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Twice the height of the Empire State - massive solar tower for AZ

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Re: Twice the height of the Empire State - massive solar tower for AZ

#51

Post by jhchen »

Spyro7 wrote: post #40

I love this technology a whole lot , but this is Hacker News so it is worthwhile to think critically about this kind of "press release"-style news posting. This article does a bit of hand waving with the numbers, and, while this is an amazingly cool project, I think that they are overselling its benefits. First, let's get the terminology right. This plant has a capacity of 200 MW. That does not mean that it produces…

The most exciting claim to me was how efficient and robust this method of harnessing solar was. In particular:

- "Because it works on temperature differential, not absolute temperature, it works in any weather"

- "Because the heat of the day warms the ground up so much, it continues working at night"

- "It requires virtually no maintenance - apart from a bit of turbine servicing now and then, the tower "just works" once it's going, and lasts as long as its structure stays standing"

If these claims are true, then it would make sense for this plant to have a much higher capacity factor than most solar plants given that the major factors lowering CF is mitigated in this design (works at night and no shutdown for maintenance). Maybe I'm stuck in CS land where we think by factors of 10 but the numbers in this article doesn't seem too far off the beaten path.

Re: Twice the height of the Empire State - massive solar tower for AZ

#52

Post by aik »

Spyro7 wrote: post #40

I love this technology a whole lot , but this is Hacker News so it is worthwhile to think critically about this kind of "press release"-style news posting. This article does a bit of hand waving with the numbers, and, while this is an amazingly cool project, I think that they are overselling its benefits. First, let's get the terminology right. This plant has a capacity of 200 MW. That does not mean that it produces…

Appreciate the analysis, however I believe you made a fairly significant error with the solar capacity percentage. Unlike other solar power, the cool thing about this structure is that it doesn't specifically require constant sunshine to work effectively being that it works off the temperature differential through the tower, rather than pulling energy strictly from solar panels. Because of this, I would imagine capacity to be much nearer to 100% than the opposite.

"for every hundred metres you go up from the surface, the ambient temperature drops by about 1 degree. The greater the temperature differential, the harder the tower sucks up that hot air at the bottom - and the more energy you can generate through the turbines... Because the heat of the day warms the ground up so much, it continues working at night;"

As for how the difference in temperature between the surface and 100s of meters in the air changes throughout the day/night, I don't know.

So according to your equation, at 80% capacity, it could cover 128k homes. At 93.3% capacity it'd reach 150k.

Re: Twice the height of the Empire State - massive solar tower for AZ

#53

Post by pyre »

ajkessler wrote: post #35
geuis wrote: post #28

Earlier quoted context omitted.

Desert environments are extremely good at preserving things, particularly technological devices. http://maps.google.com/maps?q=Mojave,+CA&hl=en&ll=35... The above link shows an aircraft storage facility in Mojave, California. There are a number of such facilities in the US, and many more worldwide. It was discovered some decades ago that you can leave a plane in the desert for years at a time, and when you come back…

I'm pretty sure that was part of the plot from The Mummy? :) In any case, desert is great for preserving stuff in terms of low humidity (ie things don't rot). Not so good for preserving stuff in terms of them getting sand blasted. Especially in AZ where winds routinely hit 100mph+ during gusts and 60mph during windstorms. Not to mention the haboobs. Also, the prototype of this tower in Spain figured out that the plas…

  > I'm pretty sure that was part of the plot
  > from The Mummy? :)
http://en.wikipedia.org/wiki/Lady_Be_Good_(aircraft)

Re: Twice the height of the Empire State - massive solar tower for AZ

#54

Post by illumen »

kylec wrote: post #29

The Arizona tower will be a staggering 800 metres or so tall - just 30 meters shorter than the colossal Burj Khalifa in Dubai, the world's tallest man-made structure. Is there any reason why this can't be constructed to be 831 meters tall to edge out the Burj Dubai?

Because, the building in Dubai will grow to 832 meters once they're done.

Re: Twice the height of the Empire State - massive solar tower for AZ

#55

Post by viggio24 »

geuis wrote: post #28
ajkessler wrote: post #12

Really? Very cool idea, but some of the claims sound downright ridiculous. First, the zero maintenance claim that is touted at least 3 times by the article seems suspicious. You can't really leave anything out in the desert sun and not have to maintain or replace it. Sun will disintegrate a lot of material, not to mention wind and sand. Anybody have any info or insight into what material they are using to create the…

Desert environments are extremely good at preserving things, particularly technological devices. http://maps.google.com/maps?q=Mojave,+CA&hl=en&ll=35... The above link shows an aircraft storage facility in Mojave, California. There are a number of such facilities in the US, and many more worldwide. It was discovered some decades ago that you can leave a plane in the desert for years at a time, and when you come back…

The Italisn S79, lost in Libya desert during Ww II and found many years later during some petrol research. Article in italian: http://www.locotoco.altervista.org/Viaggi/libia_1997-98/s79....

Re: Twice the height of the Empire State - massive solar tower for AZ

#57

Post by ahlatimer »

tedkimble wrote: post #43
ianterrell wrote: post #6

Earlier quoted context omitted.

The Census says there are 110,692,000 occupied homes in the US, so 150k is 0.136% of that.[1] That means that there would need to be 738 of them to meet demand. Now, the EIA says there are about 5700 power plants currently operating in the US [2]. Continuing with the back of the envelope math, that's almost 8 times as many as would be necessary if they all produced as much as this one. Pick whatever factor you want f…

So at $750 million a pop, that's a little over $550 billion to power US homes. Or, roughly 50% of the annual budget of the military to power all US homes for 80 years! Clearly back of the envelope numbers, but definitely something to be excited about.

Well, you can't only have these things powering US homes because I can't imagine they work that well at night.

Re: Twice the height of the Empire State - massive solar tower for AZ

#59

Post by serichsen »

Big toy.

For one, maintenance will _not_ be low. Wind turbines (and nothing else is used here) do have quite some maintenance costs, and additionally, you need to keep the greenhouse clean.

The main problem I see is the capacity. 200 MW peak capacity at 60% efficiency translates to 120 MW peak electric energy. If we assume 50% capacity factor (which I suspect is _very_ generous), we arrive at 60 MWe average output. You would need 15 of these to substitute for a single 1 GW nuclear plant.

Big toy.

Re: Twice the height of the Empire State - massive solar tower for AZ

#60

Post by Retric »

Spyro7 wrote: post #40

I love this technology a whole lot , but this is Hacker News so it is worthwhile to think critically about this kind of "press release"-style news posting. This article does a bit of hand waving with the numbers, and, while this is an amazingly cool project, I think that they are overselling its benefits. First, let's get the terminology right. This plant has a capacity of 200 MW. That does not mean that it produces…

IMO the most significant oversight efficiency of around 60% figure which is ridiculously high. Solar towers are vary low efficiency heat engines and have trouble reaching 1% efficiency (yes 1% efficiency ). The 38 km² collecting area is expected to extract about 0.5 percent, or 5 W/m² of 1 kW/m², of the solar power that falls upon it. http://en.wikipedia.org/wiki/Solar_updraft_tower
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