1732: "Earth Temperature Timeline"

This forum is for the individual discussion thread that goes with each new comic.

Moderators: Moderators General, Prelates, Magistrates

DanD
Posts: 270
Joined: Tue Oct 05, 2010 12:42 am UTC

Re: 1732: "Earth Temperature Timeline"

Postby DanD » Wed Sep 28, 2016 6:45 pm UTC

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


Don't know. Don't really care either. Even if all you manage to do is reduce fuel consumption by 20%, or 10%, you've knocked out a huge amount of fuel consumption. Maybe you manage to bring it down to something reasonable for battery storage. There is no "all at once, solve everything" solution. There are lots and lots of incremental solutions.

https://en.wikipedia.org/wiki/SkySails

commodorejohn
Posts: 962
Joined: Thu Dec 10, 2009 6:21 pm UTC
Location: Placerville, CA
Contact:

Re: 1732: "Earth Temperature Timeline"

Postby commodorejohn » Wed Sep 28, 2016 6:51 pm UTC

Malin wrote: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!

Right on. More people need to know that you can tack at 45 degrees to the wind.
"'Legacy code' often differs from its suggested alternative by actually working and scaling."
- Bjarne Stroustrup
www.commodorejohn.com - in case you were wondering, which you probably weren't.

Tyndmyr
Posts: 10170
Joined: Wed Jul 25, 2012 8:38 pm UTC

Re: 1732: "Earth Temperature Timeline"

Postby Tyndmyr » Wed Sep 28, 2016 7:41 pm UTC

DanD wrote:
morriswalters wrote:How many windmills to move 170,000 tons at 20 knots?


Don't know. Don't really care either. Even if all you manage to do is reduce fuel consumption by 20%, or 10%, you've knocked out a huge amount of fuel consumption. Maybe you manage to bring it down to something reasonable for battery storage. There is no "all at once, solve everything" solution. There are lots and lots of incremental solutions.

https://en.wikipedia.org/wiki/SkySails


Eh, if it's an entire redundant power system for only 10% of power, you're adding a crapton of complexity, maint costs, etc. Not to mention cluttering up the topside.

There's fairly low downsides with having a variety of land based power plants, but relying on multiple power sources for vehicles seems to be usually undesirable. The *vast* majority of them appear to use a single fuel source, which indicates that generally, weight/space/etc concerns outweigh the advantages of diversification.

DanD
Posts: 270
Joined: Tue Oct 05, 2010 12:42 am UTC

Re: 1732: "Earth Temperature Timeline"

Postby DanD » Wed Sep 28, 2016 7:50 pm UTC

Tyndmyr wrote:
DanD wrote:
morriswalters wrote:How many windmills to move 170,000 tons at 20 knots?


Don't know. Don't really care either. Even if all you manage to do is reduce fuel consumption by 20%, or 10%, you've knocked out a huge amount of fuel consumption. Maybe you manage to bring it down to something reasonable for battery storage. There is no "all at once, solve everything" solution. There are lots and lots of incremental solutions.

https://en.wikipedia.org/wiki/SkySails


Eh, if it's an entire redundant power system for only 10% of power, you're adding a crapton of complexity, maint costs, etc. Not to mention cluttering up the topside.

There's fairly low downsides with having a variety of land based power plants, but relying on multiple power sources for vehicles seems to be usually undesirable. The *vast* majority of them appear to use a single fuel source, which indicates that generally, weight/space/etc concerns outweigh the advantages of diversification.


Depends on the core technology. Obviously, adding an additional power source to a ship that is currently diesel powered is difficult. Adding an additional electric power source to a ship that is presently diesel-electric would be simple. At present, diesel electric ships are rare, because ships spend the vast majority of their time at full power, chugging across the ocean, so they don't need the (slight) increase in complexity of a diesel electric system over the existing diesel with power take-off. (Unlike rail engines, which benefit from using the diesel-electric connection as a transmission.) However, if you manage to knock 10% of the fuel cost off with an auxiliary electrical source that displaces little or no cargo space (picture something like flexible solar tarps that lay over containers), that would more than justify the cost of the diesel electric complexity. To say nothing of things like the kite-sail I linked to, which takes up a tiny little bit of fore-deck space, uses existing auxiliary power for control, and can knock maybe 5% off fuel costs.

User avatar
Eebster the Great
Posts: 2770
Joined: Mon Nov 10, 2008 12:58 am UTC

Re: 1732: "Earth Temperature Timeline"

Postby Eebster the Great » Wed Sep 28, 2016 8:03 pm UTC

Dan, at what point does it become obvious that it is more efficient to put those turbines on the land somewhere and use the energy to chemically make diesel? Or better yet, find a carbon neutral plan for biodiesel?

Just because you can stick sails on a container ship doesn't mean that you should. Yes we need to do something. That doesn't mean we need to try every dumb idea that occurs to us.

User avatar
Sableagle
Ormurinn's Alt
Posts: 1234
Joined: Sat Jun 13, 2015 4:26 pm UTC
Location: The wrong side of the mirror
Contact:

Re: 1732: "Earth Temperature Timeline"

Postby Sableagle » Wed Sep 28, 2016 9:04 pm UTC

DanD wrote: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.
Spoiler:
"Tacking" is turning through upwind, so to tack while going downwind would mean doing one of those fancy ruffled underlines you sometimes see on signatures.

Image

Turning through downwind is gybing, not tacking.

{Much stuff deleted here because the obvious point that a boat on a dead run isn't going at wind speed had escaped me.}

...

An image search for speeds and points reveals some WEIRD shapes.

Image

The Tornado turns out to be double-hulled and triple-sailed.
The 18-foot skiff is also multi-sailed.

Clearly I need to look into this one more.

The sail's polar diagrams are a powerful tool to compare sails (alone), nevertheless, it is necessary to appreciate the whole boat behaviour, from the aerodynamic of the sails, as well as from the hydrodynamics of the hull. The VPP (velocity prediction program) are codes that take into account the performances of sail(s) (sail polar diagram) and hull(s) (resistance versus speed curve), and the boat stability, to simulate the behaviour of the boat for different true wind angle, and true wind speed. The following diagram is a typical boat polar diagram produced by a VPP (the scale of the grid pattern is in knots)

Image
Hull shape, hydrodynamics, trim and balance et cetera ... and particularly, I'd think, having one sail partially masking the other.

Image

Actually adding another sail is going to produce a kink in the shape, yes.

Image

... and it varies from boat to boat.

Image

Faster downwind on a broad reach than on a dead run in low wind speed but faster in a dead run than on a broad reach in high wind speed.

All that comes down to "It depends on the weather conditions and which way you're trying to go," which we already knew.
Oh, Willie McBride, it was all done in vain.

DanD
Posts: 270
Joined: Tue Oct 05, 2010 12:42 am UTC

Re: 1732: "Earth Temperature Timeline"

Postby DanD » Wed Sep 28, 2016 9:17 pm UTC

Eebster the Great wrote:Dan, at what point does it become obvious that it is more efficient to put those turbines on the land somewhere and use the energy to chemically make diesel? Or better yet, find a carbon neutral plan for biodiesel?

Just because you can stick sails on a container ship doesn't mean that you should. Yes we need to do something. That doesn't mean we need to try every dumb idea that occurs to us.



It doesn't mean you shouldn't, either. In fact, I would argue that you should try "every dumb idea that occurs to us" at least to the level of a basic feasibility study, or a literature search to see if it's already been tried. I linked to a specific instance of "putting sails" on a cargo ship seems to be beneficial. It's in test and early deployment phases, and the complete data isn't in yet, but the benefit seems to be there. Whether it would work on a full scale container ship obviously hasn't been tested yet, but it does seem to work on bulk carriers.

If you can figure out how to reliably deploy solar on a container ship, and if it would produce enough power to justify a diesel electric power train, and whether the amount of fuel saved would justify in terms of cost or in terms of extra cargo capacity, it needs to be studied. Maybe we can't. Maybe there's another breakthrough in battery tech required first. Maybe it's completely impractical. But unless you've given it more thought than I've seen in this forum, it's kind of a hard to make any absolute statements.

DanD
Posts: 270
Joined: Tue Oct 05, 2010 12:42 am UTC

Re: 1732: "Earth Temperature Timeline"

Postby DanD » Wed Sep 28, 2016 9:20 pm UTC

Sableagle wrote:
DanD wrote: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.
Spoiler:
"Tacking" is turning through upwind, so to tack while going downwind would mean doing one of those fancy ruffled underlines you sometimes see on signatures.

Image

Turning through downwind is gybing, not tacking.

{Much stuff deleted here because the obvious point that a boat on a dead run isn't going at wind speed had escaped me.}

...

An image search for speeds and points reveals some WEIRD shapes.

Image

The Tornado turns out to be double-hulled and triple-sailed.
The 18-foot skiff is also multi-sailed.

Clearly I need to look into this one more.

The sail's polar diagrams are a powerful tool to compare sails (alone), nevertheless, it is necessary to appreciate the whole boat behaviour, from the aerodynamic of the sails, as well as from the hydrodynamics of the hull. The VPP (velocity prediction program) are codes that take into account the performances of sail(s) (sail polar diagram) and hull(s) (resistance versus speed curve), and the boat stability, to simulate the behaviour of the boat for different true wind angle, and true wind speed. The following diagram is a typical boat polar diagram produced by a VPP (the scale of the grid pattern is in knots)

Image
Hull shape, hydrodynamics, trim and balance et cetera ... and particularly, I'd think, having one sail partially masking the other.

Image

Actually adding another sail is going to produce a kink in the shape, yes.

Image

... and it varies from boat to boat.

Image

Faster downwind on a broad reach than on a dead run in low wind speed but faster in a dead run than on a broad reach in high wind speed.

All that comes down to "It depends on the weather conditions and which way you're trying to go," which we already knew.


Which isn't an issue with a wind turbine. It can face into the apparent wind, regardless of the direction of travel, pitch it's blades for optimum tack at the windspeed available, and provide power to a propeller in the direction of travel.

DanD
Posts: 270
Joined: Tue Oct 05, 2010 12:42 am UTC

Re: 1732: "Earth Temperature Timeline"

Postby DanD » Wed Sep 28, 2016 9:20 pm UTC

DanD wrote:
Sableagle wrote:
DanD wrote: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.
Spoiler:
"Tacking" is turning through upwind, so to tack while going downwind would mean doing one of those fancy ruffled underlines you sometimes see on signatures.

Image

Turning through downwind is gybing, not tacking.

{Much stuff deleted here because the obvious point that a boat on a dead run isn't going at wind speed had escaped me.}

...

An image search for speeds and points reveals some WEIRD shapes.

Image

The Tornado turns out to be double-hulled and triple-sailed.
The 18-foot skiff is also multi-sailed.

Clearly I need to look into this one more.

The sail's polar diagrams are a powerful tool to compare sails (alone), nevertheless, it is necessary to appreciate the whole boat behaviour, from the aerodynamic of the sails, as well as from the hydrodynamics of the hull. The VPP (velocity prediction program) are codes that take into account the performances of sail(s) (sail polar diagram) and hull(s) (resistance versus speed curve), and the boat stability, to simulate the behaviour of the boat for different true wind angle, and true wind speed. The following diagram is a typical boat polar diagram produced by a VPP (the scale of the grid pattern is in knots)

Image
Hull shape, hydrodynamics, trim and balance et cetera ... and particularly, I'd think, having one sail partially masking the other.

Image

Actually adding another sail is going to produce a kink in the shape, yes.

Image

... and it varies from boat to boat.

Image

Faster downwind on a broad reach than on a dead run in low wind speed but faster in a dead run than on a broad reach in high wind speed.

All that comes down to "It depends on the weather conditions and which way you're trying to go," which we already knew.


Which isn't an issue with a wind turbine. It can face into the apparent wind, regardless of the direction of travel, pitch it's blades for optimum tack at the windspeed available, and provide power to a propeller in the direction of travel.


And I accept the correction on "gybing". I'm not a sailor. I know the physics, not the terms.

Oh, and the "faster on a dead run in a high wind" is a function of the sail's limits. It would always be possible to design a sail for a particular wind speed that would be faster in a broad reach, it's just not possible to design one sail that is always faster. Specifically, that sail has reached the point where it is at it's mechanical limits in a dead run. At that point, the geometry of the shorter course predominates. The physics still allow it to extract more energy on a broad reach, but doing so risks catastrophic failure. (In fact, I suspect the chart recommends reefing the sail if wind increases any more).

User avatar
Eebster the Great
Posts: 2770
Joined: Mon Nov 10, 2008 12:58 am UTC

Re: 1732: "Earth Temperature Timeline"

Postby Eebster the Great » Wed Sep 28, 2016 9:32 pm UTC

DanD wrote:
Eebster the Great wrote:Dan, at what point does it become obvious that it is more efficient to put those turbines on the land somewhere and use the energy to chemically make diesel? Or better yet, find a carbon neutral plan for biodiesel?

Just because you can stick sails on a container ship doesn't mean that you should. Yes we need to do something. That doesn't mean we need to try every dumb idea that occurs to us.



It doesn't mean you shouldn't, either. In fact, I would argue that you should try "every dumb idea that occurs to us" at least to the level of a basic feasibility study, or a literature search to see if it's already been tried. I linked to a specific instance of "putting sails" on a cargo ship seems to be beneficial. It's in test and early deployment phases, and the complete data isn't in yet, but the benefit seems to be there. Whether it would work on a full scale container ship obviously hasn't been tested yet, but it does seem to work on bulk carriers.

If you can figure out how to reliably deploy solar on a container ship, and if it would produce enough power to justify a diesel electric power train, and whether the amount of fuel saved would justify in terms of cost or in terms of extra cargo capacity, it needs to be studied. Maybe we can't. Maybe there's another breakthrough in battery tech required first. Maybe it's completely impractical. But unless you've given it more thought than I've seen in this forum, it's kind of a hard to make any absolute statements.

The fact is that feasible alternatives exist. We have existing carbon-free power generation, but I keep seeing people pushing wave power and solar roads and other patently inefficient alternatives. We have nuclear ships and biodiesel, but people still want to put rotors on their ships. This can be worthwhile for the owners if they get enough in tax breaks or new investment, but it's clearly not the best use of funds from a societal standpoint.

Transitioning to alternative energy is extremely expensive. And it is an immediate need. It makes sense to concentrate on the best options rather than spread the very limited available funds among all possibilities. That necessarily means we can't fund every project.

morriswalters
Posts: 6945
Joined: Thu Jun 03, 2010 12:21 am UTC

Re: 1732: "Earth Temperature Timeline"

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

[
DanD wrote:
morriswalters wrote:How many windmills to move 170,000 tons at 20 knots?


Don't know. Don't really care either. Even if all you manage to do is reduce fuel consumption by 20%, or 10%, you've knocked out a huge amount of fuel consumption. Maybe you manage to bring it down to something reasonable for battery storage. There is no "all at once, solve everything" solution. There are lots and lots of incremental solutions.

https://en.wikipedia.org/wiki/SkySails
I don't really care either. And the fuel savings will be a function of the adoption rate of whatever technology. Although Skysails looks promising.
DanD wrote:If you can figure out how to reliably deploy solar on a container ship, and if it would produce enough power to justify a diesel electric power train, and whether the amount of fuel saved would justify in terms of cost or in terms of extra cargo capacity, it needs to be studied. Maybe we can't. Maybe there's another breakthrough in battery tech required first. Maybe it's completely impractical. But unless you've given it more thought than I've seen in this forum, it's kind of a hard to make any absolute statements.
People are doing exactly as you suggest And you better hope they figure it out, since the trade network is going to need to expand as the population does. Have we ever used less fossil fuels than the previous generation?

DanD
Posts: 270
Joined: Tue Oct 05, 2010 12:42 am UTC

Re: 1732: "Earth Temperature Timeline"

Postby DanD » Wed Sep 28, 2016 10:15 pm UTC

Eebster the Great wrote:The fact is that feasible alternatives exist. We have existing carbon-free power generation, but I keep seeing people pushing wave power and solar roads and other patently inefficient alternatives. We have nuclear ships and biodiesel, but people still want to put rotors on their ships. This can be worthwhile for the owners if they get enough in tax breaks or new investment, but it's clearly not the best use of funds from a societal standpoint.

Transitioning to alternative energy is extremely expensive. And it is an immediate need. It makes sense to concentrate on the best options rather than spread the very limited available funds among all possibilities. That necessarily means we can't fund every project.


Given the way most cargo ships are cared for, and how limited regulation is, I would consider privately owned nuclear cargo vessels to be a disaster waiting to happen.

Nuclear plants powering bio-diesel generation, fine, but keep the nukes where a host country can control them.

dolphintickler
Posts: 13
Joined: Fri Sep 16, 2016 12:04 am UTC

Re: 1732: "Earth Temperature Timeline"

Postby dolphintickler » Thu Sep 29, 2016 1:24 am UTC

gmalivuk wrote:
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.


No. None of those define what the global surface temperature is. They explain quite a lot about what measurements are made, but that is not the same thing. To see why this is so, consider mass. Mass is very commonly measured using a spring scale (especially nowadays using electronic strain gauges). However, it would be a fundamental error to try to define mass using measurements from such an instrument as it would vary from place to place. If you were to define mass as the result of any measurement, it would have to be a measurement using a balance scales instead, as that merely compares two masses, so is (potentially) much more accurate.

In theory, it's possible to define a property solely by reference to a measurement. This might be something like IQ, where a test is devised which provides a repeatable measurement, so a term is invented to describe what is being measured even though nobody really knows what it is. A physical example of this might be your oven temperature. You might bake something by having the control knob at 180. That's a somewhat arbitrary number. It may mean that the heating element is kept at precisely 180° C, or that the air temperature at the top (or some other part) of the oven stays at 180° C, or that the surface of the baking tin stays at that temperature. You don't know and don't care. This is why your friend might say that they set their oven to 190. The number does not represent a particular physical quantity, but depends on many and therefore cannot be precise, since the thing it represents is inherently vague.

However, I presume that when a climate scientist publishes measurements, models and analysis, the quantities are intended to correspond to an exact physical quantity - and differ from that theoretical (unknowable) value because of practical difficulties. This is obviously essential if measurements taken in different ways are intended to be describing the same physical thing (e.g. temperature from traditional observatories being compared against satellite observations). Consequently, when referring to something such as "global surface temperature" in a serious scientific context, it's essential to either define exactly what that means, or to have a broadly accepted definition that everyone can refer to.

morriswalters
Posts: 6945
Joined: Thu Jun 03, 2010 12:21 am UTC

Re: 1732: "Earth Temperature Timeline"

Postby morriswalters » Thu Sep 29, 2016 2:51 am UTC

If you work on your stove, quit. And I don't think you cook. The number on the knob is a referent to the temperature at the sensor. Which can be fairly accurate. The variation of temperature in the stove comes other factors. The knob marker is the set point at which the gas valve cycles on and off. But the purpose of the stove and the temperature you run at are about heat energy which is a function of the gas valve. And it is how they are rated. Some numbers of btu's.

User avatar
Eebster the Great
Posts: 2770
Joined: Mon Nov 10, 2008 12:58 am UTC

Re: 1732: "Earth Temperature Timeline"

Postby Eebster the Great » Thu Sep 29, 2016 6:47 am UTC

DanD wrote:
Eebster the Great wrote:The fact is that feasible alternatives exist. We have existing carbon-free power generation, but I keep seeing people pushing wave power and solar roads and other patently inefficient alternatives. We have nuclear ships and biodiesel, but people still want to put rotors on their ships. This can be worthwhile for the owners if they get enough in tax breaks or new investment, but it's clearly not the best use of funds from a societal standpoint.

Transitioning to alternative energy is extremely expensive. And it is an immediate need. It makes sense to concentrate on the best options rather than spread the very limited available funds among all possibilities. That necessarily means we can't fund every project.


Given the way most cargo ships are cared for, and how limited regulation is, I would consider privately owned nuclear cargo vessels to be a disaster waiting to happen.

Nuclear plants powering bio-diesel generation, fine, but keep the nukes where a host country can control them.

It depends on what kind of nuclear power generation you are using. I don't want every Tom, Dick, and Harry making their own fission reactor on their yacht. I don't even want every shipping company operating a nuclear ship (and they don't want that either). But that is not the only way to go.

ijuin
Posts: 799
Joined: Fri Jan 09, 2009 6:02 pm UTC

Re: 1732: "Earth Temperature Timeline"

Postby ijuin » Thu Sep 29, 2016 11:06 pm UTC

Eebster the Great wrote:That's an awfully big turbine for such a small catamaran.


Not really. It looks like the area swept by the turbine blades would be comparable to the combined area of the conventional sails that such a boat would use.

User avatar
Eebster the Great
Posts: 2770
Joined: Mon Nov 10, 2008 12:58 am UTC

Re: 1732: "Earth Temperature Timeline"

Postby Eebster the Great » Fri Sep 30, 2016 4:42 am UTC

ijuin wrote:
Eebster the Great wrote:That's an awfully big turbine for such a small catamaran.


Not really. It looks like the area swept by the turbine blades would be comparable to the combined area of the conventional sails that such a boat would use.

That would suggest that the turbine is no more effective than a sail on that particular vessel, which means it can't really be used as evidence that turbines are more effective than sails.

User avatar
Crissa
Posts: 284
Joined: Sun Mar 20, 2011 8:06 pm UTC

Re: 1732: "Earth Temperature Timeline"

Postby Crissa » Fri Sep 30, 2016 8:45 am UTC

gmalivuk wrote: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.
No.

User avatar
Crissa
Posts: 284
Joined: Sun Mar 20, 2011 8:06 pm UTC

Re: 1732: "Earth Temperature Timeline"

Postby Crissa » Fri Sep 30, 2016 8:54 am UTC

What surprises me is that no one seems to remember how much of the railways were electrified a hundred years ago. Nearly all the steep grade or long-grade rails were electrified in long segments to cut out the carrying of all that damn fuel (although it was mostly competing with steam).

x7eggert wrote:
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."

User avatar
PeteP
What the peck?
Posts: 1451
Joined: Tue Aug 23, 2011 4:51 pm UTC

Re: 1732: "Earth Temperature Timeline"

Postby PeteP » Fri Sep 30, 2016 9:28 am UTC

Crissa wrote:
gmalivuk wrote: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.
No.

What, no? You will have to use whole sentences. MW is mega watt, watt is energy per time, without a time span it doesn't translate to an amount of fuel.

User avatar
orthogon
Posts: 2725
Joined: Thu May 17, 2012 7:52 am UTC
Location: The Airy 1830 ellipsoid

Re: 1732: "Earth Temperature Timeline"

Postby orthogon » Fri Sep 30, 2016 9:44 am UTC

Crissa wrote:What surprises me is that no one seems to remember how much of the railways were electrified a hundred years ago. Nearly all the steep grade or long-grade rails were electrified in long segments to cut out the carrying of all that damn fuel (although it was mostly competing with steam).

Stephenson's Rocket equation?
xtifr wrote:... and orthogon merely sounds undecided.

User avatar
HES
Posts: 4795
Joined: Fri May 10, 2013 7:13 pm UTC
Location: England

Re: 1732: "Earth Temperature Timeline"

Postby HES » Fri Sep 30, 2016 12:12 pm UTC

Crissa wrote:What surprises me is that no one seems to remember how much of the railways were electrified a hundred years ago. Nearly all the steep grade or long-grade rails were electrified in long segments to cut out the carrying of all that damn fuel (although it was mostly competing with steam).

Fuel is an ongoing cost that doesn't go away when you switch. Electrification is a huge, up-front capital investment not only for the track owner, but also for the operators who have to replace all their perfectly functional rolling stock. And given their track record for installing critical safety systems...

Not saying it can't be done, just offering a why.
He/Him/His Image

morriswalters
Posts: 6945
Joined: Thu Jun 03, 2010 12:21 am UTC

Re: 1732: "Earth Temperature Timeline"

Postby morriswalters » Fri Sep 30, 2016 2:31 pm UTC

Which pretty much sums up moving to sail or solar.

User avatar
gmalivuk
GNU Terry Pratchett
Posts: 25821
Joined: Wed Feb 28, 2007 6:02 pm UTC
Location: Here and There
Contact:

Re: 1732: "Earth Temperature Timeline"

Postby gmalivuk » Fri Sep 30, 2016 2:37 pm UTC

Crissa wrote:
gmalivuk wrote: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.
No.

You made a factual error and I explained and corrected you, to which your response is "No."

Are you interested in having a real conversation or are you just here to troll?
Unless stated otherwise, I do not care whether a statement, by itself, constitutes a persuasive political argument. I care whether it's true.
---
If this post has math that doesn't work for you, use TeX the World for Firefox or Chrome

(he/him/his)

dolphintickler
Posts: 13
Joined: Fri Sep 16, 2016 12:04 am UTC

Re: 1732: "Earth Temperature Timeline"

Postby dolphintickler » Tue Oct 04, 2016 2:03 am UTC

morriswalters wrote:If you work on your stove, quit. And I don't think you cook. The number on the knob is a referent to the temperature at the sensor. Which can be fairly accurate. The variation of temperature in the stove comes other factors. The knob marker is the set point at which the gas valve cycles on and off. But the purpose of the stove and the temperature you run at are about heat energy which is a function of the gas valve. And it is how they are rated. Some numbers of btu's.


No. That's not how ovens work. Ideally, the middle of the oven is where the set temperature occurs, and since the sensor will be mounted on the wall, it does not switch at the nominal temperature. The gas will be triggered on when the temperature falls, and off when it rises, but there will be hysteresis, so these are not the same temperature. A domestic oven for cooking is not a precision instrument so, as supplied, it is not carefully calibrated to produce an exact temperature, and is not designed to be highly accurate over its lifetime. Cooking uses natural ingredients, which have inherent variation (e.g. the size of eggs) so it would be pointless trying to achieve high precision - instead food is tested to decide when it is done.

morriswalters
Posts: 6945
Joined: Thu Jun 03, 2010 12:21 am UTC

Re: 1732: "Earth Temperature Timeline"

Postby morriswalters » Tue Oct 04, 2016 3:17 am UTC

Yes, I know. The principle is used in HVAC as well as stoves. As well as any other process that operates about a set point. The probe is accurate. Hysteresis is added intentionally. Why it's added and why you need it is the point. By the way, I said fairly accurate, not precisely.

niauropsaka
Posts: 72
Joined: Mon Apr 22, 2013 8:50 pm UTC

Re: 1732: "Earth Temperature Timeline"

Postby niauropsaka » Tue Oct 04, 2016 4:20 am UTC

Eebster the Great wrote:Dan, at what point does it become obvious that it is more efficient to put those turbines on the land somewhere and use the energy to chemically make diesel? Or better yet, find a carbon neutral plan for biodiesel?

Just because you can stick sails on a container ship doesn't mean that you should. Yes we need to do something. That doesn't mean we need to try every dumb idea that occurs to us.

If one of those kites cuts fuel consumption by 5%, what would twenty of them do? I'm sure it doesn't nearly add up to 100%, but it could cut fuel costs a decent chunk, and that means that the strain on the power grid to make biodiesel or hydrogen for container ship fuel is less scary (not that container ships are the major part of "transportation costs" anyway).

And container ships with huge clusters of kitesails are no more intrinsically ridiculous than container ships burning petroleum diesel. They might even be cute. :wink:

User avatar
Eebster the Great
Posts: 2770
Joined: Mon Nov 10, 2008 12:58 am UTC

Re: 1732: "Earth Temperature Timeline"

Postby Eebster the Great » Tue Oct 04, 2016 7:33 am UTC

morriswalters wrote:Yes, I know. The principle is used in HVAC as well as stoves. As well as any other process that operates about a set point. The probe is accurate. Hysteresis is added intentionally. Why it's added and why you need it is the point. By the way, I said fairly accurate, not precisely.

I think you use the word "stove" very differently from me.

niauropsaka wrote:
Eebster the Great wrote:Dan, at what point does it become obvious that it is more efficient to put those turbines on the land somewhere and use the energy to chemically make diesel? Or better yet, find a carbon neutral plan for biodiesel?

Just because you can stick sails on a container ship doesn't mean that you should. Yes we need to do something. That doesn't mean we need to try every dumb idea that occurs to us.

If one of those kites cuts fuel consumption by 5%, what would twenty of them do? I'm sure it doesn't nearly add up to 100%, but it could cut fuel costs a decent chunk, and that means that the strain on the power grid to make biodiesel or hydrogen for container ship fuel is less scary (not that container ships are the major part of "transportation costs" anyway).

And container ships with huge clusters of kitesails are no more intrinsically ridiculous than container ships burning petroleum diesel. They might even be cute. :wink:

The idea of putting multiple sails on a ship is not revolutionary. That you cannot understand just how far back in time you are trying to take shipping is shocking to me. Sails don't just provide less thrust than diesel motors, they provide practically none by comparison.

Sure, if sails or turbines or whatever can improve efficiency by some margin that somebody can make use of, great. By all means, reduce fuel consumption by a gallon here and there. But it is not a solution to the more basic problem that we consume billions of gallons of fuel for shipping every year. I have no objection to improving efficiency. I do object to expecting a fleet of sailboats to replace modern shipping.

morriswalters
Posts: 6945
Joined: Thu Jun 03, 2010 12:21 am UTC

Re: 1732: "Earth Temperature Timeline"

Postby morriswalters » Tue Oct 04, 2016 10:01 am UTC

Oven?

User avatar
Eebster the Great
Posts: 2770
Joined: Mon Nov 10, 2008 12:58 am UTC

Re: 1732: "Earth Temperature Timeline"

Postby Eebster the Great » Tue Oct 04, 2016 3:49 pm UTC

morriswalters wrote:Oven?

Yeah to me the stove is the cooking surface and the oven is the insulated box you bake/roast/broil stuff in.

Tyndmyr
Posts: 10170
Joined: Wed Jul 25, 2012 8:38 pm UTC

Re: 1732: "Earth Temperature Timeline"

Postby Tyndmyr » Tue Oct 04, 2016 5:03 pm UTC

niauropsaka wrote:
Eebster the Great wrote:Dan, at what point does it become obvious that it is more efficient to put those turbines on the land somewhere and use the energy to chemically make diesel? Or better yet, find a carbon neutral plan for biodiesel?

Just because you can stick sails on a container ship doesn't mean that you should. Yes we need to do something. That doesn't mean we need to try every dumb idea that occurs to us.

If one of those kites cuts fuel consumption by 5%, what would twenty of them do? I'm sure it doesn't nearly add up to 100%, but it could cut fuel costs a decent chunk, and that means that the strain on the power grid to make biodiesel or hydrogen for container ship fuel is less scary (not that container ships are the major part of "transportation costs" anyway).

And container ships with huge clusters of kitesails are no more intrinsically ridiculous than container ships burning petroleum diesel. They might even be cute. :wink:


Ridiculous is when you have too much lateral force, and roll your whole ship. This is also, particularly for tankers, considered not great environmentally.

Sails don't scale indefinitely. That's why we stopped using them.

User avatar
Soupspoon
You have done something you shouldn't. Or are about to.
Posts: 2537
Joined: Thu Jan 28, 2016 7:00 pm UTC
Location: 53-1

Re: 1732: "Earth Temperature Timeline"

Postby Soupspoon » Tue Oct 04, 2016 5:37 pm UTC

Eebster the Great wrote:
morriswalters wrote:Oven?

Yeah to me the stove is the cooking surface and the oven is the insulated box you bake/roast/broil stuff in.

The stove, is techncally the internal bit where the burning happens, in whatever form. But IME can apply to the whole unit (c.f. 'range') or qualified like as with the hobs (whether or not they are independent burners or heated by the internal stove-proper, 'on the stove') or oven box (again, with gas burner making it a' true'stove in its own right or connected to the seperate burn-box-stove/fireplace, 'in the stove'). Heck, even 'under the stove' (grill) would work.

Also can be primarily a room-heater (wood/etc burning legged iron construct which is mostly combustion chamber with a 'stove pipe' out the back to pass exhaust gasses outside through the wall or ceiling), but I'd expect at least a 'hob' atop, whether or not anybody actually uses it for cooking or heating water on...

But it'd probably depend upon the context of your regular encounters with the term....

User avatar
HES
Posts: 4795
Joined: Fri May 10, 2013 7:13 pm UTC
Location: England

Re: 1732: "Earth Temperature Timeline"

Postby HES » Tue Oct 04, 2016 5:48 pm UTC

More to the point, who uses gas ovens? Even in the places I've lived that had gas hobs, the oven was electric.
He/Him/His Image

speising
Posts: 2078
Joined: Mon Sep 03, 2012 4:54 pm UTC
Location: wien

Re: 1732: "Earth Temperature Timeline"

Postby speising » Tue Oct 04, 2016 6:00 pm UTC

It's new to me that there are temperature gerulated gas ovens. I thought they are only working at a set gas valve value.

User avatar
orthogon
Posts: 2725
Joined: Thu May 17, 2012 7:52 am UTC
Location: The Airy 1830 ellipsoid

Re: 1732: "Earth Temperature Timeline"

Postby orthogon » Tue Oct 04, 2016 6:16 pm UTC

speising wrote:It's new to me that there are temperature gerulated gas ovens. I thought they are only working at a set gas valve value.

You just reminded that what we call "gas mark" (the temperature setting) can also be referred to as "regulo". Apparently Regulo was a make of gas regulator. Having said that, a gas regulator normally regulates the flow rate as opposed to the temperature, so I wonder whether it goes back to earlier ovens where the temperature itself wasn't in the feedback loop. This might explain why an arbitrary numbering scheme was used rather than a temperature.

My mum had a gas cooker. It was all in one: oven, hob and grill. Connecting it up to the gas and electric would have been an unnecessary faff. And I expect gas was seen as the fuel of the future following the discovery of natural gas in UK waters. But gas ovens have gone out of fashion now.
xtifr wrote:... and orthogon merely sounds undecided.

User avatar
Eebster the Great
Posts: 2770
Joined: Mon Nov 10, 2008 12:58 am UTC

Re: 1732: "Earth Temperature Timeline"

Postby Eebster the Great » Tue Oct 04, 2016 6:32 pm UTC

First time hearing the word "hob," too.

User avatar
gmalivuk
GNU Terry Pratchett
Posts: 25821
Joined: Wed Feb 28, 2007 6:02 pm UTC
Location: Here and There
Contact:

Re: 1732: "Earth Temperature Timeline"

Postby gmalivuk » Tue Oct 04, 2016 7:00 pm UTC

I'm pretty sure that every place I've cooked with a gas range has also had a gas oven with temperature markings on the dial. As far as I know this is very much the norm for gas cooking in the US.

I don't know how the gas flow is actually regulated in such ovens, but I've done and eaten enough successful baking in gas ovens to know it must be fairly close to the number on the dial.
Unless stated otherwise, I do not care whether a statement, by itself, constitutes a persuasive political argument. I care whether it's true.
---
If this post has math that doesn't work for you, use TeX the World for Firefox or Chrome

(he/him/his)

User avatar
omgryebread
Posts: 1393
Joined: Wed Dec 15, 2010 3:03 am UTC

Re: 1732: "Earth Temperature Timeline"

Postby omgryebread » Tue Oct 04, 2016 7:15 pm UTC

So if you put sails or turbines on top of a cargo ship, where do you put the cargo?
avatar from Nononono by Lynn Okamoto.

User avatar
orthogon
Posts: 2725
Joined: Thu May 17, 2012 7:52 am UTC
Location: The Airy 1830 ellipsoid

Re: 1732: "Earth Temperature Timeline"

Postby orthogon » Tue Oct 04, 2016 7:18 pm UTC

omgryebread wrote:So if you put sails or turbines on top of a cargo ship, where do you put the cargo?

And if the cargo were a car, where would the cargo?
xtifr wrote:... and orthogon merely sounds undecided.

DanD
Posts: 270
Joined: Tue Oct 05, 2010 12:42 am UTC

Re: 1732: "Earth Temperature Timeline"

Postby DanD » Tue Oct 04, 2016 7:22 pm UTC

I think this might be a US/UK thing, although it may also be regional in the US.

In the US a stove does mean the complete unit, to a point, specifically, we still have wood stoves or pellet stoves. You might buy a stove or an oven at the store if you want the complete appliance with both. However, a unit with just burners (and we do refer to electric units as burners, although you might here "coil" as well due to the shape) might be referred to as a stove top, frequently contracted to just stove, or a range. A unit without burners would be just an oven. Both are available solo, but neither is as common as a combined unit.

Both range and oven are also common in gas or electric. Gas ranges provide more precise control, and a faster cool down when shut off, both advantages. Gas ovens are more energy efficient (since they lack the thermal->electric->thermal sequence of electric generation), and are common when city piped gas is available. To counter that, modern convection ovens tend to be more efficient, and they aren't as available in gas.

Gas or electric ovens in the US almost always have temperature control. In both cases, it is simple on-off thermostatic control, no flow regulation. Between control error and hysteresis, you're maybe 10-20 degrees off worst case, most of which is control error, which is fine for many things. A more accurate thermometer can be used to adjust for control error if you need higher precision.

Stove tops, burners, ranges, whatever, however, both gas and electric use a proportional control, and that is entirely based on a non-temperature/non thermal energy numeric scale.


Return to “Individual XKCD Comic Threads”

Who is online

Users browsing this forum: Runningguy and 72 guests