DirtFarmer Loc: Escaped from the NYC area, back to MA

A recent post asked a narrow question about hydrogen cars. I thought it might be good to provide a thread to include a wider discussion of hydrogen as an energy source.

One concern raised in the other post was a concern about the amount of oxygen removed from the atmosphere. I believe that is less of a concern for a hydrogen powered vehicle than for a conventional petroleum powered vehicle. Oxygen is a by-product of the production of hydrogen (electrolysis of water). Burning fossil fuels consumes oxygen. Burning hydrogen recycles oxygen. Also, the power for hydrogen powered vehicles is derived from fuel cells rather than an internal combustion engine.

Electrolysis of water takes electricity, which is currently produced from fossil fuels to a large extent. Solar and wind electrical sources are very important to reduction of fossil fuel use.

A friend sent me a couple posts containing slides from a presentation about hydrogen so I thought I'd pass them along. I also found online a cartoon showing how much area is needed to power the world from solar energy. The cartoon is not dated, nor does it say anything about the efficiency of the solar energy production or energy transport, so I'd say it's more of a concept than a presentation.

Electrical energy transport from very local production sources would likely be a significant problem. The world population is 7 billion. The per capita electrical energy use varies quite widely, from 40 kwh to 53000 kwh (USA is only about 13000), but the average appears to be about 3000 kwh (https://worldpopulationreview.com/country-rankings/energy-consumption-by-country) but I'm not sure whether that is a weighted average or not. 7 billion people using 3000 kwh means 21 x 10^^12 kwh. I assume that is for one year. A year contains about 8760 hours so the energy use averages 2.3 x 10^^9 kw (2.3 Terawatts).

Hydrogen for Surface Transport (PDF)
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shell-h2-study-pdf
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petrochemist Loc: UK

Although small scale hydrogen production is from the hydrolysis of water (something done in our lab for many years & needing ultra pure water) industrial supply is I believe still from methane.

DirtFarmer Loc: Escaped from the NYC area, back to MA

In that case production of hydrogen is not carbon neutral.

petrochemist Loc: UK

That may well be the case for current production - I'm not sure of the actual reaction used, simply replacing the C-H bonds with C-O ones would certainly not be carbon neutral, but replacing them with C-C bonds (ending up with the carbon in a solid form soot, graphite or diamond...) would still be carbon neutral.

couch coyote Loc: northern Illinois

Wait, what? I can be carbon neutral and still end up with diamonds??? Sign me up!

petrochemist Loc: UK

It is possible but the energy requirements are somewhat prohibitive & artificial diamonds aren't particularly valuable. Soot/graphite are easier routes but probably still energy intensive.

dpullum Loc: Tampa Florida

Alternate fuel is a new idea to the USA and when it reared its ugly non-greasy head the petro people have crushed it. Politicians are Oliogenous, indeed their palms are greased with the green. The subject of this post, Hydrogen is a very clean fuel, especially when generated using electricity from renewable sources.

When I was living in Argentina, Cabs were fueled with liquified natural gas or propane.

In the 1960s safe Thorium Nuclear Reactors designed for the airforce while not a good fit, these reactors were run for 5 years successfully. They ran with molten salt fuel which was self-regulating and if they were to overheat the fuel is dumped into a cool vessel to solidified. Solidified the nuclear reactivity stops. They burned waste from other reactors, run at high temperatures, and are not explosive water-cooled pressure cookers; ever heard of Chernobyl, Three Mile Island, and Fukushima?

The main drawback, no bomb material, and not profitable to Nixon's California friends. Nixon ordered all research to stop and all materials to be destroyed. Oops, the researchers took data home and a reactor was hidden in a museum. The USA is slow in allowing Molton Salt Thorium Reactors, other countries are building them as part of their renewable future, China, India, and others. Designs allow mass production of modular small reactors. Interesting subject ... do a Google/YouTube search and get educated in 5 minutes. Google Thorium Reactors in five minutes.

Elon Musk has started a revolution with E-Cars, more efficient Solar Cells, and storage of off-hour power with highly efficient battery systems.

BurghByrd Loc: Pittsburgh

All are bandaids on the real problem which is overpopulation.

bw79st Loc: New York City

I asked an engineer about fuel cells and hydrogen. I can't vouch for the figures quoted as I have no expertise in this field, nevertheless this was his reply:

Unfortunately, hydrogen costs MORE to operate than either gasoline, diesel, or electricity.
Here are some arguments about hydrogen over the years that I've been following these discussions. First, it’s important to know APPROXIMATE equivalent energy density:
40 kWh electricity = 1 US gallon of diesel = 1 kg of hydrogen @ 10,000 psi

US average cost per equivalent energy unit:
$4.80 = 40kWh @ $0.12 electricity per kWh
$2.48 = diesel per US gallon
$13.50 = hydrogen per kg @ 10,000 psi

This means that assuming 100% efficiency of each of the above energy, each will move a vehicle the same distance. The actual data is as follows:
10-55% Gasoline (depending on when you start calculating the energy of oil - in the ground, or at the pump)
20-55% Hydrogen (it takes a LOT of energy to produce hydrogen)
60-90% Electricity

On the surface, it might appear that gasoline or diesel might be the cheapest, however, they are relatively inefficient in their consumption. Electricity is by far the MOST efficient, and thus lowest cost to operate per mile.
Here are those arguments:
1) Hydrogen will magically become cheaper and cheaper.
The fact that it currently costs $10-$17 per kilogram in the format required with huge multi million dollar government subsidies has no bearing on their logic.
They will always express that in the future, just on the horizon, almost within reach, is that magically lower price that just seems too good to be true. Just get millions of (presumably government funded) hydrogen cars out there, and “you’ll see”!!!
Sadly, it will never, ever be cheaper than electricity used directly into a vehicle.
2) Hydrogen is fantastically more efficient than diesel, that is currently used for trucks.
It is true that hydrogen is more efficient than diesel for truck transport, however not fantastically so. The number that they will will casually toss around is double the efficiency.
The reality is that many diesel motors are 40% efficient, and a modern-day Cummings X15 - 500 hp diesel motor is 55% efficient!!! That is huge!!! A trucking company can replace a traditional 6.5 mile per gallon truck (that is probably 8 years old with 1 million miles) with one that gets 7.5 to 8 miles per gallon, lowering their fuel cost per mile by 20%.
Hydrogen can exceed 50% overall efficiency, but it can’t come close to the efficiency of electricity.
Again, electricity easily beats diesel and hydrogen in efficiency in the 80-90% data point.
3) Hydrogen is cheaper per mile in a truck.
ELECTRIC:
$0.14 per mile @ 0.50mile/kWh (2kWh per mile)with $0.07/kWh electricity (Tesla’s stated efficiency and energy cost). To equal diesel costs with road tax, add $0.07 per mile
$0.20 per mile @ 0.35mile/kWh (3kWh per mile) with $0.07/kWh electricity (Tesla “guaranteed” energy cost at the Megacharger of $0.07/kWh, or maybe the wholesale cost of electricity, or the retail cost in the Pacific Northwest without no demand fees). To equal diesel costs with road tax, add $0.07 per mile.
DIESEL:
$0.31 per mile @ 8.0mpg with $2.50/gal diesel (latest Cummings X15 diesel motor at over 50% efficiency) Includes $0.07 per mile for road tax
$0.38 per mile @ 6.5mpg with $2.50/gal diesel (that will likely go up in price over time). Includes $0.08 per mile for road tax
$0.73 per mile @ 6.5mpg with $4.73/gal diesel (using $1.25 USD per liter in Europe equals $4.73 per US gallon... this is where Tesla may have the greatest advantage... until the governments get wise and slaps road taxes on electricity)
The above prices include road tax.
HYDROGEN:
$1.17 per mile @ 8.5mpg(e) with $10/kg hydrogen
$1.76 per mile @ 8.5mpg(e) with $15/kg hydrogen
PRICES ABOVE DO NOT REFLECT ROAD USE TAX. If hydrogen trucks catch on, expect a road tax surcharge like diesel trucks pay on fuel per gallon of approximately $0.07 per mile.

aphelps Loc: Central Ohio

The electric calculation ignores the costs of building, operating and maintaining the much larger infrastructure needed to support the electric needs of large scale use of electric vehicles. The present grid would have to be really scaled up.

SteveR Loc: Michigan

Was that a Hydrogen RV in Nashville?

DirtFarmer Loc: Escaped from the NYC area, back to MA

Some good points, and some that need to be discussed further.


I don't see what the @10,000 psi has to do with the energy density. The energy density is inherent in the hydrogen, not in the pressure unless you're using the pressure to drive something (in which case you could use any gas. In fact, a gas that has a vapor pressure below 10,000 psi would have an advantage since the pressure would remain relatively constant as you use it [neglecting thermodynamic effects]). OTOH, specifying the pressure does point out that hydrogen storage requires nonstandard containers.


Yes, production of hydrogen is expensive at present. That's because hydrogen is not as widely used as petroleum for energy and the use of hydrogen for energy is relatively new. I would expect the price to decrease as research is done on production methods for high volume hydrogen use. OTOH, petroleum is a nonrenewable source of energy and is used for lots of stuff in addition to transportation, so I would expect the price to increase in the future.


Does this assume that hydrogen is being burned in an internal combustion engine?


I would never ever predict that one source of energy would be cheaper than another, particularly when they have widely different histories of development. New sources can benefit much more than old established sources from research and development. I believe that hydrogen will become cheaper and cheaper, not by magic, but by research and development.



While it appears that electricity is the most efficient way to power transport, the production of electricity depends significantly on petroleum products at present. Research is needed (and ongoing) to shift the source of energy being converted to electricity. In fact, hydrogen powered vehicles are probably electric vehicles, as the electricity can be produced in the vehicle using hydrogen in a fuel cell. Current battery cars have range limitations and recharge time constraints. I'm not sure how a hydrogen fuel cell will compare there.


That is currently an issue with electric vehicles also. The petroleum fuel road tax is far below needed levels for infrastructure maintenance. It has been at the same level for decades, even as the price of oil has moved significantly (both up and down). A political problem there as no politician likes to increase taxes if (s)he wants to be re-elected. We need a better way to fund the infrastructure maintenance.

nospambob Loc: Edmond, Oklahoma

If electricity were generated by small turbines at or near the point of consumption, then there wouldn't be a huge loss of power seen over a grid.

Retired CPO Loc: Travel full time in an RV

Bison Bud

Something somewhat new is the production of "Green Hydrogen" by using solar, wind, or hydro sources of electricity to power the electrolysis process to produce the hydrogen. However, I think the real problem with hydrogen as a viable fuel is primarily how to safely store and transport it. I sure don't want any 10,000 PSI bottles riding along with me in any vehicle or even traveling down the highway for that matter! Anyway, using "Green Hydrogen" as a back up storage medium to batteries seems to make good sense and may just catch on. Batteries have a finite capacity which production could exceed at times. Charge the batteries first, then as they become charged move the energy produced to the electrolysis process and store the hydrogen on site.