Saturday, June 14, 2008

Radioisotope Car

The prices are rising ridiculously at the pump. How would you like to never, ever, ever, ever have to stop and fill up again?

When NASA needed an energy source for deep space probes, they didn't use gasoline, electricity, or any of the common fuel sources on Earth. They would have run out years before the probe reached the places NASA wanted to record data about. They used radioactive decay.

When unstable isotopes decay, they emit energy, some as energetic particles, but mostly heat. Heat can boil water to produce power, but in the 1800s, a preacher, tired of seeing his congregation maimed in boiler accidents, developed an engine that produced electricity directly from heat differences. So you could put one end of a pole in a fire, leave the other end out in the open air, and the difference in temperature would produce power. This engine still retains the preacher's name today, "Stirling."

Anyway, a Stirling engine with one end in a box of nuclear waste will provide electricity for hundreds of years, continuously, until the waste is totally harmless. This technique powers the deep space probes in very little space. The waste powering the probes is the side of a soda can, and provides about 100 watts of power.

We'd have to scale this up for a car, of course. Cars use horsepowers of energy, one horsepower being about 700 watts. My own car has a 90 horsepower engine, for a ridiculous 63000 watts. Thankfully, 630 soda-cans would probably fit in the space formerly occupied by the gas tank, which this car will no longer need. The "cool" end of the Stiller engine would touch the radiator on the other side of the car. The radiator would have to always run at slow speed, but the power is available. An electric engine would then be able to propel the car forward, and the excess power could power accessories, such as lights, the radio, and pump heat in or out of the passenger compartment.

The nuclear-waste-box would have to be tightly sealed. If it broke open in an accident, all kinds of hell would break loose.

EDIT: I made an order-of-magnitude error, but it still holds. Barely.

LATER DISCOVERY: The radioactive waste might fit, but the extra equipment that actually extracts the energy ensures that the smallest working model would be some 40 feet long and unable to fit in any existing parking space. This would only work if it came with huge battery banks and was driven at most .001% of the time. (That is, for every hour you spend driving it, you leave it doing absolutely nothing for a month.)


Garrett Moffitt said...

What kind of container could you use to prevent sending nuclear waste all over the freeway?

What about the addition weight of shielding?

How much does this nuclear waster weigh compared to gas?

This isn't a knee jerk anti-nuclear statement. If we could remove that risk, this would be a great idea.

themadengineer said...

Existing cars also must avoid rupturing the fuel tank. Gasoline, should it vaporize, becomes distinctly flammable, and in fact ruptured fuel tanks were what made the Pinto such a disaster in accidents.

Twice as strong as existing fuels tanks should prevent any accidents.

The waste container would be very, very, very heavy. Nuclear waste tends to be made primarily of heavier atoms, and of course, shielding is a very good idea.

Shielding would have to prevent three types of radiation of leaking through. Alpha radiation can be stopped by paper, or skin, so pretty much anything will work. Beta radiation can penetrate a thin sheet of metal, but would still be stopped by the average gas-tank thickness. Gamma radiation would be the real tricky one, as it has no mass and is stopped by a foot of lead.

A Radionuclear car would be back-heavy, clearly.

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