Are solar panel and wind turbines clean ?
They need to be changed often, they use lots of concrete (especially for wind turbines), they need lots of materials and have a quite low power factor (10-20%).
They need to be changed often, they use lots of concrete (especially for wind turbines), they need lots of materials and have a quite low power factor (10-20%).
How many tonnes of concrete per megawatt do wind turbines use, and how many do nuclear power plants use? Solar plants used to use a lot of concrete, but they no longer do.
"Power factor" is an attribute of electrical loads, not electrical generating equipment; it describes how far the load's current consumption deviates from the perfect in-phase sine wave of, say, a resistor. Perhaps you meant "capacity factor", the ratio of average power produced to peak power produced. Typical capacity factors for wind turbines are in the vicinity of 35%, although some offshore wind farms reach 60%. Photovoltaic plants typically have a capacity factor of around 25%, though in sunny places like Arizona and California it can exceed 30%. In the US, the lowest PV capacity factors are in Maine, which averages 12%. Germany's average PV capacity factor is 10%. Natural gas peakers are around 9%.
https://en.wikipedia.org/wiki/Capacity_factor
I've already thoroughly demolished this nonsense about "need to be changed often" in the case of photovoltaic panels. I don't know what wind turbine lifetimes are. Shorter, I imagine, but they still have a much higher ERoEI than PV or in fact any other power source.
> 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.
> 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.
So, if concrete requirements for wind farms dropped by two thirds from 2007 to 2013, what do you suppose they are today?
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.
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.
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
The low capacity factor (it's actually around 30% for new solar and 50+% for wind) is already accounted for in the levelized cost of energy. LCOE from renewables is a factor of 3-4x lower than from new nuclear.
I looked for some reference material and I found a "rule of thumb" which claims that PV panels lose about 1% efficiency per year of operation and can last 25-30 years.
Nuclear power stations (in China) are designed for a 40 to 60-year operating life.