Just Released! “Energy, Biology, Climate Change”

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Our newest book, published on May 6, 2015 and available at Amazon.com for $19.95.

The focus of this book is the interactions between energy, ecology, and climate change, as well as a few of the responses of humanity to these interactions. It is not a textbook, but a series of chapters discussing subtopics in which the authors were interested and wished to write about. The basic material is cutting-edge science; technical journal articles published within the last year, selected for their relevance and interest. Each author selected eight or so technical papers representing his or her view of the most interesting current research in the field, and wrote summaries of them in a journalistic style that is free of scientific jargon and understandable by lay readers. This is the sort of science writing that you might encounter in the New York Times, but concentrated in a way intended to give as broad an overview of the chapter topics as possible. None of this research will appear in textbooks for a few years, so there are not many ways that readers without access to a university library can get access to this information.

This book is intended be browsed—choose a chapter topic you like and read the individual sections in any order; each is intended to be largely stand-alone. Reading all of them will give you considerable insight into what climate scientists concerned with energy, ecology, and human effects are up to, and the challenges they face in understanding one of the most disruptive—if not very rapid—event in human history; anthropogenic climate change. The Table of Contents follows: Continue reading

Nuclear Power Generation: High Demands for Cooling Water Use

by Cameron Bernhardt

Nuclear power is often praised for its potential to replace carbon-intensive energy sources and reduce greenhouse gas emissions from electricity and power generation. Although nuclear power may offer a promising future in this regard, it is likely to place stresses on the environment in other ways, namely through increased demands on water for cooling and space for waste disposal. Byers et al. (2014) tested six decarbonization pathways to estimate current water use in the UK electricity sector and project water use to 2050 in the UK. The study observed the water use associated with cooling for all varieties of thermoelectric power plants, but nuclear power accounts for over 20 percent of the UK’s electricity mix and is likely to share a large stake in the future of the UK’s power mix. Byers et al. concluded that the pathways with the highest projected proportion of nuclear generation resulted in tidal and coastal water abstraction that exceeded current levels by up to six times. This finding suggests that nuclear power may not be as viable a future energy source as previously thought, especially in areas where water resources are relatively scarce. It seems that the UK should extend its investigations into the merits of nuclear power, and similar studies may be warranted to assess the impacts of nuclear generation in other countries. Continue reading

What Has Worked to Slow Global Warming

by Emil Morhardt

Last week, in anticipation of the United Nations climate conference in New York, The Economist concluded that the single most important action to slow global warming so far has been enactment of the Montreal protocol. Say what? This isn’t on most environmentalists’ radar as an important factor. The Montreal protocol is the 1987 international agreement to save the ozone layer by phasing out Freon and other chlorofluorocarbons used in refrigeration. But these substances are powerful greenhouse gases as well as destroyers of stratospheric ozone, and the protocol caused millions of tonnes of them not to be released into the atmosphere. The article concludes that this avoided release of the greenhouse gas equivalent of 5.6 billion tonnes (bt) of CO2. This is about twice as much avoided CO2 as the next two most effective actions, global use of nuclear power (2.8 bt) and hydroelectricity (2.2 bt), and four times that of the fourth most effective action, China’s one-child policy (1.3 bt). I’m guessing that most of the 300,000 demonstrators in New York last week are not proposing an expansion of these latter three items, but their past effectiveness does make one think. The most effective actions taken specifically to reduce energy usage and CO2 emissions have been worldwide adoption of renewables (0.6 bt), US vehicle emissions standards (0.5 bt), and Brazil forest preservation (0.4 bt). The remaining 11 items on The Economist’s list are small potatoes, totaling less than 1 bt collectively. Continue reading

Japan’s Nuclear Crisis

The 8.9 earthquake, and subsequent tsunami, that rocked Japan on March 11, 2011 have lead to severe damage at Tokyo Electric Power Co.’s Fukushima Daiichi<!–[if supportFields]> XE “Fukushima Daiichi” <![endif]–><!–[if supportFields]><![endif]–> nuclear power plant. The problems at Fukushima Daiichi arose due to the failure of the cooling system and the significant loss of water from the cooling pools.  As authorities continue to work to reestablish the cooling system, Japanese citizens wait anxiously.  Twenty-five years after the meltdown of Chernobyl-4, it seemed that the world was beginning to accept the importance of nuclear power for providing a clean and reliable source of energy in the future.  However, the situation in Japan has awakened our fear of all things nuclear.  Critics argue that the same thing that is happening at Fukushima Daiichi could happen in the U.S. and that the country would be wise to halt all nuclear energy production.  Other, conversely, argue that the Fukushima accident could create a chance for the nuclear industry to “reboot” and look for innovative technologies that may decrease the risk associated with traditional solid-fuel uranium reactors.—Carolyn Campbell

 
          The core of a traditional nuclear reactor, such as the Fukushima Daiichi<!–[if supportFields]> XE “Fukushima Daiichi” <![endif]–><!–[if supportFields]><![endif]–> reactor, contains both water and fuel rods made of zirconium and pellets of nuclear fuel, usually uranium, which set off a controlled nuclear reaction.  This reaction heats the water, creating high temperature steam, which powers a turbine<!–[if supportFields]> XE “turbine” <![endif]–><!–[if supportFields]><![endif]–> and generates electricity.  A meltdown occurs when the core gets too hot, causing the fuel rods to crack and release radioactive gases.  In the worse case scenario, the fuel pellets melt and fall onto the reactor floor, where they can eat through the protective barriers and eventually reach the surrounding environment.  In Japan, the reactors are designed to turn off automatically in case of a disaster, with the aim of preventing a meltdown.  However, even with the plant shut off, nuclear fuel rods continue to generate a huge amount of heat.  In order to cool the fuel, backup generators are meant to pump water into the plant.  These generators failed at Fukushima Daiichi, leading the fuel rods to boil off remaining water and become partially exposed.  If left exposed for long enough, the fuel rods could melt and leak radiation.  In order to avoid this, authorities are pumping seawater into the reactor to cool the fuel rods.  However, salt buildup on the fuel rods can allow them to heat up more by blocking water circulation between the fuel rods, and, in the worst case, can eventually lead to a meltdown.  Additionally, workers have released built-up gases containing some radioactive material into the atmosphere in order to ease pressure inside the plant. 
          The problems at Fukushima Daiichi<!–[if supportFields]> XE “Fukushima Daiichi” <![endif]–><!–[if supportFields]><![endif]–> have aroused concerns of similar disaster occurring in the United States.  While some critics argue that the US should halt all nuclear power generation others suggest that the accident in Japan lends a chance to recreate the nuclear industry.  It has been suggested in recent years that the solid-fuel nuclear reactors, like the ones in Japan, are an outdated technology and should be replaced by a safer and cheaper kind of nuclear energy. According to Matt Ridley of the Wall Street Journal, thorium has many advantages as a nuclear fuel.  There is four times as much thorium in the world as there is uranium; it is easier to handle and to process; it “breeds” its own fuel by continuously creating uranium 233; it can produce 90 times as much energy from the same quantity of fuel; no plutonium is produced by its reactions; and it generates much less waste, with a much shorter half life.  Neutrons are needed for a thorium reactor to run and can be supplied with a particle accelerator or uranium 235.  Both options are highly controlled and are relatively safe.  Additionally, the fuel in a thorium reactor cannot melt down because it is already molten, and reactions slow as it cools.  Whether it leads to new innovations or a general shift away from nuclear power, the disaster at the Fukushima Daiichi plant will undoubtedly alter the future of nuclear energy generation.  

Laser Transmutation of Nuclear Waste

The issue of radioactive waste is a major challenge in the widespread acceptance of a nuclear energy industry. The issues of where to store the nuclear waste and the possibility of radioactive materials leaching into the under-ground water supply seriously undermine the potential of nuclear energy.  However, with the ongoing development of ultra-intense laser techniques, researchers are exploring the possibility of laser transmutation of radioactive materials into stable isotopes.  Sadighi-Bonabi et al. (2009) analyzed the opportunity for transmutation of 93Zr, a highly radioactive nuclear waste with a half-life of 1.53 million years.  The authors suggest that through ultra-intense laser transmutation, 93Zr can be converted to 92Zr, its stable isotope.  High-energy electron generation, Bremsstrahlung, and photonuclear reactions were observed and the number of reactions that produced 92Zr calculated.  It was found that the laser intensity, irradiation time, and repetition rate of laser have strong and direct effects on the yield of 92Zr and the number of reactions. —Carolyn Campbell
Sadighi-Bonabi, R., Irani, E., Safaie, B., Imani, Kh., Silatani, M., Zare, S., 2010. Possibility of ultra-intense laser transmutation of 93Zr (γ, n) 92Zr a long-lived nuclear waste into a stable isotope. Energy Conservation and Management 51, 636–639.

 
          The disposal of long-lived radioactive waste is a significant challenge for the nuclear industry.  Through the development of ultra-intense laser technologies, the possibility of photonuclear transmutation of nuclear waste to more stable isotopes has offered new solutions to solving this problem.  When an ultra-intense laser pulse interacts with the radioactive waste, gamma radiations induce nuclear reactions for transmutation of the waste into a stable isotope.  Sadighi-Bonabi et al. focused their study on Zirconium, particularly 93Zr, a fission product in nuclear reactors with a half-life of 1.53 million years.
          In order to assess the number of reactions and laser-induced photonuclear activation of 93Zr, the authors analyzed available experimental data from focusing intensities onto a solid target.  For this study, the laser intensity was assumed to be 1020W/cm2 with a repetition rate of 10 Hz.  Calculations were also extended to higher intensities of 5 x 1020 W/cm2, 1021 W/cm2, 5 x 1021 W/cm2, and 1022 W/cm2.  The number of reactions was calculated by evaluating the energy spectrum of the laser and a cross section of the photonuclear reaction between threshold and cut-off energy.  It was found that the Bremsstrahlug spectrum, relating to the deceleration of electrons, depended on the intensity of the laser, with higher intensities increasing the number of reactions.  Additionally, irradiation time and repetition rate were found to have substantial effects on the yield of 93Zr (γ, n) 92Zr and the number of reactions.  If the target is irradiated for an hour by a laser light of 1020 W/cm2 at a repetition rate of 10 Hz, approximately 2.7 x 107 reactions will occur.  By increasing the repetition rate, yield would also increase.  However, achieving higher rates also means using more power, and more advanced lasers.  Additionally, although increased intensity of the laser would lead to a higher number of reactions and activity, there is an optimum intensity at which a maximum number of reactions is reached and, beyond that point, the overlap between reaction cross-section and the number of photons disappears.  For 93Zr (γ, n) 92Zr, this optimum intensity was calculated at 3 x 1021 W/cm2
          Through this study, it was found that laser intensity, irradiation time, and repetition rate of the laser have a significant, direct effect on the yield of 92Zr and the number of reactions.  Maximizing the efficiency of laser technology for the transmutation of radioactive isotopes will prove valuable in future efforts to solve the problem of long-lived nuclear waste. 

Nuclear Waste Disposal

While there is a growing consensus that increased investment in nuclear energy is necessary to satisfy future energy needs, the United States currently lacks a suitable permanent storage site for radioactive waste.  With more than 103 open-cycle nuclear reactors throughout the country, the issue of nuclear waste storage is a growing concern.  Schaffer (2010) assesses the current state of nuclear waste in the U.S. and proposes solutions to developing a viable nuclear waste disposal program.  First, the U.S. should reopen the licensing process for the Yucca Mountain waste disposal facility.  Additionally, to decrease the amount of waste sent to disposal facilities the U.S. should restart PUREX reprocessing plants.  Upon taking these initial steps, the government must continue to search for additionally permanent storage sites and appropriate funds to educate local communities about nuclear waste storage.  The Department of Energy (DOE) and the Nuclear Regulatory Commission (NRC) should also issue guidelines and promotions to encourage the industry to build new TRISO-fueled reactors.  Finally, further research should focus on innovative technologies that burn nuclear fuel waste. —Carolyn Campbell
Schaffer, M.B., 2011. Toward a viable nuclear waste disposal program. Energy Policy 39, 1382–1388.
Of the 103 operating commercial nuclear power plants in the U.S., all of them are of the open-cycle, batch type.  These plants produce long-lived radioactive waste in the form of ceramic-encased low-enriched uranium oxide pellets packed into zirconium-clad rods.  With the 1982 Nuclear Policy Act, the U.S. recognized the need for a consolidated storage site, and in 1987 named Yucca Mountain, Nevada as the site for deep underground repositories.  However, in response to pressures from Nevada politicians, the DOE has filed a motion to withdraw the license application for Yucca Mountain operations.  Due to this decision, the country’s nuclear waste remains stored in on-site tanks and casks, which Schaffer argues is risky, inefficient, and unsustainable.    Additionally, as more open-cycle nuclear plants come on line, the problem only gets worse.
Schaffer suggests that there are two main components to solving the open-cycle nuclear waste disposal program.  First is the issue of community confidence; in order for a permanent storage site to be developed, community endorsement is required.  Therefore, a confidence-enhancing plan should identifying three or four sites instead of just one, specify storage for a nominal period, provide adequate monetary incentives, and disclose the risks and rewards of a nuclear storage site.  The second component of a long-term solution for nuclear waste involves reducing the amount of high-level nuclear waste sent to a storage facility.  One way to achieve this is through the PUREX (Plutonium and Uranium by Extraction) process in which depleted fuel rods are cut into pieces and dissolved in nitric acid.  Uranium, plutonium, and actinides can then be extracted from the resulting liquid.  The extracted uranium-235 can be burned in heavy-water moderated reactors or fast-neutron reactors for additional energy, the plutonium-239 can be used to make MOX (mixed oxide uranium and plutonium) fuel, and the actinides can be vitrified in a design that is resistant to water leaching. 

Additional technological solutions for decreasing waste are described in the paper.  Closed-cycle fast reactor technology, such as an Advanced Liquid Metal Reactor (ALMR), has been studied for many years.  ALMR uses energetic neutrons to interact with uranium-238 to eventually produce plutonium-239.  Through pyrometallurgical processing, a mix of transnuranic elements from the used fuel can be extracted and the uranium can be reused.  This process has advantages over PUREX reprocessing, in a counter-proliferation sense, because it does not produce pure plutonium.  An alternative to reprocessing or refining is to produce nuclear waste that is self-contained, depleted to the point where it is not a proliferation problem, and can be stored in underground sites without concerns of water leaching or seismic damage.  TRISO (tri-structureal isometric) fuel reactors use fuel pebbles that, after spent, are safe to store without cooling, are resistant to water leaching, and contain highly depleted nuclear materials.  By employing such overlooked strategies for waste reduction and reopening the search for a permanent storage site the U.S. will be able to develop a more viable nuclear waste disposal program.

Hydrogen Production using Nuclear Energy

It is often argued that hydrogen is the transportation fuel of the future due to its high efficiency and versatility of use.  One way to obtain hydrogen is nuclear-based production using thermochemical water splitting.  Lubis et al. (2010) conducted a life cycle assessment (LCA) of this process in order to determine its environmental impacts.  The authors studied the impacts of both nuclear and copper-chlorine thermochemical plants using LCA methodology framework from the International Organization for Standardization (ISO) and CML-2001 impact categories.  The four main stages of the LCA include: i) goal definition and scope; ii) inventory analysis; iii) impact assessment; and iv) improvement assessment.  From this study it was found that the most significant environmental impacts come from the construction of the two plants and the operation of the nuclear plant.  In contrast, the operations of the thermochemical plant do not significantly contribute to the overall environmental impact.  In order to decrease the environmental impact of nuclear-based hydrogen production, the authors suggest developing more sustainable processes, particularly in the nuclear plant and construction. —Carolyn Campbell
Lubis, L.L., Dincer, I., Rosen, M.A., 2010. Life cycle assessment of hydrogen production using nuclear energy: an application based on thermochemical water splitting. Journal of Energy Resources Technology 132, 1–6.
          The authors undertook a LCA of hydrogen production using nuclear energy.  In order to minimize emissions, hydrogen is produced via a thermochemical cycle that involves a sequence of chemical reactions yielding a net reaction of splitting water.  This study analyzed the copper-chlorine (Cu-Cl) thermochemical cycle in which nuclear energy from a supercritical water-cooled reactor (SCWR) provides the thermal energy for driving the chemical reactions.  Therefore the emissions from the overall system are the sum of the advanced nuclear power plant and the thermochemical hydrogen production plant.  The nuclear plant is taken to be rated at 2060 MWth and the entire thermal output of the plant goes to producing hydrogen.  The thermochemical plant is assumed to have a hydrogen production capacity of 5200 kg/h of H2and a 30-year operational life.  All calculations are based on 1 h of operation of the entire plant.
          Lubis et al. utilized reported literature in order to estimate the emissions of the nuclear and thermochemical plants.  It was estimated that 4.29 kg/h of uranium is needed to produce a thermal output of 2060 MWth. For the thermochemical plant the environmental impact was estimated based on the use of chemicals in the process and use of raw materials.  In order to produce 5200 kg of H2,514,800 kg of CuCl and 189,600 kg of HCl are required.  To assess the impact of hydrogen production, the environmental impacts of emitted substances were classified into environmental impact categories.  These categories include abiotic resource depletion potential (ADP), global warming potential (GWP), ozone depletion potential (ODP), eutrophication potential (EP), acidification potential (AP), photochemical ozone creation potential (POCP), and radioactive radiation (RAD).  The quantitative environmental impacts were then calculated by multiplying the quantity of emitted substances by the relevant classification factor and the GaBi database was utilized to determine the environmental impact of emissions based on inventory analysis. 
          The LCA produced several findings regarding the environmental impact of nuclear-based hydrogen production using thermochemical water splitting.  For GWP, the system emits 0.0025 g CO2-eq over the life of the plant, with 95% of these emissions attributable to the construction of the nuclear plant and the hydrogen plant.  Additionally, regarding the AP, the emissions of the system are 0.00015 g SO2-eq, with the 99% of emissions coming from construction and the nuclear fuel cycle.  Construction contributes significantly to other impact categories including EP, ODP, and POCP, while the nuclear fuel cycle contributes significantly to ADP and RAD.  In order to decrease the environmental effects of this system the authors suggest developing more sustainable processes in the nuclear plant and the construction of hydrogen production. 

French Politics, Culture, and Nuclear Power

With over 80% of its electricity coming from nuclear power, it has been suggested that France is a model for adopting a nuclear energy industry.  However, Coombs (2010) suggests that France’s successful nuclear industry has been driven by the unique political and cultural climate of the country.  France’s independent executive branch, characterized by a lack of division of power, a weak judiciary, and a reliance on bureaucratic capability, had the ability to efficiently institute a nuclear program without objections from outside interest groups.  Additionally, the French people have been won over by the economic growth created by the nuclear industry.  Finally, the lack of natural resources in the country has contributed to the growth of the nuclear power program.   Coombs suggests that the French government’s firm support of the nuclear industry has overshadowed the negative aspects of nuclear power, especially the problem of nuclear waste disposal.—Carolyn Campbell     
Coombs, C., 2010. French Nuclear Power: A model for the world?. Hinckley Journal of Politics. 11, 7–13.

Coombs studied the costs and benefits of nuclear energy by analyzing France’s nuclear industry.  France began looking into nuclear power during the 1960s in order to decrease its dependence on foreign energy sources and was particularly affected by the quadrupling of oil prices from OPEC countries in 1973. The government began to seriously consider adopting nuclear power and was able to efficiently implement a nuclear program without much objection from outside interest groups.  Coombs notes that the French executive-empowering government structure prevents activists from being involved in a transparent debate or influencing policy.  Additionally, there is a cultural tendency within France to yield decision-making to the large group of trusted scientists and engineers in the country.  Furthermore, French nuclear power has a number of benefits including increased job creation, state revenue, and energy independence.  While nuclear power is championed in France, it is often looked upon warily in the United States.  Coombs argues that this is not because the French people do not have fears about nuclear waste and accidents, but because their cultural views and political situation influence their support for nuclear energy.  Additionally, the French have a lack of choice in the matter, with few alternative natural resources and a government structure that does not support political debate on such matters. 
          Despite the success of nuclear power, the disposal of nuclear waste continues to be an issue in France.  The idea of burying the waste has brought up ideas of the profanation of soil and desecration of the Earth.  Additionally, a rural/urban<!–[if supportFields]> XE “urban” <![endif]–><!–[if supportFields]><![endif]–> divide has been intensified with rural populations protesting against the Parisian’s energy waste ending up in their backyards.  In order to combat these issues the state has proposed “stockpiling” the waste.  This implies reversibility; that the waste will not be buried and forgotten and that future scientists may learn how to reduce or eliminate the toxicity.  However, nuclear waste is a long-term problem that France has yet to develop a permanent disposal facility for.  While France has come up with a way to “reprocess” fuel from spent nuclear rods, much of the revenue from this process comes from outside the country.  This means that other countries, including Japan, Germany, Switzerland, the Netherlands, Belgium, and Italy, are shipping their waste to and from France.  This transit of nuclear waste only increases the likelihood of an accident.  However, Coombs argues that the French public places the economic benefits derived from nuclear power above the possible health risks.
          Coombs concludes that since France’s nuclear program has led to enormous economic benefits, the negative byproducts of nuclear energy have been overlooked.  The French government was able to institute a nuclear program due to an executive-empowering institutional structure and a trusting public.  However, other countries must weigh both the costs and benefits of nuclear power when searching for renewable energy alternatives. 

Sustainability of Nuclear Fission Energy

While nuclear energy has been cited as a potential solution in achieving carbon-free electricity, there are many problems facing its development.  Nuclear generation is met with public and political opposition due to concerns regarding nuclear accidents and nuclear waste.  Additionally, very high initial investment costs make it difficult to find funding for nuclear energy projects.  Piera (2010) examines the sustainability issues related to nuclear fission energy by reviewing ongoing lines of research and development in the field and potential alternative reactor technologies.  While the analysis points out the major drawbacks of nuclear energy, those related to safety, security, and the environment, Piera highlights that nuclear fission is a sound CO2-free source of energy.  The study argues that nuclear fission has a high maturity in its current state of commercial development and has enormous potential in new phases of industrial development.  Carolyn Campbell
Piera, M., 2010. Sustainability issues in the development of nuclear fission energy. Energy Conservation and Management 51, 938–946.

          Emphasized as an important option for keeping atmospheric CO2 below 550 ppm,  nuclear power plants currently provide 16% of the global electricity generation.  While generation is increasing 1% each year, this rate is incredibly modest when compared to the global yearly increase in primary energy consumption.  Nuclear fission energy is well suited to meet the needs of future energy policies due to the guaranty of supply, environmental quality, and moderate energy costs.  However, nuclear energy development is hindered by public and political opposition as well as financing difficulties. 
          Throughout the paper, Piera assessed the concept of sustainable development as applicable to nuclear energy.  First coined in the Brundtland Report, sustainable development stressed the importance of considering social, economic, and environmental issues to ensure the same development and living conditions for future generations.  In this context, energy is a very critical issue.  While nuclear energy is considered an important energy alternative with very low CO2 emissions, current LWR reactors are inefficient.  Only 0.55% of the potential energy in mined uranium is converted into heat in the reactors, a fact that hampers the future development of nuclear energy.  Therefore, Pierra argues, future research should focus on options for new reactors and fuel cycles that could exploit natural resources up to 70% or more.  Additionally, nuclear natural resources could be more completely exploited through nuclear breeding.  Even-numbered heavy nuclei, U-238 and Th-232, cannot be considered true fuels because they do not undergo fission with thermal neutrons.  Through nuclear breeding these even-numbered nuclei can be converted into odd-numbered nuclei, specifically Pu-239 and U-233. 
          While nuclear breeding may be a solution for more efficient use of nuclear natural resources, it causes concerns related to nuclear proliferation.  Pu-239 seems to be a suitable material for nuclear weapons, a social concern that must be addressed in sustainability assessments.  Additionally, the waste burden of nuclear energy hinders the sustainability of nuclear fission energy.  While deep geological repositories have been suggested as a solution for waste storage, the radiotoxicity of nuclear waste can last for 1000 centuries.  Therefore, to make nuclear energy more sustainable the waste must be reduced as much as possible before its final disposal.  The “open cycle” in use today cannot achieve such a reduction.  By switching to a closed cycle with nuclear fuel recycling, much less fuel would need to be disposed of. 
Another concern with nuclear energy generation is nuclear accidents.  The meltdown of Chernobyl-4 had catastrophic affects on humans and the environment.  However, the reactor was running an experiment when the accidents took place and the six-safety systems had been shut off.  Generation 3 reactors have learned from the Chernobyl accident and in turn have incorporated more advanced safety systems. 

          In conclusion, Peira proposes four main sustainability technical criteria for nuclear energy.  First, nuclear reactors and nuclear fuel facilities must have enhanced safety features.  Second, natural nuclear materials must be more highly exploited.  Third, radioactive inventory of waste must be minimized before disposal.  And finally, proliferation-resistant technologies must be developed.  By achieving these criteria, nuclear fission energy will become a more sustainable and viable option for the future.  

Coupling Thermochemical Water Splitting with a Desalination Plant for Hydrogen Production from Nuclear Energy

Nuclear energy has the ability to provide a significant share of energy supply in the future without the negative environmental impacts associated with current energy resources.  While nuclear energy has mainly been used for electric power generation, it can also be used in thermochemical water decomposition to produce hydrogen.  Orhan et al. (2010) explored configurations for coupling the Cu-Cl cycle with a desalination plant using nuclear or renewable energy and assessed the viability of these systems.  It was found that capital cost of the Cu-Cl cycle per unit of hydrogen output is less for a larger capacity plant while production cost remains constant.  Additionally, the total cost of hydrogen production is inversely proportional to the relationship with plant capacity.  The overall unit capital cost of the coupled system was found to vary with production capacity, but not with the type of desalination method.  In regards to energy use, the effect of the Cu-Cl cycle is dominant on the overall efficiency of the system because the desalination plant uses much less energy.  The highest efficiency coupled system is the configuration that utilizes nuclear energy to power the desalination plant. — Carolyn Campbell
Orhan, M.F., Dincer, I., Naterer, G.F., Rosen, M.A., 2010. Coupling of copper-chloride hybrid thermochemical water splitting cycle with a desalination plant for hydrogen production from nuclear energy. International Journal of Hydrogen Energy 35, 1560–1574.

          Orhan et al. analyzed the different configurations for coupling a Cu-Cl cycle with a desalination plant using nuclear energy to produce hydrogen.  The Cu-Cl cycle consists of a set of reactions to achieve the splitting of water into hydrogen and oxygen.  The production of hydrogen through this cycle provides a pathway for the utilization of nuclear thermal energy.  Orhan et al. studied the options for coupling the Cu-Cl cycle with a desalination plant.  Case I couples the Cu-Cl cycle with a desalination plant powered by nuclear energy.  The desalination process is carried out using the waste energy from the nuclear reactor and the resulting fresh water is decomposed into hydrogen and oxygen through the Cu-Cl cycle driven by nuclear energy.  Case II uses recovered energy from the Cu-Cl cycle to drive the desalination process, with the desalination plant as a sub-system of the Cu-Cl cycle.  Additionally, process/waste energy from the nuclear reactor is used to power the Cu-Cl cycle.  One drawback of this system is the efficiency decrease in the Cu-Cl cycle due to the fact that the recovered energy is used for desalination rather than within the cycle itself.  Case III uses nuclear energy directly in the desalination process.  The Cu-Cl cycle is powered by process energy from the nuclear reactor and energy recovered from the cycle.  Case IV uses solar energy to drive desalination while process and waste energy from the nuclear plant is used for the Cu-Cl cycle.  One drawback of this configuration is that solar energy is intermittent and therefore much attention must be paid to site selection.  Finally, Case V uses off-peak electricity to power both desalination and the Cu-Cl cycle.
          The authors performed a comparison of the cost and energy use of the different configurations.  The capital cost of the Cu-Cl cycle was found to vary from 1.8 to 0.3 $/kg H2 depending on the capacity of the cycle.  The capital cost of the cycle per unit of hydrogen output is inversely proportional to the size of the system because the reaction energy of any chemical or physical reaction in the Cu-Cl cycle does not change based on plant capacity.  The overall unit capital costs of the coupled system were found to be the same for all configurations since the cost contribution of the desalination plant is small compared to that of the Cu-Cl cycle.  Case III had the highest capital and production cost of the desalination plant, using a MSF system, while Caste I, using a humidification-dehumidification system, had the lowest cost.  The unit energy consumed was also greatest for Case III, but lowest for Case V.  Finally, the energy efficiencies of the entire configuration were assessed.  The effect of the Cu-Cl cycle on the overall system is dominant, thus the overall efficiency of the systems are very similar for each case.  However, it was found that Case I had the highest efficiency since waste energy from the nuclear reactor was used.  In contrast, Case II operated at lower efficiencies using recovered energy from the Cu-Cl cycle.