PDS APES 5th Period 2009-10

Using hydrogen to create electricity is an innovative process that is currently in the research and development stage. We may hear about hydrogen power being prevalent in countries like Iceland, but it will be some time before hydrogen power becomes large scale. Nevertheless, many believe hydrogen to be the major energy carrier for the future. Notice I said  that H2 is an energy carrier, not an energy source (like oil, coal & natural gas). This means means we can’t burn H2 like oil to create energy.

A hydrogen fuel cell is a device that creates electricity via electrochemical conversion. These cells are currently used to power hydrogen automobiles. To put it simply, a fuel cell performs this equation:

H2 + O2 —-> H2O

In the process hydrogen is split into its proton and electron, and ELECTRICITY is generated. Water is then created as a by product when the hydrogen combines with an O2 molecule. Click on this link to see an excellent simulation of the reaction going on inside a hydrogen fuel cell: http://videos.howstuffworks.com/ballard/651-ballard-shows-how-a-fuel-cell-works-video.htm

Be sure to recognize that multiple fuel cells must be stacked together into fuel cell stacks in order to generate more power.

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So how exactly do we obtain the hydrogen to store in automobiles? This is where the process of electrolysis comes in. This process essentially performs the reverse reaction of a fuel cell:

H2O —-> H2 + O2

Electricity is used to separate the atoms of a water molecule in order for us to gather the H2. But this electricity used may result from burning fossil fuels; therefore, a carbon footprint can exist in the hydrogen power process although it is not a direct result of using hydrogen fuel cells. (Note: hydrogen can also be gathered by separating methane (CH4)…but this process creates CO2)

Pros of Hydrogen Fuel Cells:

-only emission is H2O

-H2 is the most abundant element in universe

-reliance on hydrogen power lessens reliance on fossil fuels

Cons:

-H2 is volatile

-must expend energy to harvest from thins like water

-lack of infrastructure (hydrogen fueling stations are extremely expensive)

-only in the research and development stage

-H2 in the stratosphere depletes ozone

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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. 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.

In class last Friday, we had a class “conversation” in which we discusses the pros and cons of Genetically Modified Organisms.

According to our textbook, a GMO is an organism whose genetic makeup has been altered by genetic engineering (inserting alien genes to obtain a beneficial genetic trait). These are also referred to as transgenic organisms. GMFs (genetically modified foods) are a sub-category of GMOs.

Gene Splicing is the process by which a gene of one organism is transfered to another (http://www.mhhe.com/biosci/genbio/virtual_labs/BL_22/BL_22.html). This technology began in the 1980s and has become more prevalent over the years.

Pros and Cons of GMOs (Summarized)

Pros:

• Allow for more production which leads to cheaper food for consumers
• Crop resistance to pesticides and herbicides provide chemical companies (“cide” producers) with a business opportunity and contribute to the first point
• This technology and/or the crops the GMOs themselves can be used to feed developing nations***(1)
• Commercial farmers prosper economically by spending less money on more crops
• Some GMFs (corn) are grown rapidly, then used to feed livestock (helps them grow bigger and faster)
• Mass production allows Americans the luxury of “picking and choosing” from a large food variety

Cons:

• Word hunger has risen despite rise in GMO use
• Large scale, GMO dependent agriculture pushes smaller farmers out of business
• Gene flow along with the mating of GMOs and wild species poses problems***(2)
• Lead to more pesticide and herbicide use (more “harmful” mutagens, carcinogens, teratogens, etc.)
• Companies like Monsonto create terminator genes (ensures that their bioengineered plants had no progeny). This forces farmers to buy new seeds year after year rather than reuse.
• Expensive technology
• Massive amounts of land needed to cultivate GMFs (leads to habitat destruction and biodiversity loss)
• Moral controversy (Do humans have the right to “play GOD”?)

***Explanations:

1. This can also be a con. It can also be argued that if developed countries simply ship this abundance of food (due to GMOs) to developing countries, then farmers in these nations will lose business opportunities which could lead to more poverty.
2. Two examples: a-legal disputes can arise if patented genetically modified seeds blow to an “unauthorized” neighboring farm (Maonsonto vs. Schmeiser).  b-mating of transgenics and wild species could cause offspring to be susceptible to viruses (could wipe out species).

A Few GMO Examples:

Liberty Link Corn has been genetically modified to be herbicide resistant.

The salmon in the back has been genetically modified to grow faster.

Final Note:

Does the consumption of GMOs come with long term health risks? The answer: None have been scientifically proven; however, this technology is fairly new.

Hi guys, take a look at question number 9 on the study guide if you will. I am confused about the equation (%) System Reliability = Technology Reliability  x  Human Reliability. First and foremost, what is the point of this equation…it seems relatively meaningless to me. Second, how do we come up with the values for human reliability and technology reliability (it seems pretty subjective). Lastly, what is another good example where this equation can be used besides the crash of the Colombia Space Shuttle?

I feel like we may have mentioned this at some point, but which type of cutting should we focus on doing. I would think selective cutting is the best because it does not fragment a habitat; however, I remember reading that selective cutting in rain forests for example is bad because pants connected or dependent upon theses trees suffer too (everything is too connected). We must have lumber, so what is the best thing to do? More tree farms could work, but they could ultimately be destructive by damaging the soil. Overall, what is the best way to get the wood we need?

Can anyone explain the difference between a stewardship worldview and an environmental world view? They seem too similar to distinguish between the two. Which one would apply where in the environmental history of the United States?

Hey guys, I am having trouble remembering what potentially renewable resources are. I know that the non-renewable resources exist in the Earth’s crust in finite quantities. And that renewable ones are things like water and sunlight. What is in the middle? Any help would be great. Please provide some examples too if you don’t mind. Thanks!

Hi class mates. I have two questions, both of which should be relatively easy to answer. For some reason, I am having trouble understanding the #/1000 part of crude death and birth rates. Why do we do this again? and what are some typical numbers of CBR? Is it true to say that if these are equal then their is no pop growth (excluding emigration and immigration)? Also, what exactly would prevalent AIDS in a nation do to its pop. graph? I know these may seem simple, but I just want to make sure I have them right.

I’m a bit confused about how a population of a species reaches its carrying capacity. To be more specific, will a population always overshoot the carrying capacity of the ecosystem and the crash? Or can populations reach carrying capacity without overshooting it? Any help is appreciated.