Solar Energy: An Introduction

Michael E. Mackay

Chapter 1 Why solar energy is important - all with Video Answers

Educators

Chapter Questions

Problem 1

Determine the time that $\mathrm{CO}_2$ will last in the atmosphere. In other words, how long does it take $\mathrm{CO}_2$ to degrade?

Anatole Borisov

Numerade Educator

09:08

Are parts per million (ppm) by number of moles and volume the same for a gas? The mixing ratio is sometimes used in atmospheric science and it is defined as the number of moles of a substance to the number of moles of everything else (not including the given substance). Sometimes the mixing ratio is similarly defined by mass rather than moles so some care should be taken to determine the definition. At what concentration limit will ppm and mixing ratio be equivalent?

Jennifer Hudspeth

Numerade Educator

01:22

Problem 3

Estimate how much plant and tree material decays every fall in the northern hemisphere.

Narayan Hari

Numerade Educator

01:02

Problem 4

How many trees would have to be planted each year to eliminate the increase in $\mathrm{CO}_2$ seen at the Mauna Loa volcano assuming this is the global concentration of $\mathrm{CO}_2$ ? What percentage of the World land area is this?

K B

Numerade Educator

02:37

Problem 5

Estimate how much the World ocean height will change if all the ice in the arctic melts.

Linda Winkler

Numerade Educator

02:33

Problem 6

If the average temperature of ocean water increases by 1 and $10^{\circ} \mathrm{C}$ how much will the ocean height change?

Khoobchandra Agrawal

Numerade Educator

02:05

Problem 7

Since 1920 the mean sea level has risen by $3.20 \pm 0.25 \mathrm{~mm} /$ year in Lewes, Delaware, USA, estimate what is the temperature rise over a 100 year period assuming this is due to climate warming only.

Prabhu Ramji

Numerade Educator

03:34

Problem 8

Compare the combustion energy density of ethanol and gasoline on a per mass and volume basis; which is a more energy dense fuel?

Khalida Dawar

Numerade Educator

01:49

Problem 9

Estimate how much E10 gasoline costs the average person in the USA each year in terms of reduced fuel mileage when driving their automobile. Multiply this result by the number of people in the USA and estimate how much money is taken out of the economy each year. Assume E10 and pure gasoline cost the same amount.

Averell Hause

Carnegie Mellon University

01:15

Problem 10

Determine how much $\mathrm{CO}_2$ a person generates per year through exhalation, how much all the people on Earth generate in a year and finally how many parts per million in the atmosphere this is.

Erika Bustos

Numerade Educator

02:19

Problem 11

If all the electricity used in the World were generated by burning wood or natural gas, how much $\mathrm{CO}_2$ would be released into the atmosphere in ppm? Compare this to the amount being released now.

Aadit Sharma

Numerade Educator

02:06

Problem 12

The National Audubon Society has a fact sheet entitled, 'Global Warming Campaign: Top Ten Things You Can Do.' Write down the ten items with a brief explanation of what they are and how much each item will reduce $\mathrm{CO}_2$ emissions if followed. If everyone in the average household in your country followed these guidelines, how much $\mathrm{CO}_2$ would be reduced in terms of atmospheric (molar) ppm?

Joanna Quigley

Numerade Educator

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Problem 13

If all the coal and liquid petroleum products used as an energy resource in the USA in one year were placed in an area the size of the continental USA, how thick would each layer be?

Victor Salazar

Numerade Educator

01:41

Problem 14

Determine how much cement manufacture and gas flares contribute to the emission of $\mathrm{CO}_2$. Describe why cement manufacture is a source of $\mathrm{CO}_2$ emission and what a gas flare is and why it is performed. Hint: The data from Oak Ridge National Laboratory are quite useful.

Reed Mckee

Numerade Educator

01:18

Problem 15

If all the coal-fired power plants were replaced by solar cells to produce electricity in the USA, how much would it cost and how much would the $\mathrm{CO}_2$ emissions be reduced in terms of ppm in the atmosphere? Compare the cost to the USA's defense budget.

Donald Albin

Numerade Educator

06:12

Problem 16

In Section 1.1 it was mentioned that $280 \mathrm{~km}^3$ of ice was being melted each year in the Arctic. Assume when all the ice is melted that the energy required to melt the ice now can be used to heat the atmosphere, how many ${ }^{\circ} \mathrm{C}$ will the atmosphere increase in temperature each year? Note the heat capacity of air is remarkably independent of pressure until extremely low pressure and can be assumed constant for the purposes of this calculation.

Khoobchandra Agrawal

Numerade Educator

01:47

Problem 17

As mentioned on Section 1.1 the seasonal ice loss in the Arctic is $16,400 \mathrm{~km}^3$, if all the Arctic ice is lost then this energy buffer no longer exists. More precisely, the energy used in melting the ice must go somewhere else and heat it up. Assume it goes to heat up the atmosphere, estimate how much it will increase in temperature. IIint: See Exercise 1.16.

Carson Merrill

Numerade Educator

00:34

Problem 18

When all the Arctic ice melts and does not return in the northern winter, estimate the reduction in shipping times from China to Europe.

Kristela Garcia

Numerade Educator

02:01

Problem 19

Professor Quaschning has introduced the term "anytime energy" in his book (see General references above) as a way to emphasize how much energy we use from the Sun. Calculate how much energy the Sun contributes to your house by its warming effect in the winter and compare it to the average electricity use for a residence. Is it a significant amount?

Prabhat Tyagi

Numerade Educator

05:02

Problem 20

Compare the amount of water used to produce electricity from various technologies such as biodiesel, coal-fired power plant, etc. Much information can be obtained from this article: W.D. Jones, 'How much water does it take to make electricity?' IEEE Spectrum, April 1, 2008.

Aspen Fenzl

Numerade Educator