Click for Nordhavn
Click for Moonen
Click for Cape Scott
Click for Nordhavn
Click for JetForums
Click for McConaghy
Go Back   YachtForums.Com > GENERAL YACHTING DISCUSSION > Technical Discussion > Alternative/Supplemental Power Sources

Login to YachtForums
Username
Password

Reply

Alternative/Supplemental Power Sources

 
 
LinkBack Thread Tools Rate Thread Display Modes
Old 02-22-2009, 03:55 AM   #16 (permalink)
Senior Member
 
K1W1's Avatar
 
Join Date: Sep 2005
Location: My Office
Posts: 5,997
Hi,

NYCAP- I am pretty sure I have seen a few cruising sailboats with an alternator that is driven by a towed prop. These are used to charge batteries which I assume also provide lights.

I have not seen this on any motoryachts. Anything you tow that takes power to turn it will be costing you fuel, there is no such thing as free power, even the sailboats pay a bit in speed loss but as their fuel is free when sailing they are the best placed to take advantage of this type of thing.

There is no reason why you couldn't use a wind generator on a motoryacht I am not sure of the overall savings thugh when you consider the cost of the equipment and the fuel to haul it around whether used or not. It would give you some battery charging at anchor without running ya genset or main engine to provide the same.

There are well known ways of harvesting the waste heat from engines and exhausts but these are generally for heating feed water etc and are not widely if at all used to provide electricity. Most of these are in use on ships that are underway for days on end so the operation of these can stabilise.

Here is some reading to cure your insomnia http://www.greenspower.co.uk/ieconomisers.shtml
K1W1 is offline   Reply With Quote
Old 02-22-2009, 07:54 AM   #17 (permalink)
Publisher/Admin
 
YachtForums's Avatar
 
Join Date: Dec 2002
Location: South Florida
Posts: 17,946
The posts in this thread have been split from the "2015" thread and moved to a new thread, titled: "Alternative/Supplemental Power Sources", which is a good subject. If we keep it constructive, maybe someone will shed some light.
YachtForums is online now   Reply With Quote
Old 02-22-2009, 08:42 AM   #18 (permalink)
Senior Member
 
Marmot's Avatar
 
Join Date: May 2007
Location: 9114 S. Central Ave
Posts: 2,681
"Anything you tow that takes power to turn it will be costing you fuel,..."

I probably should have just wrote that to begin with instead of trying to lead him make the connection on his own.

Maybe there are other captains who don't understand that the boat is moving, not the water. If there is a power "recovery" device intended to extract energy from the passage of the vessel through the water, it is impossible for it to produce net energy. It will always cause drag and increase energy consumption far beyond what it returns. Energy is lost at every conversion, otherwise perpetual motion would be a fact of life.

Wind turbines create drag until the speed of the wind exceeds the relative wind created by the vessel's passage. Does the amount of time that net power is available exceed the cost of fuel to haul the weight and drag of the wind turbine around? Probably not, unless the thing is mounted on a little sailboat where alternative power sources are heavy, expensive, noisy, and smelly.

Dragging a generator around behind a sailboat is a trade-off. The power extracted slows the boat but the wind power to drive the boat is free. Slowing the boat is usually considered a fair trade for the noise and cost of running a diesel generator. The amount of power is very low but so is the power consumption of the little boats that use that system and those things normally just charge the house battery, not supply consumers directly.

The bottom line is there is no free lunch in the energy business. There are ways to utilize the waste heat from diesels. You can use it to run evaporators, generate steam for heating or to drive a generator. But given the cost of these applications and the operating pattern of most yachts, the equipment would probably rot before it paid for its own carriage. The only practical use for heat recovery I can see as worthwhile on a yacht is the evaporator.

I see the next decade of development ripe pickings for those who sell "hydrogen boosters" and energy recovery devices to the technically challenged. Real advances will be made and efficiency improved but it will be incremental, expensive, and for the most part difficult to justify for reasons other than a legitimate environmental concern or to meet increasingly stringent regulations.

Last edited by Marmot; 02-22-2009 at 09:24 AM..
Marmot is offline   Reply With Quote
Old 02-22-2009, 02:14 PM   #19 (permalink)
Senior Member
 
NYCAP123's Avatar
 
Join Date: Mar 2008
Location: Long Island, NY
Posts: 7,527
Quote:
Originally Posted by K1W1
Hi,

NYCAP- I am pretty sure I have seen a few cruising sailboats with an alternator that is driven by a towed prop. These are used to charge batteries which I assume also provide lights.

I have not seen this on any motoryachts. Anything you tow that takes power to turn it will be costing you fuel, there is no such thing as free power, even the sailboats pay a bit in speed loss but as their fuel is free when sailing they are the best placed to take advantage of this type of thing.

There is no reason why you couldn't use a wind generator on a motoryacht I am not sure of the overall savings thugh when you consider the cost of the equipment and the fuel to haul it around whether used or not. It would give you some battery charging at anchor without running ya genset or main engine to provide the same.

There are well known ways of harvesting the waste heat from engines and exhausts but these are generally for heating feed water etc and are not widely if at all used to provide electricity. Most of these are in use on ships that are underway for days on end so the operation of these can stabilise.

Here is some reading to cure your insomnia http://www.greenspower.co.uk/ieconomisers.shtml
Thank you K1W1. Your 1st sentance was exactly the answer I was looking for. I'm quite aware of the limitations for wind generation, and suspected the same for water however I had not heard of anyone trying it (such as "an alternator that is driven by a towed prop"). As stated in the original post it was just idle curiosity.
"Mellowed with age" NYCAP
NYCAP123 is offline   Reply With Quote
Old 02-22-2009, 02:23 PM   #20 (permalink)
Senior Member
 
K1W1's Avatar
 
Join Date: Sep 2005
Location: My Office
Posts: 5,997
Hi,

Here is a bot more reading:

http://www.duogen.co.uk/whydual.htm

and try scrolling through this one, there is no registration here just scrool down from the opening page

http://www.cruiserlog.com/forums/ind...showtopic=3895
K1W1 is offline   Reply With Quote
Old 02-22-2009, 03:01 PM   #21 (permalink)
Senior Member
 
NYCAP123's Avatar
 
Join Date: Mar 2008
Location: Long Island, NY
Posts: 7,527
Quote:
Originally Posted by K1W1
Hi,

Here is a bot more reading:

http://www.duogen.co.uk/whydual.htm

and try scrolling through this one, there is no registration here just scrool down from the opening page

http://www.cruiserlog.com/forums/ind...showtopic=3895
Very interesting reading. 20 amps at 7 kts. is certainly a starting place for experimentation. Some combination of wind solar and hydro technologies may well be viable in the near future. Of course they've got to find ways to multiply the power and reduce the equipment size, but hey my componant stereo system is now an MP3 player so who knows.
Not only has my curiosity been satisfied, but I've learned something that could be valuable. Thank you.
NYCAP123 is offline   Reply With Quote
Old 02-25-2009, 08:32 AM   #22 (permalink)
Senior Member
 
Innomare's Avatar
 
Join Date: Dec 2004
Location: The Netherlands
Posts: 227
Quote:
Originally Posted by Marmot

I see the next decade of development ripe pickings for those who sell "hydrogen boosters" and energy recovery devices to the technically challenged. Real advances will be made and efficiency improved but it will be incremental, expensive, and for the most part difficult to justify for reasons other than a legitimate environmental concern or to meet increasingly stringent regulations.
I think you're right about the technically challenged. Reminds me of the millenium bug, by the way.
Innomare is offline   Reply With Quote
Old 02-25-2009, 10:43 AM   #23 (permalink)
Senior Member
 
Pascal's Avatar
 
Join Date: Feb 2008
Location: Miami, FL
Posts: 2,265
teh biggest issue is that you're going to get a lot of drag... while a impeller or prop not connected to anything will spin fairly freely, once you add an alternator/generator on that and put a load, it's going to act has a brake. Even wonder why an alternator belt will squeal under a heavy load, like after crnaking where the battery is pulling a lot of power from the alternator?

so, you're better off conecting an alternator to the engine itself than loosing a few knots to drag...

Regenration works on sailboats but doesn't produce a lot of power. Lagoon has been selling a Diesel Electric 42' cat for a few years now, seems to work but the electrical needs are pretty low... when undersail, the props spin the shaft and the motors become alternator. I don't know the numbers, but i doubt they produce a lot of power.
Pascal is offline   Reply With Quote
Old 02-25-2009, 11:08 AM   #24 (permalink)
Senior Member
 
K1W1's Avatar
 
Join Date: Sep 2005
Location: My Office
Posts: 5,997
Hi,

Pascal- I don't think the loads on a towed sailboat alternator are that great as to rob a few knots.

The ones I have seen trail a rope as a "shaft" so the load can't be that great.
K1W1 is offline   Reply With Quote
Old 02-25-2009, 02:14 PM   #25 (permalink)
Senior Member
 
Pascal's Avatar
 
Join Date: Feb 2008
Location: Miami, FL
Posts: 2,265
i agree, it works on a sailboat because the loads / needs are low. on a power vessel, especially at higher speed if you're going to produce anything singificant, the drag will be too coslty. I thought that was the scenario NYCAP was looking at.
Pascal is offline   Reply With Quote
Old 02-25-2009, 02:33 PM   #26 (permalink)
Senior Member
 
NYCAP123's Avatar
 
Join Date: Mar 2008
Location: Long Island, NY
Posts: 7,527
Quote:
Originally Posted by Pascal
i agree, it works on a sailboat because the loads / needs are low. on a power vessel, especially at higher speed if you're going to produce anything singificant, the drag will be too coslty. I thought that was the scenario NYCAP was looking at.
First, so there is no further mistaking the application I was asking about, it's to suppliment the generator in producing electricity for the boats electrical systems NOT for propelling the boat through the water.
That said, I was surprised to read that the drag behind proopeller generates 25 amps at only 7 kts. When you consider that most yachts under 46' only consume 30 amps (not counting air conditioning) that's impressive. In all things electrical though I am the student; NOT the teacher.
NYCAP123 is offline   Reply With Quote
Old 02-25-2009, 02:43 PM   #27 (permalink)
Senior Member
 
K1W1's Avatar
 
Join Date: Sep 2005
Location: My Office
Posts: 5,997
Hi,

The 20 AMPS DC you get out of your towed alernator ain't the same as the 30 AMPS AC you get out of your geberator
K1W1 is offline   Reply With Quote
Old 02-25-2009, 02:45 PM   #28 (permalink)
AMG
YF Moderator
 
AMG's Avatar
 
Join Date: Jul 2004
Location: Sweden
Posts: 4,846
I think I stick to my first comment on this, unless your engine or genset are not producing electricity as they should.

http://www.yachtforums.com/forums/72255-post2.html
AMG is offline   Reply With Quote
Old 02-25-2009, 03:07 PM   #29 (permalink)
Senior Member
 
NYCAP123's Avatar
 
Join Date: Mar 2008
Location: Long Island, NY
Posts: 7,527
Quote:
Originally Posted by K1W1
Hi,

The 20 AMPS DC you get out of your towed alernator ain't the same as the 30 AMPS AC you get out of your geberator
Like I said, "student". Didn't catch the DC. Thought they were talking AC. That's why I was surprised. Lots and lots of work to do then. Thanks.
NYCAP123 is offline   Reply With Quote
Old 02-25-2009, 07:37 PM   #30 (permalink)
Senior Member
 
Marmot's Avatar
 
Join Date: May 2007
Location: 9114 S. Central Ave
Posts: 2,681
Quote:
"First ... it's to suppliment the generator in producing electricity for the boats electrical systems NOT for propelling the boat through the water ..."
First, it doesn't matter what the purpose is, the physics are identical.

That .4 hp (25A at 12V) you produce by dragging some sort of water powered generator drive behind a power boat will require the propulsion engine to produce around .6 or .7 hp additional to make up for the drag of the silly thing and its mounting and drive system if the boat speed remains the same. If you want to convert that into real life, the propulsion engine would have to burn about a gallon of additional fuel every 4 or 5 hours just to run a microwave oven for about 10 minutes.

Quote:
"Lots and lots of work to do then."
All the work in the world won't change the equation.
Marmot is offline   Reply With Quote
Reply


Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools
Display Modes Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is Off
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On



All times are EST. The time now is 11:49 PM.

Click for Moonen
Click for Northern
Click for McKinna
Click for Bering
Click for MCC
Click for Lurssen


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2014, vBulletin Solutions, Inc.

Content Relevant URLs by vBSEO 3.3.2