Alternative Energy Demystified, 2nd edition

Stan Gibilisco

Explanations for Quiz Answers in Chapter 14

1. Aeroelectric energy exists in the earth's "atmospheric capacitor," between the surface and the ionosphere (extreme upper atmosphere). A power-generating plant based on this source could theoretically work at night; it would not rely on wind; it would work in storms or outside of them. The main limitation that this technology shares with wind and solar energy systems lies in the difficulty of storing the electricity on a large scale. The correct choice is B.

2. One of the outstanding assets of geothermal power plants is the fact that they can desalinate seawater. The process literally distills the seawater when it's pumped down into the earth. The earth's interior heat boils the seawater to produce steam, which comprises pure water vapor. When this vapor condenses, we end up with drinkable liquid water! The correct choice is C.

3. Methane, commonly known as "natural gas," doesn't necessarily burn more slowly than other fuels, so choice A won't work. Nor does it burn cooler than other fuels, necessarily, so B is wrong. Methane is generally more explosive than other fuels (except pure hydrogen gas), so C is wrong as well. That process of elimination leaves us with choice D, which is correct: Most cities of reasonable size, in the developed countries at least, already have methane pipelines, so delivery in those locations would pose no new obstacles to deployment of methane as a source of energy for home-based and other small-scale fuel-cell electric generating systems. Again, the answer is D.

4. Even though the earth-ionosphere supercapacitor extends over the entire planet, it doesn't contain enough energy to come anywhere near providing for the electric-energy needs of the whole world. In fact, it could only do for a medium-sized (or smaller) town. The only response that works here is choice A.

5. Geothermal power plants derive their energy from the earth's internal heat. We would be assured of such an environment on the slope of any active volcano, because of the proximity of hot magma beneath the surface. (Preventing destruction of the plant's hardware might pose quite a challenge, but at least we'd have plenty of raw energy available!) We'd have no such guarantees on the Antarctic ice sheet, the Arctic tundra, or the Gulf of Mexico. The correct choice is B.

6. Biomass fuels come from biological matter, usually (but not always) processed in some way. Wood, sewage, and microalgae all fall into this category. The correct choice is therefore D, "All of the above."

7. Of the three types of matter listed here, only wood is a fuel source that lends itself to direct burning for energy. The correct choice is A. You might suppose, for a moment, that choice B will work as well. In the olden days on the American Great Plains, people actually burned dried-out cow or bison manure ("cow pies" or "buffalo chips") to heat their homes and cook their food, because wood wasn't available in sufficient quantities. However, dried manure isn't the same thing as sewage. Once again, the answer is A.

8. In most binary-cycle geothermal power plants, the binary liquid resembles a refrigerant or coolant. Some systems use water. Oil, conventional diesel fuel, biodiesel fuel, or gasoline never play this role! The correct choice is C.

9. Depending on the particular type of biomass, combustion can pollute the air with any or all of the three substances given in choices A, B, and C. The correct answer is therefore D, "All of the above."

10. When a geothermal power plant is not well designed, pumping fluid down into the earth can result in the release of toxic gases (such as methane) into the atmosphere. The correct choice is B. No geothermal power plant has ever been known to cause a volcanic eruption, so choice A is wrong. No power plant can ever produce "too much" electricity. More often, the problem is not enough! Once again, the answer is B.