If hydrogen can escape from earth, then is it really a renewable source of energy?

Factual Questions
1

I understand that it could take an extremely long time, but if we get into the habit of making sure large amounts of hydrogen are available for our energy consumption needs, then doesn’t that mean there’s a potential that we could actually lose much of the planet’s hydrogen?

If so, what kind of effect could this have on the planet? would our mass decrease? Would it affect the availability of water? Is this really not worth worrying about? :dubious:

If a tanker carrying hydrogen crashes, are the contents lost to the planet forever?

2

Hydrogen as a power source isn’t (generally) captured, it’s produced.

One common source is plantlife. Plants are a renewable source.

3

true, but the hydrogen doesn’t appear out of nowhere - it comes from water mostly and is bound up with carbon as the plant grows. It’s not really produced as much as repurposed…

4

Let’s suppose that when generating hydrogen, 1% floats away and is lost forever.

Let’s further suppose that all of the world’s energy uses hydrogen combustion as an intermediate step.

According to Wikipedia, world energy consumption in 2005 was 5x10^20 Joules.

According to this article, the combustion of hydrogen yields 700,000 Joules per 5 grams of Hydrogen.

So how much hydrogen would one need to burn to generate enough energy for a year (2005)?

I guess that would be (5 x 10^ 20) Joules * 5 grams of Hydrogen / 7 x10^5 Joules.

That’s about 4 x 10 ^15 grams of Hydrogen or 4 x 10^12 kg of hydrogen.

Since I assumed a 1% loss rate, that means we would lose approximately 4 x 10^10 kg of hydrogen per year.

One obvious source of hydrogen is water, so one can ask how much water that’s equivalent to. The atomic mass of oxygen is apparently about 16 times that of hydrogen. So one would need to electrolyze 18 kilograms of water in order to get 2 kg of hydrogen.

So one would need to electrolyze approximately 4 x 10^11 kg of water to account for hydrogen losses for 1 year. That’s approximately 4 x 10 ^14 cubic centimeters of water.

How much water is in the oceans? According to Wikipeda, it’s about 1.3 x 10 ^ 9 cubic kilometers. That’s about 1.3 x 10^24 cubic centimeters.

So a year’s worth of hydrogen losses is approximately 3 x 10 ^ -10 of the oceans, by my calculation, or less than a billionth.

So it looks to me like we’d be pissing in the ocean, so to speak.

But feel free to correct my math.

5

What with rising sea levels and all, surely this is a good thing? Every little helps! :slight_smile:

6

No. Once it’s released into the atmosphere, much of it will probably be metabolized by microbes in the soil. Another big portion of it will recombine with OH radicals. I believe only a small percentage escapes to space.

Regardless of what a hydrogen-filled balloon looks like, it’s not easy for a single hydrogen atom to just float upward- it has to collide with lots of other stuff along the way. And there’s lots of stuff to collide with the closer you get to the surface of the earth. Only the hydrogen atoms that manage to make it to the exosphere (where there’s not so much stuff around to collide with anymore) have a clean shot at escaping.

7

How fast is hydrogen being created through radioactive decay?

8

It’s not, really — a few isotopes can decay via proton emission, but it’s an exceedingly rare in exceedingly rare isotopes. Are you perhaps thinking of helium?

9

Nah, I’m just not big on physics. I assumed that decay to hydrogen would be fairly common.

10

What would 4 x 10 ^14 cubic centimeters of water look like, a cubic football feild, something bigger?

11

It would be 4*10^8 cubic metres, or a cube around 740 metres a side.