fw: Electric/Diesel Hybrid Cat Proposal

[Phoenix Electric Auto Association <evchdlr@primenet.com>]

If you should have any comments or ideas, e-mail directly
at:   plkruse@iu.net

Thanks...Lanette Racine

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I have been talking off line with several of you concerning
electric boats, and electric hybrids. . . .
My proposal is that we collect some information . . . and then I could go 
off to see how I could apply it to the
boat I am building, a 60 foot powered displacement catamaran.  The goal
would be to be able to turn the props with electrical power from a bank of
batteries.  What I am interested in is determining how much range I could
reasonably get out of such a set up.  I understand that it could never be
enough to make passages, but perhaps it is possible for the time spent in
coastal cruising.  Then for passages, it would be necessary to supplement
the energy stored in the batteries with energy stored in the diesel fuel
tanks in a hybrid fashion.

As long as the energy is coming out of the diesel tanks, it will never be as
efficient as a conventional power transmission system -- or so I think.  It
may very well be like fluid power, in that a DC electric drive might enable
better overall efficiency.  This would be a good thing to determine.  Even
if time spent on diesel operation is less efficient, then the overall system
may be more efficient if the batteries can be charge by solar and wind power
when anchored or for coastal cruising.  The state of the art of electric
drives has been substantially improved, so that some of the old paradigms
may not be valid any longer.

The reason that I am proposing we do this mental exercise with my boat is
that I have designed it, and therefore have all the relevant design
parameters handy.  Anyone else should also feel free to apply the same
information to his own boat, and to report back to the list in similar
manner.  As a start, I would like to ask for the following information from
anyone who would have a good handle on the current state of the art.  I can
get all this information from electrical engineering text books, but what I
am looking for is information on current technology, especially from anyone
who has applied any parts of this technology to their own applications of
any kind.

1)  How much energy can be stored in modern batteries, of the type being
used for electric cars?  I need this information in units of energy stored
per unit weight of batteries, and also per unit volume of batteries.  Some
idea of cost would also be helpful.

2)  How much power can we reasonably expect to get from a wind generator
mounted on a boat at anchor?  I'm looking for an overall average.  This can
be in units of amps at a particular battery voltage, or in units of kWatts.  

3)  I need the same information on solar panels mounted on horizontal flat
surfaces of a boat.  Anyone who has installed these solar panels on their
boats should feel free to reply with this information.  I know what they
advertise in the catalogs, but I'm interested in actual numbers from people
with real world experiences.

4)  I need to know how efficient these modern batteries are.  In other
words, if I charge them with a hundred kW-hrs, then how many kW-hrs can I
get back out of them?

5)  What are good reasonable efficiencies to assume for the DC generators
and motors?

I'm also considering throwing even another fuel option in the pot, but that
might complicate things too much.  What do you folks think of running an
engine off of alcohol, and setting up to produce the alcohol on board the
boat.  The system would have to have a high degree of automation, so as to
require a minimum amount of human intervention to work.  Heat for distilling
the alcohol would have to come from a reasonable source:  perhaps solar, or
perhaps waste heat from the engines.  Recent developments at the University
of Florida have made it possible to produce large quantities of alcohol from
wood and paper wastes, or from more conventional starchy sources.  This is
actually being done in Brazil right now.  Without actually running the
numbers yet, I believe I could set up to make as much as 200-500 gallons of
ethanol on my boat per week, if I could feed the process with enough waste
paper, wood, potatoes, corn, or whatever.  If anyone has experience making
ethanol, then please feel free to speak up.

I'm assuming that it is not reasonable to plug into shore power at a marina
to charge your batteries, due to the cost.  I will therefore work the system
as if the boat itself much be completely independent, except for stops at a
diesel fuel dock.  None-the-less, perhaps some of you might have some feed
back for me on this, also.  Perhaps the most economical thing would be to
pay for a slip with power for a short time, and then use it to both charge
your batteries and to distill your alcohol.  How much power can we get from
a typical recreational slip?

BTW, I finally have performance numbers for DOULOS that I believe can be
trusted.  As I have posted here before, I did not trust any of the equations
in either Beebe's book or Gerr's "Propeller Handbook" for my boat. The
reason for this is that all their data seems to be with monohulls, whereas I
have a catamaran with an aspect ratio at the water line of each hull of 17
to one.  I have now been able to collect enough performance data from real
powered catamarans, mostly in service as inter-island passenger ferries in
the South Pacific, so that I can run Gerr's numbers on them to check out
Gerr's algorithm's for this sort of boat.  The result is that Gerr hits them
right on, dead nuts as they say.  I therefore now have a high degree of
confidence to apply Gerr's algorithms to my boat.  Because of this
confidence, I feel pretty good about using my design as a test case for the
electric/diesel hybrid.  A few of you have seen this table already via
private email.

Here are the numbers that Gerr's methods yield for range on 4500 gallons of
fuel in this boat.  The first column is S/L, the second is speed in knots,
and the third is range in nautical miles.  This assumes an average
displacement of 38.5 tons, which is with the fuel tanks half full.  The
forth column is hp required at 47 tons displacement, which is with the tanks
full.  The last column is hp required at 30 tons displacement, which is
where I plan to be at for coastal operations.  All power ratings are at the
propeller shaft.  Right now, I'm trying to decide if I want the ability to
put more than 200 hp total to the two shafts; since that is what I need for
the 12 knot objective for coastal operations.

 .5      3.87    43,900       9.7       6.8
 .6      4.65    30,500      16.7      10.7
 .7      5.42    22,400      26.6      17.0
 .775    6.00    18,300      36.1      23.0
 .8      6.20    17,200      39.7      25.3
 .9      6.97    13,500      56.5      36.1
1.0      7.75    11,000      77.5      49.5
1.1      8.52     9,080     103        65.8
1.2      9.30     7,630     134        85.5
1.3     10.07     6,500     170       109
1.4     10.84     5,600     213       136
1.5     11.62     4,880     262       167
1.6     12.40     4,300     317       203
1.7     13.17     3,800     380       243
1.8     13.94                         289
1.9     14.72                         339
2.0     15.49                         396
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                           ::
Paul and Cindy Kruse       ::  KJV Joh 14:27 Peace I leave with you,
165 South Kenneth Court    ::  my peace I give unto you:
Merritt Island, FL  32952  ::  not as the world giveth, give I unto you.
E-mail:  plkruse@iu.net    ::  Let not your heart be troubled,
407-453-6206               ::  neither let it be afraid.
                           ::
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