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Understanding Solar Energy

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261 points chmaynard | 2 comments | 20 Mar 25 12:09 UTC | HN request time: 0.415s | source
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Veedrac ◴[21 Mar 25 01:02 UTC] No.43430833[source]▶
The author misses a perhaps unintuitive point: the cost of storage depends also on the cost of energy. By the time you've overbuilt 2x, a full extra 100% of your demand is sitting around literally free at odd hours.

Traditionally, moving energy around means batteries, and yes maybe your battery costs more than just generating new electricity from a less efficient new solar panel at odd hours. But batteries are optimized for energy being expensive, where losses are wasteful.

Consider this really simple, dirt cheap alternative: plug your free energy into a pool of water and collect the hydrogen from it. Burn the hydrogen later, and point the light at your idle solar panels. It's hellishly inefficient, but I repeat: the energy is free. You are only minimizing capital costs, at least until other people catch up and start shifting load some other way.

The sane point on this curve probably looks something along the lines of a mix of batteries and synthetic fuels powering existing fossil fuel plants. The nice thing about going all the way to synthetic fuels and not hydrogen is that long term storage becomes trivially cheap, so it starts offsetting your winter load as well.

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pyrale ◴[21 Mar 25 08:59 UTC] No.43433329[source]▶
> It's hellishly inefficient, but I repeat: the energy is free.

Can you give pointers about who gives away hydrogen generation systems for free?

Because the cost of energy usually factors in the cost of amortizing equipment required to produce and distribute it.

> The nice thing about going all the way to synthetic fuels and not hydrogen is that long term storage becomes trivially cheap

Once you've financed all of the horribly expensive capital expenditure, and provided you disregard that operating costs actually require paying people to monitor, repair and operate that infrastructure, the rest is basically free.

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ben_w ◴[21 Mar 25 09:10 UTC] No.43433404[source]▶
> Can you give pointers about who gives away hydrogen generation systems for free?

If you don't care about efficiency (because the electricity is free), a 9 year old can make hydrogen generators out of old pencils and jam jars.

Citation: me, I did that.

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pyrale ◴[21 Mar 25 09:36 UTC] No.43433608[source]▶
I can also make some methane depending on what's on the lunch menu, but that doesn't mean cheap renewable natural gas is a solved problem.
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ben_w ◴[21 Mar 25 09:50 UTC] No.43433693[source]▶
Do you really not understand the point I'm making here?

The technical skills needed to make a device that turns water and electricity into hydrogen are so minimal that they can be performed by someone too young for you to be allowed to employ them.

When you don't care about efficiency, hydrogen is trivial.

The limiting factor is how much electricity you can shove through the water, not human effort.

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hnaccount_rng ◴[21 Mar 25 12:48 UTC] No.43435005{3}[source]▶
To be fair the problem with hydrogen isn't the production (that is ~free, once you have free energy at least some amount of time) but it's storage and then usage. Storage is a fundamental physics problem. Usage is something where low efficiency may or may not be a problem, depending on the over provisioning that we applied at the generation and storage stages.
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Matumio ◴[21 Mar 25 14:04 UTC] No.43435853[source]▶
Production is trivial, but storage and transport really isn't: https://climate.mit.edu/ask-mit/can-we-use-pipelines-and-pow...
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Calwestjobs ◴[22 Mar 25 00:11 UTC] No.43442054[source]▶
first of all, youre spreading misinformation.

storage is CHEAP AF. BUT not kind every misinfo guru from youtube tells you about.

this is cheaper - https://ethz.ch/en/news-and-events/eth-news/news/2024/08/iro...

also https://www.rotterdaminnovationcity.com/co2-neutral-living-i...

AND most importantly, WHY do you need to transport hydrogen ? You do not need. think about it. you get electricity to your plant, make hydrogen on site, store hydrogen on site for almost nothing. why do you need to transport anything ? you do not.

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1. Matumio ◴[23 Mar 25 15:18 UTC] No.43453500[source]▶
Interesting references, thanks. But both seem to be at the research and feasibility stage. From the ETH group's web page: (https://fml.ethz.ch/research/ses.html)

> To demonstrate the technical feasability of this process, we buildt a 10MWh pilot plant at ETH Hönggerberg. The first charing cycle, using hydrogen to reduce iron oxide to iron, was successfully completed over a time span of 4 months. The discharging cycle is currently ongoing.

So either they haven't managed to do a full cycle yet, or they are not updating their research page. It sounds like this should work, so I'm tentatively optimistic. But this looks like a technology you'd have to bet on, not yet a certain path to a commercial seasonal battery just waiting for mass deployment.

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2. Calwestjobs ◴[23 Mar 25 21:06 UTC] No.43455912[source]▶
ETH zurich is not inventing new reaction, google "reducing iron oxide by hydrogen". it is well known and already used technology. nothing new about this reaction, way they use it is new. all your concerns are answered in next article :

another university - university of eindhoven is using same reaction but totally different way - they just burn iron oxide in air ... https://www.youtube.com/watch?v=Qm0sIN-KhUo same thing same people - https://newatlas.com/energy/bavarian-brewery-carbon-free-ren... it is just totally primitive way and THAT is actually benefit. because it can be deployed fast and wide.

people seems to not understand how big of a energy demand is for hot water. and this can make hot water from renewable sources a reality. in most houses hot water need is roughly 50% of energy need. in low carbon houses / LEED / BREAM /Passive house / or what EU regulations already require, is energy need for hot water multiples of all other energy needs of household, because with better houses, youre lowering energy required for heating, cooling, but hot water stays same amount but bugger percentage.

planetary - with better buildings, we can lower house heating by 70-80 % no price problem, hassle free, that means we need less electricity generation for houses. + adding hydrogen generation / iron oxide reduction into mix we can just burn it and make hot water and electricity in winter from spring, summer, autumn sun.... in spring,summer,autumn you use PV for hot water + hydrogen to store for winter. booom 95+% of household consumption is gone from grid. household energy need is how much of total planetary energy need ? 20 or 40 % ? no one cares.

you do not need to transport anything if you think about this as for seasonal storage. but you can transport raw iron like university of eidhoven is proposing if your mission is to provide heat but reduce iron oxide close to renewable generation. your tansporting iron (Fe), NOT iron oxide(FeO,FeO2,FeO3)...