Gas Turbines?

[pdf27]

Originally Posted by Cheechako

Yeah, an APU is not real large. I dont know what you do with all that hot exhaust on a smaller boat. Be a good fast swamp boat though with the turbine up and exposed!

Heating & Air Conditioning? An adsorption air conditioner is surprisingly light and would basically be using free heat.
From what I've read diesel heaters are somewhat unreliable/finicky, so if these units are as reliable and quiet as claimed it might make sense having them as your main heater.

The heat also looks to be the wrong way around after doing some further reading. The turbine unit is at ~275 °C, marine diesels at 400-600 °C. I'm assuming this is because the burner has to run very lean to avoid melting the turbine. That basically means the hot gases have been heavily diluted with air compared to a diesel exhaust.
You also don't have any water cooling pumps/through-hulls/etc. to worry about.

[Cheechako]

Yeah, but the marine diesel uses cooling water to cool the exhaust... maybe you could spray inject the turbine exhaust. Heck of a big exhaust pipe out the back though!

[pdf27]

Scaling off the photo on the previous page, the exhaust pipe looks like 4". They also offer a CHP version which recovers about 40% of the remaining heat. How big would a pair of 40 hp diesels be normally?

Having said that, is there any reason you have to get the exhaust gas cold? It can't be hard to build a heat-resistant exhaust pipe, and once it gets into the atmosphere it'll mix quickly and hence cool off rapidly.

[model 10]

Turbines waste to much heat .

[pdf27]

Please read the thread - small diesel engines waste an awful lot too, it's just spread out over several directions so isn't as obvious...

[model 10]

I am suffering through the thread. Turbines suck and waste to much heat. Probably the only way they might succeede is to raise the internal temp they run at. More heat. Use it wisely.

[Rick R]

Originally Posted by pdf27

Please read the thread - small diesel engines waste an awful lot too, it's just spread out over several directions so isn't as obvious...

If they are as efficient as you say, I want one to replace my "old" diesel generator. How much does it cost, and where can I buy one?

[pdf27]

Cost right now? Only price I can find is $100,000 for a 65 kW unit, so I suspect you aren't going to be buying one any time soon.

Having said that, they look relatively simple to manufacture - so give it 5-10 years and there is reason to hope the price will drop nicely...

[nimblemotors]

I think the future are fuel cells.
Rather than combustion to generate mechanical motion that is converted to electricity,
they convert fuel to electricity.

<quote>The researchers’ fuel cell is a greatly improved version of a type that has a solid ceramic electrolyte, and is known as a solid-oxide fuel cell. Unlike the hydrogen fuel cells typically used in cars, solid-oxide fuel cells can run on a variety of readily available fuels, including diesel, gasoline, and natural gas. They’ve been used for generating power for buildings, but they’ve been considered impractical for use in cars because they’re far too big and because they operate at very high temperatures—typically at about 900 ⁰C.

By developing new electrolyte materials and changing the cell’s design, the researchers made a fuel cell that is much more compact. It can produce 10 times as much power, for its size, as a conventional one, and could be smaller than a gasoline engine while producing as much power.
</quote>

Gasoline Fuel Cell Would Boost Electric Car Range | MIT Technology Review

[pdf27]

Problem with SOFCs is twofold:
1) The only fuel cells to date capable of using liquid fuels directly run off Methanol (although conveniently those can run both ways). All the others break the liquid fuel down to produce syngas, which is then used in the fuel cell.
2) IIRC they're very sensitive to sulphur levels in the fuel. Not sure if it actually poisons the catalyst or just the reformer, but that forces you to use sorbent to clean out the syngas.

Good overview here: http://www.hydrogen.energy.gov/pdfs/...ssy_2012_o.pdf - and note that the efficiency isn't yet any better than the turbines I've been talking about.

Now if it was practical to use propane or compressed natural gas, I'd be a lot more optimistic - that's technology on the edge of commercialisation. Has been for a while though - Ceres Power for instance has been on the edge of selling natural gas powered SOFC units for a decade now, but haven't sold any yet...

[pdf27]

Found a rather interesting supplier for these - aiming at the superyacht market and a bit heavy, but at least shows the technology is moving on. See Home | Microturbine Marine Energy

Critical bits seem to be:
1) Fuel consumption is 11 litres per hour (2.9 gallons/hour) at 29 kW, 21 litres per hour (5.5 gallons/hour) at 64 kW. That's about 320 g/kWh - about the same as a heavily loaded diesel genset.
2) Exhaust temperature is 60 °C (140 °F).
3) Noise level is 55 dB(A) at 2m - significantly quieter than a diesel generator.
4) Weight is 700 kg for the 29 kW version, 900 kg for the 64 kW version - around half a tonne heavier than an equivalent propulsion diesel, although they appear to be lighter than comparable generators.
5) 8,000 hour service interval.

Using the assumptions earlier in this thread (1 kW ~ 3 hp, due to being able to use bigger propellers), the 64 kW version is broadly equivalent to a 180 hp diesel. If you do a direct conversion, it's about 90 hp.

A vaguely appropriately sized Yanmar (4BY2) burns about 10 gallons/hour at 180 HP, and about 5 gallons/hour at 90 hp.

It looks like if you need to know the price you can't afford it though...

Conclusion? Very heavy and expensive compared to a diesel unit, but fuel consumption is the same or maybe a little better, and it should be massively easier to live with.

[mcarling]

Here is the video from the link in the post above.

MME Generators: Interview with Owner of S/Y Lethantia - YouTube

[pdf27]

I'm pretty sure he also owns the company though...

[mcarling]

Originally Posted by pdf27

I'm pretty sure he also owns the company though...

That seems like a likely possibility. He may have tried a Capstone generator on his own yacht and liked it so much that he decided to become a value added reseller. Anyway, these are still expensive due to early days, low volumes, and lack of competition. I do think gas turbines represent the future for yachting, but it may take five, ten, or twenty years before they become common.

[pdf27]

Originally Posted by mcarling

Anyway, these are still expensive due to early days, low volumes, and lack of competition. I do think gas turbines represent the future for yachting, but it may take five, ten, or twenty years before they become common.

That would be my instinct too - I think they potentially make an efficient diesel-electric plant viable, but prices have to drop by an order of magnitude before that happens on any scale. Still, these guys have apparently ordered 10 generators from Capstone - which suggests they think they can sell them.

Oddly, one of the problems with this would be the people who got their fingers burnt with the diesel-electric Lagoons - which will make the number of people willing to try weird and wacky prime movers thin on the ground right now. Same people as well - a combined motor/generator with low noise and long service life sounds ideal for chartermarans to me, which is exactly who Lagoon sold to.