NUhydro Power Plants
Would Simultaneously Produce Electricity, Hydrogen & Drinking Water
If global warming becomes more of a threat, if we actually move to a hydrogen economy and if droughts become chronic, America will need a facility that can meet our electricity, transportation fuel and fresh water needs. Such a facility would simultaneously produce electricity, hydrogen for fuel cells, fuel and dependable potable water. Other countries around the world and in the Middle East, particularly Israel and Saudi Arabia, might need such facilities sooner. Nuclear power plant production of electricity is the best method for separating hydrogen from oxygen in water through electrolysis for widespread use in the marketplace. A NUhydro facility would also use heat from the nuclear plant to distill water. Ocean water would be the renewable resource used by the NUhydro plants to meet our energy, water resources and drinking water needs.
Hydrogen is an ideal environmentally friendly renewable fuel becausethe raw material for hydrogen production is water and the byproduct of hydrogen utilization is water and water vapor (See Fuel Cell Diagram at right). Its production from nuclear electricity, storage, transportation and end use do not produce any air pollutants. Hydrogen can be produced from electricity via electrolysis and can be converted into electricity via fuel cells at relatively high efficiencies. Hydrogen can be combined with oxygen without combustion in an electrochemical reaction in a fuel cell (reverse of electrolysis) to produce direct current electricity.Water electrolysis passes an electrical current through water to split individual water molecules into their constituent hydrogen and oxygen. Hydrogen can be stored in gaseous form, in liquid form or in the form of metal hydrides (metal powders that absorb and release hydrogen). If necessary, it can also be transported over long distances through pipelines or tankers.
The United States has extensive experience in using hydrogen. Much of this experience comes from our space program where hydrogen has been used as fuel for the rocket engines of launch vehicles. Our space program is currently the largest consumer of liquid hydrogen. Our experience with hydrogen includes the manufacture, liquefaction, transportation, storage, pipelining, instrumentation, operational use and safety procedures.
Cheap and abundant hydrogen used in fuel cell technology will eventually replace carbon-based fuels in the transportation sector. A fuel cell produces electricity from low-temperature oxidation of hydrogen and yields water as a byproduct. A fuel cell consists of two electrodes sandwiched around an electrolyte. Oxygen passes over one electrode and hydrogen over the other, generating electricity, water and heat. Hydrogen fuel is fed into the "anode" of the fuel cell. Oxygen (or air) enters the fuel cell through the cathode. Encouraged by a catalyst, the hydrogen atom splits into a proton and an electron, which take different paths to the cathode. The proton passes through the electrolyte. The electrons create a separate current that can be utilized before they return to the cathode, to be reunited with the hydrogen and oxygen in a molecule of water.
Using nuclear power to produce hydrogen offers the potential for a limitless chemical fuel supply with near-zero greenhouse gas emissions. As the transportation sector increasingly moves toward hydrogen fuel cells to replace the gasoline internal combustion engine and the demand for desalination of seawater grows as inadequate freshwater supplies become an urgent global concern, potable water and hydrogen in the 21st century will be what oil was in the 20th century.
Light water nuclear power plants can provide safe, efficient, and clean power for converting large quantities of seawater into usable hydrogen fuel. Compact, modular nuclear technology based on high-temperature, gas-cooled reactors are attracting attention worldwide. Small, modular nuclear power reactors in mobile or portable configurations, coupled with hydrogen production and desalination systems, could be used to produce electricity, hydrogen fuel, and potable water. The Pebble Bed Modular Reactor features small, modular, helium-cooled reactors powered by ceramic-coated fuel particles that are inherently safe. This results in simpler plant design and lower capital costs than existing light water reactors. The designs also feature coolant exit temperatures high enough to support the electrochemical water-splitting cycles needed to produce hydrogen. Seawater for distillation and electrolysis could run through a secondary loop in gas-cooled reactors.
A NUhydro plant would use ocean water to cool pressurized steam used in power plants to generate electricity. The ocean water in the secondary loop that is used to cool the primary loop turns to steam and normally escapes from large cooling towers. This distillate would be diverted to water pipes for drinking water or other water resources needs. In addition, in an electrolysis process, ocean water would be passed through a high voltage current to separate the hydrogen from the oxygen. The hydrogen would be used in fuel cells for cars, homes and other purposes. Liquid hydrogen could also be produced with a chiller and stored onsite . The salts and minerals removed from the seawater could be processed for commercial use. It would be practical and very cost effective to locate fuel cell manufacturing facilities, and even fuel cell electric vehicle manufacturing near the NUhydro plants.
One of the most common ways to desalt the seas involve some form of boiling or evaporation. In a simple still seawater can be boiled releasing steam which, when condensed, forms pure water. In the distillation process, feedwater is heated and then evaporated to separate out dissolved minerals. The waste product from the distillation process is a solution with high salt concentration. Most contaminants do not vaporize and, therefore, do not pass to the condensate (also called distillate). With a properly designed still, removal of both organic and inorganic contaminants, including biological impurities, is attained. Distillation involves a phase change which removes all impurities down to the range of 10 parts per trillion, producing water of extremely high purity. The product water recovery relative to input water flow is 15 to 50% for most seawater desalination plants. For every 100 gallons of seawater, 15 to 50 gallons of pure water.
DOE Researchers Demonstrate Feasibility of Efficient Hydrogen Production from Nuclear Energy
In a major step toward achieving President George W. Bushs goal of ensuring Americas energy security through innovative technologies, researchers at the U.S. Department of Energys Idaho National Engineering and Environmental Laboratory (INEEL) and Ceramatec, Inc. of Salt Lake City, Utah have demonstrated the feasibility of using nuclear energy to efficiently produce hydrogen from water.
With Americas growing demand for oil, also comes a host of environmental challenges. Because of the need to develop new energy sources in an environmentally sound way, the President and our Administration recognize that the benefits of hydrogen technologies are too great to ignore. This major breakthrough signals that we are systematically achieving our hydrogen goals, Secretary Abraham said.
Using hydrogen to fuel our economy can reduce dependence on imported petroleum, diversify energy resources, and reduce pollution and greenhouse gas emissions. To this end, the Department of Energy is actively exploring clean hydrogen production technologies using fossil, nuclear and renewable resources to revolutionize the way we power our Nations cars, homes and businesses.
This achievement demonstrates high-temperature electrolysis which utilizes heat to decrease electricity needed for splitting water into hydrogen and oxygen. Instead of conventional electrolysis, which uses only electric current to separate hydrogen from water, high-temperature electrolysis enhances the efficiency of the process by adding substantial external heat such as high-temperature steam from an advanced nuclear reactor system. Such a high-temperature system has the potential to achieve overall hydrogen production efficiencies in the 45 to 50 percent range, compared to approximately 30 percent for conventional electrolysis. Added benefits of the nuclear energy source include the avoidance of both greenhouse gas emissions and air pollutants.
The researchers have shown that hydrogen can be produced at temperatures and pressures suitable for integration with the new Generation IV nuclear reactor design being developed by the Department.
Energy Secretary Spencer Abraham stated, The Generation IV nuclear technologies will take us to the next level in terms of efficiency, reliability, and safety. Coupling high temperature electrolyzer technology with the Gen IV reactors provides another pathway to produce hydrogen for powering future fuel cell vehicles.
Fuel cell vehicles running on hydrogen produce no pollutants or carbon emissions.
Improvements in solid oxide electrolyzer design made by Ceramatec, Inc. will enable a 3-fold decrease in equipment size allowing greatly reduced capital costs. INEEL developed the system concept design and performed the feasibility testing.
This demonstration follows Secretary Abrahams recent announcement of a $2 million grant to Ceramatec who is teamed with INEEL, University of Washington, and Hoeganaes Corporation in Riverton, New Jersey. The team will continue to work remaining challenges to lower costs, increase materials durability and improve efficiency of the solid oxide electrolyzer technology.
This development is a major step towards the hydrogen economy and realizing the Presidents vision described in his 2003 State of the Union Address that the first car driven by a child born today could be powered by hydrogen, and pollution-free.
For more information on advanced nuclear energy concepts, see http://aaas.confex.com/aaas/2010/webprogram/Session1103.html. For more information on electrolyzers, see http://www.eere.energy.gov/hydrogenandfuelcells/production/technology_areas.html#electro.