Comment by tinco | Hacker News Reader

Comment by tinco | Hacker News Reader

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Base load in Germany is about 50GW, around 10GW of which is handled by wind and water. That leaves approximately 40GW to be handled by other means.

At 20MW per sphere, you need 2000 spheres to cover the entire base load. (Not sure where the article gets its 80 spheres number from, did I make a mistake? There's an order of magnitude difference..)

These spheres don't generate electricity, so you still need other (less constant) means of electricity generation. Germany generates solar electricity peaks of 50GW, so perhaps tripling that capacity could get them close.

Wind energy is around 20GW, but way much more constant, so tripling that could also get them close, and you could possibly do with a lot less spheres, perhaps closer to the 80 in that article.

So with a triple investment in green energy and the building of hundreds of these spheres, Germany might be able to make themselves a 100% renewable energy country. (Assuming my assumptions are close to reality)

Don't mix MWh and MW (it's commonly used to mislead, but not here). The article is declaring 20MHh of storage while using 5MW power turbine. 5MW output from 20MWh storage gives you 4h output.

Edit to add: If you want to make proper calculations, don't forget that these types of storages are very inefficient. You can't compare them with pumped hydro.

Ah thanks, I misread that. I get that these types of storages are inefficient, that's the point I was trying to emphasize, a solution like this looks interesting, but it's not a serious competitor to nuclear power, or even pumped hydro (it's basically pumped hydro, but with a human made reservoir).

it's not a serious competitor to nuclear power

How can you say that off-hand without knowing what the costs are? It's not at all obvious to me that building 3000 concrete spheres with turbines and a bunch of PV panels is any harder or more expensive than building giant nuclear power plants.

Each sphere is only worth 5 MW (for 4 hours, totalling 20 MW·h worth of electricity). 80 spheres were not meant to cover the entire base load, but just to make them a relevant factor in the grid.

>Not sure where the article gets its 80 spheres number from

That was their estimate on the minimum required to make the project economically viable, that's all.

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