Friday, May 29, 2009

Choices in Large-scale Electricity Production

Do you agree with this statement: “The working of the nation depends upon a reliable supply of electricity, day and night, winter and summer, quiet days and stormy days”? If you do, you will want to read on. This posting was sent exclusively to CARE from the members Los Alamos Education Group in Los Alamos, NM. Remember Los Alamos is where the atom bomb was developed and where the high school students have the highest IQ in the country (their parents are literally “rocket scientists"). So when scientists and engineers from Los Alamos speak up, we should listen!

This piece is authored specifically by Donald Peterson and William Stratton, who have served CARE with written commentaries in the past and were guests on the radio program CARE organized last fall on uranium mining and nuclear power. Their biographical information can be found below. From their professional and scientific background, here--through the lens of history--they analyze America’s electricity needs for the future and the possible solutions.

This is a through look that is based on in depth study. It is a bit longer than many of the postings here so you may want to print it out for reading later. We at CARE are confident that our Blog readers will find this information to be insight and an important piece in your ongoing energy education. Please let us know what you think!

Powering the National Grid
A few years ago, the National Academy of Sciences polled its members to determine the premier engineering development of the 20th century. Although the candidates are numerous, including the automobile, radio and television, and the airplane, the Academy determined that the most significant engineering accomplishment was the electrification of the nation, essentially providing electricity to nearly every home, business, and industry. The importance of this development is evident from the innumerable applications of electricity, and also from news reports showing the impact of electric interruptions due to disasters of one kind or another. Indeed, it is difficult to imagine being without electric power for an extended period. The working of the nation depends upon a reliable supply of electricity, day and night, winter and summer, quiet days and stormy days. In spite of this accolade for the electrification of the nation, critics exist--voiceing complaints about design, age, reliability, etc. More on this later.

Until the early 1970s, the time of the first oil supply crisis, most of the country’s electrical power was provided by burning coal, with a fraction provided by burning oil because it was cheap at the time. Between about 1905 and 1975, electrical power demand and the production in the U.S. rose at the phenomenal rate of 7% per year, or doubling every decade. This rate only declined for a year or two in the depression, and then accelerated a bit during World War II. Otherwise remained steady at 7% per year. The United States was not unique in experiencing a steady growth in the use of electricity.

However, in the mid-1970s, the annual increase in demand for electricity dropped from 7% a year to one or two percent, even dropping to zero percent for a year or two. A saturation effect had taken place. This reduced growth rate led to the cancellation of plans for new power stations--both coal and nuclear--in large numbers.

During the 1950s the creation of new ideas and development of designs for nuclear power stations had progressed to the point that a dozen or more small (by modern standards) nuclear power reactors were built in the late 1950s and early 1960s. Some of these were experimental in nature and were short lived, but some provided power for several years. However, the experience convinced companies, such as General Electric, Westinghouse, and Babcock and Wilcox that nuclear power could be a competitor to the coal-fired power plants. They were so convinced, they offered bargain rates to build the early large nuclear power stations to get the business started, and the utility industry responded with many orders.

The first large commercial power plant, Oyster Creek in New Jersey, produced 650 megawatts, and was licensed and began operating in 1969. It is now about to receive a license extension of another 20 years, along with most of the other operating nuclear power stations.

By 1980, 60 nuclear power stations were in operation. Between roughly 1965 and 1995, some 112 plants were built, of which 104 are still in operation. These plants provide nearly 20% of all electrical power in the United States. For the electric utilities, the initial burst of enthusiasm was economics--the nuclear plants were less expensive to build and operate than new coal fired plants.

However, shortly after this initial enthusiastic beginning, a number of factors combined to slow this introduction of nuclear power. The operation and maintenance of these new power plants was much more difficult than had been expected and an anti-nuclear movement emerged. Various organizations were created, motivated somewhat by the association of nuclear power with nuclear weapons, but also by some fears predating that time, which can be related back to the discovery of x-rays, radioactivity and the spooky pictures of a hand showing clearly bones inside the flesh. Bad experiences with radium (unregulated) contributed to the unease. (The extensive and accepted use of x-rays for medical and dental diagnostics had no apparent effect on the anti-nuclear movement, perhaps because these uses were not associated with the radiation from the fission process.) Most of the early so-called reactor safety studies were badly done with frightening results. Simultaneously, licensing, financing, and construction time and costs were rising. The expense of new nuclear plants became more than coal plants, and neither was needed because of the lack of demand for more power.

About the same time, President Carter issued an executive order halting nuclear fuel reprocessing due to concerns regarding control of plutonium and proliferation of nuclear weapons. This killed a developing industry (reprocessing of spent fuel), and, more importantly, research and development work to find a better fuel cycle than the Purex process, which was developed and used during and after World War II. (The Purex process was designed to produce pure plutonium, quite unsuited to commercial power applications.)

In the late 1980s and 1990s, when the demand for electrical power began to rise again (at a lower rate), nuclear plants were in disfavor due to expense, regulation, as well as the accidents at Three Mile Island and Chernoble. The fuel of choice became natural gas. These gas plants were inexpensive to build and natural gas was relatively cheap. Natural gas fired power grew to be about 20% of the total U.S. electrical supply, along with 20% for nuclear and 50% for coal.
We are now in the first decade of the 21st century. Fossil fuels, especially coal, have fallen into disfavor because of emission of carbon dioxide--allegedly leading to global warming. Additionally, pollutants are calimed to be responsible for thousands of deaths per year (spread over the whole population and therefore not generally observed like deaths from auto accidents). The demand for electricity is now rising 1½% to 2% per year. Nuclear power is more generally accepted, since it does not suffer from the same pollution problems, and it has compiled a record of decades of reliable, safe service at a relatively low cost. In fact, we believe that some nuclear plants produce the least expensive electricity.

Concomitantly, due primarily to the same concerns about global warming and emissions from coal fired power plants, a so-called “green” movement has emerged and is literally wildly enthusiastic about "renewable" power, such as electric power from sunshine and wind. (There are a few other options, such as power from ocean waves, or the burning of trash, but these are even less proven than wind or solar.)

The total electrical demand of the United States is a mind-boggling 600,000 to 700,000 megawatts (each megawatt is one million watts, or 1000 kilowatts [kw]. To those of us accustomed to thinking in household terms [watts or kilowatts], this is an incomprehensively large amount of power.) We expect the electric industry to provide this power reliably, at a steady, constant voltage and at a price we can afford. If one power station fails, we expect another to be available to take up the load nearly instantaneously. (The system is not perfect and large blackouts do occur, as in the northeast some years ago.)

At an annual rate of increase of 2% per year, demand for electricity will double in 22 years; if only 1.5% per year, the demand will double in 46 years. Considering that our total demand for energy of all kinds and forms is steadily increasing, population is increasing, and the fraction of energy provided by electricity is also increasing, we must plan for the higher rate of growth. We must plan for significantly greater demand for electrical power in the years to come.

Our electricity is produced by coal (50%), natural gas (20%). nuclear (20%) and most of the remaining is water power with very small amounts from solar and wind. These (especially coal) will carry the load for some time to come, but because of problems mentioned above, coal is out of favor and nuclear, wind and solar are candidates. While we have enough coal to last for at least a couple of centuries, the objections to burning more coal are numerous, so we will consider the remaining three sources--nuclear, wind, and solar--quantitatively, as well as we can. We will consider what is required to replace the electricity currently provided by coal--in the US, approximately 300,000 megawatts--with cleaner sources.

We will start with wind power. T. Boone Pickens has proposed to build wind turbines of 1.5 megawatts. More powerful wind turbines have been built, but his proposal is the first one to be considered seriously. In order to produce 300,000 megawatts, 200,000 turbines would be required. However, the operational history of wind turbines has not been good. Operational power is obtained on average only about 1/3 or less of the time, so this means that 600,000 or more would be required in differing locations to replace the electricity now produced by burning coal. The area required for each turbine is about 4 acres, indicating that the turbines would take up 2.4 million acres (3700 square miles). These numbers are enormous. At an estimated cost per turbine of 4 million dollars, the total cost is very large. This cost does not even address costs of revising the gigantic and costly electric power distribution grid to collect power from remote locations and transmit it to population centers one to two thousand miles away, or to maintain backup sources for periods of time with little or no wind. This eventuality is a failure for which we see no solution if we wish to depend on wind. Some of the criticisms of the power grid may derive from problems of this sort.

The wind option is impractical for these, as well as other, reasons.

Solar power has some obvious advantages. Enthusiasts point out that the distributed power over the entire area of the earth is enormous, the intensity is constant, it never fails, and will last for the indefinite future. It seems to be perfect, except for several weaknesses: the power is small per unit area, the earth rotates with nights as well as days, and the seasonal effect must be considered. Further, concepts for storing energy for periods when the sun is not shining are inadequate, very expensive, and do not exist for large arrays.

We will quantify, at least in part, by estimating the area required with the sun directly overhead as occurs on the equator or between the Tropic of Capricorn and the Tropic of Cancer. The Handbook of Chemistry and Physics states that the solar intensity, all frequencies, at the spot facing the sun, vertically overhead is 2 calories per square centimeter per minute. Translated into units more familiar to most of us, the intensity is 1.17 kilowatts per square yard. This energy density is reduced when passing through the atmosphere by molecular absorption, dust, and clouds. The best estimates we’ve found suggest half or a little less reaches the ground. Solar cells, at their current best, convert only 15% of the solar energy to electrical energy. Further, a solar array must include space for maintenance workers and equipment, frames to hold and secure the solar panels, and for equipment to collect and convert the direct current to alternating current. Allowing for all these factors reduces the 1.17 kw per square yard to about 0. 055 kw per square yard for the array of solar cells. (For a rooftop installation of, say 50 square yards, the power output could be up to nearly three kilowatts, enough to power the home comfortably at the middle of the day, but with little for late in the day and nothing, of course, at night without storage). An array of a square mile could produce about 170 megawatts. To replace the power generated by coal (300,000 megawatts) would require 1765 square miles, an impossibly large area. Further, this number is calculated with the sun directly overhead. Allowing for other times of day, and for winter as well as summer, as in the US, would increase the area required by a factor of five to ten or more--and this still does not consider periods of darkness. In short, solar power is completely impractical for large-scale power production, and should be reserved for special applications or for remote sites for which connection to the grid is too expensive. (A quantitative evaluation of costs for solar installation in a home was published in the Albuquerque Journal, January 15, 2009. The cost was prohibitive.)

This leaves nuclear power: We will assume that each new power plant will provide about 1500 electric megawatts. (The French and the Finns are each building pressurized water reactors of 1600 megawatts, and two similar plants are planned for China. The economies of scale keep driving the unit power level higher). In order to replace 300,000 megawatts from coal, construction of 200 such new nuclear power stations would be required. The record of the last century (and recent history) clearly demonstrates that this is feasible. For example, the French built 50-55 nuclear power plants in 20-25 years starting in the mid-1970s, all of which operate steadily and safely, and provide about 80% of their total electrical power supply. The US constructed 112 in about the same time; 104 are still operating. Since the turn of the century more than 30 new nuclear power stations have been completed worldwide and more are planned.

Some problems must be resolved in order to make such an expansion possible in the U.S. A problem (really a perceived and artificial problem) is that of spent fuel. Two possible solutions have evolved. The first and operative solution is to store the fuel, first in fuel storage pools for a few years until air-cooling is adequate, then move the spent fuel to concrete pads and place it in concrete and/or steel containers. The containers are too heavy to move without the heavy equipment, and the fuel is too hot, both thermally and radioactively, to work with without special equipment. This reduces the concerns regarding security. The area required for such a system is miniscule and the cost cannot be large. This is the current solution.

The second solution is to bury the fuel, suitably contained, in sites such as the one under construction at Yucca Mountain in Nevada. This project has been underway for years at a cost of billions of dollars, and is still incomplete. It is not a workable solution. No fuel has been stored here, nor will any be for years to come--especially now that Obama has killed the project. The authors regard Yucca Mountain as a complete waste and a mistake.

The best solution is to store fuel at the site of creation (the power station) or at a central storage facility, placed where a recycle or reprocess plant will someday be constructed. This process has been satisfactory for decades (certainly since the 1960s) and will continue to be satisfactory for decades and decades more. Ultimately, the fissionable materials remaining in the fuel (primarily uranium and transuranics) will be used in fast neutron reactors after recycle to remove the fission products. The country can not afford to throw away the 90+ % of the energy from the original fuel which remains in the "spent” fuel.

During the presidential campaign, Senator McCain presented a proposal for 45 new nuclear power stations. In this light, his proposal was far too modest. By the time 200 nuclear power stations are built to phase out coal-fired power, more will be needed, but that can be faced when the time comes. The first few plants will be expensive as, essentially, a specialized, new construction industry must be recreated. Welders, pipefitters, electricians, etc must become accustomed to the rigorous inspections conductedby the nuclear regulatory industry. A forging plant for pressure vessels must be built.

The conclusion of this brief study is that humanity has only two choices for the large scale production of electricity. These two are coal-fired or nuclear power. It should be obvious that our national choice should be the same as the one made by France about 35 years ago. We should build nuclear power stations as fast as practicable. The first few plants will be expensive and will require time. Creating a power system that is pollution free and emits no carbon dioxide will require at least a half century. We can start no sooner than now. We can do it; we must do it.

Bill Stratton has a PhD from the University of Minnesota. He is a retired reactor safety expert with extensive advisory service to the Nuclear Regulatory Commision. As a consultant to the President's Kemeny Commission, he was instrumental in explaining the minimal radiation release from Three Mile Island.

Don Petersen has a PhD from the University of Chicago. He is a retired radiation biologist involved with health effects of radiation, neutron dosimetry and effects of neutrons and alpha particles. He has had first hand experience with investigation, description and reporting of radiation accidents involving injury and fatality.

1 comment:

dsnow said...

Great article! When I was a ME student as NMSU in late 70's our Profs repeatedly stated that nuclear power over the life had been totally uneconomic and would never compete with hydrocarbons on a cost basis. Without knowing the facts behind those Profs statements one cant be too sure about those $ cost now especially since there are so many security issues with protecting countries with oil sources so that we can import it(blood & $ for oil). I suppose had we really had a true "energy plan" without politics all these years we might not be in the fix we are in now. Our first President was right we should never allowed more than one political party to exist in this nation. Dan Snow Andrews Tx