Vision of the future? H2-powered vessel.

[captain_dave]

A very interesting article. Is this our future?

https://www.cnet.com/news/this-boat-...from-seawater/

[Pitchondesign]

Not anytime soon, if ever. The article correctly states that hydrogen carries more energy by weight compared to batteries, about 10x. The article was silent on the volume of hydrogen compared to batteries.

Storing hydrogen as a gas is energy intensive, as it must be compressed. This compression requires as much as half the energy of the gas being compressed, and even more when it is stored as a liquid at cryogenic temperatures. In addition, it is highly flammable, tends to escape containment and reacts with metals in a way than renders them more brittle and prone to breakage. These are very difficult technical problems to solve on a boat. If a common rail diesel looks hard to maintain, a hydrogen system would be unimaginable.

Note that diesel contains about 40x the energy of a lithium battery by weight. My boat holds about 1,200 pounds of diesel. The equivalent in lithium batteries would be 48,000 pounds, or 50% more than my boat weighs.

Diesel is still hard to beat.

[AKA-None]

Hmmm what if you could make the hydrogen on demand? I wonder what that would look like?

[Westcliffe01]

The military who's biggest vessels are powered by nuclear reactors, have enough power on board to be able to produce fuel from hydrogen and carbon to fuel their planes. But that is not exactly a balanced energy equation at all.

[Chris31415]

The risk of fire would be another consideration. Remember the Hindenburg.

https://images.app.goo.gl/6d9cREh6UqfLQJTi7

[mikedefieslife]

Originally Posted by Chris31415

The risk of fire would be another consideration. Remember the Hindenburg.

https://images.app.goo.gl/6d9cREh6UqfLQJTi7

Remember the Hindenburg? How old are you?

Are Honda still driving around their Hydrogen fuel cell car? It must have been 10-15 years ago, they were driving around a lot. It was on every car show.

[Chotu]

Depending on the efficiency, it would be really cool to have a huge hydrogen tank and make H2 from sea water via wasted solar energy.

Imagine large arrays on Catamaran’s being put to full use making hydrogen for propulsion after they met house demands.

A big tank could be slowly filled and then used when needed.

[Westcliffe01]

So lets see: To produce 1kg of Hydrogen by electrolysis takes 180-200MJ of energy using the best known techniques.

https://en.wikipedia.org/wiki/Electr...ustrial_output


The resulting hydrogen has a calorific value of 141.8MJ


Taking the hydrogen (and oxygen) and running it through a fuel cell has a practical efficiency of ~36%. Citation: https://en.wikipedia.org/wiki/Fuel_cell#In_practice


Dang, sounding a lot like an ICE....


So overall efficiency is (141.8*0.36)/190 =26.8%


We are missing parts of the puzzle though. Seawater is hardly a good electrolyte, so one would first have to do reverse osmosis then make up a suitable electrolyte, manage the condition of the anode and cathode. Find a way to reliably separate hydrogen and oxygen, compress both gasses into storage tanks which would have to be large if pressures are not to be excessive. Then you need all the unobtanium - the fuel cell which is generally loaded with a lot of platinum



It just seems like it would be much more practical to drive the propulsion motors directly using PV panels and use excess to charge good quality batteries which can run the motors overnight, possibly at reduced power. If you consumed diesel overnight with the batteries adding to available power one would still achieve very good efficiency, especially in northern climates where heat recovery from the genny can provide the heating needed for the interior, hot water etc. In this scenario one could maintain cruise speed through the night. So put a lot of miles under the keel every 24 hours.

Originally Posted by Chotu

Depending on the efficiency, it would be really cool to have a huge hydrogen tank and make H2 from sea water via wasted solar energy.

Imagine large arrays on Catamaran’s being put to full use making hydrogen for propulsion after they met house demands.

A big tank could be slowly filled and then used when needed.

[leecallen]

Originally Posted by Westcliffe01

It just seems like it would be much more practical to drive the propulsion motors directly using PV panels and use excess to charge good quality batteries which can run the motors overnight, possibly at reduced power. If you consumed diesel overnight with the batteries adding to available power one would still achieve very good efficiency, especially in northern climates where heat recovery from the genny can provide the heating needed for the interior, hot water etc. In this scenario one could maintain cruise speed through the night. So put a lot of miles under the keel every 24 hours.

I know this is an old post, but it interests me. I've been trying to work the math on this. Here's where I am at.

I take the specs for the Torqeedo Deep Blue 100i 2500 rpm:
135 hp equivalent
100 kw peak input power

Let's assume I need that 135 hp to drive my boat at the speed I want. How many 100W solar panels do I need? 1000! And that's ideal/theoretical output, and I would only get it during the sunny part of each day. Forget about charging house batteries or running at night from battery power.

Have I misplaced a couple decimal points somewhere?

I really want to cruise under power at 8 knots or better, without feeling I am 'part of the problem' of global climate change.

[StuM]

Originally Posted by leecallen

I know this is an old post, but it interests me. I've been trying to work the math on this. Here's where I am at.

I take the specs for the Torqeedo Deep Blue 100i 2500 rpm:
135 hp equivalent
100 kw peak input power

Let's assume I need that 135 hp to drive my boat at the speed I want. How many 100W solar panels do I need? 1000! And that's ideal/theoretical output, and I would only get it during the sunny part of each day. Forget about charging house batteries or running at night from battery power.

Have I misplaced a couple decimal points somewhere?

I really want to cruise under power at 8 knots or better, without feeling I am 'part of the problem' of global climate change.

What's your question got to do with the topic of Hydrogne fuel?



But, you are correct. 135HP is about 100 KW, so you need 1000 x 100W panels in full sun to generate it.

[CarlF]

Many of us already have a carbon free power source - it's called wind.

A 15kt wind creates about .04 hp per sqft of sail.

A 50ft catamaran main/jib has about 1700 sqft of sail - or 68HP. And that HP increases by the square of the increase in windspeed.

We forget that ICE came along after sails had powered ships for centuries - and did a pretty good job of it.

As it is, almost all hydrogen today is created with natural gas. To make "green" hydrogen we need to improve the efficiency of electrolysis by a factor of about 10 and then generate enough electricity for volume production - maybe 1000 times as much wind power as we have today.. But that's where we're going.

And the ultimate answer for a diesel replacement will be when we learn how to convert hydrogen into a stable room temperature liquid fuel called E-fuels that could be put in an unpressurized tank like your current diesel tank.

EFuels are created by capturing CO2 from the atmosphere and combining it with hydrogen. When it burns the CO2 is released but doesn't create any net increase in atmospheric CO2 since it was captured. It's still decades away.

[StuM]

Originally Posted by CarlF

EFuels are created by capturing CO2 from the atmosphere and combining it with hydrogen. When it burns the CO2 is released but doesn't create any net increase in atmospheric CO2 since it was captured. It's still decades away.

Decades away? Plants are pretty good at doing that already and have been doing so for a long time. And there is no need to gerenate a lot energy to split the hydrogen out from it's most common form of dihydrogen monoxide first.

Fossil fuels are just the product of the same process over longer time frames.

[Adelie]

Originally Posted by leecallen

I know this is an old post, but it interests me. I've been trying to work the math on this. Here's where I am at.



I take the specs for the Torqeedo Deep Blue 100i 2500 rpm:

135 hp equivalent

100 kw peak input power



Let's assume I need that 135 hp to drive my boat at the speed I want. How many 100W solar panels do I need? 1000! And that's ideal/theoretical output, and I would only get it during the sunny part of each day. Forget about charging house batteries or running at night from battery power.



Have I misplaced a couple decimal points somewhere?



I really want to cruise under power at 8 knots or better, without feeling I am 'part of the problem' of global climate change.

Not going to happen except over a distance of miles, not even 10’s of mile within your life time.

What’s you current boat and engine? At what RPM does it make 8kt?

Hydrogen has promise if they can find a decent storage method. All current methods involve heavy high pressure containers and very high volumes dedicated to those containers. Storage as a liquid is too energy intensive and prone to venting boiled off hydrogen even when you aren’t using the fuel.

Storage in hydrates is being investigated. I wouldn’t count on it though.

For electro-fuels ammonia or synthetic gasoline or diesel are more likely candidates, more existing infrastructure that can be used for production, distribution and locomotive power.

You want to be greener? Get a sailboat, even if you motor everywhere you will use less fuel for the same speed. Sailboats are highly optimized for low drag.

[leecallen]

Originally Posted by Adelie

You want to be greener? Get a sailboat, even if you motor everywhere you will use less fuel for the same speed. Sailboats are highly optimized for low drag.

I am looking at 39-40 foot power cats from FP, Lagoon, and Leopard. I think they share hull designs with their sailing yachts. In which case I am already getting those benefits.

My wife and I took sailing lessons a couple of years ago. The most important thing we learned is, she doesn't want to sail. She's not into the 'work', so it would be all me. Also we will probably spend a lot of time in the ICW where there is little wind.

Originally Posted by leecallen

I really want to cruise under power at 8 knots or better, without feeling I am 'part of the problem' of global climate change.

Originally Posted by Adelie

Not going to happen except over a distance of miles, not even 10’s of mile within your life time.

That's what I am afraid of. I hope this discussion will clarify that.

[leecallen]

Originally Posted by Adelie

What’s you current boat and engine? At what RPM does it make 8kt?

Sorry I missed this. A 28' pontoon boat with a 200HP outboard. We live on the Niagara River and we boat there and in the protected areas of Lake Erie, and we have trailered it to other inland lakes.

We're preparing to retire at the end of the year and we want to cruise off Florida: the keys, Bermuda, Bahamas, and the Virgin Islands.

We're gonna need a bigger boat.