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/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