatch, such as the shark, was just thrown back in dead but as a whole animal, so I was just wondering if those are just two different ways to dispose of bycatch, or if I’m misunderstanding what I wrote from the book.