SGU Episode 582
|This episode needs: transcription, proof-reading, formatting, links, 'Today I Learned' list, categories, segment redirects.||How to Contribute|
|SGU Episode 582|
|September 3rd 2016|
|SGU 581||SGU 583|
|S: Steven Novella|
|B: Bob Novella|
|J: Jay Novella|
|E: Evan Bernstein|
|C: Cara Santa Maria|
|SS = Seth Shostak|
|Quote of the Week|
|There should be no element of slavery in learning. Enforced exercise does no harm to the body, but enforced learning will not stay in the mind. So avoid compulsion, and let your children's lessons take the form of play|
- 1 Introduction
- 2 Gene Wilder's Passing (0:26)
- 3 Forgotten Superheroes of Science (3:43)
- 4 News Items
- 5 Who's That Noisy (43:06)
- 6 What's the Word (45:41)
- 7 Questions and Emails (49:15)
- 8 Interview with Seth Shostak (55:42)
- 9 Science or Fiction (1:10:44)
- 10 Skeptical Quote of the Week (1:27:57)
- 11 Today I Learned:
- 12 References
You're listening to the Skeptics' Guide to the Universe, your escape to reality.
S: Hello, and welcome to The Skeptic's Guide to the Universe. Today is Tuesday, August 30th, 2016; and this is your host, Steven Novella. Joining me this week are Bob Novella,
Gene Wilder's Passing (0:26)
- Played Willie Wonka
Forgotten Superheroes of Science (3:43)
- Peter Fleming – Research on Sudden Infant Death Syndrome
NASA One Year Mars Study (8:00)
Muscle Confusion (14:31)
Biofuels Study (23:36)
S: This next news item's interesting. I wrote about it last week, about biofuels. There was a study that came out – if you guys saw this – looking at the carbon count. How much carbon do biofuels absorb from the atmosphere, and then release into the atmosphere?
I've never been a fan of biofuels as a method of reducing our carbon emissions. It seems like the benefit is pretty close to the line. And it also requires that we use land that we could otherwise be using to grow our food. So even if maybe, over the line in terms of producing more energy than it consumes, I'm not sure that it's really gonna move the needle too much, you know, get us closer to our goal of reducing our CO2 emissions.
In any case, this new study casts even further doubt on it. They were looking primarily at growing corn for corn ethanol as a biofuel. Of course, these calculations all depend on what feed stock you're talking about. If you're using sugarcane, the numbers look a lot better. If we develop some hypothetical algae-based or whatever feed stock in the future, it may be fantastic. Who knows? But if we just focus on corn, which is the number one feed stock for biofuel in the US right now.
What the researchers did was they asked a different question than what has been asked previously. So one of the more common ways of evaluating the efficiency of biofuel is called a “life cycle analysis” - I know we've talked about that on the show before – and LCA, And a life cycle analysis asks, “How much energy is put into creating a gallon of biofuel, and how much energy do we get out of it?”
And for a while, it was kind of questionable whether or not we were even getting more energy out of the biofuel than we were putting into it if you count, again, the entire life cycle. That's where the name comes from. So every bit of energy that goes into growing that corn, harvesting it, fertilizing it, converting it into biofuel, shipping it, et cetera. And then you finally get that gallon of ethanol to where it's being used, and then you burn it. How much energy did you spend getting it there? And for a while, there were many analyses that argued that it was actually a net negative. It cost more energy than you'd end up getting out of it at the end of the day.
But over the last twenty years, ten years I think specifically, the process has gotten more and more efficient. It seems that now we do get net energy out of the biofuel, out of ethanol, than we put into it. So these researchers are asking a different question. They're asking, “What's the carbon balance of biofuels?”
Now, up to this point in life cycle analysis, the assumption is that when you grow the corn, the amount of carbon being absorbed from the atmosphere into the corn is the same as the amount of carbon that's released when you burn the ethanol back and release the CO2 into the atmosphere, so that the offset of growing the feed stock is a hundred percent of what gets released into the atmosphere.
But the authors said, “Well, maybe that assumption is not correct, of a hundred percent offset from growing the feedstock versus burning the biofuel.” So they calculated how much extra carbon would be absorbed from the atmosphere from growing all of the corn used to make biofuel, and then how much carbon would be released into the atmosphere from burning that biofuel. And according to their calculations - which are very complicated. I really couldn't parse it. We'll link to the paper if you want to dive in there. Good luck to you. It was a very technical paper, but this is the bottom line.So actually, I'll read their conclusion. This is a quote.
“The assumption that biofuels are inherently carbon neutral is a premise of most climate-related fuel policies promulgated to date, including measures such as the LCFS and RFS that evaluate greenhouse gas impacts using life cycle modeling. However this analysis found that the gains in CO2 uptake by feedstock were enough to offset biofuel-related biogenic CO2 emissions by only thirty-seven percent over 2005 to 2013,”
That was their period of evaluation.
”showing that biofuel use fell well short of being carbon neutral, even before considering process emissions.”
Now, if you take their thirty-seven percent, and plug that into the existing life cycle analysis of corn ethanol biofuel, instead of the assumed hundred percent, what they conclude that growing corn for biofuel actually is a net increase in the amount of carbon released into the atmosphere. So by their analysis – if it's correct – these biofuels actually worsens CO2 release into the atmosphere.
E: Oh boy.
J: Oh man, that's crazy!
S: One question I could not answer – I could not find the answer to this, and that always makes me feel uncomfortable, when I can't close the loop myself, at least conceptually, what's going on here? If growing the corn only offsets thirty-seven percent of the CO2 that gets released when you burn it, then where's the other sixty-three percent of the carbon coming from? Does that mean that sixty-seven percent of the carbon in the ethanol did not come from the air into the corn? So where is that CO2 coming from? It has to come from somewhere.
Now, the study, again, as far as I could tell, didn't look at that. They were just calculating the net carbon flow, in and out of the biofuel. Some people commented that maybe it came from the soil, but that's not true. The corn does not pick up carbon from the soil. If anything, it releases carbon into the soil.
It probably comes from the fossil-fuel-based fertilizer, but that wasn't clear. I couldn't find any place in the paper that sort of discussed that explicitly. So, anyway, it's interesting. It's a very complicated area. The whole idea of trying to track every bit of energy and every molecule of carbon in a complicated process like growing corn, turning it ethanol, and shipping it and burning it and fertilizing and – it's all the things that go into doing that, is hard to track all that down.
But it tells you how close things are when little assumptions that we make, or things that we don't account for make the difference between it being a net advantage or a net disadvantage. It's certainly not a home run. And I will say (and the authors did make this explicit) that their analysis didn't even consider the effect of the increased land use to grow all this corn, to turn into biofuels, because turning a forest into farmland actually releases CO2 into the atmosphere.
Yeah, and of course, there is only so much land. I know we discussed not too long ago on the show, we're actually using pretty much all the arable land on the Earth to grow crops.
E: All of it?
S: Yeah, pretty much! There's not much left. There may be a tiny bit here or there. All the best farm land is being used. We certainly can't significantly increase the amount of farmland we have to use to grow crops. So we do have to ask going forward, if we imagine, “Where is this gonna be in fifty years or a hundred years, in terms of where are we getting our energy from, and also how are we growing enough food to feed that then what's it gonna be? Fifteen billion people, or whatever. Obviously, that's gonna keep going up.
C: Bugs and kelp!
S: Yeah, I know, we got to eat bugs.
B: Lab-grown meat!
E: Well, there's that
S: Bob, lab-grown meat is not a source of energy. That is just converting energy into a form that we want to eat. But
C: Yeah, we're gonna be having to eat all these algae blooms
C: that are happening in the oceans. We're gonna have to start using the ocean to harvest more microorganisms and eating lower down on the food chain I think.
E: Kellogg's brand Algae Flakes.
C: Yeah. (Laughs)
S: Well, we're already getting a lot of our calories by over-fishing the oceans.
E: Yeah, the ocean's in trouble.
S: I do think there will be technological breakthroughs that will change the nature of the game, but it's still, I don't think it's gonna get us away from having to think about where all the molecules are coming from that we're using.
Building Solar Panels on the Moon (32:17)
Who's That Noisy (43:06)
- Answer to last week: Wheel Harp
What's the Word (45:41)
S: All right, Cara, what's the word?
C: The word this week is glycolysis. You guys know what glycolysis is? Not you, Steve.
S: Oh yeah.
J: I know what glycolic is.
E: Yeah, glycolic, glyco.
C: Glyco, good.
B: Is that turning sugar to glycogen in the muscles?
C: It's turning sugar into something, not glycogen.
B: You know, two months ago, I knew exactly what that damn word was.
C: A lot of people listening are gonna say the same thing. So glycolysis is the metabolic pathway that breaks down glucose, as you said. That part of it is true. Starting with a single molecule of the simple sugar glucose, or C6H12O6. It undergoes ten different enzymatic reactions to finally result in pyruvate, or CH3COO minus, and one hydrogen ion.
Glycolysis is a type of catabolic pathway, also called, “glucose catabolism,” meaning that it breaks down nutrients as opposed to an anabolic pathway, one that builds up. And it occurs in all living organisms – anaerobic and aerobic. The ultimate outcome of glycolysis is actually energy production in the form of ATP, or adenisine triphosphate. It also can produce energy in the form of NADH. These are cellular energies that are necessary (especially ATP is necessary) for almost all metabolic reactions. In fact, it's actually required for glycolysis itself to occur.
It takes two ATP to undergo glycolysis, which produces four ATP, so there's still a net gain of two there. After glycolysis, different processes can occur. You've probably heard of the citric acid cycle. Think real hard back to freshman bio, also called the Krebs cycle,
C: which is followed by oxidative phosphorellation. That's where we have that proton pump when we see a ton of ATP produced. But when there's no oxygen available, glycolysis can actually lead to fermentation, like alcohol with yeast – yes, yeast is a living organism. And it undergoes this metabolic process, and that's how we make boose. Or lactic acid fermentation, which can actually occur in our own muscles when oxygen is low.
So, where did it come from? At least the word, glycolysis. The process was actually elucidated first by Louis Pasteur in the 1800's, but he didn't quite have everything worked out. He was working with wine fermentation. And then after that, Edward Buchner (I really hope I'm pronouncing that right), he discovered the pathway's individual steps. He coined the term himself in the 1890's, and it would be fifty more years until all the steps were fully described.
And glycolysis as a word is quite an easy one if you're a biology student, you're trying to remember what it means because it's the literal joining of the French roots “glyco,” meaning sweet; and later specifically a reference to sugar, and “lysis,” which means to break, release, loosen, or set free. So it follows that glycolysis is the pathway by which all living organisms break down sugar.
S: All right, thank you Cara.
(Commercial at 48:36)
Questions and Emails (49:15)
- Exoplanet Gravity
Interview with Seth Shostak (55:42)
Science or Fiction (1:10:44)
(Science or Fiction music)
It's time for Science or Fiction
Skeptical Quote of the Week (1:27:57)
S: And until next week, this is your Skeptic's Guide to the Universe.
S: The Skeptics' Guide to the Universe is produced by SGU Productions, dedicated to promoting science and critical thinking. For more information on this and other episodes, please visit our website at theskepticsguide.org, where you will find the show notes as well as links to our blogs, videos, online forum, and other content. You can send us feedback or questions to email@example.com. Also, please consider supporting the SGU by visiting the store page on our website, where you will find merchandise, premium content, and subscription information. Our listeners are what make SGU possible.
Today I Learned: