Reference no: EM133097007
Exercise - Energy Resources
Explore the connection between society and its use of energy resources. In particular, you will examine how these resources are used and some of the associated environmental issues.
Part I - Coal Geology
Recall from the textbook that coal is a sedimentary rock that originates from decaying plant matter found in swamps. As illustrated in Figure 11.1, the buried organic matter first becomes peat, and is then transformed in coal as the peat becomes more deeply buried. As the temperature and pressure of burial increase, the coal becomes more concentrated in carbon, hence gives off more heat when burned. Grade refers to the amount of heat that a particular coal gives off. Lastly, note that because oxygen levels within swamps are typically low, heavy metals tend to bond with sulfur atoms, forming various sulfide minerals that end up in coal.
1) Provide an environmental reason why lower grade (sub-bituminous) western coals are now being heavily mined despite the fact that the Appalachia region still holds vast reserves of higher grade (bituminous) coal.
2) Note in Figure 11.2 that parts of Iowa, Missouri, Nebraska, and Oklahoma contain reserves of fairly high grade bituminous coal. Why do you think that very little of the coal in this region is being mined today?
3) Mountaintop removal of coal, shown in Figure 11.3, has become a very common and controversial form of strip mining in the Appalachia region of the eastern U.S. Think of some of some pros and cons of this method and record them in the space below.
Part II - Petroleum Geology
Petroleum refers to the collection of naturally occurring organic molecules consisting mainly of hydrogen and carbon atoms, hence the name hydrocarbons. Crude oil is composed of hydrocarbon molecules that exist in the liquid state, whereas gaseous hydrocarbons make up what is collectively referred to as natural gas. As illustrated in Figure 11.4, oil and gas accumulate in places where the molecules can become trapped within porous and permeable rock formations. The key to trapping oil and gas is the presence of an overlying impermeable layer that prevents the hydrocarbons from rising to the surface. Once located, an economical deposit is extracted by drilling a well. During the refining process, crude oil is heated in order to separate the various hydrocarbon molecules based on their density (natural gas requires only minimal refining). Products refined from crude oil include gasoline, diesel fuel, kerosene, motor oils, and grease.
5) Exploring for petroleum deposits is restricted almost exclusively to sedimentary basins.
Describe the geologic reason why oil companies rarely bother to explore in igneous and metamorphic rock terrain.
6) Explain the meaning of the "oil and gas window" label located on left side of Figure 11.4.
Well Blowouts
On April 20, 2010, operators of the Deep Horizon drilling rig in the Gulf of Mexico lost control of an oil and gas well when they were in the final stages of converting the borehole into a production well. This accident, and subsequent environmental disaster, highlights the inherent dangers of extracting oil and gas. As depicted in Figure 11.5, drilling operators keep the
borehole filled with a mixture of mostly water and clay, commonly referred to as drilling mud. The dense mud is pumped down through the drill pipe where it eventually exits out the drill bit. The mud then circulates back up the borehole toward the surface, carrying rock fragments that had been dislodged by the drilling bit. At the surface the mud is sent into a pit where the rock particles are allowed to settle out. The mud is then re-circulated back down into the well.
In addition to removing rock fragments from the well, the sheer weight of the drilling mud is crucial to keeping highly pressurized oil and gas from entering the wellbore (cement seals are later installed when the well is completed). If the drilling operator is unable to contain the pressure from within the rock formation, then oil and gas can quickly travel up the borehole and onto the drilling platform, resulting in what is called a blowout. Modern wells are equipped with a blowout preventer, which is a large safety device designed to quickly seal the well should the operator be unable to control the pressure within the hole. If the blowout preventer fails, as in
the case of the Gulf of Mexico disaster (Figure 11.6), it can lead to an intense fire that is extremely dangerous. Moreover, it can be quite difficult for the operator to regain control of the well, thereby resulting in a major release of crude oil into the environment.
7) The 2010 blowout in the Gulf of Mexico (Figure 11.6) occurred after the drilling operator replaced the drilling mud in the well with seawater during the final installation of the cement seals.
a) Assuming that the drilling mud had a density of 2160 kg/m3 (18 lbs/gal) and that the column of mud was 5486 m (18,000 ft) high, use the following relationship to calculate the pressure in kg/m-sec2 at the bottom of the well. The gravitational constant is 9.806 m/sec2. Be sure to show your math, including the units.
pressure = (density of mud) x (gravitational constant) x (height of fluid column)
b) Convert the pressure you calculated into pound per square inch (PSI) using the following relationship:
1 PSI = 6896.6 kg/m-sec2
8) Following the same steps as above, calculate what the pressure (in PSI) would have been at the bottom of the well after the driller replaced the mud with seawater. Here the height of the fluid column will again be 5485 m (18,000 ft), but its density is now 1025 kg/m3 (8.6 lbs/gal).
9a) How much did the pressure decline at the bottom of the well when the driller replaced the mud with seawater?
10) Describe whether you think the need for oil is worth the potential environmental damage and economic and social costs associated with a deepwater accident, or should the U.S. put
more emphasis on replacing its energy needs with renewable sources.
Part III - Energy Future
One of the realities of our energy usage is that world reserves of light (low viscosity) crude oil are finite. The concept of peak oil describes the fact that the number of new discoveries of light crude has already peaked, and that world production will at some point also peak and begin to permanently decline (Figure 11.7). There are, of course, abundant reserves of heavy crude and tar sands, but these deposits are much more difficult and expensive to extract. This means that the world's petroleum-based economies will ultimately become more expensive to operate as we continue to deplete our remaining reserves of cheap, light crude.
Another important issue is that our heavy use of fossil fuels (coal, oil, and gas) is releasing carbon dioxide (CO2) into the atmosphere, thereby exacerbating the problem of global warming. Ultimately then, society must switch to clean and renewable sources for much of our energy needs. In this section we will examine some of the inherent difficulties in moving from a fossil- fuel based economy to one that is more reliant on clean and renewable sources of energy.
11) Figure 11.8a illustrates just how dependent the U.S. is on fossil fuels for meeting its energy needs. Our most immediate problem is that world production of light crude oil will at some point begin to decline, making it more costly to run the U.S. economy.
a) What sector of the U.S. economy shown in Figure 11.8b do you think is the most dependant on crude oil?
b) Make a list of the areas within this economic sector that could be switched over to run on electricity and those that likely will require oil to continue to operate.
12) Recall from the text that electricity is a secondary rather than a primary energy resource, meaning it requires some other energy source to produce.
a) Describe the basic problem with trying to replace some of our need for oil by using electricity that is produced by burning coal.
b) Explain what needs to be done in order for us to use clean forms of renewable energy (wind, solar, geothermal, tidal, etc.) rather than coal to produce the additional electricity we need.
c) Large quantities of electricity can also be produced using nuclear power. Describe some of the problems with expanding the use of nuclear power in the U.S.
13) Figure 11.9 shows the location of existing coal and nuclear power plants in the U.S. A vast network of high voltage transmission lines, referred to as the electrical grid, carries electricity from the power plants to homes and businesses. This grid naturally expanded over time as new power generating plants came on line.
a) Explain why the electrical generating plants are not evenly distributed across the country.
b) What does the fact that the power plants are not evenly distributed tell you about the nation's electrical grid?
14) The maps in Figures 11.10 and 11.11 show the areas in the U.S. with the highest potential for developing wind and solar power. In terms of the electrical grid, what basic problem do you think must be overcome before wind and solar power can be developed on a large scale in the U.S.?
15) From Figure 11.12 you can see that China and the U.S. are by far the largest producers of carbon dioxide (CO2) in the world. This is because these two nations consume the most energy and they rely on fossil fuels for about 90% of their energy needs.
a) Explain whether or not you think it is possible for there to be an overall reduction in worldwide CO2 emissions without the cooperation of both the U.S. and China.
b) Notice that China's per capita emission of CO2 is much lower than that of the U.S. With a population of over 1.4 billion people and a rapidly growing economy, China's future energy needs will be enormous. Explain how this will affect China's ability to scale up renewable sources of energy so as to reduce its CO2 emissions.
Attachment:- Energy Resources.rar