Future of Hydrogen Fuel Cells to Power Your Sailboat

[leecallen]

I have been reading lately about ammonia as a denser, safer hydrogen storage medium, and thinking about its applications to boating, and I came looking for this thread. I am thrilled - and not surprised - to find so much depth and good information and such lively debate.

So just to add my two cents...

I will likely never be a long term, 'round the world cruiser. So I think about the use-case of weekend boaters and coastal cruisers.

Consider the boat in its berth for a week or two with the solar cells and/or wind generator powering an electrolyzer producing ammonia, which gets stored in a tank. Then when the weekend arrives we fire up the electric motors and take off, running on pure green energy.

It kind of doesn't matter how efficient the process is, if the boat can make its own fuel from sunlight, and produce enough for our outings. (In a way it does matter, if the efficiency is so low we would be better off putting that electricity into the grid. But I'm going to ignore that for now.)

Additionally a sailboat under sail can produce additional ammonia from a towed generator, supplementing its 'battery'.

The numbers I am interested in are, how does the energy storage compare to gasoline/petrol/diesel and batteries in terms of:

• cost per horsepower (at the shaft) of the entire system
• energy density: horsepower per pound of the entire system, including the fuel)

Diesel is cheap and light per HP produced. Batteries are expensive and heavy, and also have a finite life. Where does ammonia fall on that spectrum?

And if the answer is: as bad as batteries, or worse - am I prepared to pay that penalty to enjoy my carbon-free boating experience?

[danstanford]

Originally Posted by leecallen

I have been reading lately about ammonia as a denser, safer hydrogen storage medium, and thinking about its applications to boating, and I came looking for this thread. I am thrilled - and not surprised - to find so much depth and good information and such lively debate.

So just to add my two cents...

I will likely never be a long term, 'round the world cruiser. So I think about the use-case of weekend boaters and coastal cruisers.

Consider the boat in its berth for a week or two with the solar cells and/or wind generator powering an electrolyzer producing ammonia, which gets stored in a tank. Then when the weekend arrives we fire up the electric motors and take off, running on pure green energy.

It kind of doesn't matter how efficient the process is, if the boat can make its own fuel from sunlight, and produce enough for our outings. (In a way it does matter, if the efficiency is so low we would be better off putting that electricity into the grid. But I'm going to ignore that for now.)

Additionally a sailboat under sail can produce additional ammonia from a towed generator, supplementing its 'battery'.

The numbers I am interested in are, how does the energy storage compare to gasoline/petrol/diesel and batteries in terms of:

• cost per horsepower (at the shaft) of the entire system
• energy density: horsepower per pound of the entire system, including the fuel)

Diesel is cheap and light per HP produced. Batteries are expensive and heavy, and also have a finite life. Where does ammonia fall on that spectrum?

And if the answer is: as bad as batteries, or worse - am I prepared to pay that penalty to enjoy my carbon-free boating experience?

You raise some great scenarios.
How do we use the ammonia fuel? Will it work in a fuel cell and thereby produce electricity to power the engine?

Thanks for continuing the discussion, Dan

[leecallen]

Originally Posted by danstanford

You raise some great scenarios.
How do we use the ammonia fuel? Will it work in a fuel cell and thereby produce electricity to power the engine?

Thanks for continuing the discussion, Dan

Yes. Here is a good, current article about using ammonia to generate electricity:

https://www.power-eng.com/gas/op-ed-...rogen-carrier/

[tomsnrg]

The battery based electric propulsion system is solar panel, battery packs with reasonable capacity, inverter and motor. Ship's services are powered from the propulsion battery. Probably same charging infrastructure as cars in marinas. Simple.
Ammonia requires the fuel cell to produce it and half of the energy goes away. The ammonia is gaseous and needs to be, lightly, compressed and chilled prior to being put into a storage tank. Pumps, piping, filters, water treatment in the electrolyzer, all in limited space and in aggressive marine climate. Then another fuel cell, another pump, an air compressor and another time half of the energy thrown away. You will still require battery, albeit much smaller. The membranes require controlled humidity, have limited lifetime and require purity at 99,999% for H2. Good luck maintaining this on a leisure boat.
Looking at today's automobile industry hydrogen is correctly relegated to niche solution since no significant progress was made on technology costs. What we see in H2 today are largely the death throes of a lavishly funded system that burned public money through occasionally rather mediocre minds to keep public opinion at bay when environmental concerns came up before the battery era dawned.
When thinking H2 and ammonia it may happen, perhaps, but at the giga-scale wind or solar plant with industrial liquid H2 or ammonia production and a transport infrastructure using LNG-type tankers.
The big thing in going battery electric is electrons moving, no longer molecules. No pumps, filters, tubings, fittings, seals, valves, fuel foulings. There are still some issues in energy storage. The bests minds are on this, worldwide. As for the outcome it's a rather safe bet.

[leecallen]

Originally Posted by tomsnrg

When thinking H2 and ammonia it may happen, perhaps, but at the giga-scale wind or solar plant with industrial liquid H2 or ammonia production and a transport infrastructure using LNG-type tankers.

I guess you mean: It makes more sense to take the solar panels and electrolyzers and compressors off my [theoretical] boat, and deploy them in a large-scale plant, and then transport the ammonia to fueling stations and then to our boats. Especially for the use case I described: occassional outings.

I think you are probably right.

Originally Posted by tomsnrg

The big thing in going battery electric is electrons moving, no longer molecules. No pumps, filters, tubings, fittings, seals, valves, fuel foulings. There are still some issues in energy storage. The bests minds are on this, worldwide. As for the outcome it's a rather safe bet.

Do you mean batteries will become significantly smaller, lighter, less expensive, and longer lasting? And will eventually become practical for [pleasure] boat propulsion?

[Colin Stone]

I filled my tanks in Belgium with HVO.

Neste Renewable Diesel is made from waste fats, residual materials and vegetable oils and classified as a hydrotreated vegetable oil: HVO100. The fuel has the same high performance as regular diesel, but produces up to 90% less greenhouse gas emissions (CO2e) compared to fossil diesel.
https://www.neste.be/en/neste-my-renewable-diesel-be

Drop in replacement for diesel but it is not cheap. White for propulsion is €2.80/litre and Red for generator and heating is €2.20/litre. And both plus VAT at 21%.* So quite a bit more than fossil diesel.*But going Green is going to be a more expensive way of life, so will just have to accept it.*

The fuel is certainly better for the engines as well as the environment. It has a higher cetane value, so more power and smoother running.* There is also less smoke and smell is more like a chip shop.* Every thing runs without adjustment.

It also has a very long shelf life, Up to 15 years in the tanks. Current fossil diesel with some bio added, B7, does not keep well and can suffer a dreaded "diesel bug".*

[Buzzman]

According to Neste website, the HVO100 is made by combining hydrogen with vegetable oils at high temperature.
So to claim it is 'sustainable' the hydrogen would need to be certified 'green hydrogen' made from cracking water using renewable electricity.
Their website does NOT mention this....
Probably the hydrogen is derived from fossil fuels at present, so is technically not 100% 'fossil free'....
But I'm not familiar with their process, and obviously they don't want to say too much, but in this case, what they DON'T say may be as important as what they do say...

[Colin Stone]

Is making ammonia any greener??
"A typical modern ammonia-producing plant first converts natural gas, liquified petroleum gas, or petroleum naphtha into gaseous hydrogen. The method for producing hydrogen from hydrocarbons is known as steam reforming. The hydrogen is then combined with nitrogen to produce ammonia via the Haber-Bosch process."

[leecallen]

Originally Posted by Colin Stone

Is making ammonia any greener??
"A typical modern ammonia-producing plant first converts natural gas, liquified petroleum gas, or petroleum naphtha into gaseous hydrogen. The method for producing hydrogen from hydrocarbons is known as steam reforming. The hydrogen is then combined with nitrogen to produce ammonia via the Haber-Bosch process."

I was referring to producing the hydrogen by splitting water with electricity from green sources - electrolysis. But you're right, it can be done either green or ... gray? As described here:

https://en.wikipedia.org/wiki/Steam_reforming

[Adelie]

Originally Posted by Colin Stone

Is making ammonia any greener??
"A typical modern ammonia-producing plant first converts natural gas, liquified petroleum gas, or petroleum naphtha into gaseous hydrogen. The method for producing hydrogen from hydrocarbons is known as steam reforming. The hydrogen is then combined with nitrogen to produce ammonia via the Haber-Bosch process."

The currently used processes aren't green but can be.
Hydrogen can be electrolyzed from water.
Nitrogen can be removed for the air whatever the current method.
Then the Haber-Bosch process produces the ammonia.

Alternatively hydrocarbons can be synthesized too.
Water is cracked to get the hydrogen.
Carbon Dioxide is pulled out of the air and cracked to get carbon monoxide.
Which is processed with the hydrogen to get hydrocarbons using the Fischer-Tropsch process. While not carbon free, it is carbon neutral.

What becomes out portable fuel of choice will depend on the economics of each process.

[leecallen]

I have to say, tomsnrg's response convinced me an 'onboard' system for producing ammonia is not practical. So while ammonia may be a good ultimate solution for hydrogen powered boat propulsion, the ammonia would likely be produced off-site and delivered - like carbon fuels. But the production of the ammonia *could* be green, and the conversion of ammonia to power *could* also be green (if it fuels a fuel cell and is not burned in an ICE).

[Adelie]

Why wouldn't it be "green" if used in an ICE? The combustion products are mostly normal constituents of air and it produces no CO2.

[Colin Stone]

Perhaps our renewable industry should have used these at the same time as installing solar and wind...

https://www.bbc.com/future/article/2...years-too-soon

[leecallen]

Originally Posted by Adelie

Why wouldn't it be "green" if used in an ICE? The combustion products are mostly normal constituents of air and it produces no CO2.

That article I referenced earlier says burning ammonia in an ICE produces NOx (nitrogen oxide) and unburnt ammonia. Per wikipedia:

In atmospheric chemistry, NOx is a generic term for the nitrogen oxides that are most relevant for air pollution, namely nitric oxide (NO) and nitrogen dioxide (NO2). These gases contribute to the formation of smog and acid rain, as well as affecting tropospheric ozone.

So it's not carbon but it's still not nice.

[Adelie]

Good point.
The shipping industry is going this route. Apparently those emissions can be minimized by optimizing various engine details. The question then is that hood enough?

Chemistry being sloppy, fuel cells are unlikely to have zero emissions.

The question is which will have higher emission per unit of power. I’m betting fuel cells will be better given the are likely to have better fuel efficiency and probably have fewer emissions.