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Comment by edhelas | Hacker News Reader

> Nuclear power plants built in the 1970’s used 40 metric tons of steel, and 190 cubic meters of concrete, for each megawatt of average capacity.

> Modern wind energy systems, with good wind conditions, take 460 metric tons of steel and 870 cubic meters of concrete per megawatt.

https://www.nextbigfuture.com/2007/07/constructing-lot-of-nu...

First source I found.

Wind turbine lifetimes are 20 to 25 years at the best.

I agree for solar panels, they don't need lots of concrete and only loose efficiency over time. But you would need lots of them + a complete power storage system behind. So the cost and material used to have a similar power output is still order of magnitude higher.

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My first thought to this: can the turbines be made from wood instead? Searching for it, I found this:

https://newatlas.com/timbertower-wooden-wind-turbine/25007/

Making things out of wood is generally a good idea to save on carbon footprint. I have doubts you could build a nuclear power plant from timber given all the containment & shielding requirements.

Nice! But I bet it still uses a comparable amount of steel to the reactor reactor (in the blades), and I don't think replacing steel with wood would impact the concrete usage either.

I think the blades are mostly fiberglass these days?

Glulam wood can substitute for some uses of concrete, but I'm thinking it's probably not ideal for earth contact applications. Especially in places like Ohio, which we mentioned as an example in https://news.ycombinator.com/item?id=22181187

Can you find a source from, say, the last five years? I think wind turbines have changed substantially since 2007.

> But you would need lots of them + a complete power storage system behind. So the cost and material used to have a similar power output is still order of magnitude higher.

This turns out not to be true.

https://www.forconstructionpros.com/concrete/article/1088605...

https://www.forconstructionpros.com/concrete/article/1088605... is still 7 years ago, but it says they used 30,000 "tons" (probably about 27000 tonnes in modern units) of cement occupying 122500 "cubic yards" (94000 m³ in modern units) to support the 152 2-MW turbines of a 304 MW wind farm. That's 89 tonnes (though that number is probably wildly approximate) or 304 m³ per megawatt. This is a little more than the 190 m³/MW for nuclear plants cited by the 2007 NextBigFuture artcle, but a lot less than the 870 m³/MW for wind farms they cited.

So, if concrete requirements for wind farms dropped by two thirds from 2007 to 2013, what do you suppose they are today?

Dropped by 2/3 ok. For a lifespan of, 20 years ?

Again a power plant life expectancy is 3, maybe 4 times that. And you need to do the foundation once.

You don't replace a wind turbine over a wind turbine, you need to redo the foundations (the concrete is constantly stressed and fragilized through the years), same for a power plant (also for security purposes).

This doesn't count the concrete needed for the access roads and cables to connect everything. From the article "Lafarge also supplied 20,000 tons of Type I cement for soil stabilization of approximately 44 miles of roads".

Let's try to do the maths with a modern power plant as well. Knowing that you produce more energy than in the 70' with modern turbines and we have bigger plans as well on smaller areas.

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