Environmental Physics Chapter 1: Introduction Copyright © 2008 by DBS

Environmental Physics

Chapter 1:Introduction

Copyright © 2008 by DBS

Energy: A Definition

• Energy is the capacity to do work– You must have energy to accomplish work!



Create goods

Provide services


The standard of living refers to the quality and quantity of goods and services available to people, and the way these goods and services are distributed within a population.

Highly dependent on available ENERGY resources!

Energy: A DefinitionModernization from a Rural to an Urban Society…

Fossil fuels made possible the rapid growth of population as transportation cost were reduced and human productivity increased greatly.



1973 Oil embargo

1979 Iranian Revolution

2003 Iraq Invasion

1993 Gulf War

Oil Prices

9/11

1939-1945 WW2


• Humans once had to depend on their own muscles to provide the energy to do work, today muscles supply less than 1% of the work done in the industrialized world

http://www.sciencenetlinks.com/interactives/powerplay.html

http://www.sciencenetlinks.com/interactives/powerplay.html


• Energy supplies and economic growth – access to adequate and reliable energy resources is central for economic growth


• Energy might best be described in terms of what it can do. We cannot “see” energy, only its effects; we cannot make it, only use it; and we cannot destroy it, only waste it. Unlike food and housing, energy is not valued in itself but for what can be done with it.

Energy Use and the Environment

Age of environmental awareness

Fig. 1-1b, p. 5

Increased use of fossil fuels since the industrial revolution has increased atmospheric CO2 by 30%...

Fig. 1-1a, p. 5

Which has probably increased the earth’s temperature…



• We face very tough choices

• Reduce fossil fuel burning because of concern about global warming

…what substitutes are there?

• What can take the place of gasoline in cars?

• Should food be used for fuel, when people are starving?

• Should solar energy be subsidized to compete with less expensive but more polluting fossil fuels which will run out?

Energy Use Patterns

Energy consumption increased rapidly up until the 1980s…

1940s 3% more each year

1960s 5% more each year

Decline in 1980s

The Btu or British Thermal Unit is the energy needed to raise the temperature of 1 lb of water by 1°F

Energy Use Patterns

Science, economics, and politics: shifts in the use of commercial energy resources in the United States since 1800, with projected changes to 2100.

Energy consumption increased rapidly up until the 1980s…

Shifts from wood to coal and then from coal to oil and natural gas have each taken about 50–75 years. Note that, since 1800, the United States has shifted from wood to coal to oil for its primary energy resource. A shift by 2100 to increased use of natural gas, biofuels, hydrogen gas produced mostly by solar cells, and wind is one of many possible scenarios. (Data from U.S. Department of Energy)

Experience shows that it takes ~50 years to phase in new energy alternatives

Quadrillion = 1015

Fig. 1-2, p. 7

Figure 1.2: Energy consumption in the United States over the last two hundred years, by fuel used. A Btu is a unit of energy. A quadrillion Btu (or Quad) is 1015 Btu.

Energy Use Patterns

Figure 1.3: World energy consumption, 1970–2025 for industrialized countries, developing countries, and Former Soviet Union.

Fastest growth is in developing countries

Consumption in Europe has declined slightly with the closure of energy intensive industries in former communist countries.

World energy consumption is growing by about 1.9 percent a year, on average.

Projected that developing countries will be using more energy than industrialized countries by 2025

p. 8

Morning rush hour, Canton, China.

Fastest growth is in developing countries…tend to have very low energy consumption per person but large and rapidly growing populations, requiring significantly more energy as their living standards improve.

Fig. 1-3b, p. 8

Figure 1.3: Regional shares of total final consumption for 2002.

Energy Use Patterns

Fig. 1-4, p. 9

Figure 1.4: World energy consumption by country: 2002.

U.S. has 5% of world populationuses 1/4 of the world’s commercial energy

US has one of the highest per capita rates of energy consumption of any country…

Energy Use Patterns

• What are the principal sources of energy in the US?

CoalOilNatural GasNuclearHydropowerRenewable energy

Fig. 1-5a, p. 10Figure 1.5: Energy consumption by source for the world and for the United States: 2003.

85 % from fossil fuels (Non-renewable)

p. 10

Oil fields in Texas in the 1920s.

Where in the US was the first modern oil well drilled?

Oil replaced coal as the fuel of choice

Fig. 1-6, p. 11

Figure 1.5: Energy consumption by source for the world and for the United States: 2003.

Use of natural gas has increased to ~ 23%

Large decrease in contribution from wood and coal

Rapid rise of oil and gas since WW2

Fig. 1-7, p. 11

Figure 1.7: United States petroleum production and imports: 1949–2003. (Petroleum includes crude oil and natural gas plant liquids.)

Until 1940s US produced virtually all the oil it needed

Petroleum imports begin

Current production

Current imports

Fundamental Sources of Energy

FUSION(SOLAR)

FISSION GRAVITATIONAL(PE/KE earth-

moon-sun)

Fossil fuels

Wind

Waves

Biomass

Hydro

Direct solar

Nuclear energy

(man-made)

Geothermal

(natural)

Tides

Energy Use Patterns

• Renewable energy sources– solar– wind– waves– hydro– biomass– geothermal– tidal

Wind energy is the world’s fastest growing energy source, 25 % per year

p. 12

The 350-kW photovoltaic power plant at Gun Hill Bus Depot in New York City. Solar cells supplement the terminal’s electrical energy needs.

Energy Use Patterns

• Energy is not an end to itself but is valued for what can be done with it

• End uses of energy:

Figure 1.8: United States end uses of energy by sector: 2003.

Fig. 1-8, p. 12

Fig. 1-9, p. 13

Figure 1.9: United States total energy flow in 2003 (Quadrillions of Btu). Total energy consumed—98.2 Quads—includes conversion and transmission losses of electric utilities. (NGPL = Natural Gas Plant Liquids)

Energy Resources

Estimates for coal are easiest to make…why?

To understand energy one must understand energy resources, their limitations and their uses

Reserves are not static…why?

bbl = barrels, Btu = British Thermal Unit, cf = cubic foot

Table 1-1, p. 15

2 important factors:

i) Sizeii) Lifetime

The Washington Post, 03/20/08

Energy Use in China

Figure 1.10: Energy resources used in China: 2002.

Per capita consumption is far less than USA33 Mbtu vs 333 Mbtu

GDP growing at 10 % per year

World’s largest consumer of coal

Large hydropower program to cut coal emissions

Exponential Growth and Resource Depletion

• To specify the lifetime of a resource you must also specify the expected rate of growth in its use

• Exponential growth is growth by the same percentage rate each year

• The larger a quantity gets, the faster it grows

• Consider $100 growing at 10% per year

By the 7th year the investment has doubled

By the 14th year the investment has doubled again


• A useful relationship between doubling time and percentage growth is:

Doubling time ~ 70 years

% growth rate

• If there was a growth rate of 7% for electrical energy, the amount consumed would double in about 70/7 = 10 years

• To specify the lifetime of a resource we must also specify the expected rate of growth in its use

• At 0% growth coal will last 500 years, with a 5% growth rate in the consumption of coal per year its lifetime would be less than 120 years

US coal reserves = 7 x 1018 Btu (table 1.1)

2003 consumption = 23 x 1015 Btu per year (Appendix F)

23 x 1015 x (1.05)n = 7 x 1018

n = 117


• Use of a resource will not continue to grow indefinitely

Figure 1.11: World coal production cycle. The probable exploitation of a fossil fuel (coal in this case) can be characterized by the solid curve. Production initially increases exponentially (as shown by the dashed line), but its rate of increase eventually decreases. Production then declines as extraction becomes more difficult and the rate of discovery decreases. Knowing the amount of fuel initially present, we can use this pattern to determine the lifetime of a resource; in this example, the lifetime of coal reserves is 400 to 600 years. (The amount of coal used so far is shown by the shaded area.)

Hubberts bell-shaped curve

Fig. 1-12, p. 19

Figure 1.12: United States oil production. Comparison of estimated (Hubbert) production curve (dashed line) and actual production (solid line).

Oil – estimated vs. actual

Fig. 1-13, p. 20

Figure 1.13: United States natural gas production. Comparison of estimated (Hubbert) production curve (dashed line) and actual production (solid line).

Natural Gas – estimated vs. actual


• Use of a resource will not continue to grow indefinitely

• Hubbert curves allow estimate of time of depletion and maximum use (Hubbert’s Peak)

Implies coal will last > 500 years

Implies oil will last ~ 50 years

Implies gas life extended by advances in production technologies

Oil: A Critical ResourceOil has fueled most of the increase in global energy consumption since WW2 1973 Oil embargo

1979 Iranian Revolution

2003 Iraq Invasion

1993 Gulf War

9/11

We import 56 % of the oil we use

Use is growing at 1.5 % per year

Decline in prices encouraged increase in use

p. 22

A map of the Middle East.

Energy Conservation

• Total energy consumed in an activity = efficiency of the activity + frequency of activity

e.g. energy consumed by a car depends on mpg and no. miles driven

• Energy conservation focuses on these two factors:

1. Technical fix – more fuel efficiency, CFL’s

2. Lifestyle changes – driving fewer miles, turning lights off

Energy Conservation

Energy Conservation

• Many people assert that energy prices should reflect what it will cost to replace the dwindling supplies of nonrenewable fuels, rather than just what it cots to obtain them

• Societies will not switch to RES and higher efficiency if fossil fuels are prices as if they are almost free

• Higher oil prices in 1980’s led to lower per capita energy use

• Between 1900 and 1980 per capita energy use rose from 80 Mbtu to 320 Mbtu

• Are we 4 x better off?

Figure 1.15: United States per capita energy consumption over the past 130 years.

Energy Conservation

1. Conservation technologies are cost-effective alternatives to the development of additional supply technologies.

2. Conservation will stretch the earth’s limited energy resources and gain time for the development of RES.

3. Conservation will reduce pollution of our environment.

4. Conservation technologies can be put to use more quickly than we can increase supplies. It takes several years to build new power plants whilst it takes a few days to insulate a home.

5. Conservation of fossil fuels is crucial for their use as raw materials in the pharmaceutical and plastic industries.

6. Conservation can be readily practiced by individuals and promotes good health, e.g. bicycle riding.

Economic and Environmental Considerations

• Commonly held belief that GDP only increased when using lots of energy

• Higher oil prices of the 1980s tested this theory

• Higher oil prices lead to increased conservation measures

• Energy use fell whilst GDP continued to rise

• Trend of conservation continues as can be seen by decrease in ‘energy intensity’ (Btu/GDP ratio)

Figure 1.16: United States energy use (Btu) compared to GDP over time, and their ratio.

Economic and Environmental Considerations

• Energy policy should not only be concerned with finding new sources and reducing consumption

• What do we give up, and for what?

– Do we sacrifice ANWR in return for 10 more years of oil?

– Was the 1989 Exxon Valdez Alaskan oil spill acceptable?

– Is climate change a threat?

– Is acid rain an issue?

– Is nuclear power safe?

Future Scenarios

The global energy and political situation today is dramatically different from that in the early 1970s. Lower oil prices in the 1990s brought increased oil consumption and discouraged energy conservation and the development of alternative energy resources. However, the economic environment has changed in a way that may make it easier to handle future supply disruptions or shortages

1. US depends less today on oil than we did ten years ago.

2. Oil production is more dispersed amongst world nations than in 1973.

3. Due to the volatility of oil prices in the last 30 years we have learnt to conserve fuel and use more efficient machines.

4. Strategic petroleum reserve.

5. RES are undergoing rapid growth.

Documents

Environmental Physics Chapter 1: Introduction Copyright © 2008 by DBS