Twice the height of the Empire State - massive solar tower for AZ • Hacker News Board

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

#111

Post by ohyes » Mon, Jul 25, 2011, 3:47 PM UTC

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…

They are not using solar panels, they are creating a giant heat pump. They are therefore relying on there being a heat differential between the top and bottom of the tower.

Greenhouse gets hot, creates a pressure difference between inside the greenhouse and outside of the tower at the top, air flows up through turbines. It is very simple.

There are very few moving parts and it is always going to be colder at the top of the tower than at the bottom.

Note that it isn't pure desert floor, but a man made structure that will purposefully trap heat. Imagine how hot it would get if you sat in your car with the windows rolled up in the middle of the desert. Then think about how cold it would be at 2x the height of the empire state building.

It will be colder just because of the air pressure at that altitude. Even so, the ground cools at a much different rate than air does, so I'm sure night time generation is bolstered somewhat by that.

It will have a very high capacity factor because the only thing that you should ever have to 'fix' is the turbine, which should last quite a long time.

It seems likely that cf will be much higher than even that of nuclear.

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

#112

Post by cfgvjkljhgfb » Mon, Jul 25, 2011, 3:55 PM UTC

cfgvjkljhgfb wrote: post #18

sliverstorm wrote: post #3

60%? Darn. I was hoping for better after the hype earlier in the article. Don't large steam plants approach 99%? 150,000 US Homes Is that a lot? I hate to (continue to) be a cynic, but it doesn't sound like a lot.

It claims 200MW/150,000 homes = 1.3KW for a US home !!!! So homes in Arizona don't have AC or electrical appliances and are all owned by eco-warriors

Checked the figures and 1.3Kw is the average (24*365) for Arizona.

Surprising - when I lived in Houston you needed AC running 24x7 for 6months of the year and all the other appliances where electric.

I assume, being in the desert, Arizona is cooler at night and they use propane/oil heating in the winter?

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

#113

Post by mkr-hn » Mon, Jul 25, 2011, 4:16 PM UTC

This brings up an interesting possibility. What's stopping us from engineering these towers on to buildings once the technology is proven?

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

#114

Post by Symmetry » Mon, Jul 25, 2011, 4:25 PM UTC

ohyes wrote: post #111

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…

They are not using solar panels, they are creating a giant heat pump. They are therefore relying on there being a heat differential between the top and bottom of the tower. Greenhouse gets hot, creates a pressure difference between inside the greenhouse and outside of the tower at the top, air flows up through turbines. It is very simple. There are very few moving parts and it is always going to be colder at the top…

It might continue to generate during the night, but I would be very surprised if its nighttime capacity was even a quarter what it generated during the day. Also, the glass will need to be cleaned periodically.

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

#115

Post by Symmetry » Mon, Jul 25, 2011, 4:33 PM UTC

mkr-hn wrote: post #113

This brings up an interesting possibility. What's stopping us from engineering these towers on to buildings once the technology is proven?

The huge area of glass enclosed space that needs to spread out from around the tower.

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

#116

Post by cturner » Mon, Jul 25, 2011, 4:36 PM UTC

mcdaid wrote: post #82

I wonder what effect this could have on the local climate. Pumping out hot air into cool air at height of 800 metres has got to have some affect. Now if the base is used area is used for growing plants then the air emitted at the top would be moist, which I imagine would cause cloud formation as it meets the cold air.

I'm having lots of thoughts about climates within the rings.

I'd expect the temperature ranges to change at different distances frmo the centre. It may be that you could do agriculture at some points underneath.

On the other hand, it's likely that for best efficiency they'll need to create as much momentum as possible from the device.

But - the venturi effect will be significant underneath and they might need to shape the land in sections under the rings. Is it possible you could hide crops within glass casings that improve that effect?

Will water vapour collect at any point in particular?

I'm considering a science fiction plot based around people who live in housing built around energy towers like this.

When this is built, I'd be interested to do a roadtrip to see it.

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

#117

Post by jws » Mon, Jul 25, 2011, 4:46 PM UTC

knowtheory wrote: post #14

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…

Seems to me like you'd need to keep all the glass clean too, which means more manpower & water/air power to get all the crap off. I'd be quite curious what the actual maintenance costs will be. Still, no feedstock into the process means that you'd have to have pretty serious component failure to bring the running costs up to oil plants presumably.

If I had that much glass to clean I'd certainly have robots doing it.

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

#118

Post by CapitalistCartr » Mon, Jul 25, 2011, 4:47 PM UTC

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…

From Enviro's Web site: "A single 200MW Solar Tower power station will provide enough electricity to power around 100,000 households, similar to the number of homes in a city the size of Burbank (California, USA) or Palm Bay (Florida, USA)."

They're saying, 100k, not the 150 from the article. That seems more realistic.

From the Phoenix Business Journal: " . . . air is funneled up the tower at 35 mph past 32 wind turbines at its base . . . " http://www.bizjournals.com/phoenix/print-edition/2010/10/29/... That's a pretty impressive air velocity.

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

#119

Post by geuis » Mon, Jul 25, 2011, 6:15 PM UTC

patrickk wrote: post #76

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…

Hey geuis, I'm the guy who submitted that story ;) It was in Libya during WWII that it happened: http://news.ycombinator.com/item?id=2475048

Awesome! Thanks

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

#120

Post by chrisvale » Mon, Jul 25, 2011, 7:18 PM UTC

bh42222 wrote: post #105

dlikhten wrote: post #48

Earlier quoted context omitted.

... fuck yeah! Honestly though, why compete just to show off? There its making money as the tallest structure, here it will be completely isolated, nobody comes here, whoopteedoo. Here it is also all about cost-benefit. There will be no tourism.

There will be no tourism. I'd want to see it if I am in Arizona! But I don't care if it is tallest structure in the world, I'm in it for the power engineering.

me too! did you notice what looked like a "viewing ring" at the top of the tower in the video? i wonder what all the wind sounds like up there, and if birds will circle it all day, etc.