Startech syngas
September 28, 2008 10:55 PM   Subscribe

Can Startech's syngas power a ocean capable ships engine? I am trying to determine if you could power an ocean going ship with syngas.
posted by Mr_Zero to Science & Nature (9 answers total)
There are multiple meanings of the word "can". I don't think that doing so violates the laws of physics, for instance.

It wouldn't really be feasible for an ocean capable ship to rely on a load of solid waste and an onboard converter for power. The energy density of the waste isn't high enough, so even in the best case the majority of the ship's payload capacity would be consumed carrying the waste that became its fuel.

It wasn't clear to me from reading that site just what kind of gas they were creating with that process but my guess is that it's methane and ethane and ethylene, plus probably some chlorocarbons. If those were created on shore, then in principle they could be used as fuel for a ship if it used a turbine-electric power train, which they don't usually. The problem with that kind of gas is, again, energy density. Stored as gas under pressure, then either the tank walls are thick and heavy and you're carrying a lot of dead weight around, or else they aren't, and you can't hold a lot of gas, so you have to refuel quite often.

Or else you refrigerate and liquify the stuff, which has its own problems.

What it looks like to me is that it would be possible to build a ship powered that way, but it wouldn't be economically competitive to ships that burn petroleum or some sort of crop-sourced oil, or some sort of oil produced by gasification of coal. All of those can be used in diesel engines, and diesel engines are really hard to beat for reliability and efficiency and durability when operating at that kind of power level.
posted by Class Goat at 11:09 PM on September 28, 2008

Also, diesel fuel is really hard to beat for energy density, ease of refueling, and simplicity and safety of storage.
posted by Class Goat at 11:11 PM on September 28, 2008

Let me clarify. The ship would need to travel about four thousand miles between refueling. It is not a matter of cost, is it possible?
posted by Mr_Zero at 11:17 PM on September 28, 2008

Or else you refrigerate and liquefy the stuff, which has its own problems.

How cold does it need to get?
posted by Mr_Zero at 11:21 PM on September 28, 2008

Big ships are (as Class Goat implies) usually diesels, burning fairly heavy petroleum fractions.

But there are small ocean-going ships too, and for that matter there are ocean-going ships that burn no fuel at all; trivially, their fuel needs could be met with syngas. I think you need to ask a more specific question.
posted by hattifattener at 11:22 PM on September 28, 2008

The boiling point of methane is -161 degrees C.

Liquifying and carrying the stuff would be similar to LPG, which is mainly propane and butane.

I don't see how such a ship could travel 4000 miles if it was carrying waste and used an on-board converter. But if the conversion took place on shore, it would possible to carry enough energy in liquid form in pressurized tanks to push a ship that far.

But I don't think anyone would actually do it.
posted by Class Goat at 11:31 PM on September 28, 2008

By the way, there do exist ships which use gas-turbine engines. Some of the Coast Guard's big cutters (e.g. the Hamilton class) use diesel engines for normal operations, but use gas-turbine engines when they need high speed.

But they only carry enough gas to power the turbines for about 12 hours. They use the turbines for situations where only high speed will do, like hot pursuit of pirates and smugglers. I haven't ever heard of a ship that relies on gas turbines for normal operation.
posted by Class Goat at 11:38 PM on September 28, 2008

If only the waste was somehow already out there.

Of course, it'd be a very specialized mission that could make use of that gyre. There's a reason they call that area a "no man's land" er... "no man's ocean."
posted by brownbat at 11:40 PM on September 28, 2008 [1 favorite]

Before diesel engines there were ocean-going ships powered by coal gas. See here, for example.
posted by XMLicious at 11:41 PM on September 28, 2008

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