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this post was submitted on 15 Aug 2024
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You don't need photovoltaics to use solar power. Never heard of the solar power tower? Or the ones using molten salt for heat storage?
The earth receives just over 1 billion watts of raw energy from the sun daily. Using that energy to boil steam to turn tubines caps that energy generation ability to 105,566,992 watts of power if we capture all the solar radiation that hits earth.
Humanity currently uses 17.5 terrawatts of power daily. How do you make up the 99% shortfall? Little hint, wind and hydroelectric isn't enough to make up that gap. Nuclear is currently our only option outside of asteroid mining.
Edited: I read the number wrong.
This makes zero sense. Do you mean terrawatt hour daily, or do you mean terrawatts averaged over a day? Terrawatts are a measure or power, not energy. Watts are joules per second. You can say you average a certain power in watts over a day.
Anyway since you can't be trusted with basic physics apparently I am going to work it out myself.
We generate around 180,000 TWh per year according to our world in data. That's about 493 TWh per day if we assume 365 days a year. That's the same as 1774800 terrajoules per day. Since we are looking for joules per second (watts), we can then divide by the number of seconds in a day, which is 86400 seconds. This gives us 1774800/86400 = 20 TW. So you somehow got close to the right anwser without actually understanding the units involved.
The part where you are actually way off the mark is the 1 billion watt figure. According to MIT the sun actually gives us 173,000 TW continuously, or 173 PW (pettawatts). So 20 TW is tiny in comparison. Obviously I don't expect us to capture all of that, but we are talking about things that aren't even in the same units, nevermind order of magnitude. How you managed to get this so utterly wrong I have no idea. Just looking at it I can tell that number isn't right, as China are planning to have 1200GW of solar capacity (that's 1200 billion watts) by the end of 2024 according to The Guardian.
Solar power towers are reported between 12% and 25% efficient at demonstration scales according to wikipedia. Yet you are claiming just above 1% efficiency. This dosen't sound like a great deal, but if you look into it photovoltaics aren't doing that much better. It turns out that current commerical products only offer around 21.5% according to this wikipedia article. This varies a lot depending on how old the panel is (they degrade), how it was built, what proportion is shaded, if it moves to track the sun and so on. Both of these technologies have room for improvement. Panel efficiency can vary anywhere from up to 40.6% down to as low as 8.2% wikipedia.
Edit: You have made youself an example of why we need more scientific and numerical literacy. How you got numbers so hilariously wrong is truly beyond me.
Got the numbers wrong because I relied on a quick search and got bad sources, apparently. I wasn't claiming 1% efficiency, I calculated it at a generous 28%. The 1% is what was being produced vs what DDG said we needed.
No you didn't. 28% percent of 1 gigawatt is 280 megawatts. I was incorrect to say 1%, but you didn't exactly get it right either. 106 megawatts (or 105,566,992 watts as you put it, which is weirdly specific) is closer to 10%. I beg you check both your sources and your maths in future before you reply to someone.