Saturday, July 24, 2010

Solving Future Energy Problems with Nuclear Power

Much of the future of energy lies with nuclear power. How much is yet to be determined yet, but quite possibly most of the energy input used by global society by the middle of this century will come from nuclear sources. This seems certain because the other potential energy sources, solar and wind, suffer from multiple limitations, and are far to expensive. Anthropogenic Global Warming is probably going to quickly end societies love affair with fossil fuels - I say this even though some of the good folks over at, and some of my readers still have their doubts. The real issue is the sort of social engineering advocated by the David Roberts, Joe Romm, Amory Lovins crowd as a remedy for AGW.

Because of their limitations, a shift from fossil fuels to renewables will require the powering down of society. Amory Lovins argues that this can be accomplished without nuclear power through efficiency. But critics of Amory Lovins; efficiency argument have pointed to he the work of the 19th century economists, William Stanley Jevons, who argued that energy efficiency increased the demand for energy. There is considerable evidence in support of Jevons' hypothesis, and thus Lovins efficiency solution is open to doubt. Amory Lovins has been challenged on Jevons Paradox by a number of critics, most significantly Robert Bryce and David Bradish. Although Lovins promised a response to Bryce and Bradish a couple of years ago, that response has not been forthcoming. Thus the notion efficiency can substitute for the nuclear post-carbon energy solution would appear discredited.

Critics of nuclear power have offered several arguments. They argue that nuclear power is not safe, yet nuclear power, if not perfectly safe, is at the very least far safer than the current fossil fuel based energy system. Nuclear power is arguable safer than renewable energy systems as well. In addition reactor design continues to grow safer, and still further improvements in nuclear safety are possible. Critics of nuclear safety seldom acknowledge the safety improvements over the last generation, and have failed to explain why radiation exposure levels that are considered safe in medical settings, are considered as dangerous when associated with nuclear power plants.

A second objection to the nuclear option has to do with the management of nuclear waste. Yet, nuclear waste would appear to be a misnomer. Most of the energy potential present in nuclear fuel, is not captured by current nuclear power technology. Yet nuclear research over the last two generations has shown that it is possible to build reactors that will capture almost all of the energy left in nuclear fuel. At the end of the complete fuel process, what will remain are fission products, that rapidly become safe, and do not pose unacceptable levels of risk to society. Far larger amounts of far more dangerous waste is produced by the chemical industry, and society views the operations of the chemical industry as an acceptable risk. In addition, the so called waste of the nuclear process in fact contains many valuable metals and minerals. Some of the very same radioactive isotopes which nuclear critics find so dangerous, are frequently injected into the human body as part of routine medical tests.

A third argument against nuclear power focuses on the so called nuclear proliferation risk. It is argued that plutonium contained in used nuclear fuel could be used to build nuclear weapons. In reality reacot grade plutonium, although potentially explosive, has qualities such as heat and radiation, that make it useless for building nuclear weapons. The heat from radioactive breakdown will cause the high explosives used in nuclear triggers, to breakdown. The high level of radiation from reactor grade plutonium, will damage a bombs electric componants. Thus both heat and radiation conspite to prevent the explosion of atomic bombs made from reactor grade plutonium.

A final objection to nuclear power is based on the agument that reactors are too expensive. Yet while reacots are more expensive as a source of electricity that traditional fossil fuel fired power plants, their costs per kilowatt hour of electricity is actually less expensive than that solar and wind generation sources,. At the same time, nuclear power plants offer far more reliability and flexibility than renewables. The sun and the wind can not be turned off and on in order to accomodate consumer demnd, and energy storage is expensive. A nuclear power plant can be counted on to run all night and on windless days. Thus not only is the cost of nuclear power less than the cost of renewable generated electricity, it is also more useful than renewable generated electricity.

Thus the objections to nuclear power appear to be weak. Nuclear critics attempt to disguise the weakness of their anti-nuclear case by the use of emotion laden language, and other irrational arguments.

Nuclear power offers solutions to a number of significant post-carbon energy problems for which renewables seemingly offer what are at best poor solutions, or no solutions at all.

First, there is the question of how to power water born shipping. Presently ships are powered by diesel engines, or steam turbines. Both propulsion systems used fuel derived from crude oil. Powering merchant ship with solar power would seem impractical because the required collection area for solar cells would exceed the size of the ship to a considerable extent. While reverting to sailing would be extremely romantic, it would also be equally impractical. The uncertainty of wind would play havoc with shipping schedules, and the requirement of wind power would pose a limitation on ship size.

Nuclear reactors are already used to power military ships, but the current light water reactors naval reactor would be extremely expensive for a civilian ship power source. An ideal ship propulsion reactor would be compact, built with inexpensive materials at a cost that would rival the cost of present commercial shipping propulsion systems, and would be safe and simple to operate. Although Pebble Bed Reactors have been proposed for shipboard transportation systems, most notably by Rod Adams, other Generation IV Reactors would seem to offer advantage of more compact designs. In particular sodium cooled reactors and Molten Salt Reactors would probably be considered. Molten Salt Reactors would appear to offer advantages over sodium cooled reactors, which have complex coolant and fuel fuel handling requirements, and have some safety related issues. In addition, the cost of sodium cooled reactors is quite likely to be higher than the the cost of Molten Salt Reactors. In addition, of the two reactor classes, MSR technology would appear more likely to have lower cost to build and operate, although how low is yet far from clear. It might also be possible to lower reactor costs, by tying the ship reactor to a combined Brayton and Ranken cycle system power system. Heat efficiencies of perhaps more than 60% would seem possible, with the resulting efficiency being translated into a smaller and more efficient reactor and reactor manufacturing and instalation savings.

A second area which Generation IV reactors would appear to offer a significant advantage over renewables is industrial process heat generation. For industrial heat applications, Pebble Bed and other gas cooled reactors would appear to give good heat output, and thus should be considered. Sodium cooled reactors would be at a significant disadvantage in heat output, but would provide useful heat for some industrial applications. Finally Molten Salt Reactors are capable of producing heat at temperatures up to 1200 C, although with ORNL developed technology they would be limited to 700 C. In addition to providing industrial heat, high temperature reactors are capable of supporting co generation systems. Thus high temperature coolant gasses could be first used to provide heat for an industrial process, and then cycled at a lower temperature through a Ranken cycle boiler to hear water for a steam turbine. Another system would be to use the hot coolant gases to power a closed cycle Brayton cycle turbine and then use the turbine exhaust heat as industrial process heat for industrial processes that require lower temperature. Either system would offer significant efficiencies. It is of course always possible to couple Brayton and Ranken cycle systems in a combined cycle nuclear power plant. Such an combined cycle approach would offer excellent efficiencies.

A third area in which nuclear technology would be useful would be in the area of peak electrical generation. Lettle attention has been paid at present to the problems associated with peak electrical generation. Although solar PV and thermal generating systems are often viewed as functioning as peak generation systems, a system that would reliably generate peak electricity at a competative price would be quite desirable.

Molten Salt Reactors particularly offer significant potential to produce heat that would be useful for peak electrical deman. Normally, the heat produced by a MSR would be carried by a hot salt fluid to a heat exchange where a second salt fluid would be heated, then that heat would be darried to yet another heat exchange in which gas or water would be heated for the power production system. But if full power from the MSR is not required on a 24 hour a day basis, some or all of the heat produced by the reactor could be transfered to a molten salt which would then be placed into storage, and then could later be used used to produce electricity during periods of peak demand.

Molten Salt reactors used to produce industrial heat would be useful for producing stored heat, as would reactors designed to produce intermediat load electricity (that is operate on a 16/7 or 16/5 basis).

In addition, if the cost of MSRs can be lowered by trading off the use of low cost materials for a decrease in efficiency. This is behind the idea of the "Big Lots" reactor, a sort of bargan basement approach for loweering reactor cost for reactors that would not be expected peak power most of the time, or even operate 24 hours a day.

Finally, we have the potential for the use of rejected heat from nuclear heat and power systems to produce desalinated water. Even with combined cycle nuclear generation systems, rejected hear from the Ranken cycle turbine could be used to operate a desalinization system. Heat efficiency would potentially rise above 70%. This tripple threat nuclear generation system would offer fominable savings from its various efficiencies.

Nuclear critics often complain that reactors face or creat problems with water supplies, but the use of waste nuclear heat to desalinate brakish or seawater would seeminly offer a solution to the problem. First the "coolant water" used would not disrupt urban or agricultural water supplies. But beyond that the desalinated water produced in the coolong process, would actually add to the existing water sypply. The sale of desalinated water in water short areas like Southern California would add to the reactor's revinue stream. Finally the recovery of minerals from the brine prodeced at the end of the desalination process could be processed to recover disolved minerals, and their sale would add a further source of revinue to the reactor.

Thus not only are Generation IV nuclear power plants capable of providing industrial heat, they are capable of doing so with great efficiency, that will significantly lower the cost of that heat.

Significant potential efficiencies as quite possible with Generation IV nuclear reactors. Quite appaer from the potential cost lowering effects of factory manufacture, inovative reactor siting and housing, it is to be concluded that efficiencies derived from cogenration, combined cyckes generation and the use of "waste" nuclear heat in desalinization. The full potential for lowering nuclear costs with Generation IV nuclear technology is not yet known, but it is significant. In addition Generation IV nuclear technology appears to be adaptable to many energy uses for which renewable technology is far less suited.


jagdish said...

Russian SVBR lead cooled, LEU fueled fast spectrum reactor appears to be the best of future reactors. Further developments are possible in ywo directions.The fuel could be changed to U-Pu, Pu-Th or Th-U233 without much change in reactor design. Molten lead based fluid fuels are also feasible.
As far as leveling out the hourly demand is concerned, molten salt NaCl-MgCl storage out side the reactor core but part of the heat exchanger is the economical solution.

donb said...

To me, desalinization of water is the "killer app" to take care variable power demand. A lot of the population is along the coasts. They need lots of fresh water. Power cycle reject heat is available for desalinization.

Energy is available, the raw resource (salt water) is already in use at the plant for cooling, and the desalinization process is already set up and going. The only change is some upscaling of the desalinization process.

During times of low power demand, the desalinization plant can be cranked up to use the excess heat available from the reactor. In a way, the extra fresh water is "energy storage", or at least store-able product from available excess energy. The storage of fresh water is not an exotic technology.

jagdish said...

Desalination is an important but site specific use.Low pressure distillation could be well combined with cooling for economic dual use of power generation exhausts.

rere said...

Sir, may I know your email, I would like to ask more about nuclear.
Thank you.

rere said...


Charles Barton said...

Rere, If you link to my name under contributors. you will find an email link. You can also link with me via facebook.


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