Energy resources are obviously becoming an increasingly complex and politically charged topic. Energy production, consumption, related global warming and ways out of the dilemma can hardly be covered in a single lecture. I therefore offer this material as additional info material for the interested students.

Many issues that I describe here are quite recent and are usually not found in earth sciences course text books. Some of the most recent information can be found in "State of the World, 2004" issued by the Worldwatch Institute, ISBN: 0-393-32539-3, price: $16.95 at the UCSD bookstore or for about $0.50 used/new at Amazon.

According to the International Energy Agency ( IEA) the energy demand has roughly doubled within the last 30 years. This is likely to increase as the developing countries strive to obtain similar living standards as the industrial countries.
The most widely used energy resources are fossil fuels (oil, gas, coal), nuclear power (nuclear fission) and moving water. The first two are nonrenewable energy resources, while moving water, wind and Earth's internal heat are renewable energy resource.

Hydrocarbons (oil and natural gas) now account for more than 50% of the world's energy usage (60% in the U.S.). Nuclear energy has been provided since the 1950ies. While nuclear energy was initially hailed as the ideal alternative energy resource, people now recognize a significant waste disposal problem and security issues.

The oil crisis of the 1970s illustrates the vulnerability of the current (oil-dominated) energy market. Due to increasing demands, the U.S. had to import more oil but OPEC countries limited the oil export and fuel prices increased from $1.80 to $18 per barrel. The oil market then stabilized with occasional price jumps (1979 to $30 per barrel).

Apart from increasing oil prices, the biggest problem is that oil reserves and production are finite. In the U.S., oil production peaked in the early 1970ies and is now going down and the U.S. now must import more than 50% of its oil. A peak in the global oil production is predicted for 2005. As of 2000, there were 850-1000 billion barrels of proven reserves. The consumption now exceeds the rate of discovery of oil (by factor 3).

At the current usage of 25 billion barrels per year, the known reserves will last until about the end of this century. However, increasing traffic, increasing fuel consumption per car (the current mileage of the average car in the U.S. is going down because cars get bigger!) and the strive of developing countries to "catch up" the known reserves will last a lot shorter.

Sophisticated techniques and the increasing oil prices may make secondary oil production techniques (to extract more oil from a reserve; 50% instead of the usual 30%) and the production in currently less lucrative areas or reserves (e.g. , small reserves in Alaska or less productive tar sands) more attractive. But this does not solve the air pollution problem.

Burning gasoline in traffic produces carbon oxides (greenhouse effect), carbon monoxide (pollution) and nitrogen oxides (produces toxic ozon on sunny days).

While an economically feasible alternative using gasoline for transportation is currently not in sight, alternatives to oil in power plants include coal whose reserves are currently greater than those for oil. But burning of all fossil fuels produces huge amounts of greenhouse gases. Coal is "dirty" to burn because it produces soot and sulfur products that are responsible for acid rain. With improper filters in place, there are also health issues to be considered.

• global energy demand doubled in last 30 years
• hydrocarbons now account for > 50% world's energy production
• fossil fuels account for nearly 80%
• fossil fuels are non-renewable
• U.S. oil production peaked in 1970ies
• U.S. has to import 50% of its oil
• peak in global oil production by 2005
• oil consumption now exeeds rate of discovery by factor 3


• oil reserves exhausted within 50 years
• gas reserves probably within 100 years
• coal reserves probably within 300 years
• burning fossil fuels pollutes the environment
• burning fossil fuels accelerates the greenhouse effects
• burning coal causes acid rain

Nuclear power is considered an immense energy source because a tiny amount of matter transforms into a great amount of thermal energy. For example 1g of nuclear reactor fuel yields as much energy as 2.7 barrels of oil. Nuclear power is also considered as an alternative energy source to fossil fuels in the "global warming" discussion because nuclear power does not produce green house gases. Current estimates are that the natural reserves for nuclear fuel takes about one to three times as long as oil before they are used up (about 300 years). The first nuclear power plant was built in the 1950ies.

Fission (or breaking) of nuclear bonds splits a nucleus of an atom into usually two smaller pieces of almost equal size. While some elements undergo radioactive decay naturally, e.g. by alpha, beta or gamma decay, Uranium is the only naturally occuring element that undergoes fission and is the last of the 92 naturally occuring elements. Uranium occurs naturally in granitic plutons. Circulating water can concentrate Uranium in veins of pitchblende (UO₂). Most of the naturally occuring Uranium is the relatively stable isotope 238U (half life: 4.5 Billion years). The complete nomenclature is ²³⁸₉₂U. This means that 238U has 92 electrons, 92 protons and 146 (238-92) neutrons (remember that the 238 is the total number of nucleons: protons plus neutrons). The isotope used in reactors is 235U (half life: 731 Mio years) and makes up only 0.7% of the naturally occurring Uranium. Since reactors operate with fuels at the 3% level (to sustain a chain reaction!), the reactor fuel has to be enriched. This process is difficult, energy-intensive and increases the cost of nuclear power substantially . Nuclear fuel cannot be used for nuclear bombs as the nuclear bomb material is 90% enriched.

In the U.S. nuclear power once produced up to 20% of the electrical energy but is now going down (about 10%). In other countries, this fraction can be much higher (e.g. 75% in France).

The neutrons from the fission of 235U can collide with the 238U nuclei and eventually (through repeated beta-decay) produce 239Pu (Plutonium which is the most toxic of all elements). With 94 electrons and protons, Pu is not naturally occuring. In a fuel rod both the pair of nuclei into which 235U fissions and Pu are much more radioactive than the original Uranium. After about 10 years, most of the radioactivity in spent fuel rods is due to 90Sr (Strontium; half-life 28 years) and 137Cs (Cesium; half-life 30 years). Both can be easily absorbed by the human body and then cause tissue damage.

Plutonium has a long half-life (24,000 years). After 1000 years, the main source of radioactivity from used fuel rods will be from 239Pu. A used fuel rods can be reprocessed were the plutonium gets chemically separated from the rod. Spent fuel rods currently get reprocessed in France, England and Russia and has resulted in a buildup in the supply of Pu. Indeed, breeder reactors which are used in particular in France and Japan, are designed specifically to maximize the production of Pu. Such reactors actually produce more fissionable material than they consume. There is no reprocessing in the U.S. but most Pu has been produced by other means at Hanford, Washington. Because of the huge quantities of radioactive waste produces (about 190,000 m³ highly radioactive solid waste), the site now is often called "the dirtiest place on Earth". The clean-up will cost between 50 and 200 billion dollars and last until at least 2020. Aside from questions of health and safety, plutonium poses a serious civil security problem. Only a few kilograms of "weapons-grade" material is needed for a bomb. The world's current stockpile of it exceeds 1.000 tons. The idea of reprocessing used fuel rods appeared less attractive when new uranium reserves were found in Australia in 1980. The reserves carry more Uranium than what the U.S. has mined since 1940.

1) Production of weapons-grade material: see above

2) Long-term storage: The fuel rods used up in nuclear reactors leaves behind highly toxic waste that remains radioactive for 10,000s of years (e.g. Plutonium). A system of safe long-term disposal is not yet available and reactor waste is now stored temporarily at reactor sites.
In the meantime scientists and policy makers explore several options of long-term storage:

• underground tunnels in Mts. away from earthquakes and volcanoes
• impermeable salt domes
• landfills surrounded by clay
• landfills where groundwater reacts with radioactive material to form non-movable minerals
• deep-ocean floor near subduction zones

In the U.S. the currently most feasible option (which is still being evaluated) is a depository in the Yucca Mtn./Nevada area.

The problems about long-term storage is well illustrated by a controversy about a tailings pile near Moab/UT. In the 1950s, mills nearby produced Plutonium for nuclear weapons. From 1956 through 1984, six pounds of toxic radioactive waste (incl. arsenic, mercury and ammonium) was produced for every ounce of refined U. This pile sits near the Colorado River as leaks about 15,000 Gallons of toxic chemicals per day into the river that ultimately provides 2/3 of San Diego counties drinking water. An earlier clean-up effort reduced the leak from previously 28,000 Gallons/day. While some argue that the chemicals get diluted enough to not be a threat by the time the water gets to San Diego, others argue that a possible flash flood could trigger a natural disaster that would spoil the drinking water for 18 Mio people living in Southern California. Four options, that include moving the pile ($450 Mio) or leaving it in place but sealing it ($166 Mio), are suggested to attack the problem. In the past, 22 smaller piles have been moved for $2 Billion. The U.S. government directed the Energy Department to move the pile in 1999 but the project has recently suffered from a lack of funding and attention.

3) Accidents: Though considered less of a problem than the long-term storage, there have been accidents in the past where radioactivity escaped into the environment. Most memorable, so far, was the 1986 reactor accident at the power plant in Chernobyl.

An accident of such proportions has not yet happened in the U.S.. In 1979 a cooling pump failed in the reactor "Three Mile Island" near Harrisburg/Pennsylvania. A reactor was destroyed and radioactive debris released but confined within the containment building. Although no one was harmed, most experts agree that it was a close call.

Little accidents (e.g. low-level leaks) happen much more often. E.g. some reactors in Europe leak low amounts of Tritium into the rivers that are used to cool the reactors. Reactor operators are often forced to interrupt the electric power production for maintenance and repair which is non-trivial and increases the costs of operation immensely. For example, at least partial shut-downs for maintenance happen up to a couple of times a year at the San Onofre station in southern CA.

Three Mile Island, Chernobyl and the waste disposal problem led to a slow-down in nuclear power generation. In the U.S. and other countries, no new nuclear power plants have been built since the 1980ies.

• 8,000 kg total are consumed
• 3,500 kg petroleum
• 2,300 kg coal
• 2,250 kg natural gas
• 0.02 kg uranium

ALTERNATIVES

Ground water or water pumped into the ground gets heated by hot rock at depth (e.g. volcanic areas). Decompressing water creates steam that drives turbines (e.g. Iceland, New Zealand, U.S., Italy, Mexico, Philippines, Indonesia). Only few places exist that produce large amounts of steam. The first U.S. geothermal power plant was built in 1960 at The Geysers, north of San Francisco. At that time two other geothermal power plants existed at Larderello, Italy and Wairakei, New Zealand. Current U.S. geothermal power plants include those in the Coso area (Long Valley Caldera, CA) and Salton Sea (Imperial County). Lower-grade geothermal fields are more abundant but produce less steam. There have been experiments with pumping water into "hot dry rock" (near Los Alamos) heating water and creating steam but so far, the produced steam could not produce the energy needed to pump the water into the ground. A drill hole in the Long Valley Caldera, CA, was particularly unsuccessful when it struck "cold dry rock" at 4 km depth that wasn't even volcanic. Apart from producing electricity, geothermally heated water is used to heat houses and spas. Boiling water releases a significant amount of initially dissolved (corroding) minerals. In a binary system the hot water is used to boil an organic liquid (e.g. isobutane boils at 11^oF) that drives engines. This case represents a zero emission system (i.e. not pollutants are released to the atmosphere). Geothermal power plants are rare and contribute relatively little to the U.S. power generation. For example, the Coso field produces just a half day's worth of the U.S. energy over its whole lifetime.

Moving water drives turbines. Operators build dams to create reservoirs and drive turbines at the bottom of the dams where water is released in a controlled fashion (e.g. Hoover Dam). Hydroelectric power seems an ideal energy source because it is a clean resource. Unlike nuclear power, hydroelectric power production is easy to vary and so is used in "peak times" (e.g. hot summer afternoons when lots of air conditioners are running). Hydroelectic power is now the leading export in Kyrgystan. However, hydroelectric power has a major local environmental impact and also depends on seasonal fluctuations (i.e. vulnerable to years of droughts). Another problem is that the lifetime of reservoirs is limited because the concrete retaining walls degenerate with age and the lakes fill up with sediments.

Near rivers, an alternative to reservoirs are hydroelectric power plants that utilize the power of flowing water within the river. For example, water can be diverted into a small channel to drive the turbines of the power plant. Such plants can be found along major rivers in Europe.
Another form of hydroelectric power plants are tidal power plants in certain coastal bays were the difference in the tides is large enough to create strong currents to drive turbines. Such plants are currently rare. The largest went into operation in 1966 in Brittany/France. Smaller ones exist near Murmansk/Russia, Taliang/China and Bay of Fundy/Nova Scotia.

In areas with plenty of sunshine, solar energy can be used in passive solar collectors (e.g. south-facing windows) to warm houses. Active solar collectors are usually black panels with tubes of circulating air or water mounted on roofs. These are used to heat water and even houses. The initial costs for setting up solar collectors are relatively high but in some areas, such as southern Europe and Egypt, solar collectors are used extensively. In Israel, 80% of the domestic water is heated by solar collectors. Solar collectors can even be found in northern Europe where sunshine is considerably less. There have been attempts to introduce solar collectors in southern California but so far have appeared only on individual houses. The water is often considered too aggressive to be used in solar collectors (dissolved minerals corrode the tubes). Photovoltaic elements turn solar energy into electricity. A large experimental facility exists near Hespernia, CA. In some developing countries, (e.g. Dominican Republic, Sri Lanka and Zimbabwe) photovoltaic elements the size of an open briefcase provide the little energy that is needed for domestic TV, radio and a few light bulbs. Such elements are yet too expensive for the general public. An experimental facility to use mirrors to focus solar energy into a "heating tower" that heats pressurized water to 500^oC to drive turbines is "Solar One" in the Mojave Desert near Barstow.

Following the "energy crisis" of the 1970ies, interest in wind as energy source has increased and in the 1980ies, government programs sponsered the development of windpower systems. By the late 1990ies, more than 17,000 wind turbines in California were integrated into the state's electrical grid but further development is somewhat stagnant. The difficulties include the search and purchase of large suitable tracts of land (lots of wind), noise pollution, and the development of large, efficient turbines.

Relatively recently discovered (in Permafrost and oceans beneath 525m), gas hydrates are a frozen combination of water and methane. Resources are about twice as abundant as all traditional fossil fuels taken together. Two current problems: production and transportation not yet developed; burning of methane also contributes to global warming.

Bringing together two light nuclei (H-isotopes); H is readily available; huge quantities of energy released during this process but huge amounts of energy required to initiate the process. Considered ecologically less problematic than fission (because the only radioactive element produced is Tritium) but currently not economically feasible.

Diesel Fuel: to be updated. Will not be on the tests.

Biofuels (biodiesel): derived from contemporary plant matter such as ethanol (some applications in Europe). Benefit of emitting less CO₂ than burning of traditional fossil fuels depends on the use of material to distill the biofuel (e.g. when fossil fuels are used to do this, then 110% CO₂ are actually produced, when biofuel is used, then 60% are produced). Biodiesel (e.g. esterified rapeseed oil) can be used in diesel engines without much modification. Produces less soot and SO₂ than diesel fuel but the production of greenhouse gases is just as high. The growing of crop for biofuels requires increased amounts of nitrogen-based fertilizers that increase the release of nitrous oxides into the atmosphere and increase the ozon level.

Methane: large amounts available. Burns cleaner than the rest of the fossil fuels but is a greenhouse gas. It is ubiquitous, wherever organic matter decomposes (e.g. waste dumps). An experimental facility exists at the San Diego Miramar landfill.



Electric cars: are appearing in certain areas (e.g. tourist resorts like Catalina Island or some towns in the Swiss Alps and in some cities in Europe) and for certain services (e.g. golf carts, airport terminal transportation). Electric cars are usually small however, have less horse power than ordinary cars and can't operate for long distances between charging the battery. Also, the electricity for charging the batteries has to provided somehow (currently fossil fuels?!).

Hydrogen: Hydrogen combines with Oxygen to produce water and large quantities of energy. Hydrogen has found use as fuel in powering the Saturn rockets to the moon and the U.S. Space Shuttles. It had also been used in the early zeppelins before the Hindenburg exploded. Advantages are its light weight and less production of polluting gases. Disadvantages are high production costs and perils of explosions. H and O can be combined in fuel cells to create electricity (works like a battery except that electrical energy is produced rather than consumed). Advantage is that no polluting gases are produced. Disadvantage is that useful quantities of H₂ are not easy to store in small tanks. Currently battery-operated cars could eventually be powered by fuel cells. E.g. Mercedes-Benz has announced that fuel-cells will go into commercial production by 2010. Prototype busses run in Vancouver and Chicago.

Hybrid Cars: a temporary compromise; to be updated

Nuclear power is often considered as alternative energy resource because it does not produce greenhouse gases. But the problem of long-term storage of used fuel rods has not yet been solved. Environmental issues also increased the production costs of nuclear power.

Hydroelectric and geothermal power generation probably cannot meet the great current demands. Solar and wind energy are considered expensive and are generated by relatively few energy providers.

Energy conservation seems a somewhat painful but inevitable choice not only regarding the use of energy resources in a responsible fashion but also to leave behind a livable environment for generations to come.

• greenhouse effect and global warming from burning fossil fuels
• oil spills (during production and transport)
• acidic mine runoff (dilute solution of sulfuric acid)
• landscape scarring (coal and uranium mining)
• acid rain/soot from burning fossil fuels
• production of highly toxic and radioactive waste
• civil security problems from plutonium production

A study collected urine and blood samples in 1999 and 2000 from more than 2000 volunteers. It was found that levels of lead, pesticides and tobacco residue declined. However, levels in mercury increased. About 8% had blood levels of mercury esceeding 5.8 ppb, the precautionary standard set by the EPA (federal health officials set the danger level at 10 times this which was not found in any of the woman).
Mercury exposure is likely to occur through eating fish. Mercury enters the environment mainly from the waste gases of power plants and accumulates in fish.
The study is published at the CDC web site . Also check out the ERTH15 note on Mercury in the Can of Tuna.

• Earth, Portrait of a Planet, 2005. Stephen Marshak, Norton & Company Ltd., New York, ISBN: 0-393-92502-1
• State of the World, 2004, issued by the Worldwatch Institute, ISBN: 0-393-32539-3
• Environmental Chemistry, 2000. Colin Baird, Freeman and Company, New York, ISBN: 0-7167-3135-3
• Hubbert's Peak, 2001. Kenneth S. Deffeyes, Princeton University Press, Princeton, ISBN: 0-691-09086-6
• Earth, An Introduction to Physical Geology, 2005. E.J. Tarbuck and F.K. Lutgens, 8th ed., Prentice Hall, Upper Saddle River, N.J., ISBN: 0-13-114865-6
• Earth's Dynamic Systems, 2001. W.K. Hamblin and E.H. Christiansen, Prentice Hall, Upper Saddle River, N.J., ISBN: 0-13-018371-7
• Physics, 1998. J.D. Cutnell and K.W. Johnson, John Wiley and Sons, New York, ISBN: 0-471-19768-8