Hydrogen 15x more power dense than diesel?

[Manateeman]

My manatee crew began to think their off gas was worth money.
Now they are all in a funk because they learned so much about gas storage in this thread. I’ve got eight dorades and a power vent for the battery compartment.
No way are we bringing any more gas onboard.
Captain Mark

[Nicholson58]

Originally Posted by Dockhead

I doubt if leaks from such a system (for electrical power generation anyway, not propulsion) would be greater than the amount freely vented from lead acid batteries.



The problem is incomparably easier to deal with, than dealing with propane leaks.

Wrong. From an engineering and physics point of view hydrogen is difficult to contain, especially compressed. It is the smallest molecule and will pass through pipe joints and even between the molecular structure of metal pipe. This means positive ventilation and extreme measures to prevent accumulation is mandatory. Propane is far easier to manage.

From the practical point, where do you plan to get the stuff? You can’t even get LNG most places even in the US. Try to get anything but propane or diesel and gasoline in the Caribbean. Several cruisers arriving in Antigua last season quickly shed their propane outboards for gas. Propane, while available, takes 2-5 days for a tank refill and requires an agent to handle the tanks. The cost winds up 10X gasoline and massively inconvenient.

Hydrogen is a byproduct from fossil fuel reformers and crackers or from hydrolysis. You are either going to burn fuel to run a generator to separate H2O or possibly get the power from a large solar array. The generator option is hugely inefficient, consuming more fossil BTUs than the hydrogen BTUs produced. I for one would not want tanks of high pressure hydrogen on board eve if I had a pipeline to the petroleum refiner.

I can’t imagine operating a boat with infrastructure so complex it cannot be serviced or fueled almost everywhere.

We have a well maintained 1982 built diesel that runs as well as the day it was built. 6-cyl, 115 HP. We put less than 150 gallons of fuel per season through it and the 12.5 kw generator combined. There is no way to ever justify any sort of change on fuel or carbon reduction or even cost of operation. Not being able to acquire fuel everywhere is unthinkable.

[tanglewood]

This guy will probably be the next person hauled away fro fraud, just like the guy who was going to revolutionize trucking with electric trucks.


Products conceived by people who failed high school physics, marketed and sold to other people who failed high school physics.

[RaymondR]

The whole hydrogen thing is a giant scam by the solar panel folks who know that we will never be able to use enough batteries to store sufficient solar power generated electricity to run any modern civilization.

The practicable and safety issues will always prevent hydrogen from replacing hydrocarbon liquid fuels in transport and we have perfectly adequate electrical networks in place already powering the non-mobile parts of our civilizations which only require heat sources to replace those now provided by fossil fuels.

Eventually it will become obvious to the public that the renewables only nuts are precisely that and we can get down to solving the problems with nuclear fission.

The transport industry will eventually be predominantly electric but long haul road transport will gradually die off, it is a post WW2 phenomenon anyway and we could go back to rail transport quiet easily.

[Adelie]

Originally Posted by MartinR

Several reasons actually! ease of handling, storage volume, flammability, warmer storage temperature, lubricating.

Not as efficient, though.

Cost. That's part of why it was used in the first stage of the Saturn-Vs

[Adelie]

Originally Posted by RaymondR

The whole hydrogen thing is a giant scam by the solar panel folks who know that we will never be able to use enough batteries to store sufficient solar power generated electricity to run any modern civilization.

The practicable and safety issues will always prevent hydrogen from replacing hydrocarbon liquid fuels in transport and we have perfectly adequate electrical networks in place already powering the non-mobile parts of our civilizations which only require heat sources to replace those now provided by fossil fuels.

Eventually it will become obvious to the public that the renewables only nuts are precisely that and we can get down to solving the problems with nuclear fission.

The transport industry will eventually be predominantly electric but long haul road transport will gradually die off, it is a post WW2 phenomenon anyway and we could go back to rail transport quiet easily.

Many business interests are looking for what comes after fossil fuels, it's not a scam, it's just an attempt to be at the beginning of the next big thing.

Really I think the market is going to become very fractured, different segments will use different energy sources.
Trains will all switch to electric overhead.
Ships will probably switch to ammonia with a little hydrogen to promote combustion, wind will assist and speed will go down.
Airliners are tough one, could be cryogenic hydrogen, or synthetic hydrocarbons or ammonia/hydrogen, either possibly with some supplemental battery power. Aircraft are going to get a lot more efficient and they are going to slow down. And high speed trains will replace the regional airliners. It's all about what is the most cost effective.
Truck transport (like trains) will start using overhead power on highways and arterials and use battery power at the start and end of each trip.
Commuter vehicles will be battery powered. For longer trips, people will take their personal vehicles on trains and use battery power to get to their destinations.

Recreational travel will be a lot more expensive. So less of it will be done. That includes travel by air, camping, motor boating.

The only major use segment where there isn't a somewhat clear path forward is agriculture.

Hydrogen has too many drawbacks to be a serious contender except for air travel where the tradeoff between price and speed is worth it. I really hope Toyota and the others trying to make hydrogen work are successful but I think the practical problems and the economics are stacked against them.

The title of this thread is patently incorrect:
Diesel has an energy density (MJ/liter) about 4.5x better than liquid hydrogen. And it's about 6x better than compressed hydrogen.

Hydrogen on the other hand has about 3.3x the specific energy, energy per weight or MJ/kg. But only if containment methods are ignored. If you account for the weight of the pressure vessel the advantage is more than wiped out. If you liquify the there isn't such a big weight penalty but the net energy to weight is somewhere between LFP batteries and and E85 gasoline.

If you look at the efficiency of using hydrogen vs using LFP batteries, the batteries have a big advantage. With LFP you get back about 93% of what you put in. With hydrogen it's like 20% even using fuel cells (it takes energy to electrolyze water (10%), and more to compress (10%) or liquify (25%) it and the cells are like 60% efficient.