Author Topic: Episode #597  (Read 2458 times)

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Online Sawyer

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Re: Episode #597
« Reply #30 on: December 19, 2016, 02:30:48 PM »
I reject the notion that doctors, as a class, are too stupid or too stubborn to look at all the evidence, including the evidence from nutrition science, and analyze it more accurately than untrained laypersons.
Given how many other areas of science doctors don't know as much about as they should (according to Steve's own accounts), I'm not sure why you are so confident about their level of understanding of nutrition science, even for doctors whose specialization is far removed from nutrition.

This would be a fine point if we were living in a vacuum and didn't have previous exposure to the controversies between doctors, nutrition scientists, and diet gurus.  The "doctors don't know anything about nutrition" trope is something that is not coming predominantly from the nutrition science community.  Sure they may complain from time to time about ignorance of their chosen field just like any other medical specialists, but their complaints are dwarfed by those coming from the LCHF crowd, vegetarian activists, cancer quacks, etc.  Even if there are real gaps in doctors' knowledge that need to be addressed, it's not going to solved by getting doctors to blindly accept the opinions of a minority of nutrition experts.  Getting the actual research community to all be on the same page about diet has to be a prerequisite for instituting new education standards for doctors.  This does not appear to be something that people whining about nutrition ignorance are very good at accomplishing.  They are trying to do an end-run around other nutrition researchers, and I refuse to aid them in this quest my employing their favorite catch phrases.

I won't pretend to know more about nutrition than our resident LCHF cheerleaders, but I'm still fairly confident that my cousin who got a Ph. D. in childhood nutrition from UC Davis knows what she's talking about, and is not a paid shill for Big Carbohydrate.  And yet somehow our family Christmases are not filled with her ranting about dumbass doctors poisoning her baby with sugar...

Offline gmalivuk

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Re: Episode #597
« Reply #31 on: December 19, 2016, 02:40:53 PM »
You'll note that I have not said anything here about LCHF, and if you've paid attention to the thread about that, you'll have noticed that I am in fact generally opposed to the position lonely moa espouses there.

I'm simply pointing out that "calories in minus calories out" is, while technically true (and complete), a more complex equation than is generally acknowledged by the "it's simple physics" crowd. Food types may not affect absorption and metabolism as much as some quacks claim, but they do have an effect nonetheless, as do differences between individuals in how their bodies use nutrients and store fat. Statements like "this pint of ice cream would be burned off by walking for 5 hours" are not true universally, even for the same pint, because people react to the ice cream and to walking differently. (For example, someone who's lactose intolerant enough to shit the whole pint out probably gets somewhat less than 1000 calories from it.)

"You lose weight by burning more calories than you eat" is to nutrition roughly what "you make money by buying low and selling high" is to playing the stock market.
« Last Edit: December 19, 2016, 02:45:48 PM by gmalivuk »
The world is so exquisite with so much love and moral depth, that there is no reason to deceive ourselves with pretty stories for which there's little good evidence. Far better...is to look death in the eye and to be grateful every day for the brief but magnificent opportunity that life provides.

Offline The Latinist

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Re: Episode #597
« Reply #32 on: December 19, 2016, 03:55:27 PM »
Steve gave an overview of the options for energy storage: from cryogenic storage, hydrogen to batteries. He mentioned that the round-trip energy efficiency for battery storage is 60-70%.

That is not correct. In fact batteries are much better: they have a round-trip energy efficiency of between 80% and 90%!

It is possible to approximate the battery round trip efficiency from the EPA sticker of a electric car. It's quite simple: A Nissan Leaf EV has a usable battery capacity of 22kWh for an EPA range of 73 miles. So it's net efficiency is 30.6 kWh/100 miles. The EPA rates its gross plug-to-wheel efficiency at 34 kWh/100 miles. The ratio between the two is the round trip efficiency: almost 90%.

The success (cost, CO2 Emissions, range) of electric cars very much depends on a high round-trip energy efficiency. There is a big difference between losing just 10% to heat in the battery and charger vs  over30%. Li-Ion batteries are pretty darn good!

That's not round-trip efficiency, though.  For load balancing in a power-grid, you need to be converting from line level AC to battery and back to line-level AC.
I would like to propose...that...it is undesirable to believe in a proposition when there is no ground whatever for supposing it true. — Bertrand Russell

Offline daniel1948

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Re: Episode #597
« Reply #33 on: December 19, 2016, 05:09:41 PM »
You'll note that I have not said anything here about LCHF, and if you've paid attention to the thread about that, you'll have noticed that I am in fact generally opposed to the position lonely moa espouses there.

I'm simply pointing out that "calories in minus calories out" is, while technically true (and complete), a more complex equation than is generally acknowledged by the "it's simple physics" crowd. Food types may not affect absorption and metabolism as much as some quacks claim, but they do have an effect nonetheless, as do differences between individuals in how their bodies use nutrients and store fat. Statements like "this pint of ice cream would be burned off by walking for 5 hours" are not true universally, even for the same pint, because people react to the ice cream and to walking differently. (For example, someone who's lactose intolerant enough to shit the whole pint out probably gets somewhat less than 1000 calories from it.)

"You lose weight by burning more calories than you eat" is to nutrition roughly what "you make money by buying low and selling high" is to playing the stock market.

Emphasis mine.

This is another straw man. Nobody is claiming that everyone's metabolism is the same, and nobody is giving figures about exactly how many hours of what kind of exercise will burn off how much ice cream.

The problem is when people claim that it doesn't matter how much you eat because their special diet allows you to eat all the calories you want and still lose weight.

It does matter how much you eat, and the published calorie tables are close enough for practical use. The body needs certain nutrients (with some individual variation) and the body will burn a certain amount of energy (with individual variation for basal metabolism and exercise level). You need to get a well-rounded mix of nutrients to be healthy, and whether you gain or lose weight will depend on that calorie math. There is no magical diet that will allow you to eat an unlimited number of calories without gaining weight. (Though there are drugs, such as amphetamines, that will raise your metabolism and kill your appetite so that you lose weight as they destroy your body.)
Daniel
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Offline gmalivuk

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Re: Episode #597
« Reply #34 on: December 19, 2016, 06:19:53 PM »
The problem is when people claim that it doesn't matter how much you eat because their special diet allows you to eat all the calories you want and still lose weight.
I'm not claiming that, though, so I guess now you're throwing around straw men because you think that's what I did?
The world is so exquisite with so much love and moral depth, that there is no reason to deceive ourselves with pretty stories for which there's little good evidence. Far better...is to look death in the eye and to be grateful every day for the brief but magnificent opportunity that life provides.

Offline PatrickG

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Re: Episode #597
« Reply #35 on: December 19, 2016, 07:20:57 PM »
Steve gave an overview of the options for energy storage: from cryogenic storage, hydrogen to batteries. He mentioned that the round-trip energy efficiency for battery storage is 60-70%.

That is not correct. In fact batteries are much better: they have a round-trip energy efficiency of between 80% and 90%!

It is possible to approximate the battery round trip efficiency from the EPA sticker of a electric car. It's quite simple: A Nissan Leaf EV has a usable battery capacity of 22kWh for an EPA range of 73 miles. So it's net efficiency is 30.6 kWh/100 miles. The EPA rates its gross plug-to-wheel efficiency at 34 kWh/100 miles. The ratio between the two is the round trip efficiency: almost 90%.

The success (cost, CO2 Emissions, range) of electric cars very much depends on a high round-trip energy efficiency. There is a big difference between losing just 10% to heat in the battery and charger vs  over30%. Li-Ion batteries are pretty darn good!

That's not round-trip efficiency, though.  For load balancing in a power-grid, you need to be converting from line level AC to battery and back to line-level AC.

Using batteries for balancing the power grid or for powering the car at technically hardly any different: both require 240AC->DC conversion, up-conversion to ~360V battery voltage and then DC->AC conversion. Synchronous electric motors require AC. So for the overall round trip losses there is no real difference. The conversion and battery losses are all in the overall numbers. Thanks to modern power electronics there is remarkably little loss.

Offline The Latinist

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Re: Episode #597
« Reply #36 on: December 19, 2016, 08:34:00 PM »
Here's a DoE assessment of various energy storage technologies and their benefits. It includes not only round-trip efficiencies but capital and ongoing costs, performance curves, and discussions of cycle life where relevant.  I did not see a discussion of environmental impact.  It looks pretty well-researched to me.  They conclude that at the high powers required for load balancing, the round-trip efficiency of Li-ion batteries is about .80, just shy of pumped hydro. But certainly not .90.

http://energyenvironment.pnnl.gov/pdf/National_Assessment_Storage_PHASE_II_vol_2_final.pdf

It should also be pointed out that cycle life for Ali-ion batteries is severely affected by depth of discharge.  Actually using a significant portion of the charge stored will significantly decrease their useful life.  That makes them more suitable for balancing of temporary load variance than for large-scale storage or time-shifting.
« Last Edit: December 19, 2016, 08:42:47 PM by The Latinist »
I would like to propose...that...it is undesirable to believe in a proposition when there is no ground whatever for supposing it true. — Bertrand Russell

Offline PatrickG

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Episode #597
« Reply #37 on: December 20, 2016, 12:12:59 AM »
Thanks for the interesting DOE assessment. Indeed, the lifespan of Li-ion batteries depends on the size of the charge window. laptops and phone phones use 100% but barely survive 2 years. My EV only uses 65% to get an estimated life of over 10 years (3650 cycles). The life-time requirement simply means that longer lasting batteries need to be 20-35% oversized to handle 1 cycle per day without wearing out quickly. The over-sizing has the additional advantage of reducing the current density and with that increasing efficiency.

The report writes: "Li-Ion batteries are very efficient, with dc-dc efficiency in the 0.85-95 range (Rastler 2007) and ac-ac efficiency about 0.85 (Schoenung 2003). For this study, considering the high power of the balancing application, a dc-dc efficiency of 0.8 has been used."

I really don't understand their justification for the choice for a low 80% efficiency. "High power" is a matter of putting more batteries in parallel, and should not affect efficiency. What matters is the current density per Li-Ion cell, and that can be designed such that it optimizes both efficiency and lifespan. High lifespan automatically forces a lower current density.

Since hydro doesn't wear out and can be scaled up it does seems a good long term solution for large scale storage. But it requires a proper geography with mountains.

Another factor is cost. Doing the back-of-the-envelope math of the Tesla powerwall Li-ion home storage it works out to about 7 cents per kWh for the storage. Home solar panels cost ~8-10cents per kWh (assuming 25 years), so it adds up to a generation cost of 24 hour clean energy at ~16 cent/kWh. The storage costs almost as much as the generation.

Compare that to cost of coal power at 2cents per kWh or 3.5 cents/kWh for natural gas. It's clear this does not work without heavy subsidies and government regulation. Fat chance with will work with a climate change denier in charge of the DoE :(


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« Last Edit: December 20, 2016, 12:15:56 AM by PatrickG »

Offline lonely moa

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Re: Episode #597
« Reply #38 on: December 20, 2016, 02:41:09 AM »
The problem is when people claim that it doesn't matter how much you eat because their special diet allows you to eat all the calories you want and still lose weight.
I'm not claiming that, though, so I guess now you're throwing around straw men because you think that's what I did?

Eat a high fat low carb diet and you can eat all you want.  It just happens that when one's body gets used to eating that way, one wants to eat less.  Your body isn't stupid, but it is easily tricked by high energy, low nutrient foods to eat too much to maintain a stable weight.  Sugary and high carbohydrate foods were  a boon to our ancestors as they provided lots of calories, but thos foods weren't often available.
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Offline 2397

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Re: Episode #597
« Reply #39 on: December 20, 2016, 02:47:05 AM »
Human bodies tend to get stuck on famine preparation-mode.

I wonder what the long term effects would be of engineering that option out.

Offline AtheistApotheosis

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Re: Episode #597
« Reply #40 on: December 20, 2016, 05:30:42 AM »
the answer to Fermi's paradox is that technological civilizations end up hidden and imprisoned by their orbiting space junk.

Fermi's paradox is based on a linear view of technological development, projecting current technology into the future in roughly a straight line. It doesn't work because technology does not develop in a linear way, just look at the development of the mobile phone. First, they were the size of a typewriter and powered by a car battery, then they got smaller and smaller and tiny and... then freaking enormous with a built-in PC. Now they convert to VR goggles, GPS navigator, Camera... etc. Clarks three laws state...
   
    1. When a distinguished but elderly scientist states that something is possible, he is almost certainly right. When he states that something is impossible, he is very probably wrong.

    2. The only way of discovering the limits of the possible is to venture a little way past them into the impossible.

    3. Any sufficiently advanced technology is indistinguishable from magic.

But there is a fourth law he should have included.

    4. Any sufficiently advanced technology is indistinguishable from nature.

The goals of any technological civilisation should necessarily be greater complexity leading to a technology more complex than naturally evolved organic life. And improved energy efficiency surpassing the efficiency of naturally evolved organisms. If you want an example from science fiction of what an advanced civilisation would look like after a million years of development, the planet Pandora from Avatar. A planet wide fibre optic neural network utilising bio-luminescence, people and animals with built in USB ports. The ability of the natives to upload their consciousness to the living network when near death. And a mineral with ridiculously useful properties that don't occur in nature and exists on only one known planet.

Space junk is not as big a problem as you might think. a few thousand solar powered drones would solve the problem in a few years. You just need a refuelling ship parked in orbit to refuel the drones after each mission slowly working its way around the earth. You could even recycle the space junk to supply orbiting space stations with construction material. Every problem has a million plus solutions, and one or two hundred that may work and a few that are practical and three or four that will be tried and one or two that will become the standard.

Offline daniel1948

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Re: Episode #597
« Reply #41 on: December 20, 2016, 08:45:50 AM »
Science fiction is like Nostradamus. In hindsight you can find things that seem to be accurate predictions, but for making actual predictions or finding useful explanations it is useless. Fun, but useless.
Daniel
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Offline AtheistApotheosis

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Re: Episode #597
« Reply #42 on: December 20, 2016, 09:37:20 AM »
Creating reservoirs to store energy has major environmental disadvantages, including methane emissions:
http://bioscience.oxfordjournals.org/content/early/2016/10/02/biosci.biw117.short
https://www.washingtonpost.com/news/energy-environment/wp/2016/09/28/scientists-just-found-yet-another-way-that-humans-are-creating-greenhouse-gases/?utm_term=.e85ca76f0d17
Not to mention land loss, erosion, flooding. some of the property losses from the Brisbane floods were partly the result of water release from Wivenhoe Dam. The constant rise and fall of water levels kills vegetation along waters edge which results in erosion and some landslides. Try reaching the water when you have to walk 30 to 40 meters through thick mud up to your waist with a canoe held over your head. Makes for some interesting camping places though. I've gone for a walk along the edge of Advancetown lake and Hinze dam a few times, and its strange to see forests going down and continuing into the lake with trees sticking up out of the water.  Roads down to the waters edge, and when the water is clear enough you can see it continuing down under water. would be an interesting placed to go diving, there are a few houses still down there, deep below the surface.

Offline AtheistApotheosis

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Re: Episode #597
« Reply #43 on: December 21, 2016, 04:43:12 AM »
Science fiction is like Nostradamus. In hindsight you can find things that seem to be accurate predictions, but for making actual predictions or finding useful explanations it is useless. Fun, but useless.
Michel de Nostradame, one of the most successful con man in history. Sceptics always underestimate him. An educated man who recognised the repeating pasterns of history, and used that to create the highest probability predictions possible. His predictions read like science fiction with natural and man made disasters. Future technology and politics. After all, his predictions unlike most prophets contained only few religious or fantastical predictions which covered periods safely beyond his own life time. He managed to keep his head in an age where getting a prediction wrong could get you burned at the stake or your head on a spike over the city gates. He made quite a living off the superstitious aristocracy, he was a doctor, all be it a dubious one, a herbalist and alchemist which meant he had a little understanding of biology and chemistry. And probably some understanding of the scientific method. Mind you a lot of his treatments didn't actually work, it involved a lot of leaches and magic pills. I have an old copy of the prophesies of Nostradamus from about 1964 and its interesting to see from that book how many fake Nostradamus predictions there are out there, almost all of them. He also married extremely well.

Science fiction does get a lot of things things right especially authors like Robert A. Heinlein, Gene Roddenberry, Arthur C Clarke and Michael Crichton. Quite often because they inspire scientists to make their ideas reality and some are scientists themselves. Some science fiction is science based and a lot is pure fantasy where there are few rules. Fun, but not necessarily useless.

Offline daniel1948

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Re: Episode #597
« Reply #44 on: December 21, 2016, 07:16:18 AM »
Useless as a means of imagining the future. Certainly useful as fun escapist recreational reading when it is done well. In the age of Kindle (which I love) there's a lot of self-published crap.
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