Rod Adams, a pronuclear power blogger, has done the preliminary design for a nuclear propulsion system for commercial shipping. (See www.romawa.nl and www.atomicengines.com). Certainly this would be a long range vision but, if adopted, would eventually replace much of the bunker oil burning maritime ships.

Congress has proposed future procurement for the navy to be all nuclear for major vessels, rather than just aircraft carriers and submarines. This is being considered as a cost savings measure.

Has the time come for broad adoption of nuclear propulsion by large maritime vessels?

Nuclear is cheap only if someone else is paying for the waste disposal and decomissioning. It makes sense (sort of) for navy vessels because of the space freed up and/or the option to build a smaller hull to begin with. They can also stay out at sea more or less indefinitely as long as they are resupplied with fresh food for the crew.

Wrt cost and especially, proliferation and environmental risks, container and other types of ocean-going civilian ships will continue to be powered by conventional diesel fuels (except LNG tankers). Hyundai is the only major shipbuilder still using screw propellers that are directly attached to the crankshaft of giant two-stroke diesels running at 100 RPM or so. Everyone else uses a gear box because cargo space is even more valuable than fuel economy.

It might make sense to a second look at gas turbines with stirling engine co-generation because it would free up even more space for cargo. At fuill power, hermodynamic efficiency could be higher than for single diesel engines. Part load might be a different story. Continous combustion produces much lower emissions (Esp. NOx) than the intermittent flames fronts of reciprocating engines.

One fly in the ointment is that marine gas turbines are very picky about salt spray in the intake air and sulphur in the fuel. The latter is particularly hard to deal with because bunker oil qualities vary greatly around the world. Note that even the above set of measures calls only for a limit of 2000ppm sulphur in the fuel used within 40 miles of the California coast (cp. 15ppm for ULSD). It is hard (read expensive) to scrub sulphur out of the refinery residue, which pretty much defines bunker oil for most crudes.

Another problem is that there is no world-wide infrastructure for servicing marine gas turbines and stirling motors.

Majeasy,

I agree, electric power makes for a lot of flexibility but the ship must have a source of electricity for the motors. That could be by either a diesel genset, an oil fired turbine generator or a nuclear generator. The US navy is planning on electric drive for the next generation of aircraft carriers.

Some thoughts on nuclear shipping:

Using Majeasy's number for the QM2, that is the equivalent to 115,000HP. At full throttle, 86MW would consume approximately 7500 gals/hour of bunker oil or approximately 200 gals/mile. (You thought an SUV was bad!)

The QM2 is, of course, not a cargo ship. It is a much faster passenger vessel. Cargo doesn't travel that fast because it can't afford to-it burns too much fuel. If you owned a supertanker full of oil at $70/barrel, wouldn't it be nice to double your speed so that you could haul twice as much? You could with nuclear propulsion because the cost of the added fuel consumption is trivial.

The US navy has lost two nuclear submarines (Thresher and Scorpion-God bless the souls aboard). Neither was lost for a nuclear related cause. There were, and continue to be, no known environmental contamination or other damage from either vessel.

Again, the US navy accidently ran the nuclear submarine, San Francisco, into a submerged uncharted mountain at full speed (probably about 30 mph). Over half the crew was injured and one was killed. The nuclear power plant was undamaged and brought the ship to port.

The risk of piracy is real, as it is with all shipping. It is reduced because the ship would be traveling much faster and harder to board. If you pirate a nuclear powered ship, what are you going to do with it? Any terrorist who screws around with the reactor fuel is going to very quickly get his 70 virgins. You cannot get the reactor to blow itself up. If you could, somehow, get the fuel out, it would not make a nuclear weapon.

Disposal of the spent fuel is equivalent to disposal of any other nuclear fuel. Disposal of the ship at the end of life is more complicated than normal. You can't just drive it up on a beach in India and cut it up with torches. The piece parts with induced radiation will need to be buried as low/intermediate level radiation waste as is now done with decommisioned land based reactors. (Induced radiation is relatively short lived.)

Personally, my biggest concern with commercial nuclear shipping is quality control on the training and liscensing of the reactor operators for third world flagged vessels. I think this is probably manageable with a strengthening of the IAEA.

Andrey -

minor quibble: even the most efficient diesel engines manage only 52% thermodynamic efficiency, at one operating point. 60%+ is only feasible with co-generation.

You are right to point out that ship propulsion is an extremely conservative field, because reliability is a mission-critical safety feature. Besides, production volumes are low compared to passenger cars. It's just a compeletely different world.

Btw: aircraft are not generally designed by illiterate engineers. Crashes are investigated in excruciating detail and any design weaknesses found must be corrected not only in new planes but usually also in the already deployed fleet. The Concorde was retired partly because a particular safety design weakness could not be corrected a posteriori. The space shuttle has now twice nearly gone the way of the Dodo for much the same reason, and may yet do so.

Andrey, Rafael and Majeasy:

Interesting discussion on marine propulsion as it exists today, but remember the article that initiated the discussion - it talks about new restrictions on air pollution that will add one more significant cost to ships that continue to burn fossil fuel.

While I am fully versed on the short and spotty history of nuclear power in ships outside of naval vessels (the NS Savannah, the Otto Hahn, the Mutsu and a small fleet of Russian icebreakers) I fully believe that there is good reason to believe that well designed and operated atomic engines can pose a significant competitive threat to the venerable marine diesel.

I presented a pretty detailed paper on the subject more than a decade ago for Propulsion 95, a conference sponsored by Marine Log. You can find it at http://www.atomicengines.com/Ship_paper.html. You might also want to read our pages related to commercial ship propulsion at http://www.atomicengines.com/ships.html.

All of the changes that have occurred in the market since that time have actually increased the strength of the economic equation in favor of atomic engines. Hard headed, conservative decision makers in the marine industry should at least consider the use of a zero emissions atomic engine that can operate for approximately three to five years on a single charge of fuel that costs less than 10% (per BTU) of the current cost of marine grade bunker fuel oil.

In vessels designed for voyages that last more than about a dozen days, the engines also free up cargo space and that advantage increases with increasing voyage length and massively increases if increased speed (with attendant increases in turn around) are useful.

My partners and I have a pretty good understanding of the challenges that we face in introducing our systems to the market; we have been working on our project for nearly fifteen years. However, we are getting closer and closer to overcoming the major hurdles that have slowed our progress. We have team members with lengthy experience in the marine propulsion field. We understand the environment and the customer reluctance, yet we are increasingly confident that we have an excellent alternative to continued oil addiction for a market that currently has no other choices.

I do not want to go into too much detail, but suffice it to say that there is a growing level of experience that provides excellent basis for understanding the cost of waste handling and eventual propulsion system decommissioning.

Rod Adams
President and CEO, Adams Atomic Engines, Inc.

So much safer and cleaner, so much less lucrative for government.

Nuclear seems cheap up front, but with risk, waste disposal, and decommissioning plainly accounted for it's ... really really cheap. Can the filthy tar that Andrey says is clean enough for ships to burn in mid-ocean be taken in mid-ocean for US$2 a barrel? This has been demonstrated for uranium.

The sin taxes City Hall now gets from fossil fuels, it has no hope of getting from uranium, because uranium is too inexpensive and not sufficiently sinful. That is why City Hall tries to deny nuclear's cleanliness and safety cachet.

This leads to a prediction: the QM3 will be full in seasons when other passenger liners aren't, because it will be nuclear.

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