1732: "Earth Temperature Timeline"

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ijuin
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Re: 1732: "Earth Temperature Timeline"

Postby ijuin » Sun Sep 25, 2016 2:03 am UTC

gmalivuk wrote:
bob443@mahaska.org wrote:Little bit of a correction for you here
As seems usual for this aspect of the denialist position, you seem to have missed the fact that (maybe-)humans being able to survive in a warmer Earth is not remotely the same thing as modern civilization being able to continue uninterrupted through a return to those temperatures on a much shorter timescale.


Civilization is not going to disintegrate from the consequences of warming. The real issue (aside from needing to spend trillions of dollars to build big Netherlands-style sea walls to protect coastal cities should sea levels rise) is that we may end up having twelve billion people to feed but only enough crop yields to feed ten billion in a non-malnourished state. This will result in the "excess" two billion (likely the poor in the Third World) being left to starve, and potential revolutions and wars happening when they realize that we are, in fact, leaving them for dead.

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Crissa
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Re: 1732: "Earth Temperature Timeline"

Postby Crissa » Sun Sep 25, 2016 5:37 am UTC

Tyndmyr wrote:Facts are facts. If you only accept them when people are nice, you're ...

Funny that, you tend to discard facts to be argumentative.

Weirdly you think that wind and solar not only have to be cheaper than fossil-fuel generators, they have to be done without generators.

Funny.

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Re: 1732: "Earth Temperature Timeline"

Postby Crissa » Sun Sep 25, 2016 6:05 am UTC

Also, you realize that the calculations vs the cargo ship being solar powered also 'proves' you can't power it with oil?

To generate 200MW you'd need 5 million gallons of diesel. Which seems a bit excessive, don't you think?

That's because ships don't use all their power at once, but in bits and starts.

Obviously we couldn't run them with 2.8MW of solar panels sitting topside... At least, not at their current speeds and reliability. But it isn't impossible.

-Crissa

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Re: 1732: "Earth Temperature Timeline"

Postby niauropsaka » Sun Sep 25, 2016 8:22 am UTC

That "third of fossil fuel use" that goes to transportation? Most of that isn't actually goods shipping, is it? Once we get automobile fleets onto hydrogen fuel cells, or lithium-ion batteries, or even compressed air tanks--any of which will run off an expanded renewable energy sector--then it's not so hard to have diesel production for seaships specifically. And it could be biodiesel.

When you start talking about the need for fuel for ships, I think you're trying to find a scary problem where there isn't really that hard a problem.

The real issue is how to scale up renewable energy production.

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Re: 1732: "Earth Temperature Timeline"

Postby morriswalters » Sun Sep 25, 2016 10:20 am UTC

Eebster the Great wrote:Do you really think tee shirts were the only commodity shipped over seas?
No, but it is a great shorthand for saying exactly what you are saying in one sentence.
ijuin wrote:Civilization is not going to disintegrate from the consequences of warming.
The rest of your paragraph belies that statement. Two billion people starving would be a good marker for the collapse of civilization.
Crissa wrote:Obviously we couldn't run them with 2.8MW of solar panels sitting topside... At least, not at their current speeds and reliability. But it isn't impossible.
Yet speed and reliability are what makes current ocean trade possible.

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Re: 1732: "Earth Temperature Timeline"

Postby Sableagle » Sun Sep 25, 2016 1:26 pm UTC

ijuin wrote:Civilization is not going to disintegrate from the consequences of warming. The real issue (aside from needing to spend trillions of dollars to build big Netherlands-style sea walls to protect coastal cities should sea levels rise) is that we may end up having twelve billion people to feed but only enough crop yields to feed ten billion in a non-malnourished state. This will result in the "excess" two billion (likely the poor in the Third World) being left to starve, and potential revolutions and wars happening when they realize that we are, in fact, leaving them for dead.


Ten billion? With rainfall becoming more unpredictable, with more localised torrential downpours and area droughts, more years with no rain in some places and more whole villages being rinsed into the sea, more cities being flooded by "yet another record-breaking" hurricane, more reservoirs running dry on one side of a range while the other side has bridges getting smashed to bits by the floodwaters, the whole of Bangladesh unusable for agriculture due to groundwater salination, rivers drying up, twelve billion people wanting drinking water, heat and road fuel, oil reserves getting harder and riskier to extract, another five billion people wanting homes with gardens and off-road parking and a billion people having to move inland due to flooding of coastal cities, you think we'll be able to sustainably feed ten billion?

Let's have some current stats so we have some idea what we're looking at:

Hunger Statistics
The vast majority of the world's hungry people live in developing countries, where 12.9 percent of the population is undernourished.
Sub-Saharan Africa is the region with the highest prevalence (percentage of population) of hunger. One person in four there is undernourished.
One out of six children -- roughly 100 million -- in developing countries is underweight.

2016 World Hunger and Poverty Facts and Statistics

Code: Select all

Number of undernourished and prevalence (%) of undernourishment

                         1990-2 No.          1990-2 %            2014-6 No.          2014-6 %
World                  1,010.6               18.6                794.6               10.9
Developed regions         20.0               <5                   14.7               <5
Developing regions       990.7               23.3                779.9               12.9
Africa                   181.7               27.6                232.5               20.0
     Sub-Saharan Africa  175.7               33.2                220.0               23.2
Asia                     741.9               23.6                511.7               12.1
     Eastern Asia        295.4               23.2                145.1                9.6
     South-Eastern Asia  137.5               30.6                 60.5                9.6
     Southern Asia       291.2               23.9                281.4               15.7
Latin America & Carib.    66.1               14.7                 34.3                5.5
Oceana                     1.0               15.7                  1.4               14.2


Source: FAO The State of Food Insecurity in the World 2015 p. 8



1 Central Africa 121.11
2 DR Congo 119.40
3 Sierra Leone 112.66
4 Angola 90.00
5 Somalia 83.15
6 Burundi 78.24
7 Chad 61.57
8 Eritrea 58.04
9 Kenya 56.68
10 Niger 56.01
11 South Sudan 52.53
12 Equ. Guinea 51.61
13 Mali 48.68
14 Ethiopia 48.19
15 Comoros 46.55
16 Sudan 46.47
17 Congo 46.23
18 Djibouti 41.77
19 Zambia 40.84
20 Cote d Ivoire 39.40

153 Germany 0.11
154 Hungary 0.11
155 Russia 0.11
156 Estonia 0.10
157 South Korea 0.10
158 United Kingdom 0.10
159 Serbia 0.10
160 Cyprus 0.06
161 Ukraine 0.05
162 Finland 0.04
163 Lithuania 0.03
164 Slovakia 0.02
165 Singapore 0.02
166 Austria 0.01
167 Croatia 0.00
168 Kuwait 0.00
169 Malta 0.00
170 Moldova 0.00
171 Slovenia 0.00
172 Macedonia 0.00


So, it seems you're right about which part of the world loses the most people to starvation every year. T.I.E.: Thit Izz Iffricker, as Danny Archer might put it.

I don't think that problem would stay out of "your" country, though, and when it comes down to fighting over access to a stream, it's a war of annihilation, and that looks more like ... well ...

Trigger warning: war of annihilation.

(duh)


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That's right. They'll kill your cat too!
Even the bloody British wouldn't do that ... unless it was a Mel Gibson film, of course.


So, er, let me just check something.

1.
an advanced state of human society, in which a high level of culture, science, industry, and government has been reached.
2.
those people or nations that have reached such a state.
3.
any type of culture, society, etc., of a specific place, time, or group:
Greek civilization.
4.
the act or process of civilizing, as by bringing out of a savage, uneducated, or unrefined state, or of being civilized :
Rome's civilization of barbaric tribes was admirable.
5.
cultural refinement; refinement of thought and cultural appreciation:
The letters of Madame de Sévigné reveal her wit and civilization.
6.
cities or populated areas in general, as opposed to unpopulated or wilderness areas:
The plane crashed in the jungle, hundreds of miles from civilization.
7.
modern comforts and conveniences, as made possible by science and technology:
After a week in the woods, without television or even running water, the campers looked forward to civilization again.


Huh.

verb (used without object), disintegrated, disintegrating.
1.
to separate into parts or lose intactness or solidness; break up; deteriorate:
The old book is gradually disintegrating with age.
2.
Physics.

to decay.
(of a nucleus) to change into one or more different nuclei after being bombarded by high-energy particles, as alpha particles or gamma rays.

verb (used with object), disintegrated, disintegrating.
3.
to reduce to particles, fragments, or parts; break up or destroy the cohesion of:
Rocks are disintegrated by frost and rain.


Huh.

...

Huh. Civilization looked pretty f'king thoroughly disintegrated to me in those examples.

So ... what? You think none of that could happen again because 9/11 changed everything?
Oh, Willie McBride, it was all done in vain.

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Re: 1732: "Earth Temperature Timeline"

Postby gmalivuk » Sun Sep 25, 2016 1:42 pm UTC

Crissa wrote:Also, you realize that the calculations vs the cargo ship being solar powered also 'proves' you can't power it with oil?
No, it really doesn't.

To generate 200MW you'd need 5 million gallons of diesel. Which seems a bit excessive, don't you think?
The first sentence doesn't make sense because your units don't match. You could generate 200MW with one gallon of diesel if you burned it entirely in three-quarters of a second. It would take 5 million gallons to generate that power continuously for 44 days, but then that's why the 200MW ship we were talking about uses a pair of nuclear reactors.

Big container ships burn hundreds of tons of fuel per day, which indeed does "seem excessive", but what relevance does such a subjective "seeming" have to this or any other ostensibly fact-based discussion?
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Re: 1732: "Earth Temperature Timeline"

Postby Eebster the Great » Sun Sep 25, 2016 2:28 pm UTC

I suppose it's true that you could use biofuels to power ships, with comparable performance. In the status quo there is no real benefit to using biofuel, but in a world where all other farm equipment, transportation, and electricity generation was already carbon neutral, then biofuel would be carbon neutral too.

That might be more realistic than the nuclear option.

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Re: 1732: "Earth Temperature Timeline"

Postby morriswalters » Sun Sep 25, 2016 4:10 pm UTC

gmalivuk wrote:[The first sentence doesn't make sense because your units don't match. You could generate 200MW with one gallon of diesel if you burned it entirely in three-quarters of a second. It would take 5 million gallons to generate that power continuously for 44 days, but then that's why the 200MW ship we were talking about uses a pair of nuclear reactors.

Big container ships burn hundreds of tons of fuel per day, which indeed does "seem excessive", but what relevance does such a subjective "seeming" have to this or any other ostensibly fact-based discussion?


Emma Mærsk
She is powered by a Wärtsilä-Sulzer 14RTFLEX96-C engine, the world's largest single diesel unit, weighing 2,300 tonnes and capable of 81 MW (109,000 hp) when burning 14,000 litres (3,600 US gal)[31] of heavy fuel oil per hour. At economical speed, fuel consumption is 0.260 bs/hp·hour (1,660 gal/hour).[32] She has features to lower environmental damage, including exhaust heat recovery and cogeneration.[33] Some of the exhaust gases are returned to the engine to improve economy and lower emissions,[34] and some are passed through a steam generator which then powers a Peter Brotherhood steam turbine and electrical generators. This creates an electrical output of 8.5 MW,[35] equivalent to about 12% of the main engine power output. Some of this steam is used directly as shipboard heat.[36] Five diesel generators together produce 20.8 MW,[35] giving a total electric output of 29 MW.[26] Two 9 MW electric motors augment the power on the main propeller shaft.[35]

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Re: 1732: "Earth Temperature Timeline"

Postby Mikeski » Sun Sep 25, 2016 5:23 pm UTC

If you're worried about overpopulation, Wikipedia knows who you need to yell at.

Green countries are about stable, or growing slightly. Blue ones are shrinking. Yellow-orange-red-purple are the literal "problem children".

Thus, white people talking about population growth "problems" are totally racist, though they're mostly doing their part by making white babies at below the replacement rate. (Those randy French, though... :wink: )

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Re: 1732: "Earth Temperature Timeline"

Postby gmalivuk » Sun Sep 25, 2016 6:02 pm UTC

That works out coincidentally quite close to the rate of fuel consumption I calculated, though I had higher power output because I figured perfect efficiency in converting the 48MJ/kg of diesel into electrical energy, which is of course unrealistic.
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Re: 1732: "Earth Temperature Timeline"

Postby morriswalters » Sun Sep 25, 2016 7:55 pm UTC

gmalivuk wrote:
That works out coincidentally quite close to the rate of fuel consumption I calculated, though I had higher power output because I figured perfect efficiency in converting the 48MJ/kg of diesel into electrical energy, which is of course unrealistic.
I knew your numbers would be close. What surprises me is that nobody has questioned why freight in the US train system is driven by diesel. Which drives electric motors.

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Re: 1732: "Earth Temperature Timeline"

Postby dolphintickler » Mon Sep 26, 2016 12:36 am UTC

gmalivuk wrote:
dolphintickler wrote:both of these refer to "global surface temperature" and do not explicitly state what that means

I imagine they didn't explicitly state what a degree means, either. Is that also a problem or are you capable of using Wikipedia?


If there were any significant chance of them using Fahrenheit, or other scale, it would be a problem, but I would expect almost all serious science to use Celsius (or Kelvin, which has the same size degrees). I am perfectly capable of using Wikipedia, as I must assume you are not, since "global surface temperature" redirects to "temperature record" which discusses a variety of measurement records without defining a term "global surface temperature" nor suggesting that it is a term with a standard meaning which can be assumed in every context.

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Re: 1732: "Earth Temperature Timeline"

Postby dolphintickler » Mon Sep 26, 2016 1:14 am UTC

morriswalters wrote:Had Dolphitickler cared he could have used the search function here since this subject has been covered ad naseum in other threads. However I'm bored so here is a link to the GISS Surface Temperature Analysis (GISTEMP) page at the Goddard Institute for Space Studies which goes into some detail as to why and how.


That is indeed a very interesting and relevant link. Via the FAQ, it leads to The Elusive Absolute Surface Air Temperature (SAT) which says:

Q. What exactly do we mean by SAT?
A. I doubt that there is a general agreement how to answer this question. Even at the same location, the temperature near the ground may be very different from the temperature 5 ft above the ground and different again from 10 ft or 50 ft above the ground. Particularly in the presence of vegetation (say in a rain forest), the temperature above the vegetation may be very different from the temperature below the top of the vegetation. A reasonable suggestion might be to use the average temperature of the first 50 ft of air either above ground or above the top of the vegetation. To measure SAT we have to agree on what it is and, as far as I know, no such standard has been suggested or generally adopted. Even if the 50 ft standard were adopted, I cannot imagine that a weather station would build a 50 ft stack of thermometers to be able to find the true SAT at its location.


So GISS work in terms of the SAT anomaly (I'm not sure why they don't just use a different abbreviation, such as SATA, for clarity).

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Re: 1732: "Earth Temperature Timeline"

Postby dolphintickler » Mon Sep 26, 2016 1:34 am UTC

Eebster the Great wrote:"Surface temperature" is the temperature at the surface. So if you stick a thermometer a millimeter into ground or water, you are measuring the surface temperature.


That might be your definition of the surface temperature, but it's certainly not one related to meteorology. I would expect basic temperature measurements to use something like a Stephenson screen to take measurements at a human sized amount above the actual surface. However, it would also be reasonable to use the term to refer to some or all of the troposphere, where the word surface is contrasting with the whole atmosphere. The range of possibilities means that, when it is used to refer to a precise scientific value, an explicit definition or a reference to a standard definiton should be used to avoid ambiguity.

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Re: 1732: "Earth Temperature Timeline"

Postby gmalivuk » Mon Sep 26, 2016 1:56 am UTC

dolphintickler wrote:I am perfectly capable of using Wikipedia, as I must assume you are not, since "global surface temperature" redirects to "temperature record" which discusses a variety of measurement records without defining a term "global surface temperature" nor suggesting that it is a term with a standard meaning which can be assumed in every context.

As I suspected, you're not good at Wikipedia.

The "surface air temperature" section in the "temperature measurement" article gives some description, as does the linked section of the "instrumental temperature record" article, though it was the "surface weather observation" article that I had just found when I originally suggested that maybe you're not so good at looking for information yourself.
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Re: 1732: "Earth Temperature Timeline"

Postby morriswalters » Mon Sep 26, 2016 2:29 am UTC

@dolphintickler

I'm glad you found the data useful. Say think you. I saved you about two minutes. If you read what I posted you would have seen me telling you that the surface was a nebulous concept. I had never heard of the phrase anomaly as they used it but you could fill a book with what I don't know. But the data they use to derive it is from weather stations which use shielded thermometers at chest height. Of course it could be at 10000 feet at the peak of a mountain or the the height of a ships bridge above water or in Death Valley, below sea level or at Louisville International Airport some 400 feet above mean sea level. Here's one on Everest.Image

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Re: 1732: "Earth Temperature Timeline"

Postby Tyndmyr » Mon Sep 26, 2016 1:13 pm UTC

Crissa wrote:
Tyndmyr wrote:Facts are facts. If you only accept them when people are nice, you're ...

Funny that, you tend to discard facts to be argumentative.

Weirdly you think that wind and solar not only have to be cheaper than fossil-fuel generators, they have to be done without generators.

Funny.


I'm not sure where you're getting the no generator bit from.

There's nothing at all odd with accounting for up front costs.

Crissa wrote:Also, you realize that the calculations vs the cargo ship being solar powered also 'proves' you can't power it with oil?

To generate 200MW you'd need 5 million gallons of diesel. Which seems a bit excessive, don't you think?

That's because ships don't use all their power at once, but in bits and starts.

Obviously we couldn't run them with 2.8MW of solar panels sitting topside... At least, not at their current speeds and reliability. But it isn't impossible.

-Crissa


You haven't really shown that, merely disparaged the previous work. In any case, the aforementioned solar calculation isn't intended to be a precise measurement of everything, merely back of the envelope math to illustrate how area-dependent solar power is, and how it's obviously not suited for ships. That's fine. What works perfectly well with under utilized desert need not be the same solution we use for cargo ships. Use solar for one, nuclear for another if you wish.

Removing speed and reliability from transit is a significant tradeoff. That very speed and reliability is what drives modern international trade. Long distance trade has happened for basically forever without those factors, but without them, it's mostly a thing for luxuries for upper class folks and the like. You get a very different sort of civilization with mass trade than you do without. Mass market farming and mass trade are up there with the personal automobile in terms of social impact.

Mikeski wrote:If you're worried about overpopulation, Wikipedia knows who you need to yell at.

Green countries are about stable, or growing slightly. Blue ones are shrinking. Yellow-orange-red-purple are the literal "problem children".

Thus, white people talking about population growth "problems" are totally racist, though they're mostly doing their part by making white babies at below the replacement rate. (Those randy French, though... :wink: )


*shrug* Race is incidental. The obvious factor is developmental, on a society level. Once you get lots of education and a high standard of living, smaller families become more optimal. Gotta have that security, and a high investment strategy works out. Yelling at anyone will prove mostly unhelpful.

Abandoning global trade, food shortages, etc would definitely not fix this. Famine is a short term population killer, sure, but it doesn't change the basic strategy of "have lots of kids in the good times so some survive, and you have a large social network to assist each other". Starving the poor people has never really been a good solution to anything.

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Re: 1732: "Earth Temperature Timeline"

Postby HiFranc » Tue Sep 27, 2016 7:39 am UTC

commodorejohn wrote:
HiFranc wrote:I can't remember where I heard it but I'm sure that archaeologists now have evidence that the Americas were populated before the land bridge (that is now the Bering Straits) formed.

I'd be really interested to hear more about this. Modern explorers have demonstrated that ships from ancient Egypt could have been used for trans-Atlantic crossings, but I've never heard of such a thing being seriously put forward as a possible historic event. (And anyway there's another 7-15 millennia separating that era and the period between the emergence of Beringia and the hypothesized migration to the Americas over it - but then again, I understand that Borneo, Australia, and New Zealand are supposed to have been colonized well before that, though those are considerably shorter distances.)


Unfortunately my memory is vague on that. DanD might be right that I've misremembered.

However, in relation to Ancient Egypt, trans-Atlantic crossings are lent credence by the cocaine mummies.

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Re: 1732: "Earth Temperature Timeline"

Postby Eebster the Great » Tue Sep 27, 2016 3:17 pm UTC

The "cocaine mummies" were moved many times over the course of a century. To be honest, it would be surprising if some cocaine weren't found by people looking hard enough. That's kind of the nature of cocaine dust.

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Re: 1732: "Earth Temperature Timeline"

Postby HES » Tue Sep 27, 2016 6:57 pm UTC

morriswalters wrote:What surprises me is that nobody has questioned why freight in the US train system is driven by diesel.

Because track electrification is expensive and the US is big.
Which drives electric motors.

So that peak power output puts less strain on the diesel engine.
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Re: 1732: "Earth Temperature Timeline"

Postby morriswalters » Tue Sep 27, 2016 8:40 pm UTC

HES wrote:
Which drives electric motors.

So that peak power output puts less strain on the diesel engine.
I always wondered. I assumed it had a valid engineering reason. But you see the dichotomy don't you?

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Re: 1732: "Earth Temperature Timeline"

Postby x7eggert » Tue Sep 27, 2016 9:10 pm UTC

morriswalters wrote:What surprises me is that nobody has questioned why freight in the US train system is driven by diesel. Which drives electric motors.


https://en.wikipedia.org/wiki/Diesel-el ... ansmission

"Diesel-electric powerplants became popular because they greatly simplified the way motive power was transmitted to the wheels and because they were both more efficient and had greatly reduced maintenance requirements. Direct-drive transmissions can become very complex, considering that a typical locomotive has four or more axles. Additionally, a direct-drive diesel locomotive would require an impractical number of gears to keep the engine within its powerband; coupling the diesel to a generator eliminates this problem. An alternative is to use a torque converter or fluid coupling in a direct drive system to replace the gearbox. Hydraulic transmissions are claimed to be somewhat more efficient than diesel-electric technology."

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Re: 1732: "Earth Temperature Timeline"

Postby orthogon » Tue Sep 27, 2016 9:34 pm UTC

Could you have a ship driven by electric motors powered by wind turbines? Or turbines mechanically linked to the propellers, for that matter? Could such a vessel sail directly into the wind? Or would it be limited in the same way as a sailing boat?
xtifr wrote:... and orthogon merely sounds undecided.

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Re: 1732: "Earth Temperature Timeline"

Postby morriswalters » Tue Sep 27, 2016 9:56 pm UTC

@x7eggert

Yes it's relatively straightforward, I just never gave it much thought. However electrifying the tracks is somewhat simpler than developing a solar freighter.

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Re: 1732: "Earth Temperature Timeline"

Postby Soupspoon » Tue Sep 27, 2016 10:30 pm UTC

orthogon wrote:Could you have a ship driven by electric motors powered by wind turbines? Or turbines mechanically linked to the propellers, for that matter? Could such a vessel sail directly into the wind? Or would it be limited in the same way as a sailing boat?

Consider the gearing necessary to transmit the power of air against the vanes of a windmill to (losslessy, for the sake of argument) power the vanes of a propellor to push against the heavier and more viscous fluid of the water. It is doable, more so than a theoretical wind-powered aircraft (that doesn't have the advantage of a stream of power-giving air that is independent from the mass of water through which it wishes to travel), and even has then adds its immediate speed-through-water to the wind-speed, to ramp it up, although the same viscousness eats up the additional effort quite quickly (and naturally the force against the wind-vanes also creates moving resistance, probably more so than the exposed superstructure if you're do using significant-enough wind-capturing).

I've done something very similar with a Lego 'car', wheeled with a windmill atop, and even added a connection between the wind-facing windmill cap and the steering to try to steer the device into (or away from, in another configuration!) the wind, thus following eddies around the walled yard it was released in, which effectively also stopped it from crashing into the walls... But the gearing had to be very low to avoid 'stalling' the windmill, and a suitably trimmed sail would have made for a much speedier device.


'Electric-hybrid' wind turbine powered water thrusters (to cover a multitude of sins, in that department, as electric nacelles can be fans, ducted fans, even jetski-like high velocity water-movers) would have a different set of problems (and efficiencies) to those of direct-drive gear-chains, but as I'm hardly even an armchair nautical engineer I'll only say that it probably would work (FCVO...) but hardly set any speed records.

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Re: 1732: "Earth Temperature Timeline"

Postby Tyndmyr » Tue Sep 27, 2016 10:37 pm UTC

orthogon wrote:Could you have a ship driven by electric motors powered by wind turbines? Or turbines mechanically linked to the propellers, for that matter? Could such a vessel sail directly into the wind? Or would it be limited in the same way as a sailing boat?


Sure, you can have a bunch of turbines instead of sails. Sailing directly into the wind would only be possible if one was rapidly depleting battery storage, though. Batteries give you a little more flexibility, but otherwise, it's remarkably like a sailboat overall. Albeit one with a likely far smaller cross section for wind capture.

You run into the same basic problems as a sailboat...need a keel for stability, overall motive power is reliant on the wind blowing steadily, etc. It could work, in theory, but I suspect going back to an age of sail wouldn't work out even if we embraced super high tech sails.

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Re: 1732: "Earth Temperature Timeline"

Postby Eebster the Great » Tue Sep 27, 2016 11:35 pm UTC

I can't see how it could ever be more efficient than sailing with tacking.

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Re: 1732: "Earth Temperature Timeline"

Postby morriswalters » Wed Sep 28, 2016 12:00 am UTC

Sail will always end at the same place. The wind doesn't always blow. Solar will end up somewhere similar. The sun don't always shine. If they can't electrify the rails, why would anyone think they can convert any reasonable part of the global fleet to an alternative?

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Re: 1732: "Earth Temperature Timeline"

Postby ps.02 » Wed Sep 28, 2016 1:15 am UTC

Eebster the Great wrote:I can't see how it could ever be more efficient than sailing with tacking.

Effectively, a wind turbine blade is always tacking. A wind-farm-on-a-boat may or may not be more efficient than sails, but you do get the flexibility of pointing your bow whatever direction you wish, even when navigating relatively tight spaces.

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Re: 1732: "Earth Temperature Timeline"

Postby commodorejohn » Wed Sep 28, 2016 2:15 am UTC

morriswalters wrote:Sail will always end at the same place. The wind doesn't always blow. Solar will end up somewhere similar. The sun don't always shine. If they can't electrify the rails, why would anyone think they can convert any reasonable part of the global fleet to an alternative?

Well, in fairness, powering a boat via solar is quite a bit less complicated (though certainly non-trivial) than running very large-scale electrical rail. But yes, it's not any kind of a magic bullet.
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Re: 1732: "Earth Temperature Timeline"

Postby Eebster the Great » Wed Sep 28, 2016 5:55 am UTC

ps.02 wrote:
Eebster the Great wrote:I can't see how it could ever be more efficient than sailing with tacking.

Effectively, a wind turbine blade is always tacking. A wind-farm-on-a-boat may or may not be more efficient than sails, but you do get the flexibility of pointing your bow whatever direction you wish, even when navigating relatively tight spaces.

It seems like you are introducing a lot of loss into the system though, spinning turbines to spin magnets to produce an electric current to drive a motor to spin a propeller. Alternatively, you could just be directly pushed by the wind. And a sail catches a lot more air than a turbine.

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Re: 1732: "Earth Temperature Timeline"

Postby ps.02 » Wed Sep 28, 2016 6:42 am UTC

Eebster the Great wrote:
ps.02 wrote:
Eebster the Great wrote:I can't see how it could ever be more efficient than sailing with tacking.

Effectively, a wind turbine blade is always tacking. A wind-farm-on-a-boat may or may not be more efficient than sails

It seems like you are introducing a lot of loss into the system though, spinning turbines to spin magnets to produce an electric current to drive a motor to spin a propeller. Alternatively, you could just be directly pushed by the wind. And a sail catches a lot more air than a turbine.

True. But OTOH, if the wind direction requires significant tacking, that's a pretty huge efficiency hit as well. I don't sail, but I understand you might more than double your trip distance (i.e., energy) in something close to a straight-on headwind. As a wind farm is omnidirectional, you at least don't have that loss. (Speaking of which, yes, I believe a container ship has enough surface area for several wind turbines, hence "farm". They would stick out at angles. For that but also height reasons, they'd have to be hinged/retractable per Panamax/New Panamax.)

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Re: 1732: "Earth Temperature Timeline"

Postby morriswalters » Wed Sep 28, 2016 9:42 am UTC


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Re: 1732: "Earth Temperature Timeline"

Postby Eebster the Great » Wed Sep 28, 2016 1:53 pm UTC

That's an awfully big turbine for such a small catamaran.

ps.02 wrote:
Eebster the Great wrote:
ps.02 wrote:
Eebster the Great wrote:I can't see how it could ever be more efficient than sailing with tacking.

Effectively, a wind turbine blade is always tacking. A wind-farm-on-a-boat may or may not be more efficient than sails

It seems like you are introducing a lot of loss into the system though, spinning turbines to spin magnets to produce an electric current to drive a motor to spin a propeller. Alternatively, you could just be directly pushed by the wind. And a sail catches a lot more air than a turbine.

True. But OTOH, if the wind direction requires significant tacking, that's a pretty huge efficiency hit as well. I don't sail, but I understand you might more than double your trip distance (i.e., energy) in something close to a straight-on headwind. As a wind farm is omnidirectional, you at least don't have that loss. (Speaking of which, yes, I believe a container ship has enough surface area for several wind turbines, hence "farm". They would stick out at angles. For that but also height reasons, they'd have to be hinged/retractable per Panamax/New Panamax.)

You can tack at 45 degrees to the wind, so the worst case scenario is that you multiply your trip length by √2. That's more than 70% efficient.

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Re: 1732: "Earth Temperature Timeline"

Postby speising » Wed Sep 28, 2016 4:28 pm UTC

Not really, you are drifting. That's what the keel is for, but it's not perfect.

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Re: 1732: "Earth Temperature Timeline"

Postby Malin » Wed Sep 28, 2016 4:46 pm UTC

This should be on a giant poster in every classroom, airport and gas station worldwide! Just so that noone will ever be able to say they didn't know ever again!

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Re: 1732: "Earth Temperature Timeline"

Postby ps.02 » Wed Sep 28, 2016 4:52 pm UTC

Eebster the Great wrote:
ps.02 wrote:
Eebster the Great wrote:And a sail catches a lot more air than a turbine.

True. But OTOH, if the wind direction requires significant tacking, that's a pretty huge efficiency hit as well.

You can tack at 45 degrees to the wind, so the worst case scenario is that you multiply your trip length by √2. That's more than 70% efficient.

Well, 70% multiplied by the ratio of the propulsion you get in that configuration. I don't know what that is but I bet it's nowhere near 100%.

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Re: 1732: "Earth Temperature Timeline"

Postby DanD » Wed Sep 28, 2016 5:13 pm UTC

Eebster the Great wrote:And a sail catches a lot more air than a turbine.


Some people seem to be missing that you can travel faster, tacking, than you can directly downwind. In fact, many racing vessels will tack even when sailing downwind, because their net speed is faster. This is because windpower is the cube of wind speed. The sail can never travel faster than the wind speed downwind. Across the wind, you can extract more power, because the excess is exerted by your keel on the water to produce lateral motion.

This means that a turbine, which as mentioned, is always tacking, can produce more power per unit area than a sail under some conditions. With the correct swept area, it can produce more total power, which can be transferred to the water via propeller or other method, for a net increase in speed.

ETA: It's also possible to tack considerably closer than 45 degrees to the wind. Racing yachts manage about 35 degrees to the true wind, and iceboats can make about 9 degrees to the apparent wind, maybe about 20 degrees to the true wind. At speeds greater than 6x wind speed.

ETAA: This is also the principle behind "Direct Downwind Faster than the Wind" and "DUpwindFttW", both of which have been demonstrated on land sailing vehicles.

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Re: 1732: "Earth Temperature Timeline"

Postby morriswalters » Wed Sep 28, 2016 6:26 pm UTC

How many windmills to move 170,000 tons at 20 knots?


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