Thorium-laser powered cars… Come-on! Well … maybe?

Reports recently appeared on a wide range of sites, that  briefly described some of the work of scientists at Laser Power Systems, a Massachusetts-based research-and-development firm, that being on a new turbine electric generator system powered car, one that is energized by a thorium-based laser. They are esentially talking about a nuclear-powered car.

I’d say that was incredible, but the notion isn’t necessarily a strikingly a new idea. Apparently US-based Cadillac introduced the concept of a thorium-powered World Thorium Fuel Concept at the Chicago Auto Show in 2009.

But before getting caught up in the technology, it might be helpful to put thorium into perspective. Thorium is a naturally occurring radioactive element (chemical symbol Th), found throughout the world. Thorium atoms have an atomic number of 90, with 90 protons and 90 electrons. It was discovered in 1828 and named after Thor, the Norse god of thunder.

In nature, thorium is as abundant as lead and is estimated to be about three to four times more abundant than uranium in the Earth’s crust . It is a much-touted stand in for uranium in nuclear reactors because its fission is not self-sustaining, essentially a ‘sub-critical type of reaction’.”  Thorium, found as thorium-232 (100.00%), decays slowly and has a half-life of about 14.05 billion years (An aside: Not to be cute or detract from the article, but in today’s world, is everything in the small-‘B’ biliions – no longer millions… billion dollar job programs, nano technologies measured in one-billionths of a meter). Back to the subject at hand…

Thorium is also generally if found along side rare earth depsits, and is a by-product of the extraction of rare earths from monazite sands. Thorium was traditionally use as a light emitting material in gas mantles and as an alloying material in several metals.

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, it is understood that 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.

Charles Stevens, of Laser Power Systems (LPS), recently revealed that his R&D company 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. The LPS power plant 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. (The illustration to the right is from the Cadillac concept car)

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. 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.  As Steven notes the new technology “would be totally emissions-free with no need for recharging.” Of course, the jury is still out.

The use of radioactive materials in lasers is not unheard of, and goes back as far back as the 1960’s with Bell Labs, where their researchers demonstrated the second laser ever. They used a flashlamp (a very bright light) to excite a crystal of uranium-doped calcium fluoride to lase in the infrared light spectrum. However, because of the need for a cryogenic (ultralow-temperature) system to cool the hot laser-gain medium during operation, uranium lasers never found much practical use.
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.

Whether authorities will allow thorium-powered cars to roam the streets is another question. Stevens has also not set a date for a prototype version

And if you’d like to learn more about Thorium itself and the health, safety and handling of the material, please just click on http://www.hps.org/publicinformation/ate/faqs/radiation.html