Hacker News Reader

Comment by heisenbergs | Hacker News Reader

This is obviously great new tech, though one shouldn't see this as a solution to global warming. Until we find a cheaper scale-able way of producing hydrogen that doesn't come from hydrocarbons, this isn't really a solution. Might as well burn the the hydrocarbons directly...

View on HN

Producing hydrogen when there is excess power from renewable source could be a great addition to the mix of "how to store energy when we produce more than we need, and use it when we need it".

I don’t understand why this isn’t the answer to the problem of excess renewable energy at the times we don’t need it?

Because of security. Hydrogen is pretty dangerous, much more dangerous than anything else.

Is it that much more dangerous than say LPG though?

Is security the reason that hydrogen vehicles haven’t taken off yet, or is it a question of infrastructure?

Just compare hydrogen cars with electric cars and you'll see why people prefer electric. CA has 33 hydrogen refueling stations, so many people in CA could get by with one.

Well, security is fixable. It's hydrogen after all and not a heavy gas; in case of leaks it goes up not down. leaks are still dangerous as it explodes when being mixed with oxygen. the flames are invisible, you only feel being burned but you don't see it.

but the biggest problem is psychological: The Hindenburg, still

Mostly because of the cost associated with turning electricity into hydrogen. Which I hope will be coming down in future.

For simple grid storage the efficiency is just bad. The electricity-hydrogen-electricity round-trip efficiency is about 60%, pumped hydro or batteries can do better.

So it's only worth it if you have other uses for the hydrogen or need longer-term storage, e.g. gas reservoirs.

Plus any infrastructure you build will have to be overprovisioned because by definition it'll be designed to absorb peaks and run idle the rest of the time, which makes it even less profitable.

One way it's used in France is pumping water from below hydroelectric dams to above, so the water can be reused by the dam during the day to produce electricity.

That's great, where it's feasible. Which isn't enough places, as you need abundant water, a higher reservoir, and a lower reservoir.

You can say the exact same thing about electric cars.

Hydrogen is not a primary energy source, it is an energy storage and distribution tech, just like batteries.

Yes, except you need to produce about 3x more energy for the hydrogen powered car to get the same range as the battery powered ev.

If the price of grid energy is negative, it pays to produce hyrdogen from it.

Not if the hydrogen comes from hydrocarbons, which right now is all hydrogen. In this case, it's just an inefficient proxy for fossil fuels...

... and for those wondering why: it's so inefficient to produce hydrogen with electricity that, even if you have to pay a carbon tax, it's currently almost always produced using natural gas.

That's why it's stuck in the demonstration phase, essentially.

hydrogen comes from hydrocarbons, which right now is all hydrogen

It's not! the Scandinavians are investing in "green" hydrogen, you should look at the photos of the giant electrolysers in this PDF: http://hydrogenvalley.dk/wp-content/uploads/2017/09/FCB-CPH1...

Ok, replace the energy source with a solar panel. The only thing this is doing is acting like a battery.

Exactly! If we can improve the methods of generating hydrogen, fuel cells have the potential to act as versatile, phenomenally efficient, dirt-cheap batteries, without all the issues of limited metals and dirty production - Being a better battery is a huge deal.

The reason that fuel cells are so expensive is because of limited metals. The best fuel cells are made with a lot of platinum. If fuel cells were cheap and did not need the use of limited metals, then they would be a huge deal. Until then, how you produce the hydrogen is a minor detail. (Maybe there have been amazing advancements in fuel cell tech since I last looked into it. Any links?)

Batteries don't do that great with the limited metals problem either.

The bigger issue for railroads is range; current battery operated trains have a range of about 40km, whereas this hydrogen train has a range of 1000km. You could have charging stations at every station, but then you run into issues if the distance between stations is more than 40km, or if the charging equipment at a station becomes broken.

The problem is that any non-fossil fuel derived hydrogen made from solar/wind loses more than 60% during conversion. Compare that to lithium with around 10% loss that includes outputting the energy (hydrogen would lose even more).

Hydrogen is a terrible battery with very little chance to catch up to current battery tech.

I looked for a "source of hydrogen" diagram/paragraph in the linked pdf but it's nowhere mentioned. They just call it "green" hydrogen, so I am left with the belief that it's sourced from water electrolysis, is that so?

Hydrocarbons too: longterm storage, with the sun as primary energy source.

Not a moot point, since depleting them has consequences.

Could you please expand on this? My understanding was that hydrogen was produced through electrolosys. What process does one use to go from a hydrocarbon to H2? And does that process produce CO2?

Unfortunately, the electrolysis of water is not efficient enough to produce enough H2 on an industrial scale at the moment. Most H2 is produced by steam reforming of gas: https://en.wikipedia.org/wiki/Hydrogen_production https://en.wikipedia.org/wiki/Steam_reforming

The first link says that the efficiency is 80%. Seems like that’s enough to scale, especially if electricy prices go negative during peak hours of renewable energy production. So I’m still trying to understand what the roadblocks to this are.

Historically it was the most expensive approach thanks to the high cost of electricity and higher initial capital. Here is a pretty easy to skim paper on the cost breakdown from 1980: https://pubs.acs.org/doi/pdfplus/10.1021/bk-1980-0116.ch001

The approach is quite competitive technologically and the efficiency is there but the problem is electric cost. Thankfully renewables are bringing that cost down so some areas with very cheap electric could support such manufacturing.

It's still a lot cleaner than diesel!

Why? That hydrogen most likely is created with fossil fuels, you don't avoid emissions. Actually, you will create more because the energy density of hydrogen is lower than the density of diesel, mostly due to the heavy storage tank. In other words, you need more energy per mileage to move the trains because the weight of the trains is heavier which leads to more emissions.

I think a lot of people are missing the point. A higher demand for hydrogen will incentivise companies to improve the production methods for hydrogen, hopefully with a more conscious effort to keep it green, i.e. Improving electrolysis methods.

Nobody is claiming that all hydrogen is greener than diesel, the point is hydrogen has the potential to be vastly greener than diesel, and the best way to explore that in a capitalist society is to increase the demand for it.

A small disclaimer, I know nothing about hydrogen.

Upvoted for honesty

With the steady uptake of solar panels on private homes and wind energy, it is not too far of a stretch to envision hydrogen production whenever there is more energy returned to the grid than needed.

I don't like these in-the-grand-scheme-of-things-everything-is-the-same. There is a difference between emissions from a power plant and emission from diesel cars in densly populated cities. Just step outside.

In the grand-scheme-of-things the universe will cool out either way.

Reply on news.ycombinator.com