Tesla Powerpack enough of a game changer to move to single engine ?

[desperatelyseeking]

Does the recent announcement by Elon Musk advance the case for electric propulsion on board boats? My thinking is that if you could rig a decent sized planing boat, say a 50ft Flybridge with one big engine (800hp), and have it run through a Greenline style electric motor which could also be powered by a couple of Tesla 90KWh powerpacks (or however many you need as they are infinitely scaleable) there are quite a few good advantages.
1. You only have to buy one engine meaning the cost of the batteries is somewhat offset.
2. You don't need a genset as the powerpacks could run the whole boat for as long as you need without turning the engine on.
3. You could use the powerpacks to power the boat at low speed, silent manouvering at docking etc
4. The electric engine could be used as a "get me home at displacement speed" backup negating the most often cited need for two engines if the powerpacks were of sufficient size.
5. Running costs would be slashed, fuel burn, servicing, generator running costs.
6. Solar panels could help recharge the batteries when the boat sits in the marina, which let's be honest is most of the time.

There may be marinisation issues and I'm sure Tesla aren't going to spend much time focussing on this niche end of the market but I hope someone comes up with a working solution. I guess if it took off you might see superchargers at docksides like the ones at motorway service stations.

I like the idea of a single engine, shaft driven boat that could be manouvered silently, didn't need the genny running when anchored, and had the peace of mind that it could power you a modest distance back to help should you suffer an engine failure (which is less likely on a single due to the increased motivation to have it in tip top order and the massively decreased cost of doing so).

Not sure what the fuel savings are of a single vs a twin setup but everything i have read seems to indicate it would be significant.

I'm sure there are lots of opinions on why this can't work and I'm no engineer so am happy to be put straight!

 

[annageek]

I design battery systems for a living. I've worked with several companies regarding electric drive / hybrid drives for boats, and every time, when it turns out the overal drive train + energy storage costs work out to be 4x the cost of a traditional IC engine drive, the project has come to an abrubt stop.

Take a small <3m dingy tender and suitable electric outboard. Now look at the size and weight (and cost) of a suitable battery to get you from your mooring to the pub up the river. A 4hp outboard soon makes sense from a cost / range / reliability, and even weight point of view. Now, scale that up to a planing hull 40 footer, and all you do is scale up the issues you had with the tender.

Hybrid does work, clearly. For boats, diesel-electric hybrids seem to be the best solution for the reason you've described. However, the huge additional cost up front makes it hard to jusitfy a 'technically superior' setup.

Tesla have done a good job of driving down the cost of these batteries - surprisingly so, in fact. we couldn't get anywhere near the £/Wh that they are offering, but you'll need to replace them every 5-10 years - which will soon mount up.

One other issue is that the revs needed on the drive shaft for planing speed boats is quite high. The sort of high torque motors that are used in existing marine motive applications tend to be based on motors pinched from industrial applications / plant. You therefore, to create an electric drive planing boat need to put an off the shelf motor through a gearbox (reduced reliability and reduces efficiency), or develop a new motor, which will likely be a lot heavier / more expensive than existing motors.

It can definitely all be done, and it definitely has advantages. I think, though, based on our current breed of batteries that are commercially available, it'll never be truly viable. Let's wait until graphene batteries start to come to market, though. They're going to change things!!

If you really want energy efficiency, though, you could of course always put a wind generator atop your boat and charge the batteries that way - or better still, cut out the inefficiencies of the wind-to-electric-to-motive energy conversion, and just harness the wind energy to directly drive the boat! If onlt someone could come up with something like that... Oh... hang on!

 

[Groot T]

If you really want energy efficiency, though, you could of course always put a wind generator atop your boat and charge the batteries that way - or better still, cut out the inefficiencies of the wind-to-electric-to-motive energy conversion, and just harness the wind energy to directly drive the boat! If onlt someone could come up with something like that... Oh... hang on!

Careful, I recently read a news article about a disagreement in a USA car-park which started due to a similar comment...

Let's wait until graphene batteries start to come to market, though. They're going to change things!!

This is a very interesting point and I'm eagerly awaiting the arrival of graphene batteries! The last I hear is some clever mug discovered graphene has an interesting elasticity property which plays out well if the substance is ejected from a jet-nozzle or something?
Is there any best-estimates as to when graphene batteries will be used mainstream?

Toby

 

[Avalon]

One other issue is that the revs needed on the drive shaft for planing speed boats is quite high. The sort of high torque motors that are used in existing marine motive applications tend to be based on motors pinched from industrial applications / plant. You therefore, to create an electric drive planing boat need to put an off the shelf motor through a gearbox (reduced reliability and reduces efficiency), or develop a new motor, which will likely be a lot heavier / more expensive than existing motors.

I'm not sure that the OP meant for the electric motor to drive the boat at planing speeds - that would scarcely be practical at present. But having an electric motor which will drive the boat a reasonable distance under electric power at low speeds is useful - this is what Greenline offers (at a price). Hybrid marine on the IOW (http://www.hybrid-marine.co.uk/) also offer parallel hybrid systems which can be fitted to new boats, or retrofitted to existing ones.

This is a technology which I have always found interesting, but with the current state of the art I feel that it is more suitable for inland waterways use than at sea.

 

[annageek]

This is a technology which I have always found interesting, but with the current state of the art I feel that it is more suitable for inland waterways use than at sea.

Fully agree.

Ultimately, I think something as costly and fundamental to a boat's operation as an electric / electro-hybrid system that is fit for the masses will have to be developed for the work boat market before it finds its way to the leisure boat market. Financial viability will be achieved more quickly in applications where several 1000's of hours of use are clocked up each year - rather than just 100's or 10's. I don't know, but I would imagine there aren't many (or rather, any) 'big boat' traditional IC engines out there that have been developed for leisure boating - they're all derived from industrial engines. Can't see why this would be any different if you add in an electric drive element to the system.

Is there any best-estimates as to when graphene batteries will be used mainstream?

I regularly read that by the end of this decade you'll have a graphene battery powering your phone/tablet/laptop or whatever is likely to have replaced these devices by then. I am not sure what this apparent 'hunch' is based on, but I've read reports to that effect from various 'commentators' in the various trade journals I receive and glance at as they travel from my inbox to the recycling bin.

If you really want energy efficiency, though, you could of course always put a wind generator atop your boat and charge the batteries that way - or better still, cut out the inefficiencies of the wind-to-electric-to-motive energy conversion, and just harness the wind energy to directly drive the boat! If onlt someone could come up with something like that... Oh... hang on!

Careful, I recently read a news article about a disagreement in a USA car-park which started due to a similar comment...

Pah... I was merely talking about something along these lines:

 

[BruceK]

That's priceless. I wish I had that in poster size to wind up some peeps in the club with.

 

[baylabayla3288]

There is clearly a case for hybrid propulsion in boats as well. I have been waiting for someone to make a good integrated system for fast planning boats, optimized for use at displacement speeds. I have been driving a plug in hybrid car for the last 12 monts and I have noted that once the main battery is depleated the car alternates between pure electric dive and ICE drive. When the ICE is running it is also charging the batteries. By doing so the ICE is loaded at its sweet spot from efficiency point of view and once there is enough charge it goes pure electric again for a while. This would be very beneficial in a boat also for many reasons I think. In addition to the improved pootling fuel efficiency it would be less harmful for the big diesels as they would be loaded properly when running, silent exit and arrival in harbours, less smoke when it matters, large domestic electricity supply for anchoring, allowing for larger more powerful high voltage thrusters, and so on. And off course, you would still have the go fast option.

 

[baylabayla3288]

Will change my avatar soon

 

[burgundyben]

Interesting stuff and only a matter of time.

Presumably, the scalability problem is less if only requiring displacement boat performance.

Will we see cost effective solutions for displacement boats first? Combined with a PV array on the roof?

Plus, what about gas turbine CHP style power source rather than recip engines?

Would be interested to know more about graphene batteries.

 

[desperatelyseeking]

I'm not suggesting batteries replace the ICE, we're clearly miles off that. What I am suggesting is whether we are now at a point where it is practical and economic to have one larger diesel engine rather than two smaller ones, backed up by an electric drive of some sorts as a back up/manouvering/short distance solution.
The efficiencies from running one engine instead of two are well known, the benefits of big batteries for silent running of a vessel at anchor are massive, if Tesla has got the costs and technology sorted I was just wondering if we will start to see single engine setups rather than twin.

 

[andrewbarker]

Interesting stuff and only a matter of time.

Presumably, the scalability problem is less if only requiring displacement boat performance.

Will we see cost effective solutions for displacement boats first? Combined with a PV array on the roof?

Plus, what about gas turbine CHP style power source rather than recip engines?

Would be interested to know more about graphene batteries.

There's a reasonably good piece in this month's Professional Engineering pp 8-9. Still look years off before commercial utilisation.

 

[baylabayla3288]

I'm not suggesting batteries replace the ICE, we're clearly miles off that. What I am suggesting is whether we are now at a point where it is practical and economic to have one larger diesel engine rather than two smaller ones, backed up by an electric drive of some sorts as a back up/manouvering/short distance solution.
The efficiencies from running one engine instead of two are well known, the benefits of big batteries for silent running of a vessel at anchor are massive, if Tesla has got the costs and technology sorted I was just wondering if we will start to see single engine setups rather than twin.

Actually at speeds up to 22 -24 knots in heavy boats it seems that twins are at least as efficient as a single, the prop area need to be very large. Off cource there are other savings to consider as well.

 

[RAI]

Nigel Calder has written a whole series of articles based on his new hybrid driven yacht. They started off optimistic in the design phase and slowly got more realistic as the real efficiency levels and costs became apparent. Sad, I was really hoping for a better result.

 

[Trundlebug]

Electric propulsion is coming...

First electric ferry now in operation in Norway. Interesting solution. Batteries recharge in 10 minutes!

http://www.maritime-executive.com/article/worlds-first-electrical-car-ferry-in-operation

 

[annageek]

Electric propulsion is coming...

First electric ferry now in operation in Norway. Interesting solution. Batteries recharge in 10 minutes!

http://www.maritime-executive.com/article/worlds-first-electrical-car-ferry-in-operation

Looks promising. I wonder how long the ROI will be seen when compared with a conventional steel hulled, diesel ferry?

Although they've come up with a good solution for effective recharging of the batteries (ship's battery + 2x load levelling 'refuelling batteries' on shore), when the time for battery replacement comes, it's three sets that need to be changed vs just one! When you take a look at the batteries used (these, I think: http://files3.webydo.com/42/421998/UploadedFiles/ddcc2796-010e-4146-8abf-7a14c62d9a7b.pdf, according to the report, they're discharging to about 60% depth of discharge each crossing. They claim 5000 cycles to 80% DoD, so if you apply a conservative estimate and assume you'll get around 7500 cycles out of these batteries, that equates to about a years use of worth before replacement is necessary!

That said, I'd imagine the most expensive (compared to more conventional solutions) part of the ferry is the fully aluminium hull. So even replacing a few hundred £k worth of batteries per year is in the noise when compared with the £millions extra spent on the hull.

It's nice to see though that they have gone the whole hog and made an aluminium hull, rather than (presumably) a cheaper, steel hull. With battery technology as it stands, whenever you have a battery capacity / capability problem, the best starting point is to look into changing the load, rather than to look into changing the battery. That's exactly what they've done.

 

[Trundlebug]

Looks promising. I wonder how long the ROI will be seen when compared with a conventional steel hulled, diesel ferry?

Although they've come up with a good solution for effective recharging of the batteries (ship's battery + 2x load levelling 'refuelling batteries' on shore), when the time for battery replacement comes, it's three sets that need to be changed vs just one! When you take a look at the batteries used (these, I think: http://files3.webydo.com/42/421998/UploadedFiles/ddcc2796-010e-4146-8abf-7a14c62d9a7b.pdf, according to the report, they're discharging to about 60% depth of discharge each crossing. They claim 5000 cycles to 80% DoD, so if you apply a conservative estimate and assume you'll get around 7500 cycles out of these batteries, that equates to about a years use of worth before replacement is necessary!

That said, I'd imagine the most expensive (compared to more conventional solutions) part of the ferry is the fully aluminium hull. So even replacing a few hundred £k worth of batteries per year is in the noise when compared with the £millions extra spent on the hull.

It's nice to see though that they have gone the whole hog and made an aluminium hull, rather than (presumably) a cheaper, steel hull. With battery technology as it stands, whenever you have a battery capacity / capability problem, the best starting point is to look into changing the load, rather than to look into changing the battery. That's exactly what they've done.

An interesting insight to the detail behind the scenes, thank you.

Yes although it will be costly to replace the batteries once a year, I guess it'll be cheaper than buying diesel overall.
One of the main obtsacles which people will have to get their heads around is financing occasional big lump sums (batteries) instead of the regular drip feed payments with conventional fuels.
It's like buying 80% of your fuel up front in one go, then enjoying drastically cheaper regular bills for the next year (in this case) for the electricity.

Amazing that despite the impressive life cycle of these batteries they'll only last a year in this application.

 

[JumbleDuck]

The Tesla battery packs are extremely limited in use. For example, you only get to recharge them fully 500 times before they're scrap. The good news is that that takes ten years; the bad news is that that's because they are limited to one full recharge per week. The cost per kWh is roughly the same as the Mastervolt Li-ion batteries which have been around for a while - and which are limited to 2,000 cycles.

I know someone who has fitted electric auxiliary propulsion to his sailing boat. It's nice and quiet, but the range is extremely limited (20 minutes at full power) and the installation, which uses lead-acid batteries, cost as much as three nice diesel engines. Li-ion batteries would be ideal in his case, as he could get around four times the energy stored ... for perhaps twenty times the cost.

Definitely a technology to watch; nowhere near practical or affordable yet.

 

[annageek]

An interesting insight to the detail behind the scenes, thank you.

Yes although it will be costly to replace the batteries once a year, I guess it'll be cheaper than buying diesel overall.
One of the main obtsacles which people will have to get their heads around is financing occasional big lump sums (batteries) instead of the regular drip feed payments with conventional fuels.
It's like buying 80% of your fuel up front in one go, then enjoying drastically cheaper regular bills for the next year (in this case) for the electricity.

Amazing that despite the impressive life cycle of these batteries they'll only last a year in this application.

I guess that's why certain electric cars have an option to buy the car and lease the battery for £100 or so per month.

Take the Nissan Leaf. If you do 10k miles/year, your battery lease is about £1000/year, or 10p/mile. Allow, say 0.5p/mile for the electricity you're buying, overall, you're paying 10.5p/mile. Lets say petrol prices are to £1.20/litre, then the cost per mile for a Nissan Leaf is the same as a (much cheaper to buy) conventional petrol engined car that'll average 55mpg over 10k miles... not an unreasonable figure by today's standards, for a similar sized city car. The same will apply to boats, but on a larger scale. Therefore, it's going to be a while before pure electric really makes enough financial sense for the masses... be that in cars or in boats. I also think that hybrid technology tends to sit in the financial fuzziness between pure electric and ICE engined vehicles. It may not seem that way on paper, but when you take into account things like the residual of hybrids with knackered energy storage systems, it's all much a muchness.

I realise there are environmental advantages, and they shouldn't be ignored, but I also feel that for many, being kind to the environment is usually secondary to being kind to the bank account.

Sorry to be so relentlessly sceptical about everything

 

[annageek]

The Tesla battery packs are extremely limited in use. For example, you only get to recharge them fully 500 times before they're scrap. The good news is that that takes ten years; the bad news is that that's because they are limited to one full recharge per week. The cost per kWh is roughly the same as the Mastervolt Li-ion batteries which have been around for a while - and which are limited to 2,000 cycles.

Also, when you look at using such large battery solutions / high power generation systems for the high current density, continuous demands of electric motor drives, cooling becomes a problem. On a boat, it's easy to solve as you can just use oil cooling and a seawater heat exchanger, which will be nice and efficient, but then you've got pumps, joints, gaskets etc... all of which will need maintenance to ensure reliability, cancelling out the benefits of only having one IC engine to maintain.

 

[MapisM]

Pah... I was merely talking about something along these lines:

LOL, I guess that setup might well be competitive with most sailboats, at least in terms of pointing ability...!

Your post #2 really says it all in a nutshell, with regard to the pros and cons of electric/hybrid propulsion for boats. I couldn't agree more.
I'm always surprised by how many folks can think that this is a viable proposition for planing boats, while we are still far from that even for D boats, which are clearly a much better platform to play with.

Btw, @ the OP: which are the well known efficiencies from running one engine instead of two, on planing boats? I'm not aware of any.
In a sense, it's actually the opposite: it has been proven that surface transmissions (which is the best/most efficient propulsion for fast and big vessels) work better with a high "fragmentation" of power delivery - i.e. with 3 or even 4 props.

Besides, even when Nordhavn experimented a full hybrid propulsion, they never actually aimed at significant fuel savings, and they didn't even consider throwing traction batteries into the equation, to start with.
The expected advantages were more along the lines of modularity/redundancy/reliability, though eventually they were not up to the complexity of the task, and failed spectacularly with respect to the latter.
Otoh, where should efficiency gains come from, when on a boat (as opposed to cars) there's no regenerative braking to talk of?
Yeah, wind and sun can provide some energy for recharging traction batteries, but look at vessels like the Tûranor PlanetSolar to see at what extent of PV modules and size of battery banks you must go, just to be able to cruise at 5 knots...

The Norwegian ferry is of course a notable exception, where the concept can only work only because:
1) first and foremost, each trip only lasts 20 mins. Who would want to live with such restriction, on a pleasure boat?!?
2) they made a very peculiar arrangement/infrastructure on each dock, that can't be replicated on large scale and in any marina. Well, surely not during my lifespan, anyway. But in my nephew's boots, I wouldn't hold my breath either...
3) the ferry definitely isn't built for planing speed!
Apropos, the alu construction is actually a red herring, sort of.
In fact, first of all I neither buy the idea that the vessel can be "only half as heavy as a conventional ferry, despite its ten ton batteries", nor that "aluminum hull also has double the lifetime as steel hull".
But even accepting that with a significant weight saving there can be an equally significant reduction in power demand (another idea I don't buy, with displacement vessels), well, the very same saving could still be achieved with diesel propulsion, I reckon.

All that said, I fully accept that this specific application is one where full electric propulsion can definitely make sense, and I would be more than happy to see it applied also in my home harbor, where every time the existing ferries turn their engines on you must hope that the wind doesn't blow in your direction!
But on a planing pleasure boat? Dream on...