That still requires a heat differential to produce electricity, and thus works worse in the heat. (of course, having more intense sunlight will help make up for the loss in conversion efficiency)
Not sure that this is accurate, isn't the "work" in a boiler done by the phase transition to steam and the associated increase in pressure? Unless you're referring to a particular design of solar energy production.
There is no associated increase in pressure in the boiler typically. In fact, there's usually a pressure drop. The high pressure is created in the feedwater pumps for a steam system. The boiler converts liquid at high pressure to steam at high pressure. The steam volume then expands to perform work in a turbine. A salt-plant would probably use steam near 100bar and expand it through the turbine to below 1 bar (sub-ambient) such that the saturation temperature is as close to ambient temperature as possible.
There is a significant amount of work done at the last stages of the turbine (when going from +1bar -> 0.1 bar) so increasing the ambient temperature can have a noticeable on total cycle efficiency.
Yep, but that shouldn't be a big factor in the temperature ranges under discussion.
A mirror-based concentrator can reach 3,500 C (let's say 3,700 K, roughly, though it's closer to 3,800). That's the hot side. The cold side might be about 60 C at the most (the highest temperature recorded in the Sahara appears to be 57.7 C) or about 330 K. Compare to a temperate zone setup operating at say 20 C on the cold side (say, 300 K).
The first will have a maximum Carnot efficiency of 1 - 330/3700 = about 0.91, while the second will have 1- 300/3700 = about 0.92.
As you say, the more intense sunlight (and especially the lack of rainy days) will more than make up for this.
The biggest issue with PV is cost, but you're right about the concentrated heliostatic generators being an option. They have some significant advantages over PV but require large installations. Plus, molten salt is always cool.
If we're going to talk "immappancy" where's Alaska? The infographic mentions "USA" but only displays the continental USA while using the size of the entire USA (Alaska included) in the calculations.
There are a few omissions that the infographic does. The more blatant for Europe is that they left out Scandinavia, and the European part of Russia, while the text states clearly "all of Europe".
You certainly wouldn't have learned that from that infographic. :-)
Even if comparing countries to continents were valid, that map completely omits the two largest countries in the world, and only includes three of the top nine (#10 is an African country).
Also unsettling is how they say "all of Europe" is included. There is absolutely no way that chunk labeled "Eastern Europe" contains Ukraine, Belarus, Romania, Bulgaria, etc. It's large enough to maybe represent just the Ukraine.
Do children in other countries/continents answer more accurately on these questions? I'd also like to know the actual responses, since I highly doubt that the majority of American schoolchildren responded with exactly "largest in the world," unless it was a multiple choice exam, in which case I'd like to see all the available responses.
Thanks for that link :-D Was wondering a size comparison earlier while reading a HN post about Tesla superchargers (Texas vs Netherlands(my home) http://mapfight.appspot.com/texas-vs-nl)
There are no down arrows on submissions. They only appear on comments after users reach a certain karma threshold."
So I guess a collusion of puppet accounts in some script that automates upvoting can be used to game the system pretty easily without the story falling from grace for a while - as there exists no mechanism for the community to do so.
While there's no downvoting for submissions, they can be flagged by users with a certain karma level. Flagging acts like a heavily weighted downvote for moving a story down the list, and at a certain number of flag the story is made [dead] and no longer appears at all to most users.
Of course, flag too many of the wrong stories, like I apparently did, and you lose the ability to flag.
oh I indeed have the flag link. I thought that was only to be used in dire circumstances - like people posting a large stash of say, credit card information or child pornography - not for a story which I thought had bad science (such as this)
I flagged most non-tech political stories because I think they rarely lead to interesting conversations.
Apparently that was "abuse" of flagging. It would have been nice to have had some guidelines. Ah well, we still get plenty of political stories, and they still turn into 99% tribal warfare.
An appropriate comparison would be Asia, which is considerably larger than Africa. North America (which includes Canada and Mexico) is somewhat smaller than Africa, but not by much.
Russia, Canada, China, the United States, Brazil, Australia, India, Argentina, and Kazakhstan are all larger than any African country.
Africa is a heterogenous continent, with vast numbers of different cultures, languages, natural resources, climates...
Treating it any kind of unit doesn't make sense. It definitely doesn't make sense to compare it with unitary countries on any level, and even less sense to compare it on the basis of geographic size.
Canada is a huge country, but that's not why it's wealthy. The Netherlands is a tiny country, but that's not why it's wealthy, either.
It's all relative. I live in California, US. I know how big the US is relative to Cali... so I know how big United States is. I have a point of reference. Comparing Africa to USA gives me a way to mentally model what the difference in size means.
Comparing a continent to a country makes sense the same way that you might compare the size of a child to an adult. They don't have to be the same. You just know which of the two you are and get a sense of how big the other is.
OMG, I always wondered how come Greenland, such a huge piece of land, had nothing much going on with it. I always thought it to be very very big, because it is very very big. Now I realize that it is one-third the size of Australia. Makes me want to find a globe soon and compare.
Off topic. But does anyone know why it seems like countries and even states (like Florida, I'm from there) seem to have worse economies as they get closer to the equator?
Off topic. But does anyone know why it seems like countries and even states (like Florida, I'm from there) seem to have worse economies as they get closer to the equator?
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[ 3.3 ms ] story [ 212 ms ] threadThere is a significant amount of work done at the last stages of the turbine (when going from +1bar -> 0.1 bar) so increasing the ambient temperature can have a noticeable on total cycle efficiency.
Yep, but that shouldn't be a big factor in the temperature ranges under discussion.
A mirror-based concentrator can reach 3,500 C (let's say 3,700 K, roughly, though it's closer to 3,800). That's the hot side. The cold side might be about 60 C at the most (the highest temperature recorded in the Sahara appears to be 57.7 C) or about 330 K. Compare to a temperate zone setup operating at say 20 C on the cold side (say, 300 K).
The first will have a maximum Carnot efficiency of 1 - 330/3700 = about 0.91, while the second will have 1- 300/3700 = about 0.92.
As you say, the more intense sunlight (and especially the lack of rainy days) will more than make up for this.
There's a decent image of solar pressure across Africa on wikipedia: http://en.wikipedia.org/wiki/File:SolarGIS-Solar-map-Africa-....
Even if comparing countries to continents were valid, that map completely omits the two largest countries in the world, and only includes three of the top nine (#10 is an African country).
http://mapfight.appspot.com/africa-vs-au
http://mapfight.appspot.com/africa-vs-europe
http://mapfight.appspot.com/africa-vs-usc
Edit: The answer is "there are none". from http://ycombinator.com/newsfaq.html:
"Why don't I see down arrows?
There are no down arrows on submissions. They only appear on comments after users reach a certain karma threshold."
So I guess a collusion of puppet accounts in some script that automates upvoting can be used to game the system pretty easily without the story falling from grace for a while - as there exists no mechanism for the community to do so.
Of course, flag too many of the wrong stories, like I apparently did, and you lose the ability to flag.
So we get what we get.
Apparently that was "abuse" of flagging. It would have been nice to have had some guidelines. Ah well, we still get plenty of political stories, and they still turn into 99% tribal warfare.
An appropriate comparison would be Asia, which is considerably larger than Africa. North America (which includes Canada and Mexico) is somewhat smaller than Africa, but not by much.
Russia, Canada, China, the United States, Brazil, Australia, India, Argentina, and Kazakhstan are all larger than any African country.
Africa is a heterogenous continent, with vast numbers of different cultures, languages, natural resources, climates...
Treating it any kind of unit doesn't make sense. It definitely doesn't make sense to compare it with unitary countries on any level, and even less sense to compare it on the basis of geographic size.
Canada is a huge country, but that's not why it's wealthy. The Netherlands is a tiny country, but that's not why it's wealthy, either.
Comparing a continent to a country makes sense the same way that you might compare the size of a child to an adult. They don't have to be the same. You just know which of the two you are and get a sense of how big the other is.
My theory is that the harder life is the more successful it is. Which is the opposite of what you would expect.
In hot places shelter is not really needed, you don't need to store food for the winter, and you don't need as much food (although you do need water).
In cold places you have to plan for the winter, and that effort translates into improving your life in all things, not just shelter and food.
You might like this book: http://en.wikipedia.org/wiki/A_Fire_Upon_the_Deep
Also see: https://en.wikipedia.org/wiki/Resource_curse
The other maps in the collection are also interesting http://edge.org/documents/Edge-Serpentine-MapsGallery/
Whoever made this map under-represented the African island, even though the whole point is to highlight under-representation of Africa.