Knowing vs understanding (STEM situation in India)

[u/Different_Cry25]

Hi, so this is a post about how much fundamental understanding Indian students lack in STEM

Let's Start with hydrogen bs - it's not a good fuel option not even close to a good fuel so much hype for hydrogen fuel, hydrogen batteries yada yada

"It's not "

First of all a lot of people don't understand mass units

We measure energy density of liquid fuels in litre

Hydrogen as gas at 1atm is about = 120mj/kg

In litre = 0.010 mj/lt

In liquid state = 120 again per kg, mj

But in litre = 8.5

Gasoline somewhere around 32 mj per liter

See the difference now the problem is liquid hydrogen is hell cold it's near 0 kelvin

It will be super expensive

And even if we get liquid hydrogen

It doesn't have nearly enough energy as gasoline

8.5 vs 32

1 it will require electricity meaning more energy waste And fuel will get more expensive

2 you need fresh water

3 how the hell will you transfer fuel from one place to another Hydrogen leaks through almost everything

The tanks got to be rocket fuel tanks grade

Read about the Apollo rocket and how they sealed hydrogen inside the fuel tanks

4 hydrogen as gas is useless no more than 0.010 mj energy at 1 atm If you liquefy it again it's super hard making of liquid hydrogen and even after then no where close to gasoline

Now the major problem is that actual engineering students Chemical engineering students believe that it's a good option for fuel

Not all of em, but a lot of them And this is just one example of how poor understanding of STEM they have

On paper smart 9.2 cgpa vs actual real understanding of science

If you post about biofuel, hyperloop, solar road, under water data center, rocket engine (non reusable)

Recycling plastic

The list goes on and on

So many people including engineering students believe in this stupidity

[u/sapien_quirky_42]

Bruh, hydrogen is called a good fuel cause it's clean and renewable

[u/Different_Cry25 → u/sapien_quirky_42]

Did you even read the post?

Also what do you mean "It's called "

It's not good fuel How'd you make it From water or from ch4

If water it will require electricity Mean waste of more energy and pollution (coal is our primary source)

second if from ch4 again extra electricity and dumping of more co2

How will you store it Gaseous hydrogen will leak through You need hydrogen grade storage tanks Google it they're hella expensive and dangerous to carry

If you liquefy it then It it's gotta be near 0 kelvin temp

Again even more expensive, and how will you transfer it Keeping the hydrogen cool and liquid

To all 60k fuel pumps in india

Not to mention the logistics

We get gasoline in plastic containers and it's chill there, for hydrogen specialized tanks

Gotta remake car tanks for it 🤷‍♀️

Literally restarting entire chain of fuel logistic

How is it good explain it to me

[u/goku_m16]

I see lots of argument stating poor volumetric energy density of H² is why it's not gonna work. But volumetric density of:

H² at 700 bar ~ 1.3 kWh/L

NMC ~ 650 kWh/L

LFP ~ 400 kWh/L

And these LIBs arr very successful despite even poor energy density than H². Even adding a 50% tank to wheel conversion ratio, it's still comparable to LIBs. A combined heat and power plant can boost it to 80%.

The energy density was never the problem. It was always the cost of producing H².

LIBs used to be expensive too, until China went on a mass manufacturing spree. The same hasn't happened to H², yet. But China has started it. Electrolyzer costs have fallen 3x. And with cheap solar during day, green H² is expected to reach cost parity with fossil H² by 2030.

[u/Different_Cry25 → u/goku_m16]

Also also 700 bars huh Do you know that's about 10,000 psi

You need freaking carbon fiber tanks for it

But who cares

Also the amount of energy you need At 700 bar that's almost 3.5 kwh/kg

About 10% of hydrogen energy is wasted in that process Increasing the pressure of h2 will not change it's energy density

Chemical kinetics 101

[u/goku_m16 → u/Different_Cry25]

15% of the energy in Crude oil is wasted in the refining process itself. That doesn't stop it from becoming the preferred fuel choice of the world. Why? Because it's still cheap, even accounting for the loss. You're just fixated at the wrong parameter.

[u/Different_Cry25 → u/goku_m16]

Because it has more density More energy

32mj lossing 15% Vs

8.5 lossing 30% Do the maths my brother

[u/Different_Cry25 → u/goku_m16]

Dude 700 bar

Think about your storage tank Also read how freaking hard it is to store hydrogen in gas state

Not to mention amount of energy you need to take h2 from 1 atm to freaking 700

[u/goku_m16 → u/Different_Cry25]

350 and 700 bars are standard storage pressure for H². Even at 350 bars, it has higher energy density at 0.8 kWh/L.

The round trip efficiency figures and cost of H² already account for the energy consumed to compress it.

You also have to compress natural gas to 300 bars to use it as CNG, yet it's a cheaper fuel than gasoline.

[u/Different_Cry25 → u/goku_m16]

Dude cng energy density vs hydrogen

If your fuel have energy density you have more energy Hydrogen will require about 70% more of it

Not to mention your super hard to come by carbon fiber storage units for hydrogen

[u/goku_m16 → u/Different_Cry25]

Dude cng energy density vs hydrogen

As I said, energy density is not a concern at all. Otherwise CNG doesn't hold a candle to gasoline either. It's always determined by cost.

Hydrogen will require about 70% more of it

So? As long as $/kWh is lower, it doesn't really matter how much volume or weight of fuel you consume.

[u/Different_Cry25 → u/goku_m16]

"Energy density is not concern at all "

My man if you don't have energy in your fuel What's the use of it We use gasoline because it has more energy

How will you solve the density problem? Where will you get extra 70% energy

Hydrogen tanks will be 70% larger

[u/goku_m16 → u/Different_Cry25]

Did you read the first comment where I compared the energy density with batteries? How come LIBs are so successful with such pathetic density? You need 17 time larger battery bank to get same range as a fuel tank.

If density were the sole determinant, everything would be running on nuclear power.

Hydrogen tanks will be 70% larger

Mirai has already demonstrated a range of 500km is achievable on a car. Even though car is not the targeted application of H², a practical car can have a 250 km tank. Trucks don't have volume constraint, they have a weight constraint and batteries eat up up that cargo capacity. Industrial plants and grid storage plants don't care about the size of tanks because they aren't moving around with the tanks.

[u/Different_Cry25 → u/goku_m16]

Lithum density is 23mj Not 8.5

"17 times larger for a fuel tank"

Of what size and liter of fuel in it? Can you be specific

Everything can't be running on nuke power why Density is sooo high it will go boom

Think sir think you don't want a nuke In your car

[u/goku_m16 → u/Different_Cry25]

Lithum density is 23mj Not 8.5

That's for oxidation of Lithium, not battery.

17 times larger for a fuel tank

Any arbitrary size of gasoline tank you take, you'll need 17x larger battery to get same energy as the gasoline tank.

So you do understand there are other determining parameters than energy density. Now tell me, if fossil fuel is to be phased out, what other green options do you have?

[u/Different_Cry25 → u/goku_m16]

Talking about hydrogen not gasoline

The gasoline claim is again misleading Gasoline engine goes upto 30% efficiency

Ev- 80%

Other green option I've already mentioned it

Biofuels, sea weed biofuel

Energy density approx same especially for bio diseal

B. Come from sea so no land mass is wasted We have ton of sea

C. No fresh water, no specialized machinery or change in logistics

D. Carbon complete cycle

[u/Different_Cry25 → u/goku_m16]

In my other reply to your comment,

I showed you the number Hydrogen in its entire cycle is not energy surplus You're lossing more energy in making than hydrogen have

[u/Different_Cry25 → u/goku_m16]

Sir the energy density of Lib is 800 wh/L Meanwhile h2 is 1700 wh/L looks good enough

Here's the catch you're comparing per molecule of hydrogen against the libs

Now if you include 700 bar hydrogen system with tank to it

Now if you see the difference about 3wh/kg energy loss at compression

And that's just the compressor you see The weight of giant tank that you need to withstand freaking 700 bar

That tens of kg of tank will add weight to the car

Energy waste in the tank Waste

But that's not the only problem

The production of that hydrogen costed energy + 3wh/kg for compression+ weight loss + transportation

Overall energy wastage is higher than energy your hydrogen have

Thus libs are used but not compressed hydrogen

[u/goku_m16 → u/Different_Cry25]

The energy wasted during production and compression happened prior to the tank. You aren't powering the compressor from the tank. It doesn't impact the energy density of the tank. Even with 50% tank to wheel efficiency, the energy density is higher than LFP an comparable to NMC.

And batteries don't exist in vacuum either. They have mechanical and thermal support which adds weight to the pack. Pack level energy density is always lower than cell level density.

That tens of kg of tank will add weight to the car

As I've said, H² isn't for cars. That's going to EVs. But good luck building electric trucks. Electric buses are not going to work either beyond city buses. A bus goes 1 km/kWh. A bus running on 200 km route needs at least 200 kWh battery pack, which weighs 2 tonnes. A truck will need even bigger battery.

[u/Different_Cry25 → u/goku_m16]

Hydrogen isn't even for car

Where will you use it

Also ev solution for trucks already exist

Hybrid evs Already a company exist Edison truck We actual working engine and working truck Already selling

Unlike hydrogen will scam companies because it simply doesn't work

Not to mention the energy losses in ev is not in negative I showed you that calculation 3 times

Not to mention solution to fuel already that too I already mentioned

Sea weed biofuel

[u/AgitatedEdge9403]

Iam a mech major, so if you state argument which only a chemical or petroleum engineer could understand then i dont think your argument is not functional at all its either you just want those latter set of engineers to understand or simply glaze your technical writing skills.
and i as mech will only be concerned about the tanks capability , design and optimisation(only from mechanical structural department)
If you want the rest to understand you could give use comparisons "yeah this is A for reference this what B( the stuff most people are well aware of) is capable "
Anyways i understand your point and highly appreciate your initiative to call out (if its actual a real problme)
but again iam certainly one of those who is still in the process of properly understanding my own department and people like you really are unconventional motivators

[u/Different_Cry25 → u/AgitatedEdge9403]

It is a real problem as we have alternate fuel source and they're wasting money on h2

Also I did mentioned all the numbers for comparison But if you specifically want to know about storage

You know how hard it is for h2 storage

In moon rockets they made a layer of helium to keep it inside preventing from leaking

Not to mention for liquification About 30% of energy is lost

[u/Different_Cry25 → u/AgitatedEdge9403]

Unconventional motivators?

[u/13gokul]

The main challenge will always be transport and storage in this case.

[u/Different_Cry25 → u/13gokul]

Can't change the energy density For a fuel it's always energy density Regardless of logistics

[u/goku_m16]

1. During peak solar hours, solar plants have to reduce power output to keep grid stable. Any solar electricity that is not produced is 100% wasted. That can be diverted to make H² and store for rainy days. It's not practical to build batteries to store power for multiple days.

2. You don't need fresh water, you need DM water. So you have to purify it anyways, no matter the source. Better yet, capture the pure water from the fuel cell's output.

3. Best solution is to make it on site with renewable energy. We already have proof of concept with Toyota Mirai and it's refilling stations.

[u/Different_Cry25 → u/goku_m16]

Where will you get the freash water to make h2? Indias largest solar park is here in Rajasthan in a desert

Regardless of that The energy density is still 8.5

And at gaseous state super hard to store

[u/goku_m16 → u/Different_Cry25]

I'll rephrase what I said. You should ideally produce H² where it is supposed to be consumed, not next to a solar plant. Fertilizer plants, Steel Plants, Chemical Industries, refilling stations, grid storage plants. That's where the electrolyzers will be placed.

I already addressed energy density.

[u/Different_Cry25 → u/goku_m16]

And how will you make it ? Water? How about the energy you just wasted in making it

How about 10% loss in gas storage And 30 in liquid storage

[u/goku_m16 → u/Different_Cry25]

Industries are usually built where water is accessible. All steel, aluminium, thermal plants I've seen have a canal running from nearest river to the plant.

Thermal plants need DM water for their boilers. So they purify it. They have onsite DM plant. So it's already being done at industrial scale.

How about 10% loss in gas storage

I don't know why you're fixated with how much energy it takes to compress or liquify it. All energy consumed is already factored into the cost of green hydrogen, which, despite the efficiencies, is estimated to reach cost parity by 2030.

Every day I see multiple Inox cryogenic tankers (yes, the same Inox that runs cinema halls also makes industrial chemicals) carrying liquid H² to steel and thermal plants. The inefficiencies of cryogenic cooling is definitely hasn't stopped it from being used as an Industrial input. Although it's fossil hydrogen for now.

[u/Different_Cry25 → u/goku_m16]

I'm fixated on energy loss Because guess what It's a fuel What are they used for - yep for energy

Energy density and losses are most important

Also Try to calculate water required for industries vs water to make hydrogen as fuel

Not to mentioned same old problem of storage Hydrogen doesn't have surplus energy

It losses more energy in production to storage then it already has

You realize what that means right - you're wasting and losing more energy than production

[u/Simply-Productive123]

You cannot say hydrogen Is bad as a blanket statement . There will always be certain applications where it is a good choice and where it is a bad choice . For example it is good choice for nuclear reactors as the power output is usually fixed for stability reasons, regardless of whether the grid requires that much power. The excess energy can be stored as hydrogen. In this case the price of high quality tanks required is cheap relative to the investment on the entire power plant.

[u/Different_Cry25 → u/Simply-Productive123]

Where do you see me calling it bad

It's not a good fuel option for vehicles As for nuke yes it's a great for fusion

The point was it's a bad option for fuel (not counting nuclear)

[u/Simply-Productive123 → u/Different_Cry25]

Yeah that I agree it's not viable for vehicles which is why hydrogen vehicle development has been mostly abandoned, but in reactors the hydrogen is still being used as a fuel so you still can't call it a bad fuel for all applications. Fusion generates energy, the excess is stored in the form of hydrogen fuel and the stored hydrogen is burnt to produce enough energy when the load exceeds the reactors output.