electric boat calculation

1kwh / kg ???
That is such an outrageous claim that it either has to be a mistake or deceitful claim by the company.

I consider this a decent deal and performance for modern batteries:
http://elitepowersolutions.com/products/product_info.php?cPath=27_29&products_id=118

I am sure that some more exotic ones can beat that but at higher price. On above link the pack weighs 36kg for 3kwh pack. And that is modern LiFePM pack.

If 1kg/1kwh was true I would be building 20kwh e-motorbike as we speak.

 

after all philosophy, ok, this is best calculation on this post till now )

To conclude: If we want to run at full power (100kW) then we need around 350kg of cells per hour!
but this is not so lot... as I was say on start.. by my construction where I think between power yacht and sailing yacht. Keel have 6 tons only.
If I go to power boat project, I must not buy "mast+keel" and this is lot money too.

I can go with 6 tons of batteries... this is 17 hours of work by full power. if this is true than it is great calculation

 

I was read here: http://en.wikipedia.org/wiki/Altairnano

 

if "12kg for 1kwh" is best right ratio kwh:kg than we have calc is lot less optimistic:

1.5 hour in full speed ))

 

Nissan Leaf's battery per wikipedia.

"The battery and control module together weigh 300 kilograms (660 lb) and the energy density of the cells is 140 W·h/kg" (battery is 24 kwh)

and continues:

"It is estimated that each battery pack costs Nissan $18K and expected to be half as much when mass production of the battery packs begins."

Now I would guess that that is about as optimum as today's technology and big production runs allow.

I know Jeremy knows his electric stuff and wonder if his 600wh/kg is more theoretical for the chemistry than realistic in real pack.

 

You're right, this is the theoretical capacity for raw cells, with no battery management system, no safety enclosure and no wiring. The real world, practical energy density is a fair bit lower.

This whole project seems wholly impractical using current technology, so I didn't bother to correct the figures for all the parasitic weight in the battery pack. The astronomical cost of a lithium battery weighing tonnes, plus the immense complexity and cost of a battery management system to control it, makes the idea wholly impractical.

Jeremy

 

Talking about batteries, I wouldn't choose anything else than conventional, flooded, deep cycle, lead acid batteries. It is the best performance for a reasonable price, they are reliable and they can stand "hard" treatment.

A typical 48V array that stores up to 20kWh in full charge weights about 0.8 tons.
For 200kWh we would need 10 times more which means 8 tons.
It is not too much but it is not light-weight.

Having a large battery bank is always good for such a system, but the key is - again - the power and energy management.
just like in the hybrid cars, we need the battery to take over the loads during the long, low consumption periods and to be used as an energy "buffer" during the short and high consumption periods with the engines working while cruising.
With such a usage, the battery is not necessary to be very large.

 

Yes this is good idea too... on any way if we add in system generator he can work in these moments as example. On any way by diesel engine, diesel work all the time.. this approach with temp generator work in right moments can help one step

 

I hope this is not hijacking the thread, but I am wondering about the possibility of using a plug in hybrid diesel electric power system for cruising inland waterways, such as the canals of France, in a replica barge fitted out as a pleasure craft.

I am speaking here from a very inexperienced and speculative point of view, but here is what I am thinking.

First, most canal cruising is going to be done for only a few hours per day under power, so the amount of kWhr used for propulsion in a day would typically be relatively modest.

Second, in a lot of cases shore power may be available, which could be used for recharging the battery bank, and when shore power is not available the on-board generator (which would need to be pretty hefty) could be used for recharging the battery bank.

Third, most cruising is done at a low speed and wouldn't require too much power, so one could probably get away with a relatively modest sized diesel powered generator and perhaps a medium sized or medium large battery bank.

Fourth, the on board generator could be used to augment the battery power when one needed to really goose the power level, such as when crossing a less protected waterway or when traveling on a river, or when the battery power got a little low.

There is, of course, the issue of cost, and likely the issue that an appropriate system is probably not commercially available, though the Steyr hybrid system might be pretty close in concept. Let's tackle the issue of cost first. It would no doubt be very expensive, but the possible energy savings alone (e.g. using cheaper electric power rather for most of the cruising energy rather than expensive diesel fuel with road tax applied) would probably allow the system to pay for itself in... well I dunno, maybe a thousand years or so. Maybe in that sense it is not practical, but look at it another way. A pleasure boat itself, regardless of type, would pay for itself, in the best case, in maybe..., well again I dunno how long, but the best guess would be never.

So it really comes down to pleasure derived from owning and using the boat. For some people owning a boat with a whiz-bang gizzmotron power system might be a significant part of the pleasure in owning a boat. For others, probably most boat owners, there would be, at most, a limited interest in this kind of thing.

Now let's tackle the issue of availability of a system............ hm........ anybody know anything about this issue?

By the way, if this would go better in a different thread just say so and I will start the conversation in a different thread.

One more thing added after the original post: the weight of the battery bank is probably not much of an issue here, at least not if the craft was designed with this in mind from the beginning. The boat would probably be designed so the weight and placement of the battery bank would just count toward the ballast budget of the boat.

 

There are a few electric inland waterways boats here in the UK. I hired a Norfolk Broads sailing boat with inboard electric power a few years ago and was impressed. She'd cruise under electric power at around 4kts for maybe 10 to 12 hours before needing a charge, with just a modest array of lead acid batteries down in the keel.

I know of a few diesel electric hybrid boats, including some that use solar panels for augmentation. They work reasonably well and have the major advantage of being able to position the generator anywhere in the boat. One potential problem with the hybrid diesel electric approach is efficiency. Boats aren't like cars, they have a relatively modest peak to average power ratio, average power being maybe 60% to 70% of peak power (cars tend to have a peak to average power ratio of maybe 8:1 or even 10:1, meaning average power might only be 15% of maximum power). This means there isn't a big saving to be had by downsizing the engine on the generator, although it may be enough to make it worthwhile.

There are an increasing number of British canal boat builders looking hard at using hybrid or electric power though, as with more shore power charging points becoming available and environmental concerns bringing pressure to bear on internal combustion engine use people are coming around to the idea that electric power is viable.

Jeremy

 

Hi alanrockwood, it sounds like the usage profile can be succesfully combined with electric propulsion / power management for a good result.
Can you give me an idea of the average size of such a boat?
I also need to know the maximum / cruising power needed to move a boat like this.
A system like this can be combined easily with solar panels and that is the reason we are happy if the boat has large horizontal surfaces available for them.
Keep in mind that the system can be also used for the other electric loads of the boat and this is maybe importand for boats with commercial usage (many electric loads operating for long periods, e.g. TV sets, lighting, air-conditioning, etc.

 

pvgenesis and Jeremy,

Thanks for the responses.

Concerning sizes and the like, 20x4.4 meter might be considered a typical size. Here is a link to an example. http://www.dutch-barges.net/thomas.html. This particular boat runs roughly 20 to 40 tons, depending on the length.

Speeds are limited on most canals to a few knots, so typical cruising power tends to be rather low. I'll try to look up some typical propulsion power requirements later.

Some boats have a lot of electrical gizzmos on board because a lot of people use them as live-aboard long-term cruisers, so they have washing machines and all sorts of other household appliances. Some people even sell their houses and cruise in their barges full time on the canals of Europe, especially France, but also some of the other heavily canalized (my word) countries.

 

Once again, just to remind that I have only a little experience in boat designing.

The size and the weight seem to be just enough for a system like the one I have in mind. Maybe if the internal height could be a bit higher there would be more space for the batteries.
In terms of horizontal surfaces, it looks like there is enough room for 2 – 3kWp of PV panels, mounted in a reversed and wide angled “V” position.
Depending on the season, the geographical position, the actual weather, the shadows by nearby structures and the average daily consumption, this PV power could be enough to cover the daily demand of a typical household consumption.
Of course it is always better to consume less energy by using energy-efficient appliances (led-lighting, energy-class A+ refrigerators / washing machines, gas oven, etc.) and by following the simple and well-known common advices for energy saving.
That way might be possible to achieve a slow battery re-carging while the boat is stationary, although it would be enough success not to use the generator on regular basis.

Concerning the electrical part (this is my part!), supposing you use an electric motor for propulsion, with existing commercial technology it is possible to have a 27kW 3-phase system by combining 9 units inverter / chargers from Outback (in order to use products from your country!). Total cost of about 30000 USD, total weight of about 0.5 tons.
This is enough to drive an AC 3-phase electric motor to produce a mechanical power of more than 30hp. Maybe this is enough to cruise in a speed of a few (5 to 8??) knots.
Of course the maximum engine power can be more than this, e.g. 50hp, but this can only be available with the generator running.
The nominal power of generator must be at least 20% more of the maximum power the vessel will possibly need, e.g 60kVA -3phase.

The transition from battery / inverters mode and slow cruising speed to generator mode and maximum speed can be fully automatic although there will always be a time “gap” of maybe 20 seconds in between. This is probably essential and might arise some safety issues.
The generator will also start / stop automatically in order to recharge the battery bank up to the preset level.

A battery bank of at least 100kWh @ C5 would be necessary for such a system.
Depending on the type of the battery (deep-cycle, marine type at least) this could be a weight of 2.5 to 5 tons and a cost of 15000 to 40000 USD (for a premium long lasting battery).

An amount of 3kWp of PV panels costs something like 8000 – 9000 USD.

I don’t know the cost of the vessel itself but I suppose that a total amount of about 50000 – 70000 for a complete power / energy management and storage system is not too much.
The generator will be in stand-by just for assistance when the boat is stationary.
Note that for a daily consumption of 30kWh (which is a really heavy consumption – almost twice of a typical household) and with no help at all from the PV array (heavy winter clouds), the generator would need only 2 – 3 hours of operation to compensate.
While cruising in low speed (up to 30hp), the generator will run with a duty cycle of about 50% (e.g. 1,5 hours running, 1,5 hour stopped) in order not to discharge the battery deeper than e.g. 50%.

This means that there will be a great saving in generator’s total operating hours. The time saving might be much more than 50% for a boat spending much time stationary!
You can give me an idea of the yearly saving of fuel and maintenance / repairs.

The battery can be discharged in DOD (Depth Of Discharge) up to 80% or even 100% only in emergency situations.
It is a matter of a full case study report to determine exactly all the above sizes but I believe that this is close enough to give you an idea based on real life.
We have already such systems operating in order to electrify small hotels or any other business premises in remote areas.

 

…and some additional – probably - important notes and thoughts….

- It would be preferable to use 48V DC electric motors for prupolsion. We would avoid the need of the inverter / charger array and the additional loses they introduce in the system. Only 2 or 3 units for 6 to 9kW would be enough just for the boat’s household loads.
- Depending again on the geographical position where you use your boat, a number of low-noise small wind turbines can also assist the system.
- The system can be fully automated and remotely monitored by experienced people. Manual operation of the generator is always available in case everything else has failed.
- Apart of the main large generator which is absolutely necessary while cruising for more than a couple of hours, maybe a smaller one (e.g. up to 10kVA 1-phase) can be proved more efficient while the boat is stationary. It can also be a low-cost emergency back-up for any reason.
- I believe that it would be very convenient to implement such a system in a boat in designing stage in terms of the available space for the system itself and for the batteries. It is always very difficult to fit a system like this in a boat designed for a diesel engine.

I hope this is helpful for you…

 

Just to clear up this part...
There is no power interruption at all in between. The "gap" of 20 seconds is the delay from the point when the additional power is needed, until the point when the generator is actually connected (by the system) to the loads and the full power is available.
The maximum possible power interruption during this transition can be 20 milliseconds. This is hardly noticable and short enough not to cause any problem to vessel's systems.