Chapter 17: Energy: Some Basics

Chapter 17: Energy: Some Basics

Energy Crisis in Ancient Greece and Rome

• Greeks and Romans used wood to heat there homes.– As local supplies ran out had to bring it in from farther

away.

• Eventually both societies learned to build houses south facing– Allows sun to heat house in winter– Sustainable

• In Rome laws pasted to protect a person’s right to solar energy.

Energy Today and Tomorrow

• Energy situation facing the US today is similar to that faced by Greeks and Romans.– Use of wood peaked 1880s– Coal use peaked 1920– Reaching the peak of oil and gas use

• The decisions we make today will affect energy use for generations.

Energy Basics

• To understand energy it is easiest to begin with the idea of force– We have all exerted force by pushing or pulling– The strength of force can be measured by how

much it accelerates an object– Think of pushing a car uphill

Energy Basics

• In physicists’ terms– Exerting force over a distance moved is work

• Work is the product of a force times a distance

– Energy is the ability to do work

• When the car id higher on the hill the potential energy of the car has increased

• Energy can be converted from one kind to another– The total energy conserved

– First law of thermodynamics

Energy Basics

• To illustrate the conservation and conversion of energy think of a tire swing– At highest position all energy is stored potential

energy– At lowest position all energy is kinetic energy

• Energy of motion

– With each swing friction slows the swing generating heat energy

• Eventually all the energy converted to heat and the swing stops

Energy Basics

• Energy quality– The ability of the energy to do work

– The higher quality of the energy, the more easily it can be converted to work.

– The lower the energy quality, the more difficult it is to convert to work.

• Second law of thermodynamics– Energy always tends to go from a more usable (higher-

quality) form to a less usable (lower-quality) form.

– When you use energy, you lower its quality.

Energy Efficiency

• Two fundamental types of energy efficiencies are derived from the first and second laws of thermodynamics: – the first-law efficiency and the second-law

efficiency.

• First-law efficiency deals with the amount of energy without any consideration of the quality or availability of the energy.

Energy Efficiency

• Second-law efficiency refers to how well matched the energy end use is with the quality of the energy source.– Low values indicate where improvements in

energy technology and planning may save significant amounts of high-quality energy.

Energy Efficiencies

• Electricity generating plants have nearly the same first-law and second-law efficiencies. – Generating plants are examples of heat engines.– Produces work from heat. – Most of the electricity generated in the world

today comes from heat engines • Use nuclear fuel, coal, gas, or other fuels.

Energy Source and Consumption

• Industrialized countries small percentage of the world’s population, but consume a disproportionate share of the total energy produced in the world. – E.g. US with only 5% of the world’s

population, uses approximately 25% of the total energy consumed.

Fossil Fuels and Alternative Energy Sources

• 90% of the energy consumed in the US comes from fossil fuels– Petroleum, natural gas, and coal.

– They are essentially nonrenewable.

• Other sources of energy– Include geothermal, nuclear, hydropower, and solar

– Referred to as alternative energy sources.

– Solar and wind, are not depleted by consumption and are known as renewable energy.

Energy Consumption in the US Today

• US dependent on the three major fossil fuels – coal; natural gas; and petroleum.

• From 1950 to late-1970s, energy consumption increased tremendously– From 30 exajoules to 80 exajoules.

• Since about 1980, energy consumption has increased by only about 20 exajoules.– Suggests that policies to improve energy conservation

through efficiency improvements have been at least partially successful.

Energy Consumption in the US Today

• Energy losses are associated with – the production of electricity and transportation.– Most occur through the use of heat engines

• Looking at the generalized energy flow of the US for a particular year – We imported considerably more oil than we produced– Consumption distributed in three sectors:

residential/commercial, industrial, and transportation.

• We remain dangerously vulnerable to changing world conditions affecting the production of oil.

Energy Conservation, Increased Efficiency and Cogeneration

• Conservation of energy– Simply getting by with less demand for energy.

• Increased energy efficiency – Involves designing equipment to yield more

energy output from a given amount of input energy (first-law efficiency)

– Better matches between energy source and end use (second-law efficiency).

Energy Conservation, Increased Efficiency and Cogeneration

• Cogeneration – Processes designed to capture and use waste

heat rather than release it as a thermal pollution.– Using that waste heat, can increase the overall

efficiency of a typical power plant from 33% to as much as 75%

– Could provided an estimated 10% of the power capacity of the US

Building Design

• A spectrum of possibilities exists for increasing energy efficiency and conservation in residential buildings. – Design and construct homes that minimize the energy

consumption

– Design buildings to take advantage of passive solar potential

– For older homes:insulation, caulking, weather stripping, installation of window coverings, storm windows, and regular maintenance.

Industrial Energy

• Industrial production of goods continues to grow significantly.– U.S. industry consumes about one-third of the

energy produced. – More industries are using co-generation and

more energy-efficient machinery.

Automobile design

• Early 1970s, the average US automobile got 14 mpg. • By 1996, the average was 28 mpg for highway

driving.– Fuel consumption rates did not improve much from 1996

to 1999.

• In 2004 many vehicles sold were SUVs and light trucks with fuel consumption of 10–20 mpg. – A loophole in regulations permits poorer fuel consumption – SUVs declined in 2006.

Automobile design

• Today, some hybrid (gasoline-electric) vehicles exceeds 90 mpg on the highway and 60 mpg in the city.

• Improvement has several causes: – Increased efficiency and resulting conservation of fuel

– Cars that are smaller, w/ engines constructed of lighter materials

– Combination of a fuel-burning engine with an electric motor

Values, Choices, and Energy Conservation

• Ways of modifying behavior to conserve energy include the following:– Ride a bike, walk, or take a bus or train to work.– Using carpools to travel to and from work or

school– Purchasing a hybrid car (gasoline-electric)– Turning off lights when leaving rooms– Taking shorter showers (conserves hot water)– Putting on a sweater and turning down the

thermostat

Values, Choices, and Energy Conservation

– Using energy-efficient compact florescent lightbulbs

– Purchasing energy-efficient appliances

– Sealing drafts in buildings with weather stripping and caulk

– Better insulating your home

– Washing clothes in cold water whenever possible

– Purchasing local foods to reduce energy in transport

– Using powerstrips and turning them off when not in use

Energy Policy

• U.S. energy policy during the past half-century has not moved us closer to energy self-sufficiency.– We import more oil than ever.– In the late 1990s, the US spent $2

billion per year on R and D for energy.– By comparison, $45 billion per year

went to R and D for the military.

Energy Policy Act of 2005

• Some of the provisions are as follows.– 1. Promotes conventional energy sources– 2. Promotes nuclear power– 3. Encourages alternative energy– 4. Promotes conservation measures– 5. Promotes research– 6. Provides for energy infrastructure

Hard Path vs. Soft Path

• Hard path involves finding greater amounts of fossil fuels and building larger power plants.– Continuing the past emphasis on quantity of

energy used.– Requires no new thinking; no realignment of

political, economic, or social conditions; and little anticipation of coming reductions oil.

Hard Path vs. Soft Path

• According to hard-path proponents, we should – 1. Let the energy industry develop the available

energy resources – 2. Let industry, free from government

regulations, provide a steady supply of energy with less total environmental damage.

Hard Path vs. Soft Path

• The second road of energy policy is called the soft path.

• It involves energy alternatives that emphasize – energy quality, are renewable, are flexible, and

are environmentally more benign than those of the hard path.

Hard Path vs. Soft Path

• These alternatives have several characteristics:– They rely heavily on renewable energy

resources, such as sunlight, wind, and biomass.– They are diverse and are tailored for maximum

effectiveness under specific circumstances.– They are flexible, accessible, and

understandable to many people.– They are matched in energy quality, geographic

distribution, and scale to end-use needs.

Energy for Tomorrow

• Future changes in population densities as well as intensive conservation measures will probably change existing patterns of energy use.

• To stabilize the climate in terms of global warming, use of energy from fossil fuels would need to be cut by about 50%.– Reductions in energy use need not be

associated w/ lower quality of life.

Energy for Tomorrow

• What is needed is increased conservation and more efficient use of energy:– More energy-efficient land-use planning that

maximizes the accessibility of services and minimizes the need for transportation.

– Agricultural practices and personal choices that emphasize

• 1. Eating more locally grown foods • 2. Eating more vegetables, beans, and grains.

– Industrial guidelines for factories that promote energy conservation and minimize production of waste.

Integrated, Sustainable Energy Management

• Integrated energy management recognizes that no single energy source can provide all the energy required.– Range of options that vary from region to

region will have to be employed. – The mix of technologies and sources of energy

will involve both fossil fuels and alternative, renewable sources.

Integrated, Sustainable Energy Management

• A basic goal is to move toward sustainable energy development, implemented at the local level.

• Would have the following characteristics:– It would provide reliable sources of energy.

– It would not cause destruction or serious harm to our global, regional, or local environments.

– It would help ensure that future generations inherit a quality environment with a fair share of the Earth’s resources.

Integrated, Sustainable Energy Management

• A good energy plan is part of an aggressive environmental policy with the goal of producing a quality environment for future generations.

• A good plan should do the following:– Provide for sustainable energy development.– Provide for aggressive energy efficiency and

conservation.

Integrated, Sustainable Energy Management

– Provide for the diversity and integration of energy sources.

– Provide for a balance between economic health and environmental quality.

– Use second-law efficiencies as an energy policy tool.

Integrated, Sustainable Energy Management

• The global pattern of ever-increasing energy consumption led by the US cannot be sustained w/o a new energy paradigm– Includes changes in human values rather

than a breakthrough in technology. – Choosing to own fuel-efficient automobiles

and living in more energy-efficient homes are consistent with a sustainable energy system.