Environmental Physics
Chapter 1:
Introduction
Copyright © 2012 by DBS
Energy: A Definition
• Energy is the capacity to do work
– You must have energy to accomplish work!
Energy is a major building block of modern society…
Energy: A Definition
Energy: A Definition
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!
Modernization from a Rural to an Urban Society…
Energy: A Definition
Fossil fuels made possible the rapid growth of population as transportation cost
were reduced and human productivity increased greatly.
Cost of gas –
Energy is crucial to everyday life
Energy: A Definition
1979 Iranian Revolution
1973 Oil embargo
2003 Iraq Invasion
1939-1945 WW2
9/11
1993 Gulf War
Energy: A Definition
•
Energy supplies and economic growth – access to adequate and reliable energy resources is
central for economic growth
Energy: A Definition
•
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 – machines dominate
http://www.sciencenetlinks.com/interactives/powerplay.html
Energy: A Definition
•
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.
•
Use of energy directly affects the environment.
Energy Use and the Environment
Age of environmental
awareness
Increased use of fossil fuels since the industrial revolution
has increased atmospheric CO2 by 30%...
Which has probably increased the earth’s temperature…
Energy Use and the Environment
http://faculty.rmu.edu/~short/envs1160/envs1160-media/CNN-Vol5-Throw-Away-Society.mov
Energy Use and the Environment
•
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
Energy consumption increased rapidly up until the 1980s…
Science, economics,
and politics:
shifts in the use of
commercial energy
resources in the United
States since 1800, with
projected changes to
2100.
Experience shows
that it takes ~50
years to phase in
new energy
alternatives
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)
Quadrillion = 1015
Figure 1.3: 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
Projected that developing countries
will be using more energy than
industrialized countries by 2025
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.
Figure 1.5: World energy consumption, 1970–2025 for industrialized countries,
developing countries, and Former Soviet Union.
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.
Morning rush hour, Canton, China.
p. 8
Figure 1.5: Regional shares of total final consumption for 2007.
Energy Use Patterns
US has one of the highest per capita rates of energy consumption of any country…
Figure 1.6: World energy consumption by country: 2008.
U.S. has 5% of world
population
uses 1/4 of the world’s
commercial energy
Energy Use Patterns
•
What are the principal sources of energy in the US?
Coal
Oil
Natural Gas
Nuclear
Hydropower
Renewable energy
93 % from fossil fuels
(Non-renewable)
Figure 1.7: Energy consumption by source for the world and for the United States: 2003.
Oil replaced coal as
the fuel of choice
Where in the US was
the first modern oil well
drilled?
Oil fields in Texas in the 1920s.
Use of natural gas has
increased to ~ 23%
Large decrease in
contribution from
wood and coal
Rapid rise of oil and
gas since WW2
Figure 1.9: Energy consumption by source for the world and for the United States: 2003.
Until 1940s US
produced virtually all
the oil it needed
Current
imports
Current
production
Petroleum imports begin
Figure 1.10: United States petroleum production and imports: 1949–2003. (Petroleum includes
crude oil and natural gas plant liquids.)
Fundamental Sources of Energy
FUSION
(SOLAR)
FISSION
Fossil fuels
Nuclear energy
Wind
(man-made)
Waves
Geothermal
Biomass
(natural)
Hydro
Direct solar
GRAVITATIONAL
(PE/KE earthmoon-sun)
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
The 350-kW photovoltaic power plant at Gun Hill Bus Depot in New York City. Solar cells
supplement the terminal’s electrical energy needs.
p. 12
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 1.12: United States end uses of energy by sector: 2009.
Figure 1.13: 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
To understand energy one must understand energy resources, their limitations and their uses
2 important
factors:
i) Size
ii) Lifetime
Estimates for coal are
easiest to make…why?
Reserves are
not static…why?
bbl = barrels, Btu = British Thermal Unit, cf = cubic foot
Residence Time
•
Average amount of time a particle exists before it is removed. Can be used to
measure remaining reserves. Defined as follows:
Residence time = amount of substance in the system
rate of flow from the system
e.g. example 1.1: US oil reserves are est. at 29 x109 bbl (from previous table), current
production is 6 MBPD. How many years will it last?
Note: this is a simplification as both of these numbers change.
The Washington Post, 03/20/08
Energy Use in China
Per capita consumption is far less than
USA
33 Mbtu vs 333 Mbtu
GDP growing at 10 % per year
World’s largest consumer of coal
Eenergy usey may eventually surpass US
Figure 1.15: Energy resources used in China: 2002.
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 $1000 growing at 10% per year
By the 14th year the
investment has
doubled again
By the 7th year the
investment has
doubled
If we plot this graph
what does it look
like?
Exponential Growth and Resource Depletion
•
A useful relationship between doubling time and percentage growth is:
Doubling time ~
70 years
% growth rate
•
To specify the lifetime of a resource we must also specify the expected rate of growth in its use
•
Growth rate of 7% for electrical energy, amount consumed would double in about 70/7 = 10 years
•
If we want to find out exactly how much of a resource is present we need to solve a different
equation
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 n years, find n:
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
Resource Depletion
•
However: Use of a resource will not continue to grow exponentially indefinitely
Hubberts bell-shaped curve
Figure 1.18: 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.)
Resource Depletion
Oil – estimated vs. actual
Figure 1.19: United States oil production. Comparison of estimated (Hubbert) production curve
(dashed line) and actual production (solid line).
Natural Gas – estimated vs. actual
Figure 1.20: United States natural gas production. Comparison of estimated (Hubbert)
production curve (dashed line) and actual production (solid line).
Exponential Growth and Resource Depletion
•
•
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 oil will last ~ 50
years
Implies coal will last > 500 years
Implies gas life extended by
advances in production
technologies
e.g. fracking
Oil: A Critical Resource
Oil has fueled most of the increase in global energy
consumption since WW2
1979 Iranian Revolution
1973 Oil embargo
We import 56 % of
the oil we use
2003 Iraq Invasion
Decline in prices encouraged
increase in use
9/11
Use is growing at
1.5 % per year
1993 Gulf War
A map of the Middle East.
d
p. 22
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 1.23: United States per capita energy consumption over the
past 130 years.
Energy Conservation
1.
2.
3.
4.
5.
6.
Conservation technologies are cost-effective alternatives to the development of additional supply
technologies.
Conservation will stretch the earth’s limited energy resources and gain time for the development of
RES.
Conservation will reduce pollution of our environment.
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.
Conservation of fossil fuels is crucial for their use as raw materials in the pharmaceutical and
plastic industries.
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 (prev. ed.): United States energy use (Btu)
compared to GDP over time, and their ratio.
Figure 1-24 p27
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?
Figure 1-25 p28
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.
Chapter 1 Questions
2. What energy source has seen the most rapid growth in the past 50 yrs? Why?
3. If world use of oil is 78 MBPD, how long will it last?
(hint: use example 1.1)
5. If the world’s population is increasing at 1.3 % per year and there were 5 billion
poeple in 1986, in what year will there be 10 billion?
15. Should environmental impacts always be given first concern when it comes to the
use of energy?
24. Find the present numbers for US consumption of energy. Cite your URLs.