INTRODUCTION

A US company says it will have a nuclear-powered prototype vehicle on the road within two years. Laser Power Systems from Connecticut is developing a method of propulsion that uses thorium to produce electricity to power a car engine. Thorium is an element similar to uranium and because it is such a dense material it has the potential to produce massive amounts of heat. According to Laser Power Systems CEO, Charles Stevens, just one gram of thorium produces more energy than 28,000 litres of petrol. Mr Stevens says just eight grams of thorium would be enough to power a vehicle for its entire life. In an interview with Ward’s Auto, he explained small pieces of thorium were used to generate heat and were positioned to create a thorium laser. The lasers heat water to produce steam and power a series of mini-turbines. Mr Stevens said an engine weighing approximately 227kg would be light enough and compact enough to fit under the bonnet of a conventional car. If it were that simple though, petrol would already be a thing of the past. Mr Steven said developing turbines and generators that were usable and portable was much more difficult than making the thorium lasers.

“How do you take the laser and put these things together efficiently” This is the question Mr Stevens and the 40 workers at Laser Power Systems are currently trying to answer. If they can get the technology to work, however, Mr Stevens says thorium-powered cars could “run for a million miles”. “The car will wear out before the engine. There is no oil, no emissions – nothing.” If thorium does become a major power source of the future, Australia would be well placed to become a global energy giant.

According to the US Geological Survey, Australia has the first highest level of thorium in the world, accounting for somewhere between one quarter and one sixth of the world’s thorium reserves.

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Thorium:-

Thorium is a natural radioactive chemical element, with the symbol Th and atomic number 90. It was discovered in 1828 and named after Thor, the Norse god of thunder. In nature, virtually all thorium is found as thorium-232, and it decays by emitting an alpha particle, and has a half-life of about 14.05 billion years (other, trace-level isotopes of thorium are short-lived intermediates of decay chains). It is estimated to be about four times more abundant than uranium in the Earth's crust and is a by-product of the extraction of rare earths from monazite sands. Thorium was formerly used commonly as the light source in gas mantles and as an alloying material, but these applications have declined due to concerns about its radioactivity. India, Canada, Germany,   Netherlands, United Kingdom and the United States have used thorium in various experimental and power reactors as fuel. There is a growing interest in developing thorium fuel cycle for various reasons, including its safety benefits, its high absolute abundance and relative abundance compared to uranium.

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Characteristics of thorium:-

Physical properties Chemical properties Compounds Isotopes

Physical properties:-

Pure thorium is a silvery-white metal, which is air-stable and retains its luster for several months. When contaminated with the oxide, thorium slowly tarnishes in air, becoming gray and finally black. The physical properties of thorium are greatly influenced by the degree of contamination with the oxide. The purest specimens often contain several tenths of a percent of the oxide. Pure thorium is soft, very ductile, and can be cold-rolled, swaged, and drawn. Thorium is dimorphic, changing at 1360 °C from a face-centered cubic to a body-centered cubic structure; a body-centered tetragonal lattice form exists at high pressure with impurities driving the exact transition temperatures and pressures. Powdered thorium metal is often pyrophoric and requires careful handling. When heated in air, thorium metal turnings ignite and burn brilliantly with a white light. Thorium has one of the largest liquid temperature ranges of any element, with 2946 °C between the melting point and boiling point. 

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Chemical properties:-

Thorium is slowly attacked by water, but does not dissolve readily in most common acids, except hydrochloric acid. It dissolves in concentrated nitric acid containing a small amount of catalytic fluoride ion.

Compounds:-

Thorium compounds are stable in the +4 oxidation state. Thorium dioxide has the highest melting point (3300 °C) of all oxides. `When treated with potassium fluoride and hydrofluoric acid, Th4+ forms the complex anion ThF2−6, which precipitates as an insoluble salt,K2ThF6. Thorium(IV) hydroxide, Th(OH)4, is highly insoluble in water, and is not amphoteric. The peroxide of thorium is rare in being an insoluble solid. This property can be utilized to separate thorium from other ions in solution. In the presence of phosphate anions, Th4+ forms precipitates of various compositions, which are insoluble in water and acid solutions. Thorium monoxide has recently been produced through laser ablation of thorium in the presence of oxygen.

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Isotopes:-

Main article: Isotopes of thorium

Twenty-seven radioisotopes have been characterized, with a range in atomic weight from 210 u (210Th) to 236 u (236Th). The most stable isotopes are:

232Th with a half-life of 14.05 billion years, it represents all but a trace of naturally occurring thorium.

230Th with a half-life of 75,380 years. Occurs as the daughter product of 238U decay.

229Th with a half-life of 7340 years. It has a nuclear isomer with remarkably low excitation energy of 7.6 e V.[10]

228Th with a half-life of 1.92 years.

All of the remaining radioactive isotopes have half-lives that are less than thirty days and the majority of these have half-lives that are less than ten minutes.

History:-

Swedish chemist Jöns Jakob Berzelius analyzed a mineral from the Falun district in 1828 and determined that it contained a new element, which he named thorium after Thor, the Norse god of thunder. Morten Thrane Esmark found a black mineral on Løvøy Island, Norway and gave a sample to his father Jens Esmark, a noted mineralogist. The elder Esmark was not able to identify it and sent a sample to Berzelius for examination in 1828. Berzelius analyzed it and gave it the same name as the misidentified sample of xenotime. The metal had no practical uses until Carl Auer von Welsbach invented the gas mantle in 1885. Thorium was first observed to be radioactive in 1898, independently, by Polish-French physicist Marie Curie and German chemist Gerhard Carl Schmidt. Between 1900 and 1903, Ernest Rutherford and Frederick Soddy showed how thorium decayed at a fixed rate over time into a series of other elements. This observation led to the identification of half-life as one of the outcomes of the alpha particle experiments that led to their disintegration theory of radioactivity.

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The crystal bar process (or "iodide process") was discovered by Anton Eduard van Arkel and Jan Hendrik de Boer in 1925 to produce high-purity metallic thorium. The name ionium was given early in the study of radioactive elements to the 230Th isotope produced in the decay chain of 238U before it was realized that ionium and thorium were chemically identical. The symbol Io was used for this supposed element.

Estimated world thorium resources

Country Tones % of total

Australia 489,000 19

USA 400,000 15

Turkey 344,000 13

India 319,000 12

Venezuela 300,000 12

Brazil 302,000 12

Norway 132,000 5

Egypt 100,000 4

Russia 75,000 3

Greenland 54,000 2

Canada 44,000 2

South Africa 18,000 1

Other countries 33,000 1

World total 2,610,000

Occurrence:-

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Monazite, a rare earth and thorium phosphate mineral, is the primary source of the world's thorium.

Thorium is found in small amounts in most rocks and soils; it is three times more abundant than tin in the Earth's crust and is about as common as lead. Soil commonly contains an average of around 6 parts per million of thorium. Thorium occurs in several minerals including thorite  (ThSiO4), thorianite (ThO2 + UO2) and monazite. Thorianite is a rare mineral and may contain up to about 12% thorium oxide. Monazite contains 2.5% thorium, allanite has 0.1 to 2% thorium and zircon can have up to 0.4% thorium. Thorium-containing minerals occur on all continents. Thorium is several times more abundant in Earth's crust than all  isotopes of uranium combined and thorium-232 is several hundred times more abundant than uranium-235. 232Th decays very slowly (its half-life is comparable to the age of the universe) but other thorium isotopes occur in the thorium and uranium decay chains. Most of these are short-lived and hence much more radioactive than 232Th, though on a mass basis they are negligible.

Thorium extraction:-

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Thorium has been extracted chiefly from monazite through a complex multi-stage process. The monazite sand is dissolved in hot concentrated sulfuric acid (H2SO4). Thorium is extracted as an insoluble residue into an organic phase containing an amine. Next it is separated or stripped using an ion such as nitrate, chloride, hydroxide, or carbonate, returning the thorium to an aqueous phase. Finally, the thorium is precipitated and collected.

Several methods are available for producing thorium metal: it can be obtained by reducing thorium oxide with calcium, by electrolysis of anhydrous thorium chloride in a fused mixture of sodium and potassium chlorides, by calcium reduction of thorium tetrachloride mixed with anhydrous zinc chloride, and by reduction of thorium tetrachloride with an alkali metal.

Laser:-

Short for “light amplification by stimulated emission of radiation”

A device that creates and amplifies electromagnetic radiation of a specific frequency through the process of stimulated emission. The radiation emitted by a laser consists of a coherent beam of photons, all in phase and having the same polarization. Lasers have many uses, such as cutting hard or delicate substances, reading data from compact disks and other storage devices, and establishing straight lines in geographical surveying.

A Closer Look A laser emits a thin, intense beam of nearly monochromatic visible or infrared light that can travel long distances without diffusing. Most light beams consist of many waves traveling in roughly the same direction, but the phases and polarizations of each individual wave (or photon) are randomly distributed. In laser light, the waves are all precisely in step, or in phase, with each other, and have the same polarization. Such light is called coherent. All of the photons that make up a laser beam are in the same quantum state. Lasers produce coherent light through a process called stimulated emission. The laser contains a chamber in which atoms of a medium such as a synthetic ruby rod or a gas are excited, bringing their electrons into higher orbits with higher energy states. When one of these electrons jumps down to a lower energy state (which can happen spontaneously), it gives off its extra energy as a photon with a specific frequency. But this photon, upon encountering another atom with an excited electron, will stimulate that electron to jump down as well, emitting another photon with the

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same frequency as the first and in phase with it. This effect cascades through the chamber, constantly stimulating other atoms to emit yet more coherent photons. Mirrors at both ends of the chamber cause the light to bounce back and forth in the chamber, sweeping across the entire medium. If a sufficient number of atoms in the medium are maintained by some external energy source in the higher energy state a condition called population inversion then emission is continuously stimulated, and a stream of coherent photons develops. One of the mirrors is partially transparent, allowing the laser beam to exit from that end of the chamber. Lasers have many industrial, military, and scientific uses, including welding, target detection, microscopic photography, fiber optics, surgery, and optical instrumentation for surveying.

The American Heritage Science Dictionary Copyright 2005 by Houghton Mifflin Company. Published by Houghton Mifflin Company. All rights reserved.

Any device that can produce or amplify optical radiation primarily by the process of controlled stimulated emission. A laser may emit electromagnetic radiation from the ultraviolet portion of the spectrum through the infrared portion. Also, an acronym for "light amplification by stimulated emission of radiation."

How Does It Work:-

A laser is an optical oscillator, which is made out of a solid, liquid or gas with mirrors at both ends. To make the laser work, the material is excited or "pumped," with light or electricity. The pumping excites the electrons in the atoms, causing them to jump to higher orbits, creating a "population inversion." A few of the electrons drop back to lower energy levels spontaneously, releasing a photon (quantum of light). The photons stimulate other excited electrons to emit more photons with the same energy and thus the same wavelength as the original. The light waves build in strength as they pass through the laser medium, and the mirrors at both ends keep reflecting the light back and forth creating a chain reaction and causing the laser to "lase."

In simple laser cavities, one mirror has a small transparent area that lets the laser beam out. In semiconductor lasers, both mirrors often transmit a beam, the second one being used for monitoring purposes.

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Laser Action:-

The combination of spontaneous emission first, and then stimulated emission, causes the laser to "lase," which means it generates a coherent beam of light at a single frequency.

Who Invented It:-

In 1957, the laser was conceived by Gordon Gould, a graduate student in physics at Columbia University. When Gould filed for patents in 1959, he found that Columbia professor Charles Townes and Arthur Schawlow of Bell Labs had already filed for them. The year before, AT&T had, in fact, demonstrated a working laser at Bell Labs. In 1977, after years of litigation, a court awarded Gould rights to the first of three patents and later to all of them. He finally reaped millions in royalties.

Developing the Laser

This photo of the development of the helium-neon laser was taken at AT&T's Bell Laboratories in 1964.

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Steam Turbine:-

A steam turbine is a device that converts the heat energy in captured, pressurized steam, and converts it to mechanical energy. The first historical example was the famous steam engine of Hero of Alexandria. This device was little more than a pot and spout on a rotating spit. When set over a fire, the water in the pot would boil, creating steam, this would then escape out the spout. The thrust generated by the escaping steam would turn the pot on the spit.

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A typical power station steam turbine and its external parts Source

The primary type of turbine used for central power generation is the condensing turbine. These power-only utility turbines exhaust directly to condensers that maintain vacuum conditions at the discharge of the turbine. An array of tubes, cooled by river, lake, or cooling tower water, condenses the steam into (liquid) water. The cooling water condenses the steam turbine exhaust steam in the condenser creating the condenser vacuum. As a small amount of air leaks into the system when it is below atmospheric pressure, a relatively small compressor removes non condensable gases from the condenser. Non-condensable gases include both air and a small amount of the corrosion byproduct of the water-iron reaction, hydrogen. The condensing turbine processes result in maximum power and electrical generation efficiency from the steam supply and boiler fuel. The power output of condensing turbines is sensitive to ambient conditions.

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Electricity Generation:-

The main use for steam turbines today is in generating electricity. Turbines used for this have fan blades mounted on a rotor. The rising steam turns the blades, and thus the rotor. This rotary motion is then directly transferred to running a generator. This is how the heat energy of steam is turned to mechanical energy, and then into electricity. All thermal power plants natural gas, oil, coal, nuclear and geothermal operates on this principle.

There are two types of steam turbines.

1. Non-Condensing (Back-pressure) Steam Turbine2. Extraction Steam Turbine.

Non-Condensing (Back-pressure) Turbine:-Figure shows the non-condensing turbine (also referred to as a back-pressure turbine) exhausts its entire flow of steam to the industrial process or facility steam mains at conditions close to the process heat requirements.

Non-Condensing (Back-Pressure) Steam Turbine

 

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Usually, the steam sent into the mains is not much above saturation temperature. The term “back-pressure” refers to turbines that exhaust steam at atmospheric pressures and above. The specific CHP application establishes the discharge pressure. 50, 150, and 250 psig are the most typical pressure levels for steam distribution systems. District heating systems most often use the lower pressures, and industrial processes use the higher pressures. Industrial processes often include further expansion for mechanical drives, using small steam turbines for driving heavy equipment that runs continuously for long periods. Power generation capability reduces significantly when steam is used at appreciable pressure rather than being expanded to vacuum in a condenser. Discharging steam into a steam distribution system at 150 psig can sacrifice slightly more than half the power that could be generated when the inlet steam conditions are 750 psig and 800°F, typical of small steam turbine systems.

Extraction Turbine:-The extraction turbine has opening(s) in its casing for extraction of a portion

of the steam at some intermediate pressure before condensing the remaining steam. Figure illustrates the

Extraction Steam Turbine

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The steam extraction pressure may or may not be automatically regulated. Regulated extraction permits more steam to flow through the turbine to generate additional electricity during periods of low thermal demand by the CHP system. In utility type steam turbines, there may be several extraction points, each at different pressure corresponding to a different temperature. The facility’s specific needs for steam and power over time determine the extent to which steam in an extraction turbine is extracted for use in the process.

In large, often complex, industrial plants, additional steam may be admitted (flows into the casing and increases the flow in the steam path) to the steam turbine. Often this happens when using multiple boilers at different pressure, because of their historical existence. These steam turbines are referred to as admission turbines. At steam extraction and admission locations there are usually steam flow control valves that add to the steam and control system cost.

The long history of steam turbine use has resulted in a large inventory of steam turbine stage designs. For example, the division of steam acceleration and change in direction of flow varies between competing turbine manufacturers under the identification of impulse and reaction designs.

Manufacturers tailor clients’ design requests by varying the flow area in the stages and the extent to which steam is extracted (removed from the flow path between stages) to accommodate the specification of the client. When the steam expands through a high-pressure ratio, as in utility and large industrial steam systems, the steam can begin to condense in the turbine when the temperature of the steam drops below the saturation temperature at that pressure. If water drops form in the turbine, blade erosion occurs from the drops impact on the blades. At this point in the expansion the steam is sometimes returned to the boiler and reheated to high temperature and then returned to the turbine for further (safe) expansion. In a few large, high pressures, utility steam systems install double reheat systems. With these choices the designer of the steam supply system and the steam turbine have the challenge of creating a system design which delivers the (seasonally varying) power and steam which presents the most favorable business opportunity to the plant owners. Between the power (only) output of a condensing steam turbine and the power and steam combination of a back-pressure steam turbine essentially any ratio of power to heat output can be supplied.

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Electrical Efficiency:-

The electrical generating efficiency of standard steam turbine power plants varies from a high of 37% HHV4 for large, electric utility plants designed for the highest practical annual capacity factor, to under 10% HHV for small, simple plants which make electricity as a byproduct of delivering steam to processes or district heating systems.

Steam Generator:-

A steam generator that uses the heat from the combustion of an organic fuel is called a steam boiler, whereas one that operates on electricity is called an electric boiler. With the advent of atomic power plants, the term “steam generator” was applied to boilers heated by heat transfer from the atomic reactor; such boilers produce secondary steam that is fed into the turbine. Steam generators are built with either a vertical or horizontal boiler arrangement.

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U.S. NRC image of a modern steam turbine generator

A steam generator is a device used to boil water to create steam. It may refer to:

Boiler (steam generator) , a closed vessel in which water is heated under pressure

Supercritical steam generator  or Benson boiler, a high-pressure steam generator that operates in the supercritical pressure regime, such that no boiling takes place within it.

Steam generator (auxiliary boiler) , a steam-powered boiler used on ships to produce a low-pressure steam, from a high-pressure supply.

Steam generator (boiler) , an oil- or gas-fired boiler, based on a low-water content mono tube coil.

Steam generator (nuclear power) , a heat exchanger in a pressurized water nuclear reactor

Steam generator (railroad) , a device used in trains to provide heat to passenger cars

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Description:-

In commercial power plants steam generators can measure up to 70 feet in height and weigh as much as 800 tons. Each steam generator can contain anywhere from 3,000 to 16,000 tubes, each about three-quarters of an inch in diameter. The coolant (treated water), which is maintained at high pressure to prevent boiling, is pumped through the nuclear reactor core. Heat transfer takes place between the reactor core and the circulating water and the coolant is then pumped through the primary tube side of the steam generator by coolant pumps before returning to the reactor core. This is referred to as the primary loop.

That water flowing through the steam generator boils water on the shell side to produce steam in the secondary loop that is delivered to the turbines to make electricity. The steam is subsequently condensed via cooled water from the tertiary loop and returned to the steam generator to be heated once again. The tertiary cooling water may be re circulated to cooling towers where it sheds waste heat before returning to condense more steam. Once through tertiary cooling may otherwise be provided by a river, lake, or ocean. This primary, secondary, tertiary cooling scheme is the most common way to extract usable energy from a controlled nuclear reaction.

Loops also have an important safety role because they constitute one of the primary barriers between the radioactive and non-radioactive sides of the plant as the primary coolant becomes radioactive from its exposure to the core. For this reason, the integrity of the tubing is essential in minimizing the leakage of water between the two sides of the plant. There is the potential that, if a tube bursts while a plant is operating, contaminated steam could escape directly to the secondary cooling loop. Thus during scheduled maintenance outages or shutdowns, some or all of the steam generator tubes are inspected by eddy-current testing.

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Typical operating conditions:-

Steam generators in a "typical" PWR in the USA have the following operating conditions:

SidePressure, MPa

(absolute)Inlet

Temperature, °COutlet

Temperature, °C

Primary side (tube side)

15.5 315 (liquid water) 275 (liquid water)

Secondary side (shell side)

6.2 220 (liquid water)275 (saturated

steam)

Tube material:-

Various high-performance alloys and super alloys have been used for steam generator tubing, including type 316 stainless steel, Alloy 400, Alloy 600MA (mill annealed), Alloy 600TT (thermally treated), Alloy 690TT, and Alloy 800Mod.

Dynamo:-

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Dynamos are no longer used for power generation due to the size and complexity of the commutator needed for high power applications. This large belt-driven high-current dynamo produced 310 amperes at 7 volts, or 2,170 watts, when spinning at 1400 RPM.

Dynamo Electric Machine [End View, Partly Section]

The dynamo was the first electrical generator capable of delivering power for industry. The dynamo uses electromagnetic principles to convert mechanical rotation into pulsed DC through the use of a commutator. The first dynamo was built by Hippolyte Pixii in 1832.

Through a series of accidental discoveries, the dynamo became the source of many later inventions, including the DC electric motor, the AC alternator, the AC synchronous motor, and the rotary converter.

A dynamo machine consists of a stationary structure, which provides a constant magnetic field, and a set of rotating windings which turn within that field. On small machines the constant magnetic field may be provided by one or more permanent magnets; larger machines have the constant magnetic field provided by one or more electromagnets, which are usually called field coils.

Large power generation dynamos are now rarely seen due to the now nearly universal use of alternating current for power distribution and solid state electronic AC to DC power conversion. But before the principles of AC were discovered, very large direct-current dynamos were the only means of power generation and distribution. Now power generation dynamos are mostly a curiosity.

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8 grams of thorium could replace gasoline in cars:-

The price of oil is on an upward spiral due to increasing demand and diminishing supplies. Short of finding vast new untapped reserves buried somewhere under out feet, we need to find an alternative sooner rather than later.

Unless you have a lot of money to spend on an electric vehicle, everyone who drives a car today relies on oil for the gasoline that keeps it running. Although replacing the petrol engine with a battery and electric motor seems to be where we are heading, it only really shifts the problem to the power stations rather than the fuel pumps.

There may be another way to power our cars, however, and it would mean never having to refuel you car–be it with gasoline or an electric charge. The

principle is fairly simple. The thorium would be lased to generate heat, which would then produce steam in a closed-loop system. That steam would then power a generator to produce electricity. Since it only takes a thin sheet of aluminum foil to

shield the world from the weak thorium radiation and the element can't be weaponized, it's thought to be perfect for mobile power generation.

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Charles Stevens is an inventor and CEO of Laser Power Systems. His idea is to replace the gasoline engine with an electricity generator that doesn’t require a battery. He is proposing the use of the rare earth mineral thorium in conjunction with a laser and mini turbines that easily produce enough electricity to power a vehicle.

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Scientists say that just eight grams of thorium could be enough to power a vehicle for somewhere around 300,000 miles of driving. If this all sounds a little far-fetched, it may pay to remember that thorium is already on automakers' radar. Cadillac introduced the thorium-powered World Thorium Fuel Concept at the 2009Chicago Auto Show.

Thorium is abundant and radioactive, but much safer to use than an element such as uranium. When thorium is heated it becomes extremely hot and causes heat surges allowing it to be coupled with mini turbines producing steam that can then be used to generate electricity. It also helps that it has a very large liquid range between melting and boiling point.

Combining a laser, radioactive material, and mini-turbines might sound like a complicated alternative solution to filling your gas tank, but there’s one feature that sells it as a great alternative solution.

Stevens has worked out you’d require a 227kg, 250MW thorium engine in order to power a typical road car. Within that system 1 gram of thorium produces the equivalent of 7,500 gallons of gasoline. So if you fit the Thorium engine with 8 grams of Thorium, it will run the vehicle for its entire lifetime without needing to be refueled while all the time not producing any emissions. The engine lasts so long in fact, that it could be taken from one vehicle and used in another as and when they wear out.

The issues to overcome are the radioactivity and the mining of thorium to make this engine possible. Stevens says the radioactivity can easily be contained with aluminium foil. As for the mining, the reserves are there, with 440,000 tons alone in the U.S., we just need the mining facilities to extract it in large enough quantities. With the potential benefits that is sure to happen.

Stevens admits that his biggest hurdle isn’t the thorium and laser aspects of the system, but the mini turbines which have to be made small enough to fit inside a vehicle while generating enough electricity. Even so, Stevens believes he’ll have a working prototype by 2014 and the potential to not only replace, but improve upon the gasoline-powered engines we rely on today.

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Conclusion:-

So here by I conclude that using up thorium in vehicles will increase efficiency of vehicle.

This is eco-friendly.

In this car runs at lifelong 8 grams thorium only.

Zero-emission.

Radiation is controlled by minute thickness aluminum layer.

Harmless to human health.

There is no need of any refining oils.

Cost is too low compared to fuel.

Maintenance free at life time.

The thorium car has more advantages compare to present fuel cars.

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Reference:-

http://www.thorium.tv/en/thorium_health.php

http://tuckiomaminado.blogspot.in/2009/06/100th-post-cadillac-world-thorium-fuel.html

http://www.geek.com/articles/geek-cetera/8-grams-of-thorium-could-replace-gasoline-in-cars-20110812/

http://www.txchnologist.com/2011/the-thorium-laser-the-completely-plausible-idea-for-nuclear-cars

http://en.wikipedia.org/wiki/Steam_turbine

http://www.thetruthaboutcars.com/2011/08/are-you-ready-for-the-thorium-laser-steam-turbine-electric-powertrain/

http://en.wikipedia.org/wiki/Boiler_(steam_generator)

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