Nuclear Power, Fossil Fuels, Renewable Energy, Conservation, and Carfree Cities
J.H. Crawford and R.W. Hollier
15 June 2005
There are basically four approaches to managing the gap between static/declining oil production and rising demand. Any combination of these measures could be selected.
The first is to build many new nuclear power plants, an approach that has received little attention in the past 20 years, since the terrible disaster at Chernobyl. In addition to issues of reactor safety, nuclear power is expensive and the disposal of high-level radioactive wastes has never been demonstrably solved. However, many people now see nuclear power as the best choice with respect to both fossil fuel depletion and greenhouse gas emissions. Since nuclear power has been off the agenda in North American and Europe for decades, we thought it would be useful to bring the present generation into the picture with respect to nuclear power issues. We also want to provide those who have been following these issues in past decades with an update concerning new developments. Therefore, this method will receive detailed consideration in this paper, even though the authors believe that it is the least desirable alternative. A future paper will examine the nuclear power option in even more detail.
The second approach is to turn to alternative fossil fuels, of which there are a number. This was the topic of much discussion at ASPO in Lisbon. There are still huge deposits of natural gas that have not been developed, although these are all inconveniently located and would require liquefaction and transport by LNG ships to North American markets. Natural gas can also be turned into liquid fuels by reasonably simple processes. There is a lot of coal around the world, and technologies are being developed that would "sequester" carbon dioxide (CO2) emissions of coal-fired power plants in old natural gas wells, where, in theory, they would remain out of the biosphere indefinitely. (Other methods of disposing of CO2 have also been proposed, including the dumping of liquefied CO2 onto the sea bed, where it is hoped that it would lie inertly.) Coal can also be turned into liquid fuel. Finally, there are the "unconventional oils": heavy oils and tar sands, some of which are already in commercial exploitation. Any increase in fossil fuel consumption further exacerbates the risk of climate change unless the emissions are successfully sequestered. Many of the processes for using unconventional oil or converting other fossil fuels into liquids have the disadvantage that the methods are always less than 100% efficient and thus add even more to the output of CO2.
The third approach is to turn to renewable energy sources. Many people think of these as modern developments, but in truth mankind's first sources of energy were renewable (firewood and other biomass) and remained so until coal was tapped to fuel the industrial revolution. Before turning to coal, hydropower and wind energy were also developed on quite a large scale. The use of non-renewable fuel is thus an aberration in human history.
The fourth approach is energy efficiency and energy conservation, which did not receive a great deal of consideration at the ASPO meeting. In his ASPO presentation, Robert L. Hirsch thought that a 10% reduction in US demand over 10 years would be difficult to achieve due to the long life and slow turnover of vehicle fleets. He also projected an improvement in the new-vehicle fleet-weighted fuel efficiency of only 30-50%. Very much better results have already been demonstrated.
This paper will deal only in passing with the question of the "hydrogen economy." Some writers have postulated that hydrogen is a magic bullet for our energy woes. Nothing could be farther from the truth. Hydrogen is an "energy carrier" (and a rather inefficient one at that). Free hydrogen does not exist in useful amounts in nature. All of it must be manufactured using one of several processes, all of which consume more energy than is embodied in the hydrogen. Hydrogen is, thus, a net energy loser. This point must be stressed in any discussion of hydrogen. Both nuclear power and renewable energy sources can be used to produce hydrogen, but the hydrogen is only a carrier of the energy, not a primary energy source.
Nuclear EnergyThere are two basic nuclear processes that release large amounts of energy, nuclear fission and nuclear fusion. Both processes have been used in bombs, but at present only nuclear fission has been applied in a controlled process to generate electricity on a large scale. Up to now, controlled fusion has been a laboratory process that has yet even to suggest that it is nearly ready to yield commercial power. We will not consider fusion further, as any contribution that it might make is too speculative and too far in the future to be of interest in today's looming crisis.
Nuclear FuelsIn the early years of nuclear power production, uranium-235 (U235) was by far the most important nuclear fuel isotope. However, natural uranium consists of only about 0.7% U235, and nearly all of the remainder is non-fissile uranium-238 (U238). Furthermore, many popular reactor designs in past decades could not sustain a fission chain reaction with natural uranium containing only 0.7% U235, requiring the uranium to be "enriched" to 2-4% U235, a complex and costly process. Some traditional reactor designs, however, such as the Canadian CANDU, will operate with unenriched uranium.
Supplies of U235 are limited and production might peak in just 30-40 years if an aggressive nuclear program is initiated, according to a paper presented at the 2005 ASPO meeting in Lisbon. It is however possible that recovery of uranium from seawater might greatly extend the time to peak production.
New reactor designs depend increasingly on fissile isotopes other than U235 as fuel and on breeding of fissile fuel from fertile isotopes such as uranium-238 (U238) and thorium-232 (Th232). Some new designs make it easier to use mixtures of various fissile and fertile isotopes in varying proportions as fuel.
There is increasing interest in using thorium-232, a fertile isotope, as a component of reactor fuel. The earth’s crust contains about three times as much thorium as uranium. Some new reactor designs can use fuel that contains more thorium than uranium (up to three times as much). India, possessed of large thorium reserves, has been the leader in thorium-fueled reactors.
Plutonium 239 (Pu239), an element not found in nature in useful amounts, can be used both to make atomic bombs and to power nuclear reactors. Pu239 is produced as an inevitable by-product of the operation of most present-day nuclear reactors, a fact that causes considerable concern that widespread availability of plutonium could lead to proliferation of nuclear weapons among the world’s nations and even to terrorist groups.
Reactor TypesUp to the present, pressurized light-water reactors (PWR) burning slightly enriched uranium have been the principal reactor type used in the USA and Western Europe. We have many reactor-years of experience with PWR installations, including quite a few releases of radioactivity and one serious partial core meltdown (Three Mile Island), an event that we had been assured was impossible. In particular the French seem to have managed their extensive network of PWR reactors well enough to suggest that, properly implemented and regulated, this technology might be safe enough for wide-scale, long term use.
However, if new nuclear power plants are built in large numbers in decades to come, it is not a foregone conclusion that many of them will be mature PWR designs. The nuclear industry is starting to promote innovative "Generation IV" designs, some of which are based on new fuel cycles and reactor types with which there is only limited practical experience. Many of these new designs are claimed to be "inherently safe." In practice, this usually means that they are thermally stable - as the reactor gets hotter, the nuclear reaction slows down without outside intervention. This is certainly a highly desirable trait that not all reactor types possess, but it is not a sufficient basis for claiming that a reactor is safe.
Of the new designs, the pebble bed modular reactor (PBMR), a further evolution of the high temperature gas-cooled reactor (HTGR), is probably the favored choice. These reactors have the property that they operate at temperatures high enough that they could be used to generate hydrogen directly and possibly at high efficiency, without the need to first use the heat to generate electricity. It is claimed that a pebble bed reactor cannot melt down because it does have thermal stability, and the reactor will cool passively after shutdown. However, while core meltdown is the most serious nuclear accident, it is certainly not the only danger.
Risks of OperationThe consumption of fossil fuel brings with it large and well-known risks, including serious air pollution, greenhouse gas emissions, and accidents during recovery, transport, and refining. The total cost in human life from these risks, and the risk to the stability of the Earth's climate, are very large indeed.
With nuclear power, the main risk is that of a catastrophic accident, such as the one at Chernobyl in 1986, which released a substantial percentage of the radioactive elements in the core of the reactor into the biosphere. The area near the plant was contaminated with radioactive pollutants that will remain significantly hazardous for decades at least, and much of Europe was exposed to appreciable levels of radiation.
Finally, there is always the risk of operator error. Most serious nuclear accidents have indeed involved significant operator errors, but there is also the possibility of deliberate erroneous operation by someone intent on causing harm. It is essentially impossible to design a nuclear reactor so that an insider or intruder armed with knowledge of operating procedures and possessed of malicious intent could not provoke a catastrophic failure.
It seems unlikely that any reactor design can be claimed to be fully safe. It is, however, not out of the question that the risks of nuclear power, taken as a whole, are lower than those entailed in the production of energy from fossil fuels. Even the production of energy from renewable sources involves distinct risks, such as the shedding of rotor blades by a wind turbine. Given that the safest energy is the energy you never use, it seems clear that from a safety standpoint, the only logical thing to do is to use as little energy as reasonably possible.
Waste ManagementNo long-term repository has yet been brought into use for the storage of the highly radioactive wastes from nuclear reactors, despite decades of effort. The Yucca Mountain facility, after years of development and the commitment of over $60 billion in funding, has never entered operation due to a series of problems. DOE expects that the facility will need to be guarded and maintained for the next 10,000 years (!!) at an estimated cost of $500 million per year. This gives a total price tag of $5 trillion, or half of one year’s GDP for the USA.
Waste disposal has been argued about ever since the dawn of the nuclear age, and there is today a substantial amount of material awaiting permanent disposal. It cannot be said for certain that a safe and affordable solution will ever be found. It seems reasonable to delay further development of nuclear power until an acceptable means of waste disposal has been definitively tested, shown to be economically viable, and placed in service. In the meantime, highly radioactive spent fuel elements sitting in storage pools near reactors are at huge risk of terrorist attack. Fuel elements under transport are at special risk of attack or hijacking.
Fossil Fuel ProspectsWhile we may be at or near the peak of production of conventional petroleum, there remains a lot of other fossil fuel. Natural gas supplies are probably sufficient for some time, although most supplies are located inconveniently and may require liquefaction and transport in LNG tankers. Quite a lot of energy is wasted in chilling and condensing the gas. Gas, at least, has the advantage of contributing the least to the CO2 burden per unit useful energy and is also the cleanest-burning fossil fuel
More problematic is coal, which is a filthy fuel and contributes very high levels of CO2 output per unit energy. There is now talk of compressing CO2 outputs from power plants and pumping the material (in liquid or gaseous form) into depleted gas wells, where it would in theory remain trapped indefinitely.
Other sources of hydrocarbons also exist, such as the tar sands of Alberta, which contain a huge amount of energy. It is difficult and expensive to extract this bitumen and convert it into syncrude, which does have the advantage of being a relatively clean fuel. The processing of this fuel also consumes a lot of energy.
Still other approaches include in-situ gasification of coal, which may actually consume more energy than is contained in the gasses produced, but since all that energy is considered otherwise unrecoverable, there is still a net gain in useful energy. This approach releases the highest amount of CO2 per unit of useful energy of any process so far proposed.
We can doubtless continue to fuel the world's economy using fossil fuels for some time to come, perhaps even including substantial increases in the total amount of energy consumed. Eventually, however, these fuels will be for all practical purposes exhausted, by which time we must in any case have developed sustainable alternatives.
Given that the amount of CO2 in the atmosphere has reached alarming levels, it seems to the authors that we should begin now to consider alternatives to continued reliance on fossil fuels.
Development of Renewable EnergyA number of systems have been tested for renewable sources of energy. Indeed, many of these have been in widespread use throughout history, including wind mills, water mills, and firewood. Other systems, such as photovoltaic panels that make electricity from sunlight, have been developed in more recent times.
In most cases, the cost of energy from these systems is fairly high, but wind power is already approximately competitive with power from nuclear or fossil sources. This would be especially true if consumers of "dirty power" were made to pay a surcharge for the emissions of CO2 and other air pollutants or for the creation of radioactive waste in proportion to their costs to global society.
We must be careful in assessing renewable energy systems. The growing of corn and fermentation of it into ethanol is one system that has been fairly widely deployed in the USA. Unfortunately, it may actually consume more energy (mostly from petroleum) in its production than is contained in the ethanol. Even if there is a gain (which has been the subject of considerable debate), it is not large, and the secondary effects, including the diversion of productive farmland and accelerated soil erosion, are significant. In other cases, the use of agricultural wastes to produce useful energy seems to be a clear-cut winner. Each system must be analyzed on its merits, including the energy consumed in the process.
We must also be alert to unanticipated dangers in any new energy technology applied on a large scale. Regarding wind power, it appears that massive development of wind farms might alter wind flows sufficiently to influence global atmospheric processes. There are aesthetic objections to the siting of wind turbines, and issues regarding bird strikes have been raised.
Clearly, further research is urgently needed in these areas, and we need to come up with a comprehensive plan to rapidly build up the capacity of sustainable energy infrastructure, which today supplies only a small portion of the world's total consumption. Do remember that, until about 1800, nearly all energy used by mankind was produced from renewable sources. Remember also that large-scale deforestation appears to have been the cause of the collapse of a number of civilizations in antiquity and even today.
Energy Efficiency and Energy ConservationIt seems that the safest approach is to begin immediately to improve the efficiency with which energy is being used. This approach can sustain a high standard of living while imposing smaller externalized costs. It is, in fact, a win-win strategy, although there are clearly limits to what can be achieved by these means.
We must begin immediately to improve the fuel efficiency of the world's automobile fleet and to reduce the incentives to drive. We must reduce highway speeds from current levels, as all elements of the vehicle become lighter if the top speed and acceleration are reduced. Volkswagen has already sent its Chairman to a board meeting in a car that gets 235 mpg (no, that's not a misprint) and travelled over the usual high-speed German autobahn. If this same car required a top speed of only 50 mph, an even smaller power plant and even higher efficiency would be possible. This car was built using conventional technology - nothing more than a small, highly efficient diesel engine plus energy-efficient vehicle design.
Buildings must become much more efficient in their use of energy, and many designs have already been successfully demonstrated.
The book Factor Four: Doubling Wealth - Halving Resource Use: A Report to the Club of Rome describes many ways to reduce energy consumption, sometimes to surprisingly small values.
The Role of Carfree CitiesThe carfree city is thought by the authors to be one of the most effective instruments in achieving dramatically reduced energy consumption while at the same time providing large improvements in the quality of life. The arguments will not be repeated here, but the reader is urged to consult the web site www.carfree.com or read the book Carfree Cities.
ChoicesEconomics are a major consideration in any energy strategy. Fossil fuels from alternative sources will be fairly expensive to develop and the fuels will cost more. (There are secondary advantages to some of these fuels, such as the low sulfur content of syncrude, which means cleaner exhausts.) Energy from renewable sources is today more expensive than energy from many other sources, although the difference is not terribly large. However, renewable energy is becoming steadily cheaper to deploy as the advantages of scale and the growth of experience makes these sources more attractive (and more reliable). Nuclear power, once claimed to be "too cheap to meter," has proven to be the most expensive energy source in direct costs of all. In externalized costs, nuclear energy has the huge additional costs of catastrophic accidents and long-term waste management. Renewable sources have low external costs and the scope for catastrophe is very limited. On a purely economic basis, energy conservation and investments in renewable energy would appear to be the most practical choice and carry the least uncertainty.
Policy RecommendationsPeak oil is more or less here. Even if small increases in production are achieved in the next 10 years, rapidly increasing demand from China puts us in a fuel shortage starting roughly now and getting steadily worse, first as demand continues to increase and then as production begins to decline. Almost nothing can be done to avert shortages in the range of 5-20% within 10 years. As the modest shortfalls of the 1970s showed, this is almost certain to lead to extreme price increases, economic shocks, and eventually more efficient use and reduced consumption. Coal, tar sands, deep-water oil, and a host of other fossil fuel strategies are mentioned, but even the peak in US coal production may be as little as 20 years away, and the other approaches will not soon yield oil in the quantities that will be demanded.
The one guaranteed-safe approach to petroleum exhaustion and greenhouse gas emission is a reduction in the consumption of energy. While the developing nations, in particular China and India, are certain to want to increase their per-capita energy consumption, it is possible to limit this growth while at the same time dramatically reducing the energy consumption of the rich nations. This can even be achieved without appreciable reductions in the "standard of living" while at the same time improving "quality of life." The carfree city is, of course, at or near the top of the list of required strategies. In the USA, about two-thirds of all petroleum is used for transport. The simple strategies of modal shift (away from cars and towards walking, cycling, and efficient public transport) and dramatic improvements in vehicle fuel efficiency could by themselves reduce US oil consumption by half. This assumes that driving is cut by more than half and that fuel efficiency improves from the currently roughly 25 mpg to at least the 50 mpg level of the Toyota Prius.
Even this is just a beginning. If we adopt the Interstate Rail proposal, we would convert some capacity of the Interstate Highways to rail use, and trains are inherently more energy-efficient than road vehicles. We should also cut highway speeds from the current de-facto 70 mph to 45 or 50 mph, which greatly reduces required power output (especially when considering that most current vehicles are capable of 100 mph or more). Very high power is only required during acceleration from 50 mph to 70 mph. Much lower acceleration is acceptable without lengthening highway acceleration ramps if the flow of traffic is slowed to 45 or 50 mph.
Agriculture now runs on oil and gas. Both the fuels used to till crops and the feedstocks for the production of huge amounts of fertilizers and chemical pesticides come from petroleum and gas today. As already noted, it is possible to convert coal into liquid fuel or to use it as a feedstock in chemical production, but the environmental costs with coal are even higher than with oil. Huge amounts of energy are also used to move perishable foods long distances at high speeds, sometimes even by air. We need to begin immediately to reduce the energy-intensiveness of the entire food production and distribution process.
The use of agricultural byproducts ("bio-mass") should be considered in cases where the material is already available and the waste products can be returned to the land, where it is needed to assure continued soil fertility.
We urgently need a tax on fossil fuels, based on the total amount of carbon emitted in the production and consumption of each fuel. Such a tax might be the most effective means to achieving the Kyoto targets, as well as the deeper cuts in CO2 emissions that later treaties almost certainly will require.
The situation is by no means hopeless. The one quick and easy thing to do is to dramatically cut use. This can most easily be achieved by ever-tighter rationing or by ever-increasing taxes on non-renewable energy. At the same time, development of renewable energy should be accelerated. The time to implement these measures was 30 years ago, but today would be better than next year. Urge your leaders to act now. The carfree city should be expressly mentioned as a vital ingredient in the conservation mix. Do your part.
Nuclear Materials Originally written as part of a FAQ document on nuclear weapons, this very extensive backgrounder about nuclear materials describes in detail the properties of heavy elements used as nuclear fuel. (1999)
Nuclear Reactor Types
Thorium (November 2004)
Annex 9. Perspectives of the Thorium Fuel Cycle (apparently 1996)
"Nuclear Power Plant Design Project: A Response to the Environmental and Economic Challenge Of Global Warming" [PDF!] MIT study comparing the pebble bed HTGR design with advanced PWR and BWR designs (1998)
Nuclear Reactor Accidents
Chernobyl accident summary (N.D.)
The 300 MWe pebble bed reactor at Hamm-Uentrop, Germany, an advanced "inherently safe" design, that suffered an accident in May 1986 in which 41 pellets were damaged, releasing radioactivity into the environment and resulting in permanent closure of the plant. Several nuclear industry web sites refer to this plant as an example of an advanced HTGR design, but none of them mention the accident. (N.D.)
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