8 Grams of Thorium Could Power a Car For a Lifetime

THORIUM IS NOT AN ALTERNATIVE ENERGY IT IS THE FUTURE OF GREEN ENERGY

Laser Power Systems is Developing Cars Fueled by Nuclear Power.

Thorium lasers: The thoroughly plausible idea for nuclear cars.

8 grams of thorium could replace gasoline in cars.

 

 

Nuclear powered cars aren’t exactly a new idea, designers have been fantasizing about them for decades. However, recent research by Charles Stevens, head of Laser Power Systems, suggests that it may be far more possible than previously imagined. The problem Stevens was setting out to solve was bigger than “getting off gas” but rather, the problem of having to fuel cars at all. He believes that 8 grams of the rare-earth mineral thorium, lasers, and mini-turbines could solve that problem by providing the equivalent of 60,000 gallons of gasoline, enough to take a Hummer 960,000 miles, all with no emissions.

 

Granted, thorium is radioactive, which screams “dangerous” to many people, but it is a lot safer than, say, uranium. According to Stevens, its radioactivity could be easily confined with aluminum foil. The bigger hurdles with the technology hardly involve radioactivity at all: While there are 440,000 tons of thorium in the U.S. alone, no one has really set up any facilities for the purpose of mining it out. That may have to change.

The other issue — a frustratingly practical one — is the matter of making the turbines small enough to fit comfortably in the car and still provide sufficient energy to keep it moving. Still, Stevens expects that he can have a prototype by 2014.

 

The move from gasoline to hybrid, electric, and ethanol is going pretty slowly at the moment, and one large reason (besides price) is the comparative inconvenience of some of those technologies. Getting your ethanol or having your battery charged can be a lot more annoying than getting gas, and if you have a hybrid it’s not any harder, but it still isn’t any easier. Stevens’ technology could prove to be a game changer because not only is it greener, but you would never have to pay for fuel of any sort ever again and that’s a huge selling point from an economic and convenience perspective.

I’m getting carried away here though. The fact of the matter is that if this technology does eventually reach prototype stage, there is going to be a lot of “but it’s nuclear” fear; the need for millions of dollars for research and production; a thorium mining infrastructure that needs to be built; and if it ever reached consumers, the cars would doubtless be expensive and experimental and there’s no telling what might go wrong. For the moment though, I’ll just hope that I only have to fantasize about nuclear powered cars for a few more decades. 

Some proposed technological innovations seem so far out that they are easy to reject out of hand. But sometimes, a new idea has a kernel of plausibility. Such is the case with a new project to develop a thorium laser power generation system that its creator says could provide electricity for the grid, stand-alone power applications and even cars.

Charles Stevens, an inventor and entrepreneur, recently revealed that his Massachusetts-based R&D firm, Laser Power Systems (LPS), is working on a turbine/electric generator system that is powered by “an accelerator-driven thorium-based laser.” The thorium laser does not produce a beam of coherent light like conventional lasers, but instead merely heats up and gives off energy.

Thorium, a silvery-white metal, is a mildly radioactive element (with an atomic weight of 90) that is as abundant as lead. It is present in large quantities in India and is a much-touted stand in for uranium in nuclear reactors because its fission is not self-sustaining, a type of reaction called “sub-critical.”

The idea has energized the small but active thorium community, which holds that it is the answer to our clean energy needs because it could, effectively, power a car forever. The new technology “would be totally emissions-free,” Stevens said, “with no need for recharging.”

Laser Heating

The LPS power plant, for all its whiz-bang properties, isn’t a complete departure from traditional power generation: the thorium is lased and the resulting heat flashes a fluid and creates pressurized steam inside a closed-loop system. The steam then drives a turbine that turns an electric generator..

A 250-kilowatt unit (equivalent to about 335 horsepower) weighing about 500 pounds would be small and light enough to put under the hood of a car, Stevens claims. And because a gram of thorium has the equivalent potential energy content of 7,500 gallons of gasoline, LPS calculates that using just 8 grams of thorium in the unit could power an average car for 5,000 hours, or about 300,000 miles of normal driving.

Stevens isn’t the only one who believes thorium could power cars. In 2009 Cadillac introduced a thorium-powered concept car at the Chicago Auto Show. Designed by Lorus Kulesus, the sleek World Thorium Fuel Concept did not contain a working thorium-fueled nuclear-fission reactor that could generate the electricity to power it. But somebody at General Motors thought the idea to be sufficiently interesting to build a vehicle to show it off.

Thorium as a Power Source

Researchers in Russia, India and more recently, in China and North America, have studied using thorium as fuel for nuclear reactors, partly because it is more difficult to use in atomic weapons than uranium or plutonium.  In addition, only a thin layer of aluminum foil is needed to shield people from the weakly emitting metal.

Although prototype thorium-fueled nuclear reactors have been developed, the technology has never been adopted for commercial use because the nuclear powers opted after the Second World War to focus on uranium-based atomic energy. (Incidentally, the major powers chose to focus on Uranium reactors precisely because it could be weaponized, Stevens has said).

Thorium-Based Laser

Stevens’ innovation is to use thorium to make a laser, not a nuclear power reactor.

Indeed, the use of radioactive materials in lasers is not unheard of either. After all, when Bell Labs researchers demonstrated the second laser ever in 1960, they used a flashlamp (a very bright light) to excite a crystal of uranium-doped calcium fluoride to lase in the infrared light spectrum. Because of the need for a cryogenic (ultralow-temperature) system to cool the hot laser-gain medium during operation, however, uranium lasers never found much practical use.

The key twist to Stevens’ thorium-laser power concept is that it would use a radioactive element-based laser to produce heat, not a beam of coherent light.

Remaining Technical Hurdles

Stevens says that developing a compact turbine and generator set is proving to be more difficult than making the thorium laser itself. “We can build the laser, but the biggest problem has turned out to be integrating it efficiently with the turbine and generator,” he notes. LPS’ thorium laser itself is simply an adaptation of the MaxFeLaser, a design Stevens built in1985.

Stevens said his company has fabricated a modified Tesla turbine (no relation to the car company) to convert steam pressure into rotary motion. Unlike more familiar turbine types, a Tesla turbine is a bladeless centripetal-flow unit with a set of smooth disks that are placed in motion by directing moving gas, via nozzles, at the edges of the disks. The viscous (boundary-layer) drag on the disk surfaces that is produced by the gas flow causes them to rotate.

Further, after having found no off-the-shelf high-speed generators that fit his special application, his team has had to design a custom unit to efficiently produce electricity for his one-of-a-kind power plant.

Whether authorities will allow thorium-powered cars to roam the streets is another question. Stevens has not set a date for a prototype version (Ed. a prior version of this story incorrectly stated he had).

Steven Ashley is a contributing editor at Scientific American magazine, where he writes and edits articles on general science and technology topics. Ashley’s work has been published in Popular Science, MIT’s Technology Review and Physics Today, among others.