Home > Articles > Engineering

  • Print
  • + Share This
This chapter is from the book

1.3. Energy

Energy is required for all economic activity. Inexpensive energy makes possible a high standard of living and many of the conveniences enjoyed in modern societies, such as heating, lighting, electronic devices, travel, and virtually all forms of communications. Therefore, an understanding of global energy supplies, and the environmental impacts associated with energy production and use, is important in understanding our ability to sustain current standards of living.

Energy is often categorized as renewable or nonrenewable. Examples of renewable energy sources include solar radiation, wind, and biomass. Fossil fuels (crude oil, coal, and natural gas) are nonrenewable energy sources because of the long periods necessary for regeneration, which can be on the order of millions of years. As the 21st century begins, the world relies primarily on fossil energy. Petroleum, coal, and natural gas supply 86% of world energy supplies, as shown in Figure 1-1.

Figure 1-1

Figure 1-1. World energy use in quadrillion (1015) BTU (quads) (EIA, 2009a)

From 1980 until 2006, world energy use increased from just under 300 quadrillion (1015) BTU (quads) to more than 450 quads (an increase of more than 50%). Currently, fossil fuels make up 86% of the world’s energy consumption (EIA, 2009a), while renewable sources such as biomass (including animal waste), hydroelectric, solar, and wind power account for only about 8% of the energy supply. Nuclear energy provides roughly 6% of world energy demand.

Similar energy data for the United States are shown in Figure 1-2. The left-hand side of the figure shows that the distribution of energy sources in the United States is similar to that of worldwide energy sources. Fossil fuels account for 84% of energy use; nuclear and renewables account for roughly equal portions of the remainder. The only significant difference between the U.S. patterns of energy supply and worldwide patterns is the source of biomass-derived fuels. In the United States, ethanol derived from corn was the dominant biomass-derived fuel, whereas worldwide, animal waste used as fuel and ethanol derived from sugarcane were the dominant biomass-derived fuels.

Figure 1-2

Figure 1-2. Energy sources and uses in the United States, expressed in quads per year; lines connecting energy sources and demand sectors show the percentage of energy sources provided to various demand sectors (left) and the percentage of the demand provided by various sources of energy (right). (EIA, 2009b)

The right-hand side of Figure 1-2 shows the patterns of energy use in the United States, where more than 40% of the energy used is used to generate electricity. The remaining nonelectrical uses are transportation, non-electricity-generating industrial uses, and residential and commercial (largely building) energy use. Lines, with percentages noted at both ends, connect energy sources and energy uses in Figure 1-2. The percentages on the left-hand side of the diagram show the ways in which different fuels are used. The percentages on the right-hand side of the diagram show the types of fuels that are used for different energy applications. The percentages make clear that not all energy sources can be used in all applications. For example, 100% of nuclear power and 91% of coal are used to generate electricity. These fuels are not widely used for other purposes. Transportation relies almost exclusively (95%) on petroleum. Few other fuels are used for this application.

Example 1-1. Per capita energy use

Using the data in Figures 1-1 and 1-2, compare per capita annual energy use in the United States and worldwide. Assume a U.S. population of 300 million and a world population of 7 billion. Convert the result, expressed in BTU per person, into the number of gallons of gasoline that would be required to provide the energy. Assume that the energy content (higher heating value) of gasoline is 124,000 BTU/gal (Argonne National Laboratory, 2011).

Solution: Per capita energy consumption in the United States is more than five times greater than the worldwide average.

U.S. per capita annual energy use = 99.3 * 1015 BTU/300 * 106 people = 330 * 106 BTU/person.

Global per capita annual energy use = 450 * 1015 BTU/7 * 109 people = 64 * 106 BTU/person.

To convert BTU into gallons of gasoline equivalent, assume that the energy content of gasoline is 124,000 BTU/gal.

U.S. per capita annual energy use = 330 * 106 BTU = 2700 gallons of gasoline equivalent per year.

Global per capita annual energy use = 64 * 106 BTU = 520 gallons of gasoline equivalent per year.

Another way to map energy use is shown in Figure 1-3. This mapping, produced by Lawrence Livermore National Laboratory (2010), shows energy sources on the left and energy uses on the right, as in Figure 1-2. Figure 1-3 distinguishes between domestic and imported sources of energy, showing that the primary form of imported energy in the United States is petroleum. In mapping the flow from energy sources to energy uses, Figure 1-3 shows energy losses. These losses come about for a variety of reasons. The largest single category of loss is in electric power generation, amounting to more than a quarter of all U.S. energy use. This loss is in part a result of the laws of thermodynamics, since generating electrical power generally involves converting heat (from burning fuels) into mechanical work (turning a generator with steam made from the heat from burning the fuel). This “waste” heat is not really lost; energy is conserved. Instead, it is simply available at too low a temperature to be of significant economic value in power generation, so it is released into the environment as hot water or hot gases. Example 1-2 illustrates typical energy losses from fuel source to final end use.

Figure 1-3

Figure 1-3. Mapping of energy sources and uses in the United States for 2008, quantifying energy losses (Lawrence Livermore National Laboratory, 2010)

Example 1-2. Efficiency of energy use

Determine the efficiency of energy utilization for a pump. Assume the following efficiencies in the energy conversion:

  • Crude oil to fuel oil is 90% (0.90) (i.e., the energy required to produce and refine crude oil consumes 10% of the energy of the crude oil input to the process).
  • Fuel oil to electricity is 40% (0.40) (i.e., the conversion of thermal energy into electrical energy occurs with an efficiency of 40%, roughly the average for the U.S. electrical grid).
  • Electricity transmission and distribution is 90% (0.90) (i.e., losses of electricity in transmission from the power plant to the point of use are 10%).
  • Conversion of electrical energy into mechanical energy of the fluid being pumped is 40% (i.e., the efficiency of the pump in converting electrical energy into the mechanical energy of the fluid is 40%).

Solution: The overall efficiency for the primary energy source is the product of all of the individual conversion efficiencies.

Overall efficiency = (0.90)(0.40)(0.90)(0.40) = 0.13 or 13%.

As shown in Figure 1-3, more than half of the energy used in the United States is lost in the process of converting the energy into useful forms, such as electricity. As shown in Example 1-2, the losses that occur between the source of the primary energy and the desired outcome of using the energy (such as moving a fluid through a pipe, or delivering horsepower at the wheel of a car, or illuminating a room with a lightbulb; see the problems at the end of the chapter) can be much larger. Improving energy efficiency is the work of engineers, and as shown in Figure 1-4, engineers have continuously improved the energy required per unit of economic output (the T in the IPAT equation) in both developed and developing economies.

Figure 1-4

Figure 1-4. World energy intensity—total primary energy consumption per dollar of GDP using purchasing power parities (BTU per U.S. dollar (2000)) (EIA, 2009a)

Improving energy efficiency can reduce costs and conserve natural resources. It can also reduce environmental impacts. A variety of environmental impacts are associated with energy consumption. Fossil fuel combustion releases carbon dioxide into the atmosphere. Because of its long residence time in the atmosphere and because it readily absorbs infrared radiation, CO2 can cause global warming. Furthermore, combustion releases oxides of nitrogen and, for some fuels, sulfur into the air, where photochemical reactions can convert them into ground-level ozone and acidrain. Hydropower energygeneration causes landinundation, habitat destruction, and alteration in surface and groundwater flows. Nuclear power has environmental problems linked to uranium mining and spent nuclear fuel disposal. Renewable fuels are not environmentally benign either. Traditional energy usage (wood) has caused widespread deforestation in localized regions of developing countries. Solar power panels require energy-intensive use of heavy metals and creation of metal wastes. Satisfying future energy demands must occur with a full understanding of competing environmental, natural resource, and energy needs.

  • + Share This
  • 🔖 Save To Your Account

InformIT Promotional Mailings & Special Offers

I would like to receive exclusive offers and hear about products from InformIT and its family of brands. I can unsubscribe at any time.

Overview


Pearson Education, Inc., 221 River Street, Hoboken, New Jersey 07030, (Pearson) presents this site to provide information about products and services that can be purchased through this site.

This privacy notice provides an overview of our commitment to privacy and describes how we collect, protect, use and share personal information collected through this site. Please note that other Pearson websites and online products and services have their own separate privacy policies.

Collection and Use of Information


To conduct business and deliver products and services, Pearson collects and uses personal information in several ways in connection with this site, including:

Questions and Inquiries

For inquiries and questions, we collect the inquiry or question, together with name, contact details (email address, phone number and mailing address) and any other additional information voluntarily submitted to us through a Contact Us form or an email. We use this information to address the inquiry and respond to the question.

Online Store

For orders and purchases placed through our online store on this site, we collect order details, name, institution name and address (if applicable), email address, phone number, shipping and billing addresses, credit/debit card information, shipping options and any instructions. We use this information to complete transactions, fulfill orders, communicate with individuals placing orders or visiting the online store, and for related purposes.

Surveys

Pearson may offer opportunities to provide feedback or participate in surveys, including surveys evaluating Pearson products, services or sites. Participation is voluntary. Pearson collects information requested in the survey questions and uses the information to evaluate, support, maintain and improve products, services or sites, develop new products and services, conduct educational research and for other purposes specified in the survey.

Contests and Drawings

Occasionally, we may sponsor a contest or drawing. Participation is optional. Pearson collects name, contact information and other information specified on the entry form for the contest or drawing to conduct the contest or drawing. Pearson may collect additional personal information from the winners of a contest or drawing in order to award the prize and for tax reporting purposes, as required by law.

Newsletters

If you have elected to receive email newsletters or promotional mailings and special offers but want to unsubscribe, simply email information@informit.com.

Service Announcements

On rare occasions it is necessary to send out a strictly service related announcement. For instance, if our service is temporarily suspended for maintenance we might send users an email. Generally, users may not opt-out of these communications, though they can deactivate their account information. However, these communications are not promotional in nature.

Customer Service

We communicate with users on a regular basis to provide requested services and in regard to issues relating to their account we reply via email or phone in accordance with the users' wishes when a user submits their information through our Contact Us form.

Other Collection and Use of Information


Application and System Logs

Pearson automatically collects log data to help ensure the delivery, availability and security of this site. Log data may include technical information about how a user or visitor connected to this site, such as browser type, type of computer/device, operating system, internet service provider and IP address. We use this information for support purposes and to monitor the health of the site, identify problems, improve service, detect unauthorized access and fraudulent activity, prevent and respond to security incidents and appropriately scale computing resources.

Web Analytics

Pearson may use third party web trend analytical services, including Google Analytics, to collect visitor information, such as IP addresses, browser types, referring pages, pages visited and time spent on a particular site. While these analytical services collect and report information on an anonymous basis, they may use cookies to gather web trend information. The information gathered may enable Pearson (but not the third party web trend services) to link information with application and system log data. Pearson uses this information for system administration and to identify problems, improve service, detect unauthorized access and fraudulent activity, prevent and respond to security incidents, appropriately scale computing resources and otherwise support and deliver this site and its services.

Cookies and Related Technologies

This site uses cookies and similar technologies to personalize content, measure traffic patterns, control security, track use and access of information on this site, and provide interest-based messages and advertising. Users can manage and block the use of cookies through their browser. Disabling or blocking certain cookies may limit the functionality of this site.

Do Not Track

This site currently does not respond to Do Not Track signals.

Security


Pearson uses appropriate physical, administrative and technical security measures to protect personal information from unauthorized access, use and disclosure.

Children


This site is not directed to children under the age of 13.

Marketing


Pearson may send or direct marketing communications to users, provided that

  • Pearson will not use personal information collected or processed as a K-12 school service provider for the purpose of directed or targeted advertising.
  • Such marketing is consistent with applicable law and Pearson's legal obligations.
  • Pearson will not knowingly direct or send marketing communications to an individual who has expressed a preference not to receive marketing.
  • Where required by applicable law, express or implied consent to marketing exists and has not been withdrawn.

Pearson may provide personal information to a third party service provider on a restricted basis to provide marketing solely on behalf of Pearson or an affiliate or customer for whom Pearson is a service provider. Marketing preferences may be changed at any time.

Correcting/Updating Personal Information


If a user's personally identifiable information changes (such as your postal address or email address), we provide a way to correct or update that user's personal data provided to us. This can be done on the Account page. If a user no longer desires our service and desires to delete his or her account, please contact us at customer-service@informit.com and we will process the deletion of a user's account.

Choice/Opt-out


Users can always make an informed choice as to whether they should proceed with certain services offered by InformIT. If you choose to remove yourself from our mailing list(s) simply visit the following page and uncheck any communication you no longer want to receive: www.informit.com/u.aspx.

Sale of Personal Information


Pearson does not rent or sell personal information in exchange for any payment of money.

While Pearson does not sell personal information, as defined in Nevada law, Nevada residents may email a request for no sale of their personal information to NevadaDesignatedRequest@pearson.com.

Supplemental Privacy Statement for California Residents


California residents should read our Supplemental privacy statement for California residents in conjunction with this Privacy Notice. The Supplemental privacy statement for California residents explains Pearson's commitment to comply with California law and applies to personal information of California residents collected in connection with this site and the Services.

Sharing and Disclosure


Pearson may disclose personal information, as follows:

  • As required by law.
  • With the consent of the individual (or their parent, if the individual is a minor)
  • In response to a subpoena, court order or legal process, to the extent permitted or required by law
  • To protect the security and safety of individuals, data, assets and systems, consistent with applicable law
  • In connection the sale, joint venture or other transfer of some or all of its company or assets, subject to the provisions of this Privacy Notice
  • To investigate or address actual or suspected fraud or other illegal activities
  • To exercise its legal rights, including enforcement of the Terms of Use for this site or another contract
  • To affiliated Pearson companies and other companies and organizations who perform work for Pearson and are obligated to protect the privacy of personal information consistent with this Privacy Notice
  • To a school, organization, company or government agency, where Pearson collects or processes the personal information in a school setting or on behalf of such organization, company or government agency.

Links


This web site contains links to other sites. Please be aware that we are not responsible for the privacy practices of such other sites. We encourage our users to be aware when they leave our site and to read the privacy statements of each and every web site that collects Personal Information. This privacy statement applies solely to information collected by this web site.

Requests and Contact


Please contact us about this Privacy Notice or if you have any requests or questions relating to the privacy of your personal information.

Changes to this Privacy Notice


We may revise this Privacy Notice through an updated posting. We will identify the effective date of the revision in the posting. Often, updates are made to provide greater clarity or to comply with changes in regulatory requirements. If the updates involve material changes to the collection, protection, use or disclosure of Personal Information, Pearson will provide notice of the change through a conspicuous notice on this site or other appropriate way. Continued use of the site after the effective date of a posted revision evidences acceptance. Please contact us if you have questions or concerns about the Privacy Notice or any objection to any revisions.

Last Update: November 17, 2020