Fuel direct from sunlight

[Uncle Fester]

I know these reports keep popping up regularly but this one looks a bit more promising because it seems quite simple
and very cheap to produce with existing materials I am aware of from other mass produced products:




The big breakthrough I see compared to PV systems is the energy storage. No batteries required, just a couple of pressure tanks
for energy with enough grunt not only to power my car but propel one of these : (I am not saying the panels on my roof will be enough for my personal space jet or course , unless I have a VERY LARGE roof)

I bet the Chinese will be onto this low cost energy the minute they can get it running on larger scale
but of course with only the 19th century coal age our current government is heavily subsidising
we won't see any of this in Australia.

[Onefella]

Now we will grow our solar panels.

Hydrogen certainly seems to be a better way of storing potential electricity than our current batteries.

[allover]

Read a press release from CSIRO a fortnight ago claiming that they had developed artificial Photosynthesis in a leaf like structure, claimed they were working in conjunction with a American institute?
Wonder if the same organisation?

[gordon_s1942]

I note in the article it says that the Hydrogen and Oxygen are kept separate containers because if they mix, an explosion can occur.
Even though Hydrogen is a fantastic clean burning fuel, it is just so volatile that makes it difficult to handle.
Even the tiny amount given off by a Car battery during charging, has exploded doing considerable damage.
So lets hope further R & D will proceed to tame this GAS as it is a Fuel of the future.

[Uncle Fester]

I note in the article it says that the Hydrogen and Oxygen are kept separate containers because if they mix, an explosion can occur.

Yes that is the whole point

I still remember chemistry class (back in the 1970's when they still could teach you cool stuff) where the teacher electrolysed a little water and collected all the gas in a test tube and told us to stand back a bit when he held it in front of the bunsen burner. That was the loudest explosion I had heard to date.
He did have it wrapped in a cloth.

So, no wonder both gasses in compressed form can send things up to space.

Of course you can use them separately, the hydrogen in a fuel cell, the oxygen for breathing on a Moon base or manned Mars missions while consuming our CO2 ...hell it is photosyntheses, you could also make human fuel in form of sugar and starch or other hydrocarbons and almost instantly, not like old Nature that needs six months to grow a grain of wheat.

[lsemmens]

It does seem strange that if Hydrogen and O2 get mixed it can go BANG, but if H2 and O re mixed we get the stuff that puts out the result of the BANG! It's all in the chemistry.

[Uncle Fester]

Here is another step further towards hydrogen production with the discovery of an extremely cheap catalyst:


Apparently the catalyst can also work directly from sunlight, so another approach to artificial photosynthesis using an-organic materials.

[trash]

it is just so volatile that makes it difficult to handle.

Well, that's just not true. It stores in a gas tank just fine without issue. It can be compressed, again without issue.
Though it takes a lot of energy to liquefy it to get good storage capacity out of it.

Even the tiny amount given off by a Car battery during charging, has exploded doing considerable damage.

But this is in exceptional circumstances where the hydrogen that has escaped has been trapped in the presence of oxygen (air).
I can show you an example of hydrogen burning with a candle flame just like LPG. And at the same time that flame serves as a wick on a bomb where the speed of the burn changes to >1000fps using nothing but hydrogen and air the whole time.

It does seem strange that if Hydrogen and O2 get mixed it can go BANG, but if H2 and O re mixed we get the stuff that puts out the result of the BANG! It's all in the chemistry.

There's nothing "strange" going on here. It's a simple exothermic reaction. Chemical energy is converted into thermal energy. The difference between the two is nothing but simple calculus.
Each burns and gives off the same energy. The difference "dt" is time. One burns fast, the other burns slow.

Petrol burns slow in an internal combustion engine. If the fuel burns too fast, the engine 'pings'. If we dump the contents of the car's fuel tank into the airspace 50m above the car, the FAE (fuel air explosion) is the petrol burning extremely quickly. Enough to weaponise it.

Diesel, another fuel that you can literally extinguish a flame in. Burns slowly when combined with oxygen under pressure. But add a solid oxidiser to it like NH4NO3, and it burns at extremely fast.

Hydrogen isn't popularly used because it's magically dangerous. It's not used because it's not very practical unless you have a lot of room to store it.


Imagine this scenario.
I have developed a new "lithium beryllium" battery. It's very light, and it is very cheap to make. 0.1 cent for a 1KWhr of storage. Which weighs just 10kg.
Wow, that would be awesome. But lets say that our 1kWhr of battery occupies 2 cubic metres of space.

This is the scenario that hydrogen faces.

[lsemmens]

The difference between the two is nothing but simple calculus.

Therein lies the problem. Calculus is anything but simple! I never could wrap my head around it. You write some numbers, draw a squiggly line, write some more numbers, make a great synaptic leap and come up with an answer. Not this little black duck! I understand the theory but that's about it.

[trash]

hahah... calculus is actually very simple. The problem is that people always want to tackle complex problems with it
A computer is just a machine that adds numbers, and people want to do mind boggling stupid complex stuff with them!

Calculus is basically all about how fast things change. That's pretty much it. (Ok, a bit about areas under curves too if you want to run it backwards)

[Uncle Fester]

Calculus is only a theoretical way to explain things we observe.

H2O is the end result of the exothermic reaction.
While the reaction is chemical the whole process is not.
To make it explosive again you need to add energy from an external source.
This energy is supplied here by the sun or electricity to separate the H and O.
Also how the energy is released depends on external physical factors.

Perhaps it helps to think a bit like a rechargeable battery if you like, only in reverse and ignoring any electrolyte.
The state of H2O becomes the electrodes. When it is charged it is H2 and O2 and discharges to H20, but
very fast if you want in the rocket motor or very slow in a fuel cell or a regulated flame.
The energy in a decent sized Li-ION battery can also be released quite fast if you short it and it will explode but still
a lot slower than the H2 O2 "Battery" can.

[trash]

Errr, the either process is chemical

Ether the energy is released as a photon or an electron.
If you burn hydrogen
2H2 + O2 → 2H2O + photon (heat)

If you react it in a fuel cell
Cathode: 2H2 → 4H+ + 4e– (electricity)
Anode: 4H+ + O2 + 4e– → 2H2O

To make it explosive again you need to add energy from an external source.

That's not quite correct, since adding energy from external source will enable it to burn.
"explosion" implies an exponential (and preferably high velocity and often uncontrolled) burn.
To do that the fuel and the oxidiser need to be in very close proximity (mixed).

That energy to start the reaction is in the form of a photon or an electron with enough energy.

In a fuel cell the reaction is initiated by a catalyst.
The fuel and oxidiser are aqueous ions. It's not possible for them to explode because (they're under water) the reaction is regulated by the flow of the electrons from the cathode to the anode.

---

I had a lithium battery "go rogue" on me last weekend. I have some pretty computer controlled addressable LED's on my roller skates.
They can chew a bit of power when they're running flat stick so I decided to run them off AA lithium instead of alkaline.
One of the AA cells had a failure and my skates caught fire.

It's rather confusing when somebody says "you're on fire" in an unfamiliar context.
Then to discover you are actually on fire causes your brain to react in very strange ways. Like an idiot I figured I could just shake my foot and flick the fire off.
The battery then turned into a rocket motor shooting out a lot jet of gas and sparks. You can imagine I was in a hurry to get this thing off my foot before it finally exploded

[lsemmens]

Thanks trash, I needed a laugh for the day! I can just imagine you hopping around on one skate watching the "fireworks"!

[Uncle Fester]

Is there a chance that a bystander caught your rocket skates experiment on their smartphone and can upload it on Utoob?

But see, even a normally slow recombination in an chemical reaction can turn into an explosion !


...but I agree I should have said " To make it POTENTIALLY explosive again you need to add energy from an external source."

[trash]

No. I had been making pretty coloured skate lights for a lot of people. The kids love them, girls of course like pink lights on their skates.
I make them in all colours and some even multi coloured. The ones I wear are addressable LED's so they change colours and patterns and are very psychedelic.

Of course everybody thought the pyrotechnics were a planned display and wasn't out of character for me.
Some of the kids said "That was cool trash! Do it again!"

I won't be doing it again, I'm sticking with AA Alkaines.