EnergyTech Marine Group’s new 83 HD-X sail or motor yacht is radically different.
(Updated July 27 2008)
This is the story of what had to be done to design and deliver the industry’s first full electric
Super Yacht. The new construction vessel is nearing completion. A construction history slide
show can be found here.
[Slideshow]This vessel goes far beyond the definition of full hybrid, such as the Prius automobile. The
Prius is simple by comparison. The 83 HD-X runs in full electric mode, which a Prius does not.
Not only do we deliver full electric mode, but we deliver it with the option of never having to
recharge it by plugging in or running engines, because the energy can be completely regenerated
using the vessel's internal hydro- electric turbines. It can scoop up enough free energy under sail
or anchored in a strong current to power all of the living comforts for a dozen passengers without
having to plug in or use fossil fuels. Of course it also offers the option of rapidly recharging with
the diesels in its Pulse Buffering Power Core. (click on Pulse Buffering Power Core on home page)
THE DESIGN MANDATE
The design goal included offering the option to be able to fast cruise 12 to 14 persons anywhere in
the world non-stop (motoring when necessary), with all of the creature comforts of a resort hotel
without ever having to stop to refuel or plug in. A zero emissions mode was also a must.
In order to achieve these goals, the design team had to redesign almost every standard system normally
found on a sailing yacht. It had to be propelled by jet drives instead of props and shafts. The fuel of
choice had to be electricity. The mechanical thrust had to come from high power electric motors like
a locomotive or cruise ship. Since the electric capacity would require the power of up to 32 tons of
8D lead acid batteries (which is impossible in an 83 foot yacht), we had to build our own super
energy-dense Lithium-Ion batteries. The regeneration requirements were so great that we had to design
in twin encapsulated hydro-electric turbines. There is no other large yacht offered that can deliver the
83 HD-X mission profile.
These special requirements necessitated the greatest reliability. This meant simpler in every way than
a normal yacht. It had to have less moving parts, technologies of greater proven reliability, and
complete redundancy. Not only would it have to be uncomplicated, it would have to be efficient
beyond any scale previously used. It would also, obviously, require the capability of regenerating its
own energy on the go.
The goal was to never have to stop anywhere, or anytime, that you didn’t want to, while enjoying all of
the creature comforts of air conditioning, dishwashers, washers and dryers, electric lights, home
entertainment systems, and anything else that a house might have. Besides the convenience of
skipping a refuel stop, in an uncertain world, we have seen times when there was a shortage of fossil
fuel. Besides, diesel isn’t free and our regeneration refueling option is.
Almost everyone on the design team has done global cruising and is well aware of the shortcomings of
traditional technologies to get through long passages or remote cruising grounds. The technical
limitations of a vessel dictate where it can go, and for how long. We wanted to deliver the freedom of
unlimited global range, without the need to stop for fuel. We wanted to deliver this without having to
live like Robinson Crusoe.
[Top of Page]ELIMINATING OLD SYSTEMS THAT WON’T MEET THE DESIGN GOALS
We started by making a list of all of the traditional components to a yacht that would hinder us from
meeting our design objective. It was an amazing exercise. We ended up having to throw out almost
everything that one would normally start with when building a yacht. For instance, if the vessel had to
be capable of being powered diesel-free, then we had to throw out diesel drive trains. If the hotel
load/house load electrical systems had to run for days without using diesel fuel, we had to throw out
the 120 volt-240 volt gensets. If we had to power the hotel load electric systems to the levels of tens of
thousands of watts, we had to throw out lead acid batteries and so on.
For various reasons, the list of what we tossed out because it stopped us from meeting our design
mandate, or was complicated, or unreliable, grew and grew. We also had to eliminate props, shafts,
struts, transmissions, alternators, 12 volt cabin lighting, and on and on. This old technology stuff just
wouldn’t get us to design requirements. We had to replace this entire infrastructure with technologies
that could achieve our design goals better.
All replacement technologies had to be proven to be more reliable and had to have been around for at
least ten years. We ended up with a yacht that was less expensive, more efficient, more reliable,
lighter, and required a fraction of the interior volume to house the systems.
[Top of Page]POWERING
We haven’t forgotten that this is a sailing yacht, but we are first going to address mechanical
propulsion rather than wind propulsion because anyone who has ever done global cruising in a sailing
yacht knows full well how much you supplement with engines.
For motoring, we use water-glycol cooled permanent magnet motors that were more powerful than
200 horsepower diesels. They can be powered by our Power Core energy system's large lithium-ion
battery bank or its powerful super capacitors. It is dramatically simpler than standard diesel propulsion.
It has considerably fewer moving parts and it is much more fuel-efficient.
[Top of Page]INDUSTRY’S FIRST LARGE-SCALE LITHIUM-ION BATTERY BANK
The batteries required for this design simply did not exist anywhere at any price. We wanted to offer a
practical propulsion range using our Power Core energy system.
For years people have speculated about a house battery bank of lithium-ion technology since it is vastly
superior to lead acid chemistry. That’s a great idea until you go to your marine store and try to
purchase a voltage regulator to handle the charge. This technology requires a sophisticated computer
logic regimen that can’t be purchased anywhere for large scale systems. Even if you had a large-scale
lithium-ion battery where would you ever get a voltage regulator that could handle its incredibly
sophisticated charging needs. No one makes one.
We ended up building our own Lithium-Ion batteries as part of our Power Core energy system. It
replaces hotel load generators and the primary propulsion fuel system. It is able to store the required
energy volume in a very compact space.
Our Arc Lite brand sealed lithium-ion battery has turned into an industry in and of itself.
In our tests, we are starting the biggest V8 hemi engines as well as 500 plus horsepower diesels with
our ultra tiny battery that will fit in your hand. See pictures on our web slide show at
EnergyTechMarine.com. (Do not try this at home. This is a complex technology that requires huge
safety considerations to avoid thermal run-away and explosion. Do not try to wire a bunch of cobalt
based Li-Ion batteries, like computer batteries, together and start a truck. They will probably blow up
like a satchel charge. We use special safe cobalt free chemistries.
Our full size battery offering, which propels the yacht as well as provides hotel loads, delivers
unprecedented power for its size. It can deliver a sustained half million watts of power without heating up.
[Top of Page]ELECTRIC MOTOR ADVANTAGES
Some of the advantages of the electric motor include: It’s simpler, it has enormously fewer
moving parts, brushless, lighter, cooler, more efficient, tiny in size, lower cost, no noise, no vibration,
no emissions, no transmission. Also, an electric motor delivers 100% of its torque at one rpm. A diesel
delivers little or no torque until it builds to speed.
Also the electric motor is maintenance free and should run for 50,000 hours. No oil changes, no glazed
rings, no dipsticks, no exhaust system to swallow water, no fuel filters and so on.
[Top of Page]EASE OF REFUELING
Electric energy is totally renewable. Not only that, but it can be regenerated on the way. It is also
handy that regenerated electricity happens to be free. The Power Core energy system on the 83 HD-X
can be recharged from our twin hydro-electric turbines, which are encapsulated in flumes in the hull.
Our hydro-electric turbines work just like a hydro-electric plant for a small village that acquires its
electricity from the flow of water.
Once again, the technology is simpler, lighter, more efficient, and has fewer moving parts. Compare
the spinning turbine in our hydro system to all of the moving parts in a diesel genset.
As you voyage through the ocean you encounter millions of kilowatts of free energy just lying or
blowing around on the surface of the sea. It would be a waste of time to scoop it up in vast quantities
if you didn’t have a way to store it. Until the EnergyTech Marine Group Power Core energy system
entered the scene there was no place to put it if you captured it. Our energy storage capacity is so huge
it allows us to employ industrial level electrical energy capture technology to scoop it up by the
thousands of kilowatt-hours.
Hydro-electric generators power everything from Las Vegas and the Pacific Northwest to great
portions of the industrialized world with an efficiency that cannot be matched by anything else.
Hydro-electric energy is clean and renewable and it is free if you own the turbine generators.
Our EnergyTech Marine hydro-electric turbines can generate a half million watts -hours of energy per
day. What would there be to do with such a system unless you had some way to store that energy for
future use? Are you going to plow it into your six 8D lead acid cruising batteries, which will absorb
only 4,300 watts? Or pour it instead into our half megawatt-hour Power Core lithium-Ion energy
storage system, which will accept it as fast as it can be dumped in?
Our large-scale energy capture system allows a yacht to be wind energy powered even when the wind
isn’t blowing. Since the sail rig is larger than is required, there is little performance sacrifice to
capturing millions of watts-hours of free energy per week while on a voyage. You open the turbines
only when sailing. Due to the design of the 83 HD-X, the amount of drag it creates is less detrimental
to boat speed than you would think.
[Top of Page]HOW NEGATIVE EFFECTS OF DRAG ARE ELIMINATED
First, by eliminating props, shafts, and struts and replacing them with special displacement-hull jet
drives we have eliminated the amount of drag that is induced when the flumes are opened to the
turbines. When charging is finished, the scoops are closed and the underside is cleaner and more
efficient than normal sailing yachts. When the turbines are opened and charging you are no worse off.
Second, reserve power to overcome the drag of the scoops is designed into the sail plan. For a
displacement hull, it takes a certain amount of power to achieve hull speed. A vessel’s hull speed is
relative to its water line length. Sailing yachts, like trawlers, are displacement hull vessels. The longer
the water line length, the faster the vessel can go (we don’t need to get into the fact that this velocity is
not a linear calculation to make our point). Once the vessel approaches hull speed, it begins to require
more and more power to go even a little bit faster until it reaches its theoretical wall. At that point,
adding more power, for all practical purposes, won’t propel you any faster.
It is therefore senseless to put more sail power on a vessel than is required to move the vessel at hull-
speed. That is, of course, unless you would like to divert some of the power of your rig to perform
other work before you reach hull speed and still have enough surplus power to go as fast as you want.
This is of course exactly what our design does.
Over-size the rig and you can harvest the excess wasted energy by driving the hull faster even after you
have opened the hydro-electric flumes and turned the pounds (psi) of pressure created by moving
through the water into electric energy.
[Top of Page]POWER TO WEIGHT ADVANTAGES
Most important to us was that electric fuel weighs nearly zero. Our Pwer Core weighs the same whether
its super capacitors or its lithium-ion batteries are full or empty. This alone makes it a good choice. The
weight of all the fuel/energy we use to mechanically power the vessel, including hotel loads, must be
carried with us at the expense of some amount of work. Every ton of diesel fuel we carry requires us to
push another ton of water out of the way in front of us as we travel on our voyage. Just ten days worth
of diesel can easily weigh five to ten tons. Imagine the inefficiency of pushing that much water out of
the way again and again every 83 feet of a thousand mile voyage.
[Top of Page]ELECTRIC MOTOR ASSIST IS MORE EFFICIENT THAN DIESEL ENGINES
Motor assist while sailing, if you choose to employ it, it is much more efficient with electric propulsion
because it usually requires only a few horsepower to top off your speed requirements.
Let’s say you need to make a destination by a deadline and the sails alone are not achieving your target
cruising speed. By engaging a traditional 300 horsepower diesel engine at a thousand rpm (about 16
horsepower) you might add the extra speed you require. This is a common occurrence in passage making.
This is the worst of all worlds because you are torturing your diesel by greatly underloading it and
probably therefore glazing the rings. It is also a terribly inefficient operating range for fuel consumption
and pollution, not to mention that you are trying to coax propulsion out of the torque curve where it has
very little to give.
Instead, on the 83 HD-X you have the option to run in battery mode on presumably free fuel
(electricity) you scooped up the last time the wind blew. With 422 horsepower of electric motors at
your disposal, you can draw on as much or as little of the power as you like while it delivers maximum
torque at all points of power. 16 horsepower would represent very little draw on the batteries and it would
eliminate accelerated aging on Power Core's diesel engines.
[Top of Page]LITHIUM-ION VS. LEAD ACID
Our Lithium Ion batteries are like nothing you have ever seen before. If you have lived in a
world of lead acid cruising batteries, our specs will seem like a fairy tale to you. Most people do not
realize the limitations of their flooded deep cycle lead acid, Gel, AGM or golf cart battery. These are
all lead acid batteries with little difference on the grand scale of things.
You could simply never achieve what we are doing with lead acid batteries. First, lead acids do not
accept a charge fast enough to make them useable for our applications. Any charge larger than about
25% of their total amp capacity can go entirely to waste because they won’t accept it. Their lead plates
require long time periods to absorb the charge. They also don’t like to give up their charge very fast.
If you want to get at all their rated amps, it takes about 20 hours to squeeze them out. If you try to draw
them down any faster, they never give you all of their rated capacity.
If you run lead acid batteries dead (10.5V) a few times (as in your TV blinks off due to low battery) ,
they suffer some amount of perminant damage. You can never run them down more than 50% without
severely shortening their life. The grim reality in a cruise environment is that you can never really
recharge them to more than 75%-80% of their capacity, which also greatly shortens their life. Plate
sulfation occurs when lead acid batteries are left only partially charged. The lead acid acceptance rate
after they reach a 75% charge slows so rapidly that it takes hours of diesel generation or alternator time
to reach a full charge. At this state of charge, they will accept only a fraction of the energy fed to them.
It basically can’t be done away from the dock. This is fine for someone who goes out for the weekend
once a month and returns for weeks plugged into shore power. We, instead, are talking cruising, as in,
being away from the dock indefinitely.
You never want to discharge your lead acid battery lower than 50% and it is impractical to charge it back
up to more than 80% which only leaves you 30% of its capacity to work with. But it gets worse. A lead
acid deep cycle battery gives up its energy so slowly that it is useless for propulsion or serious inverter work.
If you require it to give it up at a rate higher than its 20 hour rated capacity, It can lose as much as 50% of
what it has stored to the Peukert effect and you can be left with only about 15% of its rated capacity.
(See Peukert's Law)
[Top of Page]HOW DO LEAD ACIDS PERFORM AS A LARGE YACHT POWER SOURCE?
Not everyone realizes the demands placed on a battery bank when you use an inverter. Let’s look at
requirements placed by hotel loads on our 83 HD-X in a cruising environment. You might have the
dishwasher, a coffee maker, the microwave, all the refrigeration, and cabins with a couple of hair
dryers all running at the same time. There would typically be much more than this running in the
background, but this will make the point.
Now let’s see what it would take to deliver this inverter load with a lead acid battery. To start, let’s
examine the draw from the bank for just one hair dryer and nothing else.
The dryer will consume, on average, 1,500 watts at 120 volts. This 1,500 watt load is a typical travel
hair dryer. This means that one 8D (the largest deep cycle lead acid battery available) operating at 12
volts DC has to have its voltage inverted up to 120 volts AC. The hair dryer is consuming its amps at
120 volts. Since watts divided by volts = amps, the hair dryer is consuming 12.5 amps at 120 volts.
The battery must deliver this current through the inverter at 120 volts; this means it must deliver ten
times the amps at 12 volts to meet the requirements. The battery is therefore required to output at the
rate of 120 amps. This is huge.
We are skipping efficiency losses and power factors and so on. They only make everything look worse,
so we are actually painting a best case scenario.
Let’s start with the one 8D lead acid, deep cycle. It will cost $500-$575and weighs 160 pounds. It’s
rated at 240 amps. So it will run the hair dryer consuming 120 amps of 12 volt energy for two hours,
right? Not even close.
It is rated to give up 240 amps over a period of 20 hours at a constant rate of discharge. This means no
more than 12 amps in an hour. To draw current faster than it’s rated delivery starts it down a vicious
curve of waste. Remember, accelerated discharge ignites Peukert's Law and loses part of the 240 amp
capacity. It must give the inverter 120 amps continuous to run the hair dryer. This is ten times its
rated capacity.
Let’s forget for a moment the waste factor that occurs when you take the amps faster than the battery
is rated to give it up, because there is an expensive fix for this problem. Let’s instead explore the other
limiting factors we have already mentioned and come back to the over-discharge subject in a moment.
Let’s remember, once again, that we can’t discharge past 50% without shortening the battery’s life.
This virtually makes it a 120 amp hour battery instead of 240 amp hours. On cruise, you cannot
practically recharge past 80%, so this makes it a 72 amp hour battery. So does this mean it will run the
hair dryer for 36 minutes? Not even close. In reality, it would lose so much of its capacity to Peukert's
law, due to over discharge, that it might deliver for only seven to twelve minutes before you would have
to shut it off and recharge. (Don’t actually try this experiment at home, over discharge can be dangerous).
The only solution for lead acid chemistry if you want to use all of the amps you put into your battery
without losing half of them, is to put in enough extra batteries in parallel to allow you to discharge
the whole bank only at the rate of 1C, or one times the rated capacity divided over its rated hours. If
your hair dryer consumes at the rate of 120 amps from your battery bank then your only solution is to
install ten batteries. Together they will deliver your 120 amps instead of just the 12 amps that a single
battery is capable of without losses. It takes ten batteries to provide this usage without huge amp loss.
This of course will run your hair dryer all day without wasting any of the amps that you worked so
hard to put in your bank. The point is that this is also what you must do to even run your hair dryer for
a few minutes without wasting amps lost by accelerated discharge. This is why you should never
have twin switched house battery banks. Just create one large bank because you can discharge at
greater load levels without waste.
To recap, with lead acid chemistry you cannot use more than half the amps without prematurely
destroying your battery. You must return a discharged battery to full charge without prematurely using
it up (sulfating), which you cannot achieve away from the dock because it will accept only a fraction
the energy you feed into it. So, due to low absorption rates, you simply have to sacrifice this margin as
a cost of going cruising. If you must remove the amps from your bank faster than your battery is rated,
you can arrive at the point where you must put two amps into your battery for every one you are
able to use. That number is after charging efficiency losses (80% efficiency for lead acid), internal
discharge losses, etc. It is not a pretty picture and there is no way around it.
In short, this is why when you go cruising, the hair dryers never works off of the inverter after the first
five days, and the microwave blinks off and the TV goes off earlier every night. Nothing ever works
like it is supposed to and so you end up living on the generator.
Usually living only on the generator is short lived in a cruising environment because few skippers
understand that if the generator is not loaded to about 70% of its generating capacity it will deteriorate
the engine by under-loading it.
The problem is that when you go to the inverter to just run a hair dryer or make a pot of coffee and it
fails, you start the genset in an under-loaded state. Most cruising yachts have a large genset to run the
large requirements of hotel level loads like air conditioning and washers and dryers and so on and then
a tiny generator to run small loads if the inverter fails. But the same thing happens here to your small
genset when you try to power a tiny draw like a 75 watt TV and DVD player.
If you don’t have a robust installation like we outlined here, you can quickly convert the net usable
capacity of each of your 8D batteries to a mere 36 amps. This, by the way, is the
number you get on the first day that your lead battery is brand new. As it approaches the end of its
cycle life, it can still be considered good and deliver only 16 net usable amps (cycle life ends for a lead
acid battery when it fails to hold half of its rated capacity and each cycle of its life is shorter until it gets
there). No matter what you do, if you want to include things like an inverter in your cruising energy
strategy, you must have a matched, large battery capacity.
We have encountered many voyagers who have ended up at the next step, which is trying to scrape
by on the alternators on their main engines, as they glaze their diesels by under loading them to the
point of failure. Sadly, almost none of these people have any idea how they got there. It also happens
in the charter business, but it is such a lucrative venture that they can continually replace the damaged
equipment.
So how do large yachts cruise if none of this stuff will deliver? They have two or three gensets, which
run night and day blowing carbon dioxide and slurping down gallons of diesel. They slog on around
the clock creating vibration and noise and testy neighbors in their anchorage. This would hardly meet
our design requirements. The EnergyTech Marine Group's Power Core Lithium-Ion energy system
replaces all house generators and simply supplies everything the guests require instantly on demand.
Our system will power everything for days without a recharge.
The mission profile of yachting has totally changed, but most of the technology to meet the challenge
would look very familiar to Thomas Edison. If you want to build in an electric option for your yacht,
traditional systems are obsolete and need to be tossed out. They simply will not deliver the required
infrastructure to provide the mission requirements for yachts above eighty feet.
[Top of Page]
MINIMAL EXPECTATIONS FOR CREATURE COMFORTS
There are a handful of hybrid options for small boats using lead acid technology to power tiny motors
of a few dozen horsepower. Super yachts are vessels above 25 meters. To go diesel free for powering
in that size range you must graduate to a more advanced energy technology.
The expectation of any luxury yacht, sail or motor, over 80 feet is that it has everything. Every
passenger wants every amenity instantly on demand, without even thinking about it. Air conditioning,
hair dryers, anything offered in a luxury hotel room. This isn’t like the days of sun showers and foot
pump faucets, and ice chest drinks. This is five star hotel level amenities. You couldn’t give away a
super yacht that didn’t have air conditioning in every cabin.
The reality is that in a cruising environment you can only get at and use about 30% of the rated amps
in a lead acid battery bank. That by the way is only an average of 15% over the life of the battery, and
7.5% if you are using an inverter and factor in the Peukert effect.
No one has a lead acid battery bank of the capacity that would support the systems on the 83 HD-X. It
would be impractical to produce. To equal what we offer on the 83 HD-X would require 32 tons of lead
acid deep cycle 8D marine batteries. Full time cruising would require replacing this bank once a year.
Since you can’t get there from here using lead acid batteries, you can see why we had to employ a
more advanced system. There simply isn’t anything out there that you can buy off the shelf that will
deliver the levels of energy required for our mission. Not NiCads or NiMHs or commercial lithium-ion.
We required a net usable 500 KWH battery bank to deliver all of our required options.
What does our Lithium-Ion battery system allow you to do that lead acid technology does not? The
answer is almost un-imaginable.
The EnergyTech Marine Group Lithium-Ion battery system occupies 81 cubic feet instead of 1,000 and
delivers the same energy. It can deliver 100% of its energy in less than an hour instead of 20
hours for lead acids, without overheating or without lost amps. This means it can run gigantic inverter
loads in real time without amp losses.
Almost no matter how much recharge energy you throw at it, it can absorb it all so rapidly that it can
achieve 100% charge in an hour instead of 8-12 hours. The point is there is no waste of the energy
you throw at it because its acceptance rate does not reject perfectly good energy offered to it. Lead acids commonly accept only 8% to 12% of what you generate for a recharge after they reach 75% state of charge.
Unlike lead acids, you can run our system to 70% (DOD) depth of discharge and it doesn’t care. It
performs with a flat curve of power delivered right up to the moment we cut it off. It also accepts its
rechargeflat right up to the moment of completion without slowing to a trickle like a lead acid.
The recharge cycle life of our EnergyTech Marine Lithium-Ion batteries is orders of magnitude
beyond any lead acids. The life cycles of lead acid batteries are so few that they end up
costing more over time than our hugely efficient Power Core Li-Ion batteries.
[Top of Page]
HUGE PROBLEM SOLVED BY OUR ENERGY SYSTEM
As we discussed there comes a point in large yachts at which you require so much hotel load energy
that normal batteries cannot possibly deliver it. At this point they are forced to go to diesel generators
running around the clock.
Our exclusive Lithium-Ion energy system allows a yacht to deliver the above energy demands without
any hotel-load diesel generators at all. This allows us to cruise free of any fossil fuel requirements.
Add to this freedom, the fact that our system is not sensitive to generator load leveling or battery over-
discharge problems. Every appliance is always there on demand.
You end up with a system without traditional diesel generators that actually performs without destroying
itself in a few months.
[Top of Page]