The future of batteries, solar, and electric motors....

[Kinnigit]

First of all, this question is more about the industry 15 years from now. So keep that in mind.

I've been looking into getting into sailing, another conversation, and in the 1,000's of hours of research (ADHD) into systems, I came up with a solid curiosity as to what systems will look like down the road when we buy our world cruising catamaran and retire.

-Lithium batteries are all the rage but the price reflects their infancy in the market.
-Solar has been around for years but is taking leaps and bounds now due to interest in alternative power. Size and qauntity of panles vs power output will get better.
-Electric motors are swinging deep into mainstream with companies like Tesla, and the like, having a new mass demand to pilot cars. That will translate into marine sooner or later.

So, as a person who is in his 30's, and a IT engineer, I am wondering if 15-20 years down the road if we could be sitting at a full electric line of Lagoon 450's, for instance, in theory.

Theory?

-Solar power advanced enough to power any realistic power needs between day cycles?
-Advanced wind and motion generators?
-Boat windows that have solar power elements built in and remain transparent.
-Electric motors replace diesel engines? I can think of a mountain of pros there when it comes to maintenance and supporting systems, lines, holes in the boat.
-Lithium batteries will be smaller or X times as powerful and lasting than current sized units. (Due to the demand even now for them to become better everyday)

Just thinking out loud.

In 20 years could we realistically see a full electric line of boats as standard market options?

[Paul Elliott]

20 years is a long time. But look at the current numbers and areas of likely improvement.

Prius electric motors are around 90% efficient, so there's not a lot of room for improvement there.

Solar panel efficiencies are currently around 20%, with some experimental panels getting close to 50%. So I suppose we could see a practical doubling of panel output if the cost can be reduced.

Lithium batteries are perhaps 5-8x more energy/weight efficient than lead-acid batteries (depending on the chemistry), and the cost should be coming down over time. It's impossible to know if there will be any major efficiency breakthrough, but as I mentioned, 20 years is a long time.

Diesel fuel still contains more than 10x the energy density (by volume) than the best lithium battery, and 60x the energy density of lead-acid batteries. By weight, it's even more dramatic: Diesel fuel contains 250x more energy than a lead acid battery.

Diesel engines are about 40% efficient at optimum, and less so at lower power levels. There are also minor transmission losses.

How this all adds up depends on how you plan to use the boat. Motoring long distances is the worst case, and here the issue will be energy storage and recharging. With current technology the best batteries will not be able to store better than 1/10th the energy of similar-size fuel tank, and even with the 2x efficiency of an electric motor that's still a huge reduction in energy storage.

Since you can't store enough energy, you have to recharge it. The power available from the best solar panels comes nowhere close to making up for the energy used in typical motoring (unless you cover 100% of the boat's surface with panels, and put them on wings for more surface area, and significantly reduce your motoring speed and don't motor into headwinds).

Here are some useful links:
https://en.wikipedia.org/wiki/Compar..._battery_types
https://en.wikipedia.org/wiki/Energy_density

[NCGunDude]

I've been going through the same thought process, with a 10 year horizon toward fulfilling my sailing dream.

My current thinking is all electric with backup genset.

So, the calculation becomes... what is the range for an electric powered engine, and how long is the recharge time on solar versus diesel?

Then there's LED lights, microwaves, and *gasp* A/C.

I'm also looking at a tri-hull for minimal drag and draft. G/L

[Kinnigit]

Thinking out loud here. Again, my opinion and curiosity is from a normal non-sailing Joe who has rebuilt several cars over the years. Not boats.

OK, you have 2x 3cyl diesel engines. I would imagine they are very efficient, in relations to my knowledge of automobile technology the small diesel engines can be highly conservative on fuel, and I would imagine the "miles per gallon" equates to an equation you solve to say this many gallons in my tank equals how far I can go.

So 400 gallons of diesel in your tanks. This would equal to x amount of nautical miles/hours you can operate the engines before you have to find someone to buy gas from.

My interest and curiosity would be at what point, down the road, could you operate your sailing vessel (sticking to a sailboat here) where you have enough solar/wind/future tech to recharge your battery systems enough, per daylight cycle, to operate the engines just as often as you would normally in sailing without having to top off a diesel tank?

As a tank of fuel depletes at x rate per hour but the hard variable is that it does not fill itself back up by any other means other than buying new fuel. With solar/wind/ etc actually recharging the systems by more natural causes.

At what point, I wonder, does the technology begin to meet in the middle of usage vs recharge? I know now that works if you use it to support your support systems(fridge, NAV, AC, etc) but I wonder when that could include enough to keep the electric engines going as well.

Again, this is just me thinking out loud. Honestly I am curious as I hope that when I actually jump in a boat 20 years from now, and point it to circumnavigate the world, that technology has propelled marine travel to move away from the need to constantly be looking at the fuel gauge during a passage.

Question #2 in my head. How much cheaper would it be to travel the world in a sailboat if you never had to put a drop of diesel in the boat?

[Paul Elliott]

All of this depends on how you plan to use the boat. You have mentioned circumnavigation, so I suppose we are talking about long-distance passagemaking. For example, the Nordhavn 43 is a diesel-powered trawler-style powerboat with a fuel capacity of 1200 gallons and a range of around 3300 NM (cruising at 7 kts). This will just get you from the Galapagos to the Marquesas in 18 days. The fuel burn rate will be about 67 gallons per day.

So figure the energy contained in 67 gallons of diesel fuel (38 kWh / gallon), and divide that by two (to compensate for the difference between diesel engine efficiency vs electric). This is the daily power consumption: 1.27 Megawatt hours.

Now figure out the battery capacity needed to store that power on a daily cycle, and the solar panels needed to recharge the battery.

Obviously duplicating the Nordhavn is not going to work. Does anyone else have any boat comparisons that would be appropriate?

[NCGunDude]

I listed a backup genset, because you could

1) provide current directly to the distribution grid in the event of battery failure

2) recharge the battery bank in the event of a lack of solar or wind power

I'm guessing the second option would be the most common. Lots of capacity would prevent continually having to run the generator.

[Augi]

I am new to sailing and and have looked into going as electric as possible on a new boat. Paul Elliot's post is spot on.

It seems to me the best solution if you want to go as electric as possible and need to be able to motor a long way at ample speed, unless huge technological break throughs are made is go with a parallel hybrid set up. That way you always have the diesel available. But you are going to have increased weight, complexity and cost of having the electric available until your batteries are depleted and you need to turn on the diesel to keep notoringt and re-charge the batteries.

It all depends on the planned use. Hanse has an all electric 310 available. But you are limited in range, speed and power to get out of trouble if you need it. You get the benefit of quieter, odor free propulsion with better maneuverability. That will work for some uses but not for crossing oceans and have a enough of a safety margin.

[Lake-Effect]

I'm expecting the following two developments in the marine world:

1. More efficient high capacity batteries to become cost-effective and mainstream. This could be lithium batteries, or some new technology. This will make electric-only daysailors more feasible.
2. Better diesel-electric hybrid engines, that can take advantage of stored electricity for short periods of motoring, and direct diesel propulsion for longer periods or when batteries are near empty.

Solar and wind will always be important supplementary charging sources. I don't see complete freedom from combustion engines or shorepower charging for a while yet.

[Paul Elliott]

On my 44-ft sailboat, I probably spend $2000 a year for sails - new sails every five-10 years and repairs as needed. Racing from San Francisco to Hawaii (battery charging via diesel engine on the way there, a day or two motoring on the way home) we generally burn about 50 gallons of diesel on the 4,500 NM round-trip. Many people spend less on sails.

Our 300 watts of often-shaded solar panels supplies about half of our at-sea power, and close to 100% of our power when at anchor. Our electrical needs are pretty typical for a modern 40-footer.

[Kalinowski]

I've recently converted our Pearson 424 ketch to electric propulsion and couldn't be happier. One power source being overlooked here is the juice generated when the rags are up and the motor left in gear. The motor turns into a silent generator and tops off the battery bank when we return to harbor. We have no plans to circumnavigate, but long distance sailing would certainly generate significant amounts of power.

[Kinnigit]

I plan to take our boat anywhere in the world but most of our time will be going from port to port and island to island and staying long enough to see all items of interest. The sailing will be just to get to the next destination.

Even if I went full electric I would still want, and maybe this is more of a preset time feeling, that I would want a diesel generator on board just in case of a power bank failure.

That being said I am sure you wouldn't need a 400g tank for the generator. It could be a purpose built system just in case all other energy means dried up. Including fuel capacity.

A diesel hybrid idea is interesting. Electric for a certain use time and then flip over to diesel if you pass the usage range. If I could get a few hours of use out of the electric side per day without killing other systems, I would say under normal circumstances the diesel side would be off most of the time.

Food for thought. Yumm.

[Paul Elliott]

Originally Posted by Kinnigit

Even if I went full electric I would still want, and maybe this is more of a preset time feeling, that I would want a diesel generator on board just in case of a power bank failure.

That being said I am sure you wouldn't need a 400g tank for the generator. It could be a purpose built system just in case all other energy means dried up. Including fuel capacity.

What I'm trying to say is this: Do the math. Consider your use-cases, and what it will take to survive the most difficult parts (this is why I worked the math for the Galapagos / Marquesas passage). The data are available for the current technology, and we can make whatever estimates we like for future advances.

If you are serious about this, handwaving isn't good enough. Do the math. There's a reason that small-vessel passagemaking is done on sailboats. Traditional passagemaking powerboats are usually 40 ft or larger and have large fuel tanks. True electric passagemakers are usually strange creatures with insanely massive solar arrays. Improved battery technology is nice, but doesn't solve the critical problem of recharge energy generation.

Hybrid sail / electric with solar and hydrogeneration sounds promising, but you had better plan on mostly sailing. I don't think the diesel-electric hybrid is a solution for a passagemaker, but it might be nice for a short-hop vessel.

So do the math. It's not that difficult.

[Ironman162]

I can't help wondering how these big cruise ships do it? I can't see any sails and understand it uses electric motors. There are literally thousands of people on these boats with every thinkable luxury.

Amazing stuff! I guess if you run a big diesel generator full time when you are on the boat, you could power just about anything including propelling motors

[StuM]

Originally Posted by Ironman162

I can't help wondering how these big cruise ships do it? I can't see any sails and understand it uses electric motors. There are literally thousands of people on these boats with every thinkable luxury.

Amazing stuff! I guess if you run a big diesel generator full time when you are on the boat, you could power just about anything including propelling motors

F'ing big diesel generators and fuel tanks to supply the electricity.

Typically a large cruise ship will have maybe 50 MegaWatts of generating power, burn up to 30 tons of fuel per day and 80% of that is used to generate the propulsion power with only 20% needed for "every thinkable luxury".

[sandiegoskipper]

Being an automotive engineer, I see this for sail powered boats.
1) Lithium "air" battery packs. Light weight and power dense.
2) Wind generators.
3) Diesel back-up generator to recharge batteries and serve as a "get me home" propeller drive (folding).
4) Reverse charge main propeller thru a transmission that switches ratios from "power out" to "power in" - so the motor becomes an alternator while under sail.
5) The boat draws less with LED and other low draw electrical components.
6) An in the water "swell charger" that harnesses the boat's motion to produce a recharge current in addition to more efficient tow-behind chargers.
7) Solar arrays in ways we cannot imagine today. Perhaps integrated into the sails.
8) Far more energy efficient radar and communication draw as demand for that parallels electric propulsion growth.