NATURALLY DANGEROUS: Surprising Facts About Food, Health, and the Environment.
By James P. Collman, Professor of Chemistry, Stanford University
Chapter 8. Is the Sky Falling??
© James P. Collman, 2003. All rights reserved
Concern over global warming has brought attention to various forms of renewable
energy. Among methods of generating renewable energy, wind-power is an important
growing source. Currently wind-power provides only 1% of all electricity globally,
but in Europe, where it is subsidized and politically promoted, wind-power
is more important: it provides 20% of the electricity in Denmark, 10% in Spain
and about 7% in Germany. In the U.S it is far behind, but rapidly growing.
Wind-power is still subsidized, but it is becoming cheaper; the current cost
of wind-generated electricity is about10 cents per kilowatt-hour, which is
still about twice the price of coal generated power. The overall global wind-energy
potential is 72,000 gigawatts (GWs), almost 5 times the world's total current
electric energy demands. The efficiency of windmill generators and their rotor
blades have been greatly improved and these continue to become more efficient.
The most efficient windmills are the largest. Up to 50% of the kinetic energy
of the wind can now be extracted by the best windmills, nearly the theoretical
limit of 59%. Offshore windfarms cost more than onshore ones, but the land
under the offshore machines is far less expensive. Serious problems remain
in developing the power grid to transmit power, particularly from rural locations,
and since the wind does not always blow, and it is both difficult and expensive
to store electric energy, expensive, traditional reserve power generators
must be available when the wind does not blow. If carbon taxes are passed,
wind-power will become more competitive. But esthetic problems, the noise
generated by windmills, and the danger they pose to birds are factors opponents
use to resist wind-power. (The Economist Technology Quarterly, December 6,
It is well established that major volcanic eruptions such as those of Indonesia’s Mount Agung in 1963 and the Phillippines’ Mount Pinatubo in 1991 cooled the oceans by throwing particles and clouds into the atmosphere and shielding the sun. This effect lasted up to 18 months. During this chilly period, the sea level dropped, because water contracts when it is cooled. The contraction of water as temperatures are lowered is small, but the volume of the ocean is huge; the result is a drop in sea level of several millimeters. Sea levels are measured from satellites. The recent prediction of sea level rises from global warming comes principally from warming the water on the surface of the sea, not from melting glaciers. (Science News, November 5, 2005, Vol. 168, Page 294)
The use of ethanol derived from corn as a biofuel is a controversial topic. One appeal of bio-fuels such as ethanol from corn derives from the fact that the corn took up carbon dioxide from the air, perhaps as much as would be released to the atmosphere when the fuel was burned as a fuel.
Some facts are useful in thinking about this growing practice. The U.S. currently uses 140 billion galleons of gasoline per year. Last year, 5 billion gal. of ethanol derived from corn are added to gasoline. In the near future this figure is predicted to rise to 9 billion gal. But, because ethanol has only two-thirds the energy value of gasoline, 9 billion gal. of ethanol would replace only 6 billion gal. of gasoline, which is just 4.3% of the U.S. total. But producing 9 billion gal. of ethanol from corn will require over 20 million acres of corn, which is approximately one fourth of the current U.S. acreage currently planted in corn.
This increased use of corn to produce ethanol for fuel will not directly affect corn available for human consumption because relatively little of the corn crop is eaten by the public. Half of the corn crop is used as animal feed in the U.S.; 20% is exported and used to feed animals; another 20% is diverted into ethanol as a biofuel, and 10% is used in industry, especially for food related products, such as high-fructose corn syrup. Much of this sweetener is employed in soft-drinks. Diverting more corn to ethanol production is predicted to increase the price of corn and to drive up prices of cattle, hogs, poulty, and dairy products.
There is a raging debate over the amount of energy required to grow and convert corn into ethanol. Does this require more energy than one gets back in burning energy as a fuel? David Pimentel, an agricultural sciences professor at Cornell University and some other academic scientists and engineers say yes - producing ethanol from corn is a net loss of energy. But a growing number of scientists and economists disagree with Pimentel. Many other issues, especially the amount of carbon dioxide that is produced upon using bio-ethanol as a fuel, farm-state politics, subsidies, and industrial interests such as those of Archer Daniel Midlands (ADM) complicate this problem. ADM produces 20% of the ethanol from corn today and will double their production in a year.
Another issue is the potential use of corn stalks and waste (stover) as well as other inexpensive forms of cellulose such as switch grass to produce ethanol. There is a lot of cellulose available, but the enzymes required to produce ethanol from cellulose are expensive and inefficient. Research on these enzymes is in progress, but don't expect this problem to be solved in the near term.
Finally, the development of more fuel-efficient vehicles could have a major impact on this issue.. For example a 3% increase in fuel efficiency would reduce the need for as much gasoline as was "saved" by the use of ethanol as a bio-fuel. (Chemistry & Engineering News, January 1, 2007, page 19)
On page 190 in Naturally Dangerous one conservation measure is casually proposed: to use fluorescent light bulbs in place of traditional incandescent bulbs. Now Wal-Mart, a company often criticized by many on the left side of the political arena, has "gone green" by promoting consumer use of compact fluorescent light bulbs, proposing to sell 100 million of these more efficient lights by the year 2008. For people on either side of the global warming conflict this is a "win-win" situation, but it is unlikely to happen because this idea is in conflict with human nature.
Some facts are instructive. Fluorescent bulbs use about 20 percent of the energy required by comparable incandescent bulbs and for an average bulb one should save about $8 a year in the electric bill. Replacement of 100 million traditional light bulbs with fluorescent bulbs would save Americans $3 billion in electric costs, and avoid the need to build power plants that could supply 450,000 homes! For those interested in the amount of the greenhouse gas, carbon dioxide emitted, the average saving in carbon released into the atmosphere is an amazing 100 lbs. per bulb replacement. Moreover, the lifetime of a fluorescent bulb is between 5 and 10 times longer than a comparable incandescent bulb. So what is the problem, those figures are really impressive?
Upfront costs are much higher: $2 to 4 for a fluorescent compared with $0.25 to 0.60 for an incandescent bulb. There is also some mercury pollution associated with disposal of used fluorescent bulbs, whereas there is no mercury in incandescent bulbs. But 4 milligrams per bulb over a lifetime of two or three years is not much and Wal-Mart has offered free disposals to capture the mercury. U.S. jobs would be lost if so many fluorescent bulbs were sold because these are made overseas, whereas incandescent bulbs are still made in this country. The overall advantages of fluorescent light bulbs are nevertheless overwhelming, but the difference in initial cost has such a strong influence on human nature that even polished advertisements cannot overcome this barrier. So most social scientists think Wal-Mart's green venture will not achieve its goal. (New York Times, 01/02/07, page 1)
Geologists and paleoclimatologists have been accumulating evidence from ancient soils, plants, and seashells that paint a controversial picture of the World’s climate over a very long period – from the present to 550 million years ago. In very ancient times some scientists claim that the concentration of carbon dioxide in the atmosphere was up to 18 times the levels that are currently present. Moreover, in some of these ancient times when very high carbon dioxide levels were in the atmosphere, the Earth was cold and was undergoing ice ages. Other scientists are unconvinced that this evidence from the deep past is convincing or is relevant to the current consensus about increasing carbon dioxide levels, which they believe will cause catastrophic global warming from the greenhouse effect. The evidence from ancient fossils seems to be growing stronger and with it a debate is developing between different groups of scientists about whether there is a direct correlation between carbon dioxide levels and the World’s climate. Most climatologists believe that doubling the carbon dioxide level would raise the Earth’s temperature by as much as 8 degrees Fahrenheit, but skeptics basing their arguments on analysis of ancient fossils, propose that that the temperature rise might only be 2 to 3 degrees.
An old idea has emerged as a part of this debate - that changes in cosmic rays may have been an important factor in controlling the climate. As readers may remember from Naturally Dangerous, cosmic rays that bombard our Planet from outer space, contribute to cloud formation. Clouds shade the Earth from the sun and cools the climate. Conversely, a reduction in cosmic rays should lessen cloud cover, allowing the Sun to warm the Earth. The relative importance of greenhouse gases such as carbon dioxide and of cosmic rays is not agreed upon. These arguments are just appearing in the popular press. ( New York Times, November 7, 2006 , page D1)
There has been a lot of speculation about the rise in global sea levels (GSLs) as the result of global warming. For example in the movie, “An Inconvenient Truth” promoted by politician Al Gore, it is suggested that the sea level might increase by 20 feet in the next century. Of course such an increase would cause a lot of havoc, which is emphasized in the press, It is instructive to know how much GSLs have actually gone up during the recent past. These increases are found in an article written by climate experts in a recent article in Science (vol. 313, 11 August, 2006 , page 827). Over the past century the GSL increased by 1.7 mm per year, but over the past decade, as the Earth has become warmer this rate of increase has accelerated to 2.8 mm per year. Most Americans do not use the metric system. They know figures such as inches and feet. There are 10 mm in one cm and 2.54 cm in one inch. A rough calculation shows that according to the figures given above, the GSL may go up by as much as 8 inches over the next century. Such an increase would be noticed and will probably be harmful in some low-lying areas, but the estimates indicated in this movie are extreme. Science is becoming politics.
Sometimes it is useful to put a problem in perspective, especially when that problem is very large, very expensive, and very political. Because of ignorance or political bias, the national media often does not give the facts and present the technical and economic difficulties underlying huge new projects. Because of long-term concerns over available energy sources and the release into the atmosphere of the greenhouse gas, carbon dioxide, the conversion of biomass (plant products derived from the sun’s energy via a process called photosynthesis) into liquid fuels is gaining political momentum. Biomass is said to be a “renewable” source of energy that could free us from using so-much expensive and dwindling petroleum for driving automobiles. So what are the facts and the problems in accomplishing this?
Each year the Earth receives about 4000 times as much energy from the Sun as the whole World is predicted to need by the year 2050. So there is plenty of energy from the sun, but the only efficient way to capture this is through photosynthesis, that is growing plants: grass, trees, sugar cane, even corn. Foods and waste plant products, which are complex carbohydrates such as cellulose, and something called lignin, which is found in wood chips, must be transformed by enzymes into liquids such as ethanol, the same stuff that is in alcoholic beverages. This process is known as fermentation. Brazil does the best job of this by obtaining one fourth of its vehicular fuel from the fermentation of sugar cane into ethanol. Sugar cane is presently the most economical source of this alcohol and tropical climates such as that in Brazil or the Philippines are best suited to grow sugar cane economically. The US uses, corn, a valuable food source to produce ethanol. Compared with corn, it costs 30% less to produce ethanol from sugar cane. The federally-mandated US program is probably uneconomic and may be a waste of energy when all the energy requirements: fuel, fertilizer, transportation, and processing are taken into account. Recall that natural gas must be used to make the ammonia fertilizer that is required to produce high yields of corn. Natural gas or other energy sources such as coal or even cow manure are also needed to power the distillation of ethanol. Moreover, ethanol cannot be shipped in gasoline pipelines, so it must be transported by trucks, which burn fossil fuels and release carbon dioxide in the process. Massive subsidies underpin the US ethanol program, with political support from large corporations such as Archer Daniel Midlands, ADM, (currently holding 24% of the US alcohol market), farmers and other voters in farm states, as well as environmentalists. For example huge and growing profits are beginning to accrue in the farm states from the corn to alcohol program; this further enhances the political motivation behind this program. The ethanol-from-corn industry is heavily subsidized; for example a 51-cent-a-gallon tax credit is currently given to the refiners and blenders that mix ethanol into gasoline. In 2007 the politically-well-connected corporation, ADM is slated to earn $1.3 billion from its ethanol/fuel program. No politician who expects to get reelected would dare speak against this immoral use of a valuable food source in a World where some people are still starving, as a fuel! Presently, using 90 corn-to ethanol refineries, the US produces 4.5 billion gallons of ethanol each year from corn. Because of the US Energy Policy Act of 2005 this amount is expected to increase to 7.5 billion gallons by 2012. This is still a small fraction of the current ground transportation used annually in the US : 140 gallons (gasoline and diesel). If we were to replace as much as 30% of that fuel by ethanol, the US would have to produce 60 billion gallons of ethanol each year, which could probably not be done using only corn.
Fuel derived from such a massive alcohol program would contain 85% alcohol, whereas current “gasohol” fuel uses only 10% alcohol. The latter does not require modification of automobile engines, but the former 85% alcohol mixture would necessitate modification of the engine and fuel injection system creating “flexible fuel” vehicles. There are other problems. Ethanol contains less energy per unit volume than gasoline; consequently cars running on ethanol gasoline mixtures get lower mileage. Moreover, ethanol cannot be shipped in gasoline pipelines because it gets wet and separates so the ethanol must be shipped by truck or train and blended near the gas stations. All this costs additional money.
An emerging struggle is also beginning to develop between food production and ethanol/fuel production. This conflict is beginning to place a strain on food prices. Increasing demand for corn will raise corn prices, which are now $2 a bushel. Above $3 per bushel of corn, the live stock industry will be forced to raise meat prices and this would lead to increased inflation.
There are other potential plant sources that can be used to produce ethanol besides corn. It is estimated that all sources of biomass: corn stalks, wood products, switch grass, etc. might amount to 1.3 billion tons. These sources are cheaper to produce than corn is; corn requires extensive fertilizers, and plowing, etc. In fact many people believe that the alcohol derived from corn may contain less energy than the energy used to produce that corn. In theory, it should be possible to produce 100 gallons of ethanol from the cellulose in each ton of dry biomass. If this could be accomplished the US could produce 130 billion gallons of ethanol from these renewable sources. Such a gigantic alcohol for fuel program would be welcome in terms of reducing America ’s dependence on petroleum as well as the amount of carbon dioxide released into the atmosphere, because growing the same amount of biomass would recapture the carbon dioxide. released upon burning ethanol in automobiles. But can such a program be accomplished, and what would it cost? The facts are sobering.
The conversion of cellulose, a “complex carbohydrate” (see page 12 in Naturally Dangerous for definitions) into ethanol is presently very difficult and prohibitively expensive. Large amounts of expensive enzymes must be used and the cellulose must be broken down to simple carbohydrates such as glucose before fermentation takes place. These special enzymes are derived from exotic sources such as fungi involved in “jungle rot” or in elephant dung. The cost of a gallon of cellulosic ethanol is said to have dropped from $6 to around 50 cents. But much more research and development is still necessary before this becomes a commercial success. Large companies are unwilling to invest in cellulosic ethanol without massive Federal support.
After a modest amount of ethanol is produced during fermentation, either from corn of cellulose, the enzymes become poisoned so that the ethanol must be distilled from the dilute ethanol/water mixture. Recall the production of whiskey from page 37 in ND. This concentration of ethanol by distillation requires energy, costs money, and releases carbon dioxide. Another problem is that components in some of the biomass inhibit the enzymes that are used in fermentation. These are serious, difficult problems, which cannot be solved immediately and will require years of research, but the current research grants and expenditures in non-medical microbiology, plant biology and chemical engineering are mediocre and would have to be increased by massive amounts in a focused program similar to the “Manhattan Project” that produced the first atomic bombs during World War II. (abstracted from: Chris Somerville, Professor of Plant Biology, Stanford University, Science, Vol. 312, 2 June, 2006, page 1277, The Wall Street Journal, June 29, 2006, page 1, and a New York Times article: NYT, June 25, 2006, page 1)
With the rising costs of petroleum and natural gas, the U.S. has a growing economic problem. Approximately 70% of the petroleum we import is used to produce liquid fuels such as gasoline for automobiles and diesel fuel for trucks and airplanes. The rising requirements for petroleum propelled by the rapidly growing economies in China and India and coupled with the violence in many of those parts of the Middle East where much of the petroleum comes from, have combined to drive the price of oil over $70 a barrel; perhaps it will go above $80? We cannot fuel our automobiles, airplanes and trucks on coal or on natural gas; liquid fuels are essential to the U.S. economy. The U.S. does not import natural gas, except in pipelines from Canada . The price of natural gas has also been rising sharply. One of the important uses of natural gas is to make ammonia for fertilizer, although we could import ammonia from countries, which have surpluses of cheaper natural gas. There are plans to import liquefied natural gas into the U.S. , but this method is both expensive and dangerous – especially with regards to terrorist attacks.
Beyond these serious economic problems, ecologists have become concerned about global warming from the release of carbon dioxide into the atmosphere as the result of burning gasoline and diesel fuels as well as burning natural gas and coal in power plants to produce electricity. These two issues, economics and ecology come into conflict when the U.S. considers using its huge stores of coal to manufacture diesel and methane, the major component in natural gas. But we have a lot of coal and it is relatively cheap. For example the coal in the ground in Illinois represents more energy than all of the oil thought to be present in Saudi Arabia , the country that has the greatest petroleum reserves. In fact the U.S has coal reserves of about 496 billion tons, half of which are thought to be recoverable using modern mining techniques.
During the Second World War, Nazi Germany had limited petroleum reserves (mostly in the Balkans), but the Germans had massive coal supplies. The Germans used an inefficient technology, the Fischer-Tropsch process, invented in the 1920s to produce diesel fuel for their tanks and aircraft from coal. Later, under the stress of the apartheid regime, South Africa used an improved version of this process to produce liquid fuels. Now the Fischer-Tropsch process is being considered in the U.S. , China , and Australia to turn their ample coal reserves into diesel fuel. The problems are price and the fact that this process produces extensive amounts of carbon dioxide, the principal green-house gas that ecologists are trying to reduce. (Recall from Chapter 8, that water vapor is actually the major green-house gas, but nothing can be done to control the amount of water vapor in the air.) Many politicians and concerned scientists want the U.S. and other highly developed countries to limit the amount of carbon dioxide that is released into the atmosphere.
What are some of the facts? In the context of its energy content, coal is 1/7 th the cost of natural gas and 1/23 rd the cost of diesel fuel. But much of this energy is lost in turning coal into diesel fuel, or even into an equivalent of natural gas. Moreover, a large amount of carbon dioxide is given off during the transformation of coal into diesel fuel. During this process coal is first transformed into hydrogen gas and carbon monoxide with carbon dioxide as a byproduct. The impact of driving a car on the diesel made from coal would be to release, both in the Fischer-Tropsch process and in the combustion, of double the carbon dioxide that would be released from driving a vehicle using petroleum-derived diesel. Diesel made from coal is estimated to cost $100 a barrel! Improvements can be made in this process and other cost advantages may be realized such as capturing the sulfur in the low grade Illinois coal and using the carbon dioxide produced in the process by injecting it into old oil fields to stimulate more oil production, but the release of massive amounts of carbon dioxide into the atmosphere during the transformation of coal into liquid fuels may be a “show stopper”, especially when liberal lawmakers are asked to support the subsidies to launch such a massive, expensive new industry. By the way, the cost of “bio-diesel” made from plant oils is even more expensive, but much less carbon dioxide is released in the process. Another major problem from an industrial point of view is the fear that such a massive investment in new fuel plants might be destroyed if the price of petroleum were to plummet. (Matthew L. Wald, New York Times, July 5, 2006 , page C1)
An unremitting source of renewable energy is that derived from manure. Anaerobic (oxygen-free) digesters, contain bacteria that convert all types of manure (from cows, turkeys, and hogs) into methane, the major component of natural gas. Odors from sulfur compounds can be scrubbed, rendering the gas “pipeline-quality”. Useful, saleable byproducts that can be obtained from cow manure include fibrous solids used as cow bedding as well as liquid fertilizers and the excess heat produced. As readers may recall from Chapter 8, methane is a significant greenhouse gas and these reactors prevent the methane normally produced by animal waste from escaping into the atmosphere. If they use these devices, farmers would no longer have to maintain lagoons and other means of controlling this odorous waste product. Dairies have large numbers of cows, which generate large quantities of manure. It is estimated that 70,000 dairy and swine farms could provide enough energy from manure digestion to power more than 560,000 homes, while keeping 1.4 million tons of methane out of the atmosphere. Using several different business models these digesters appear to be profitable, but it is difficult to disentangle the role of subsidies. In one example a dairy with 600 cows paid $960,000 for a digester (half subsidized by the State and Federal Governments) and pipes its methane to a generator, and sells the resulting electricity for 3.5 cents per kilowatt-hour. It is said that digesters need to get at least 6 cents per kilowatt hour to break even, but utilities often will pay only 2 cents. Considering all the factors, these modern manure-to-energy systems are becoming economic and are spreading through dairies and hog factories. (New York Times, July 4, 2006 , C1)
During an evening-news broadcast on the prestigious National Public Television News Hour by Jim Lehrer, a physicist from Columbia University suggested a simple way to reduce carbon dioxide in the atmosphere and mitigate the effects of this greenhouse gas that is involved in global warming. Professor Klaus S. Lackner appeared on the show and demonstrated his method, which he said is related to a science project his daughter is involved with. Professor Lackner had a meter, which measures the carbon dioxide in the air and showed that the level was high in a closed room in which people were breathing, thus expelling this greenhouse gas. Then Lackner carried out his simple remedy for this "problem". He took a solution of sodium hydroxide, a common base, and showed that when this is exposed to the room air, the carbon dioxide level on his meter fell. Since sodium hydroxide is relatively inexpensive, this led Lackner to propose a method of lowering the carbon dioxide concentration in the air. He displayed drawings of huge platforms that had fans that would draw air through sodium hydroxide solutions. Lackner showed a map with such platforms distributed over much of the earth. This episode has many flaws, but it is tragic to have such nonsense preached to a nation-wide audience of non-scientists. What are the problems and facts behind this "solution"?
As a strong base in water, sodium hydroxide (caustic soda) has been known to react with carbon dioxide for well over one hundred years and sodium hydroxide is one of the cheapest bases, the cheapest being calcium oxide or lime. But how cheap is sodium hydroxide and how is it made (there are no sodium hydroxide ores on Earth)? Caustic soda is manufactured from electrolysis of brine, from seawater. The annual production of caustic soda in the U.S. is over 10 million tons! Seawater is cheap, but the electricity required to carry out this electrolysis is not free as the average citizen who pays their electric bills know. Moreover, the electrolysis process is somewhat inefficient. But "where does that wire go?" I asked this question of a young college student studying ecology, who was going to solve the energy problem by plugging an electric car into the wall socket. Production of electricity requires power, produced in most cases by burning fossil fuels: coal, gas, or petroleum. The byproduct is carbon dioxide! Lackner's "solution" reminds me of a dog chasing its tail. Beyond that, a simple cost analysis of the amount of sodium hydroxide that would be required to remove a meaningful fraction of the carbon dioxide in the Earth's atmosphere, disregarding the cost of his mythical towers, would be astronomical.
How did a "card carrying scientist" come up with such a foolish solution? Lackner was trained as a particle physicist, but he has evolved into a Professor of Geophysics. Engineering cost estimates are not his strong suit. Nor is his understanding of the second law of thermodynamics, which states there is no free lunch. His research is undoubtedly supported by our taxes and seemingly from energy companies. Scientists who publish their ideas in well-respected scientific journals have their articles vetted by experts in whichever subject. Mistakes are sometimes made. But it is inexcusable for a respected, non-commercial national news program to broadcast such nonsense. Perhaps the politicization of the global warming issue and the rush to "educate the public" explains this faux pas?
After writing the above, I have had correspondence with Lackner, who told
me, but not the PBS audience that he intends to remove the carbon dioxide
from his sodium carbonate product, returning to sodium hydroxide. His method
is feasible but in my opinion and that of other scientists I have consulted
the overall process would cost vast sums and could never be implemented on
the proposed massive scale. Lackner is "a true believer", but passion
does not change economics and the PBS program should have been balanced.
A careful examination of the geological record supports the concept that
periods when ice sheets melted and retreated are connected with increased
earthquakes and volcanic activity. Conversely the pressure that ice sheets
exert on the Earth's crust may suppress earthquakes. Removing this pressure
is thought to trigger earthquakes and volcanic activity. These changes can
be slow, over thousands of years. Some geologists believe that present-day
earthquakes may have their origins in a postglacial rebound. For example melting
of the ice sheets after the last ice age, 10,000 years ago is thought to have
triggered a surge of volcanic activity in Iceland and a wave of earthquakes
in Scandinavia. Such connections between glacial retreat and seismic and volcanic
activity have been made in many parts of the World, such as New Zealand, California,
Alaska, and the Swiss Alps, over long geologic times. Will this phenomenon
be invoked in the current exaggerated political debates over global warming?
Time will tell, but wait for a dramatic geologic event. (Wall Street Journal,
Sharon Begley, page A13, June 9, 2006)
World wide concerns over global warming and impending shortages of petroleum have prompted an analysis of future energy requirements and the prospects of developing "renewable" energy resources. The following data were taken from a DOD workshop, co-chaired by a chemist, Nate Lewis (Cal. Tech.) and a physicist, George Crabtree (Argonne Labs.) ¨C Science, 22 July, 2005, page 548.
At the present time humans consume power at a steady rate of 13 trillion watts (13 TW). Relevant to global warming, 85% of that power is derived from fossil fuels (petroleum, natural gas, and coal), resulting in release of CO2, a principal greenhouse gas. What is shocking is that the world wide power demand is projected to rise by another 30 TW up to 43 TW by the year 2050! That increase is projected on the basis of economic development in countries such as India and China and global population growth. Such enormous growth in energy production could result in substantial, some say catastrophic changes in the Earth's climate. Thus scientists and engineers are searching for massive increases in energy from sources that do not generate CO2; these are called "alternative and renewable" energy sources.
To illustrate the gigantic problems involved in producing so much power, consider the possible use of new nuclear power plants to generate only 1/3 of the projected new demand by 2050. Nuclear power is an alternative energy source that does not generate carbon dioxide. Such an effort would require the construction of 10,000 new nuclear plants, each capable of generating a gigawatt (one billion watts) of power, enough to provide for a small city. Generating such a massive amount of nuclear energy would necessitate opening a new nuclear reactor every other day for the next 50 years! Recall that the last nuclear power plant was built in the U.S. about 30 years ago!! Fusion power, the mechanism that produces energy in the Sun, could theoretically provide a large source of energy, but after spending tens of billions of $s, no viable fusion reactor has been developed and such may be 50 years away, if then.
The currently most economic source of renewable energy is from harnessing the wind. This technology, which also does not produce carbon dioxide, is already capable of producing electricity for $0.05 per kilowatt-hour, which is close to the cost of electricity from coal and gas powered generators. Recent estimates of generating electricity economically in the U.S. from wind turbines gives a figure of up to 6 TW of power, which is a large amount, but it would be insufficient to meet much of the projected needs. This figure might be much greater, up to 72 TW if these wind turbines were operated 80 meters above the ground, where the wind speed is much higher, but the costs would also be much greater. Other forms of alternative, or renewable energy are: geothermal, ocean waves, and biomass. Each has its problems. Geothermal is limited to the few volcanic regions that could be developed and by the high cost of drilling. Noise and pollution from sulfur dioxide present ecological problems. Ocean-wave-power is limited by high construction and maintenance costs. To produce sufficient quantities of Biomass necessitates converting land that must be committed to growing food.
Because of the great current and future demand for energy, traditional fossil fuels will be used in spite of the release of carbon dioxide with the potential problems in raising the global temperature. Some of the released CO2 could be injected deep in the earth or in the ocean, but these processes are expensive and are still being developed. Natural gas is being used to produce electricity because it releases fewer pollutants and generates less carbon dioxide per unit of energy, but the U.S. supply of natural gas is becoming squeezed and consequently its cost has been rising. At this time one power plant fueled by natural gas is being opened in the U.S. every three and one-half days! About two hundred years of natural gas is estimated to be available, including gas, which can be obtained from remote locations outside of the U.S. The world's petroleum reserves are being depleted more rapidly so that the production of petroleum is expected to reach its maximum sometime within the next 50 years. Many types of transportation such as automobiles and airplanes are dependent on liquid fuels derived from petroleum. About 60 percent of petroleum is converted to liquid fuels. This impending crisis from high costs and shortages of petroleum is driving oil prices ever higher. For this reason ethanol produced from biomass and switch grass are being considered to augment future liquid fuel supplies. In Brazil most of the automobile fuel is derived from ethanol make from sugar cane.
Two thousand years of coal reserves are estimated to be available worldwide, but burning coal produces more carbon dioxide than natural gas or petroleum. Nevertheless, coal will be used because it is required to sustain the energy needs of modern civilization.
The large remaining energy source is solar, radiation from the sun. Solar energy is renewable, and huge, but dilute and expensive to capture and convert into electricity by using solar cells. The high costs of solar panels are slowly falling and their efficiency is rising, but the distribution and storage of solar electricity are still major problems. How much solar energy can be generated and at what cost? Potentially far more solar energy is available than is needed, but intensive and extensive research and engineering will be required to realize the potential of solar cells. Some facts are useful to put this evolving technology in perspective. The surface of the Earth receives more energy in one day than all humankind requires in one year! But sunlight is a dilute form of energy. For instance, to obtain 20 TW of power from solar panels operating at 10% efficiency would require covering 0.16% of the Earth¡¯s surface with such solar panels. The magnitude of this area can be illustrated by considering that if solar panels covered the roofs of the 70 million separate houses presently in the U.S., would generate only 0.25TW, which is only one-tenth of the electric power consumed in the year 2000. Other economic and ecological problems require constructing gigantic energy grids to transport electricity generated from solar farms. Storing solar energy is also a formidable problem. A simple but specialized possibility is to pump water up a hill to a storage reservoir, from which energy can be released as the water is allowed to flow back down the hill through a generator. Another long-term possibility is to make hydrogen gas using excess electricity generated from solar cells and later use that hydrogen in fuel cells, but there are many problems with this version of the "hydrogen economy". These are discussed elsewhere in Naturally Dangerous
What about the current cost of electricity produced from solar cells? Electricity
from solar cells now costs $0.25 to $0.50 per kilowatt-hour compared with
$0.05 to $0.07, $0.025 to $0.05, and $0.01 to $0.04 from wind power, natural
gas, and coal, respectively. Solar energy is still too expensive to compete
without subsidies or "niche" uses such as isolated locations far
from electric lines. Beyond this it is important to recognize that only 10%
of the world's energy use is electricity. It should be clear that research
directed towards making cheaper, more efficient photovoltaic devices (solar
cells) is an important investment.
Living plants are considered to be a major weapon against global warming because during photosynthesis plants take up the greenhouse gas, carbon dioxide, and convert it into carbohydrates. Now along comes surprising evidence that a wide variety of living plants emit another greenhouse gas, methane, under normal growing conditions! This finding could help explain observations from space that large plumes of methane have been observed above tropical forests. Moreover, this new finding could also explain the recently observed slowdown in the growth of methane in the atmosphere because this decrease could be the result of deforestation. Scientists already knew that methane has been entering the atmosphere as a result of the decay of dead plant material, and from swamps and rice paddies from the action of anaerobic bacteria. As a result of this new finding, that living plants can also emit methane, it is now estimated that between 10% and 30% of the annual amount of methane entering the Earth’s atmosphere may come from a combination of living and dead plants. (Chemistry & Engineering News, January 16, 2006 , page 26; Nature 2006, 439, 187)
Methane is a major green house gas, more than 20 times as potent as carbon dioxide, but with a shorter lifetime in the atmosphere. The Earth’s early atmosphere is thought to have had methane concentrations more than 500 times as great as today. There are three sources of methane: anaerobic microorganisms, heat induced degradation of organic matter trapped in sediments, and chemical reactions of carbonates and carbon dioxide by reducing agents in the Earth. The methane produced by microorganisms can be distinguished from that formed by other mechanisms by measuring the amount of an isotope, carbon-13 in the sample. Methane from biological sources has a smaller fraction of carbon-13. Samples of transparent quartz taken from Western Australia were found to contain bubbles, comprised of small drops of water. Methane was found in these water droplets and according to its carbon-13 content, this methane is of biological origin. These quartz samples were dated by using radioactive sources and were found to be between 3.49 and 3.46 billion years old. This means that methane-producing bacteria were present on the Earth much earlier than had previously been thought. (Ueno, et. al. Nature, March 23, 2006 )
Molecule for molecule, methane (the main component of natural gas) is at least 20 times as potent a green house gas as carbon dioxide is. On the other hand, methane does not last as long in the atmosphere because it is transformed into carbon dioxide through reaction with oxygen. Until very recently, methane was thought to be generated by anaerobic bacteria in oxygen-free environments, such as the digestive systems of cows, and sheep, and in the soil of swamps and rice paddies. Termites and decaying garbage dumps were also recognized as methane sources, again in oxygen-free environments. Now it has been discovered both in laboratory experiments and in satellite observations of the air over topical forests that plants, from grasses to trees produce serious amounts of methane. In fact, it is now estimated that 150 metric tons of methane per year, up to 20 percent of the amount that enters the atmosphere, comes from plants, not from anaerobic microbes in the soil. The mechanisms explaining methane production in plants is not understood, but there is good laboratory evidence that this can occur in an oxygen environment. Higher temperatures and sunlight were also shown to increase methane production. Perhaps the mechanisms behind plant production of methane are related to the familiar generation of volatile hydrocarbons by plants. Some readers may recall the “smoke” over the air in the Smoky Mountains of North Carolina and Tennessee. This new discovery will cause people to reconsider planting shrubs, grasses, and trees to take up the greenhouse gas, carbon dioxide, that is the focus of those trying to mitigate global warming. (Science News, January 14, 2006, Vol. 169, page 19)
Methane, the major chemical in natural gas, is an important greenhouse gas. Every methane molecule is 20 times more potent than carbon dioxide, but there is less methane in the atmosphere. Moreover, methane has a shorter lifetime than carbon dioxide in the atmosphere, because methane reacts with oxygen forming carbon dioxide. Over the past 200 years the concentration of methane in the atmosphere has doubled; this increase is larger than that of carbon dioxide. Where does this methane come from? Many places: termites, cow and sheep flatulence, leaking gas wells, petroleum production, and coal mines and deposits. It is little recognized that about 25 per cent of atmospheric methane results from anaerobic microbes that live in the oxygen-poor soils in rice paddies. This occurs when these microorganisms consume dead plants and roots from growing rice plants. Scientists are trying to develop methods to reduce the amount of methane that comes from rice paddies. (Science News, August 13, 2005, Vol. 168, page 99)
For those who believe that a hydrogen economy based on fuel cells is in the near future, consider the following, sobering problems. Firstly, it is important to remember that hydrogen gas is not an energy source (there are no hydrogen wells on Earth). Instead, hydrogen is an energy storage medium and carrier. Like any actual energy, such as electricity, hydrogen must be made from an energy source such as coal, natural gas, nuclear power, or hydroelectric power. When all the energy penalties involved in extracting hydrogen from water or natural gas are taken into account, only 45 – 55 per cent of the energy available in those sources remains in the hydrogen. For comparison, when these energy sources are converted into electricity, one retains about 90 per cent of the energy.
The cheapest current method of making hydrogen uses natural gas, a process termed steam reforming, breaks down the natural gas into hydrogen and carbon dioxide. During this process, 15 per cent of the energy in natural gas is lost. At the present time, it costs about $5 to produce enough hydrogen that is equivalent to the energy in one gallon of gasoline. Hydrogen gas has a low density and at atmospheric pressure hydrogen takes up 3,000 more space than an energy equivalent amount of gasoline. For this reason the hydrogen in a vehicle must be compressed into a gas or cooled and liquefied. Tanks of compressed hydrogen would take up to eight times as much space as a normal gas tank to provide an equivalent amount of fuel. Hydrogen’s low density means that 21 tanker trucks of Hydrogen would be required to carry the energy now carried in one tanker of gasoline! Such hydrogen tankers would use an amount of energy equivalent to 40 per cent of their hydrogen to travel 500 kilometers! The major argument in favor of a hydrogen fuel cell vehicle is to reduce greenhouse gases, but if the hydrogen were produced from fossil fuels such as natural gas, coal or oil, there would be no net reduction in greenhouse gases, just displacement from a plant to a vehicle. Only hydrogen produced from solar, wind, or nuclear power escapes this reality. When did you read that in the popular press?? (Robert F. Service, “The Hydrogen Backlash”, Science, August 13, 2004 and Power Engineering, August 2004)
Lured by Federal funding there is a “gold rush” to develop automobiles propelled by fuel cells as a panacea for the gasoline consuming, greenhouse gas emitting (carbon dioxide) vehicles now on our highways. There is a lot of hype behind this idea. Remember that hydrogen gas, the only fuel that works in fuel cells, does not occur in nature. There are no hydrogen wells on earth. Thus hydrogen must be manufactured and this consumes energy. Currently the cheapest source of hydrogen is methane from natural gas, but that would release carbon dioxide and consume an important resource. Another, less efficient method would be to use electricity to dissociate water into hydrogen and oxygen, a process known as electrolysis. The electricity could be generated from coal, also producing carbon dioxide, from nuclear(a phobia for most environmentalists), or from hydro sources (waterfalls), which are limited. A sobering fact is that “all of the electricity sold in the U.S. today would be needed to replace all our gasoline with hydrogen” (The Hype About Hydrogen, by Joseph Romm, Island Press, 2004). Other depressing facts that cannot be overcome by engineering: to give a vehicle a 100 mile range would require a hydrogen tank with a volume 4 times that of a gasoline tank). A single tank truck carrying 1000 gallons of gasoline can provide fuel for 800 cars, but the same size truck carrying hydrogen could fuel only 80 fuel cell cars. The overall infrastructure required to support a hydrogen-fueled fleet is estimated to cost $600 billion! There are additional serious, perhaps in surmountable problems with the “hydrogen economy”, which appears to have political support from both parties and from many scientists who will need to do basic and engineering research before practical fuel cell vehicles can be realized. Research is important and should be supported, but if you are over 50, don’t expect to buy a fuel cell powered car in your lifetime. Hybrid cars are here and now and do get improved mileage. More on them later.
It has been said that governments will tax anything. New Zealand is imposing a tax on flatus, the methane rich gas emitted by sheep and cattle. This per-animal tax has been given apolitically correct name, it is called an “emission levy”. The reason for this novel assessment is to conform to the Kyoto Protocol. Remember that methane is a potent greenhouse gas. New Zealand farmers call this by another name: the f(--)t tax!
Diesel soot strongly contributes to global warming, but there is relief insight. A remarkable emission control system that cleans up diesel exhaust is being installed across Europe. Although more efficient than their gasoline-fueled internal combustion cousins, diesel engines pollute the air with fine soot particles. You have seen and smelled the diesel smoke while driving behind a bus. These particulates are known to be a health hazard, but ordinary exhaust catalysts cannot remove this soot. Many scientists and most environmentalists do not realize that this soot is also a powerful greenhouse aerosol. Now the diesel pollution problem is improving in Europe because of this new CRTu’ process, invented at Johnson Matthey. Although this new diesel exhaust catalyst was developed in 1989, it could not be used until sulfur-free diesel fuel became available, because sulfur inactivates (poisons) the platinum-based exhaust catalyst. Now that sulfur free diesel fuel is available, the CRTu’ system is selling briskly in Europe: 5,000 systems were sold in 2002 and 500 a month are now being sold. It is interesting that the CRTu’ system, which was awarded the UK’s biggest engineering innovation award, the MacRobert Award, makes use of a toxic component in the exhaust gas, nitric oxide, to convert soot particles into carbon dioxide. You might remember from pages 137-8 in Chapter 6, that this molecule, nitric oxide, is a hormone that is made in many parts of our bodies. The question is when will this diesel exhaust purifying system reach the United States ; sooner if those people interested in global warming were aware of the ecological and health problems associated with diesel engines.
As costs for wind generated energy fall and natural gas prices rise, market forces are helping drive increased production of wind power. It is estimated that within a decade, electricity generated from wind and other nontraditional sources, including solar photovoltaic devices, will double (Wall Street Journal, 6/19/03, p. A4). Although wind generated power is still subsidized and problematic, it is getting cheaper, In the 1980s electricity from windmills cost 38 cents per kilowatt hour; that has fallen to between 3 and 3.5 cents. By comparison electricity from traditional natural gas generators has risen from1.5 cents to 5.5 cents per kilowatt hour. A recent study by Navagant Consulting projects that within a decade renewable energy production in the U.S. and Canada will grow from the present value of 27,000 megawatts to 60,000. Recall that a megawatt is 1,000,000 watts or 1.000 kilowatts. The increase in the cost of natural gas is caused by several factors: a shortage in natural gas, which is being used in greater amounts because of increased power demands and the environmentalistÕs resistance to coal fired power plants. Shutting down nuclear power plants would make this matter worse. In all aspects of energy production, economic forces are as important as environmental concerns, and political subsidies usually become permanently embedded in the apparent cost structure.
A remarkable book review by physicist, Freeman J. Dyson, in The New York Review of Books, May 15, 2003, gives broad insights into the great uncertainties underlying global warming (which he refers to as global weather changes). For anyone interested in this complicated, political/scientific subject, this review is a must-read. Below, I mention a few main points. The book being reviewed is: The Earth’s Biosphere: Evolution, Dynamics, and Change, by Vaclav Smil. Dyson’s review emphasizes the enormous gaps in our knowledge and the superficiality of our understanding of the effects that human activities may have on the Earth’s climate.
The impact that increasing carbon dioxide may have on the Earth is discussed from two different phenomena: carbon dioxide acting as a greenhouse gas (as described on page 178 in Naturally Dangerous) and carbon dioxide’s stimulation of plant growth. Which effect, the physical one, or the biologic alone is more significant and: are these effects good or bad? He points out that the physical effect is not simply “global warming”, but is manifest in changes in rainfall, cloudiness, and temperature. Why? Because the warming by infrared radiation is unevenly distributed. It makes a big difference whether the air is dry or wet. Remember from Chapter 8 that water vapor is the main greenhouse gas. This means that the radiation effect from water can dominate that from carbon dioxide. Thus it is argued that carbon dioxide’s major effect is on dry air, usually cold dark air, which has less water vapor. The warming effect caused by carbon dioxide is more important in places that are cold, for example in the arctic or at high altitudes. Because of this, the heating effect of carbon dioxide is localized, making cold places warmer, but to think of global averages is misleading. It is also true that changes in rainfall are more significant than changes in temperature.
The stimulation of plant growth by carbon dioxide is also complex. Nearly 10 percent of the carbon dioxide in the atmosphere is converted into plant growth each year and about the same amount is returned to the atmosphere by plant decay and plant burning. The growth rates of roots and shoots are affected differently by carbon dioxide, and these are difficult to predict, in part because water is again an important factor. Dyson mentions that in theory a crop yield should increase approximately with the square root of the available carbon dioxide. This means that a 30 percent increase in carbon dioxide concentration, as is thought to have occurred over the past 60 years, should have produced a 5.5 percent increase in the world’s biomass, including plant foods. But the water supply is also important and can be a limiting factor. Another fascinating factor is the distribution of carbon dioxide, which is in low concentration in the air (less than the inert gas, argon). Dyson claims that a field of corn would consume all the carbon dioxide 3 feet off the ground in only 5 minutes, if the air were still. When the carbon dioxide concentration is increased, plants make more roots compared with shoots. This is because fewer leaves are required to collect the more readily available carbon dioxide. But, when such plants decay, a greater portion of carbon dioxide ends up in the topsoil, which is also an important reservoir of carbon dioxide. Dyson calculates that an area half that of the U.S. would on average receive a net increase of carbon dioxide in the topsoil of about 0.1 inch per year, summing to five billion-tons. This compares with four billion-tons of carbon dioxide that is known to be increasing in the atmosphere at the present time. Such a small increase in the topsoil would be impossible to measure and we don’t have a clue as to whether the topsoil is presently increasing or decreasing! Deforestation and erosion are obvious important variables.
Smil’s book also discusses the equally complex issue of the sea level, which is slowly rising, but is it due to human activities. A rise between 1800 and 1900 could not have been (not enough carbon dioxide was released). Changes in the shape of the earth following the last ice age is a possible, natural cause; no one is certain.
It is argued in Naturally Dangerous that global warming could result either in forestalling a new ice age (we are overdue) or inciting a new ice age. Similar arguments are presented in Dyson’s review. The “bottom-line”, is that no one knows! These massive uncertainties about global weather changes and their underlying mechanisms remain controversial. That is a major message that I took from this fascinating review.
Brown clouds of soot, apparently created by dried-dung fires on the Indian continent, have blown 1000 miles out over the Indian Ocean. Two miles thick, and dispersed over an area the size of the United States, this cloud is probably involved in global warming. The detailed effects of such clouds is uncertain; they may shade and cool the surface of the earth, but the soot particles absorb sunlight and radiate heat, thus warming the atmosphere. Millions of Indian housewives cook with this plentiful, cheap fuel. The Indian government has become touchy about this brown cloud and don’t want to fund further studies. The U.S. government wants to know more, because this situation adds to their objections to the 1997 Kyoto Protocol, which exempts developing countries such as India and China from cutting emissions of greenhouse gases. This treaty, which the U.S. did not ratify, does not mention soot as a greenhouse gas, but it surely is. Another plume of pollution over the ocean east of China contains of soot that is polluted with mercury from coal-burning power plants. It appears that this pollution cloud has affected weather over China, causing droughts in one area and heavy rainfall in another. As those who have read Chapter 8 know, global warming is complicated and political. (Wall Street Journal, 5/6/03, page 1)
A huge effort to develop renewable energy sources is being driven by political pressure stemming from concerns over global warming and other environmental issues. A survey of renewable energy use in the U.S. shows it has been falling, not rising! Some facts are interesting. The bottom line is that most of this decrease can be attributed to drought conditions that have reduced generation of hydroelectric power by 23%. It is true that some solar energy applications are growing, but these are selective. For example, the number of solar collectors , which use sunlight to heat swimming pools has increased sharply, and installations of photovoltaic devices in U.S. homes grew by 80% last year. Nevertheless, the Energy Department estimates that overall amount of solar energy conversion has been decreasing. Overall, the energy generated from solar devices is small compared with one large nuclear plant.
Other forms of renewable energy have also fallen. Burning of biomass such as wood products and the use of alcohol fuels in automobiles fell about 2%, but wind power grew more than 3%. All-in-all, the consumption of renewable energy fell last year to the lowest level in12 years. Because of their concern over global warming, environmentalists enthusiastic about solar and wind power, but, in spite of subsidies, the major impediment is cost. (New York Times, 12/8/02, page 30)
Environmental concern over global warming has driven politicians to consider energy efficiency in the context of reducing the major greenhouse gas, carbon dioxide. Fuel cells have been advocated as an energy-efficient, environmentally friendly energy source. In a letter to Chemistry and Engineering News, April 7, 2003, page 4, Reuel Shinnar of City University of New York, presents a devastating analysis, which seems difficult to refute. He states that the most energy efficient electric power source is a combined-cycle turbine (CCT), which presently has a thermal efficiency of 56%. By burning natural gas these huge devices produce electricity with a minimal waste of carbon dioxide. He claims that new CCT plants are even more efficient (up to 60%) and may eventually rise to 65%! This compares with present day fuel cells, which generate electricity by first converting natural gas into hydrogen, have a thermal efficiency of approximately 30%. The ramification of these numbers, taken from Shinnar’s table, is stunning. Consider a 1 GW (billion watt) power plant competing with fuel cells over a 10-year period. The fuel requirement for the CCT requires 60 billion equivalents of oil less than fuel cells. Moreover, compared with the CCT plant, equivalent fuel cells would give off between 24 – 49 billion tons more of carbon dioxide over this 10 year period. If these figures are correct, the promotion, by politicians, of fuel cells for large electric power plants is hot air and would be more damaging to the atmosphere. Fuel cells do have an place in small, mobile devices such as batteries, because fuel cells are much cheaper and lighter than energy-equivalent batteries. The U.S. military is already using fuel cells on the battlefield.
Green energy is “alternative or renewable energy”; meaning energy not derived from coal, gas, or petroleum. Concern over global warming and carbon dioxide emissions is motivating environmentalists to advocate renewable energy. Energy from the sun is a favorite alternative, but is there enough solar energy? The following calculation may be of interest. According to an authoritative source the total average solar irradiation on Earth is 1 kW/m2. The average consumption of electricity per US household is 35 kWh/day. Assuming 10% efficiency for converting sunlight into electricity and 10 h of sunshine a day on average, the electricity consumption of an average household could be satisfied with a solar-cell panel of 35 m2 (nearly half the area of a football field). With 10 million households in the U.S., the total solar-cell panel area required to satisfy the electricity needs of all U.S. households comes out to be 350 km2, which is a square 19 km (11 miles) on a side. It’s trivial to find a place to install such a solar-energy farm in the U.S., with 365 days of 10 h/day of sunshine. Such a location might otherwise be useless (a desert). Solar energy may not solve the energy needs of our society but this calculation shows that the reason is not because the solar flux (energy from the sun) is insufficient. Photovoltaic devices are too expensive, the energy during the day must be stored when the sun isn’t shining, and one has to keep the bird droppings off.
Wind energy is moving center stage as a growing renewable energy source, but there are problems – both economic and environmental. Wind energy manufacturing and construction costs are falling and reliability is increasing, while fuel costs (the wind) remain zero. Construction costs have fallen to $1 million per MW (megawatt) which is still higher than construction costs for natural gas-based power plans, at around $600,000 per MW (Chemistry and Engineering News, 3/24/03, p. 27). There are tradeoffs: wind is free, produces no greenhouse emissions or air pollution, but the wind does not always blow and gas is always available. Wind energy is subsidized. For example there is a federal tax credit of about 1.7 cents per kWh of wind-generated energy over a 10-year period. The electricity consumption of a typical U.S. household is 27 kWh per day. Wind energy in the U.S. is growing, but it is still puny. Less than 1% of the U.S. energy is produced from wind turbines; compare that with a typical nuclear plant that generates more electricity than one fourth of all the wind power in this country. There is more wind energy being produced in Europe, largely because of political forces and larger subsidies. The green leader, Germany now produces the most; 4.7% of its electricity comes from heavily subsidized wind power. An amazing 20% of Denmark’s electricity comes from harnessing the wind. There are environmental problems associated with wind power: dead birds, noise and aesthetics. A plan to build a huge, 130-turbine, 400-MW offshore wind facility five miles off the coast of Cape Cod has been opposed by former newsman Walter Cronkite and politician Robert F. Kennedy Jr.; both are usually environmental advocates. The Audubon Society is concerned about the deleterious effect of offshore wind farms on migrating birds. At the Altamont Pass wind farm in California, 61 radio-tagged golden eagles were killed over four years. Bigger machines are more efficient so that huge turbines are being built. The largest machines have three turbines with blades 50 meters long (half the length of a football field), each weighing up to 16 tons. The tip-speed of these blades is 70 to 80 meters per second. These turbines can produce 3.6 MW of electricity. Even larger machines are being planned. Because of land costs and the presence of steady winds, offshore wind turbines are likely to be produced. Every wind farm needs access to nearby transmission lines. This can be an economic problem instates with cheap land and steady winds such as the Dakotas and Wyoming. The U.S. will have more wind powered electric generation in the future, but it will be a small fraction of the energy consumption.
In November 2002 a new attitude appeared with regard to global warming. Whereas it is agreed that the global climate is changing, perhaps due to human action, rather than fighting the change, it may be better to adapt to the impact of weather change. This concept dominated a recent meeting about international climate in New Delhi. This is a striking departure for policymakers and tends to de-politicize this issue. There is a rising realization that even if emissions of greenhouse gases were greatly reduced today, the impetus already set in motion by a century-long accumulation cannot be reversed. Perhaps the realization that other sources such as carbon-particles in aerosols mentioned below are also major factors drove policy makers to this new attitude. Moreover, there are no ready substitutes for cheap, plentiful fossil fuels such as petroleum, natural gas, and coal. (New York Times, November 3, 2002)
According to a paper by Mark Z. Jacobson to the Dec. 11, 2001 meeting of the American Geophysical Union, in San Francisco, diesel soot contributes almost half as much as carbon dioxide to global warming. Carbon soot absorbs light energy at all wavelengths from the infrared through the visible into the ultraviolet and then emits this energy as heat in the infrared. Because soot has a rather short lifetime in the atmosphere (it rapidly reacts with oxygen in the air to form carbon dioxide), controlling soot should have a major cooling effect on the climate. This powerful green house gas from diesel vehicles was not considered in the 1997 Kyoto Protocol, nor have most computer models of global warming considered diesel soot. This is a major argument against diesel engines. The media seems to be ignorant of the role that soot has in global warming.
When a star dies, subatomic particles referred to as cosmic rays bombard the Earth. Some scientists suggest that cosmic rays may be able to trigger an ice age. The explanation for the effect of cosmic rays on the Earth’s climate is a strange tale connecting the solar wind with the disruption of cosmic rays. When dark spots appear on the face of the sun, sunspots, the earth is known to become warmer and harvests are more bountiful. Since the late 1700’s it has been known that sunspot activity rises and falls over 11-year periods. Although sunspots produce additional energy from the sun, this increase is only about one percent, not enough to cause much additional warmth on the Earth. However, the effect is thought to be magnified because sunspots produce a “solar wind” of energy and particles. One result of this solar wind that most people are familiar with is an increase in the northern lights; another result of the solar wind is a deflection of the cosmic rays that otherwise would pepper the Earth. Cosmic rays have been correlated with cloud formation; such clouds cool the Earth. Cosmic rays are proposed to ionize tiny particles in the Earth’s atmosphere, promoting the formation of water droplets, which form clouds. Clouds reflect solar radiation and thus cool the Earth. Some scientists have proposed that intense episodes of cosmic rays are responsible for the occurrence of ice ages, about every 145 million years. There is some evidence supporting this hypothesis, but not all scientists agree. (Kathleen M. Wong, California Wild, Winter 2003, p. 36)
In Chapter 8, I mentioned a theory that global warming could lead to another ice age. Terrance Joyce, a respected scientist specializing in physical oceanography, explains how global warming can cool parts of the Earth, and he gives some interesting historical examples. The Gulf Stream normally carries warm water from the tropics past the East Coast of the United States and on to Europe, substantially warming the atmosphere in both regions. Part of the driving force that propels this circular ocean current is the sinking of heavy salty water from the warm tropical ocean to great depths in northern regions. This phenomenon is similar to a conveyor belt. Whenever too much fresh water is added to this stream, for example from melting Arctic ice, the North Atlantic water becomes less salty and less dense, thus slowing or altering the Gulf Stream current. Joyce proposes that about 500 years ago changes in this ocean current were responsible for cooling the climate in northern Europe and in the northeastern United States producing the “Little Ice Age”, which lasted for 300 years. This cold climate might explain the notorious winter that George Washington’s soldiers experienced at Valley Forge. (The New York Times, April 18, 2002)
A proposal to partially mitigate global warming is to use gaseous hydrogen in fuel cells in place of burning fuels such as natural gas and petroleum in electric power plants or in internal combustion engines. A fuel cell converts hydrogen and oxygen (from the air) directly into electricity with nearly perfect efficiency. The only byproducts are water and a small amount of wasted heat. Fuel cells have been touted as efficient, pollution-free devices that can provide electric energy in homes and businesses and to power automobiles. Good electrode catalysts are required to make fuel cells practical; recently, very efficient fuel cell catalysts have been developed. It has been proposed that in the future fuel cells will power automobiles that are very energy efficient and produce water, but no carbon dioxide in their exhaust. It would appear that an impending “hydrogen economy” will solve two great societal problems: reducing the major green-house gas, carbon dioxide, and producing energy more efficiently. As with most fantasies, this would be wonderful if it were only true! This seemingly attractive technology has many difficulties.
The gaseous element, hydrogen does not occur in Nature; there are no hydrogen wells anywhere on Earth. If hydrogen is to be used as a fuel, it must be manufactured, shipped, and stored. How would hydrogen be produced? Electrolysis of water is one possible answer. In this process water is converted into hydrogen and oxygen using electric power. Unfortunately this method would result in a net loss of energy, because electrolysis requires more electric power to produce hydrogen than would be created by the most efficient fuel cell using the same amount of hydrogen. Looking at this as a solution for reducing the amount of the greenhouse gas, carbon dioxide is a false premise. More carbon dioxide would be generated by using hydrogen in a fuel cell to generate electrical power than by simply burning the hydrocarbon in a power plant.
The combustion of carbon fuels such as coal, oil, or natural gas in power plants generates most of our electrical energy; the remainder comes from hydroelectric or nuclear power. The two latter energy sources do not produce carbon dioxide as a byproduct. The World does not have excess hydroelectric power sources, except in a few remote locations such as New Zealand. Society is unwilling to build more atomic power plants, although this is one of the few methods by which additional energy can be produced without generating the greenhouse gas, carbon dioxide. Alternative sources of energy such as solar and wind-power are too inefficient or limited to have any significant impact on society’s energy requirements.
The cheapest current method for producing hydrogen is not electrolysis of water, but rather to use a reaction involving oxygen and methane. Unfortunately, the energy in the hydrogen produced by thus process is less than the energy contained in the methane. The overall process: converting natural gas to hydrogen and then using that hydrogen in a fuel cell to generate electrical power would therefore not only result in an overall loss of energy, but it would also produce more carbon dioxide byproduct. This is true even though the fuel cell is 100% efficient!
There are additional troubles with a hydrogen economy. The storage and transport of hydrogen is a serious, unresolved problem. Hydrogen gas has a very low density. A tank of hydrogen, necessarily under pressure, possesses much less energy that an equivalent volume of natural gas or especially of liquid hydrocarbon(gasoline or diesel fuel). Moreover, hydrogen gas destroys welds in natural gas pipelines so that is would be difficult to ship hydrogen through these existing pipelines. There seem to be no viable methods to make hydrogen more dense except to compress it or to cool it to a liquid at very low temperatures. Both techniques are expensive.
However there is hope in using hydrogen to improve the efficiency of vehicles, because the internal combustion engine is inherently less efficient than fuel cells. How would the hydrogen fuel be provided to a fuel cell to propel such an automobile? Some scientists and engineers have suggested that hydrogen could be produced from a tank of natural gas within the fuel cell powered vehicle. This would require a miniature chemical factory within the machinery of the car, bus, or truck. In theory, this complex technology could result in higher mileage than an internal combustion engine using the same tank of natural gas, but it would produce the greenhouse gas, carbon dioxide. A practical, economic system of this sort is still in the future.