PUAF 741

Global Environmental Problems

Spring 2006

Problem Set #2

Due: 15 February
1.

In Chapter I of Harte, read problem 1 and estimate how many dental hygienists there are in the United States.

 
2.

In chapter I of Harte, read problem 4 ("Exhausting Fossil Fuels (I)"). Redo Harte's calculation for oil and do exercise 1 using the current consumption rates of coal and natural gas you calculated in problem set 1, assuming that the "estimated stocks" given in Appendix VII.2 are the remaining stocks of these resources.

 
3.

In chapter I of Harte, read problem 7 ("Sulfur in Coal") and do exercise 1 for mercury only. Compare to the value I gave in the first class.

 
4.

In appendix VI of Harte, we find that 29,000 trillion cubic meters of water is stored in the world's ice--almost all in Antarctica and Greenland ice sheets. If this ice melted, roughly how much would sea level change? HINT: assume the area of the ocean remained unchanged. EXTRA CREDIT: Compare this sea level rise to the elevation above sea level of a common landmark.

 
5.

The specific heat of water is 1 calorie per gram; this means that it takes 1 calorie (4.184 J) to raise the temperature of 1 gram of water 1 C. Referring to the information provided class notes, calculate the flow of water, in cubic meters per second, necessary to operate a power plant producing 1000 megawatts of electrical power using (a) coal, (b) geothermal, (c) ocean thermal energy. Compare each to the average flow of the Susquehanna River. What do you conclude? HINT: The class notes give the efficiency for converting heat to electricity for given source (hot) and sink (cold) temperatures. Use the efficiency to calculate the amount of heat energy per second needed to generate 1000 MW of electrical power. Then calculate the amount of heat energy extracted when cooling 1 cubic meter of water from the source to the sink temperature. Combine the two to get the needed flow of water.

 
6.

On average, how many of the hydrogen atoms in Caeser's last drink will you drink in your next drink? HINT: Estimate the size of a drink and the number of H atoms in it, and the fraction of water molecules contained in a drink.