NNadir
NNadir's JournalFamily Redux: I had a wonderful kind of angry bitter political argument with my son.
Once when we were first married, my father and my stepmother - who had been married to my father for less than six years - came to visit us in California.
My father and I hadn't seen each other for about a year or so at the time, and we loved each other very much.
We had this big deal screaming argument with each other over the war in Vietnam - which had been over for more than a decade at the time - and my stepmother told my father that she thought they were going to get thrown out of our apartment and would have to go to a hotel.
My father just laughed and remarked about how proud he was of how I kept pulling books off my bookshelves to bolster my hotheaded argument.
The next morning we drove down to San Diego harbor so he could reminiscence about his last visit to San Diego, where he spent a day loading ammunition on his aircraft carrier during World War II.
It was a wonderful visit. I very much miss the ability to have heated political arguments with my father, who died in 1993.
The other night I had the chance to have a heated argument with my son over Michael Bloomberg. It was like the old days.
My wife - who'd been there for that San Diego argument - remarked on how heated the argument was.
"It's a family tradition," I said.
My son, who loves stories about his grandfather - who he never met - and I just laughed.
Life is beautiful, and then you die.
The art of misleading the public
This book review is in the current issue of the scientific journal Science.
The review is by Sheril Kirshenbaum.
The book is:
The Triumph of Doubt: Dark Money and the Science of Deception David Michaels Oxford University Press, 2020. 344 pp.
The Art of Misleading the Public Science 14 Feb 2020: Vol. 367, Issue 6479, pp. 747
A large excerpt of the review:
Michaels is the quintessential voice on the influence of special interests in policy-making and government inaction. An epidemiologist and professor of environmental and occupational health at George Washington University, he spent 7 years leading the U.S. Occupational Safety and Health Administration (OSHA) under President Obama and previously served as President Clinton's assistant secretary of energy for environment, safety, and health.
His book offers account after account of unethical bad actors working against the public good on issues ranging from asbestos to climate change. Powerful firms and individuals seeking personal gain repeat the tactics of a well-worn playbook of denial and misdirection proven effective by Big Tobacco more than 50 years ago. Michaels pulls no punches, naming the corporations and people responsible for fraud, deception, and even what he terms “climate terrorism.” He reveals the dirty ways that industries have succeeded at shaping their own narratives regarding safety and health by producing articles and diversions designed to deny and distort science while confusing the public.
When a Boston University brain study found that 110 of 111 National Football League (NFL) players' brains showed pathologies consistent with the rare disease chronic traumatic encephalopathy (CTE), the NFL hired its own conflicted scientists to counter and discredit these troubling findings. When reports from the International Agency for Research on Cancer, the U.S. National Toxicology Program, and the World Health Organization independently linked alcohol consumption to certain cancers, the alcoholic beverage industry claimed that these associations were not real and doubled down on its messaging that moderate drinking is good for us. When the opioid epidemic hit the United States, ravaging families and communities, well-documented evidence suggests that drug companies suppressed research and misrepresented the clear science demonstrating that opioids are addictive and easily abused.
What is most striking in The Triumph of Doubt is that Michaels is not merely reporting on how corporations and industries manufacture uncertainty. Rather, he provides an insider's perspective on the machinations taking place in the nation's capital, in courtrooms, and across the country...
Physico-chemical properties of Chernobyl "Elephant's Foot" Lava.
I'm on a couple of technical news feeds at my job and an article in one of them caught my eye since I am interested in all things involving nuclear energy. The news item is here: Innovative Material Could Help Clean Up Chernobyl and Fukushima.
Whenever one reads a press release about science with the word could in the title, one's "critical thinking required" alarm should light up and start buzzing loudly. I would argue that 95% of the time, or perhaps more, when this happens one should expect to read a distortion, wild inflation, or overly optimistic or overly pessimistic interpretation of a laboratory finding that has little to do with what actually happened in the laboratory.
I am an old man. For my entire adult life, I have been reading how so called "renewable energy" could power the entire world, "by 1995," "by 2000," "by 2010," "by 2015," "by 2020..." and so on.
Reality:
Here is a table of sources of energy taken from the data found in the International Energy Agency’s 2017, 2018, and 2019 Editions of the World Energy Outlook published annually:
A table of changes:
Sources:
2019 Edition of the World Energy Outlook Table 1.1 Page 38] (I have converted MTOE in the original table to the SI unit exajoules in this text.)
IEA 2017 World Energy Outlook, Table 2.2 page 79
Sometimes, I'd guess maybe 10% to 15% of the time, one is inspired to actually look at the original source article - if, in fact, one has been published - to find out what is actually being stated by the scientists who did the work, without added journalistic or marketing spin.
In the case of the above cited news article, here is the actual paper to which the news item actually refers:
Synthesis, characterization and corrosion behaviour of simulant Chernobyl nuclear meltdown materials. (Hyatt, et al, npj Materials Degradation volume 4, Article number: 3 (2020))
It is open sourced; anyone can read it.
It does contain the following statement in the abstract:
"LFCM" is defined above in the abstract as "Lava-like fuel containing materials."
The event at Chernobyl was, and always will be, the worst case for nuclear reactor technology. All the money spent to "clean up" Chernobyl will save very few lives, because 34 years later, very few lives are now at serious risk.
Recently elsewhere in this space I wrote this in response to a comment:
Let's say that the death toll of air pollution averaged, over the last 34 years, five million people per year, a lower rate than what is currently understood.
That works out to 170,000,000 deaths from air pollution in the 34 years since Chernobyl.
Of course, the fact that we don't pay attention to one, and microexamine the other makes no difference in the actual numbers.
And then there's climate change. Do you grasp how serious, how much death and destruction will be involved in comparison to Chernobyl?
Here are some things that have killed more people than 60 years of nuclear operations: Automobiles, aircraft, fatty foods, water, house fires...
Do we routinely assume that cars, aircraft, fatty foods, water and houses are "too dangerous?" Do we say any of these things should be phased out? (For the record, I do believe that cars should be phased out, but that's just me.)
I'm a scientist. I am trained to think critically. In general this means rejecting journalistic impressions, which are often geared at making people not think critically but rather in emotive and/or sensationalist terms.
Look at politics. "But her emails..."
I look at journalism about nuclear energy in exactly the same way, "...but her emails..."
We could save more lives that we propose to spend to "clean up Chernobyl and Fukushima" to some absurd standard of safety if we spent the same amount of money to stop destroying the planetary atmosphere. That's my could statement.
Nuclear energy, overall, saves lives by preventing dangerous fossil fuel waste, including but limited to air pollution, from killing people, which it does continuously, with and without accidents occurring, that is, during normal operations.
Reality.
From the above data from the IEA, despite all the hoopla about solar and wind energy saving the world, all the cheering, all the "could power 100% of world energy by 'year such and such'", after an "investment" of trillions of dollars devoted to wind and solar every decade, coal has been the fastest growing source of energy on this planet in the 21st century.
Again, it's open sourced; you can read all about the "LFCM simulant" in the original paper, if you're interested. I found looking through the references in the paper to be interesting, since the references refer to some of the real "Chernobyl Lava" that has been recovered from the reactor.
The real Chernobyl lava is interesting though. I could not access some of the papers through Google Scholar, but I was able to download reference 17, which is not, I believe, open sourced. Here it is:
Physico-chemical properties of Chernobyl lava and their destruction products (Andrey A. Shiryaev, et al. Progress in Nuclear Energy 92 (2016) 1040-118)
It contains this text:
Here is a picture of the "elephant's foot:"
The person in this picture was of course, in great danger; it may be "Mr. Vladimir Zirlin of the V.G. Khlopin Radium Institute" referenced in the text above. The grainy nature of the picture is almost certainly connected to radiation exposure of the film during the trek to take the photograph. If this is Mr. Zirlin, he was still publishing papers as late as 2012.
Development of New Generation of Durable Radio-luminescence Emitters based on Actinide-doped Crystals (Zirlin et al., Procedia Chemistry Volume 7, 2012, Pages 654-659).
He seems to have lived at least 22 years after taking the picture, and, in fact, was still working 22 years after taking the picture. It would hardly be surprising however, if his life has been significantly shortened by the act of taking the picture than if he had not taken the picture, and bravely carried the samples out of the reactor for analysis, whereupon they were sealed in an acrylic resin.
Anyway, let me return to the interesting Progress in Nuclear Energy paper. It begins with a description similar to those one can read in many places both in the general and the scientific literature, with more or less detail. These descriptions are very popular and wide spread in both the professional and general news, as people are far more interested what's going on in Chernobyl since 1986 than they are in the 170,000,000 deaths from air pollution since 1986 that I postulated above.
Here is the introduction:
In the RBMK reactors the reactor basement plate is a cylinder 14.5 m in diameter and 2 m in height, filled with serpentinite with bottom and top steel lids interconnected by stiffening ribs and water tubes. During the explosion a 100-110_ sector of the basement plate was pushed approx. 4 m down, merging the reactor shaft with a former sub-reactor room 305/2 (e.g., Arutyunyan et al., 2010). The amount of nuclear fuel in the room 305/2 is estimated at 65-80 tons of UO2 (Borovoi et al.,1998). Before and shortly after the explosion the fuel reacted with zircaloy and later with construction materials (sand, concrete, serpentinite, steel), leading to the formation of so-called lava-like fuel-containing materials (LFCM) or Chernobyl “lava” (Burakov et al., 1994, 1997a,b; Ushakov et al., 1997). Several days after the accident considerable fraction of the initial lava pool spread into other rooms of the reactor building (Burakov et al., 1997a), forming vertical and horizontal flows which solidified into a highly radioactive glassy material with inclusions of high-uranium zircon crystals (Zr1-xUx)SiO4, particles of molten stainless steel, uranium oxide dendrites and grains, and particles of Zr-U-O phases (solid solutions in the system of UO2-ZrO2). Several varieties of the lava are known (e.g., Anderson et al., 1993; Borovoi et al., 1990, 1991a, 1991b; Burakov et al., 1994, 1997a,b; Pazukhin, 1994; Pazukhin et al., 2006; Savonenkov et al., 1991; Trotabas et al., 1993): 1) brown lava; 2) black lava, and 3) much less abundant and less studied polychromatic lava. On the lower levels of the reactor building the flow of brown lava entered water in the bubbler tank forming pumice-like material (Borovoi et al., 1991a; Trotabas et al., 1993). Controversy still exists about the total amount of uranium in all “lava” streams in comparison with initial fuel inventory. Estimates vary from 9-13% (Kiselev and Checherov, 2001) to >80% (Arutyunyan et al., 2010) of total amount of the ChNPP fuel; the rest is believed to remain in inaccessible premises of the reactor, possibly as fuel rods fragments.
Since 1986, and 1990, when the lava samples were first collected at Chernobyl, there have been huge advances in analytical chemistry, and the purpose of the paper is to utilize these lava samples using this new technology:
In addition, some new samples were acquired:
Aerosol particles were collected in 2010-2014 at the distance of 20-30 cm from the lava heap in room 012/7 (level 0.0 m, the first floor of the Bubbler tank (Borovoi et al., 1991a)) using a pack of three Petryanov filters with different particulate retention sizes mounted on the nose of the air blower Н810 RadeCo operating for 2 h at a pump rate 100 dm3/min. Daily variations of the air temperature in this room are negligible, annual variations are within 4С -9С in winter and 13-С in summer). Chemical and radionuclide (e.g., 137Cs/241Am) composition of the particles collected is consistent with composition of the heap (Pazukhin et al., 2003; Ogorodnikov et al., 2013).
2.3. Spontaneously detached individual sub-millimeter particles
These chips were collected in 2013-2014 on the planar cuvette placed for 6 months on the floor 0.50 m in front of a lava heap in room 012/7 (see chapter 2.2). These particles are of particular interest, since their detachment from the lava accumulation appears to be spontaneous. The particular lava agglomeration is mechanically heterogeneous: the internal part is highly porous (pumice-like or granulated, see Fig. 1G, H) since it was formed when hot brown lava stream entered in contact with water in the Bubbler tank, whereas the outer shell is glassy due to rapid quenching (Borovoi et al., 1991a; Pazukhin et al., 2003). The glassy shell was partly broken by researchers. The exact origin of the studied particles e the heaps’ shell or interior or even destruction of eventual pieces of pumice observed in this room is unclear.
There is reference in the excerpts above to several isotopes of interest in connection with the Chernobyl event, specifically, 137Cs and 90Sr. These two elements, cesium and strontium, and in fact their salts and/or oxides, are highly volatile at the temperatures described during the Chernobyl meltdown, and it is well known that they were widely distributed across Europe in detectable amounts. (It should also be noted that being radioactive, they can be detected as extremely low levels, not all of which represent a severe health risk.)
I have long been following with interest the behavior of environmental loads of Cs-137 in particular, since its volatility suggests some interesting possibilities in nuclear reactor engineering that may be of use when future generations if and when they find the where-with-all and resources to clean up the dangerous fossil fuel disaster that we have left for them, in deep contempt for their lives, something that will only be possible using nuclear technology, given the high energy to mass ratio of nuclear fuels.
For example, before being banned from Daily Kos for telling the truth, the truth being that opposing nuclear energy is akin to murder, I wrote this somewhat sardonic piece in 2010: Post-Chernobyl Radionuclide Distributions in an Austrian Cow. At that time, in 2010, 45.6% of all the Cs-137 released by the Chernobyl accident had decayed to non-radioactive Ba-137. As of this writing, about 54.3% has decayed, 45.7% remains.
Neither Austria nor the rest of Europe has been depopulated by eating cows containing Cs-137 since 1986. (Cows all around the contained Cs-137 well before 1986 from open air nuclear weapons testing. In fact, about 17.7% of the Cs-137 released by the 1945 Trinity nuclear weapons test in 1945 is still radioactive. It seems to be inevitable that New Mexican cows have detectable Cs-137 in them.) Eating cows, by the way, is generally bad for you. More people have died from fatty foods since 1986 than have died from Chernobyl, way more people, hundreds of millions of people in fact. Chernobyl or not, no one ever proposes banning cows because eating them is "too dangerous."
Anyway. Anyway. Anyway.
Here are some tables on the elemental composition of the Chernobyl lava:
A few elements listed here have long lived radioactive isotopes that may be detectable in the samples: They are zirconium (Zr-93 as a fission product and from radioactive induction in Zr-92 in structural materials), iron (Fe-60 from radioactive induction of short lived Fe-59, in turn from the induction of Fe-58) and, of course, uranium, which has been radioactive since the formation of the Earth, and which would have been radioactive whether or not it had ever been in the core of the Chernobyl Unit 4 reactor.
The specific activity - the number of radioactive decays per gram - of none of these elements is particularly high; in every case they are way lower than the specific activity of cesium-137.
Here are some pictures of radioactive lava:
The caption:
By the way, in the first week of April 1986, the concentration of the dangerous fossil fuel waste carbon dioxide in the planetary atmosphere was 349.79 ppm. (The week ending April 6, 1986 from the data at the Mauna Loa CO2 observatory.) In the first week of April 2019, the same figure was 413.13 ppm. Unlike the world wide levels of Cs-137 since the much discussed Fukushima event, the levels of the dangerous fossil fuel waste are going up, not down. Since April 6, 1986, using the figures reported at the Mauna Loa observatory this morning, for the week of February 9, 2020, the concentration of this dangerous fossil fuel waste in the planetary atmosphere has risen by 64.61 ppm.
Unless you are Mr. Zirlin or a colleague involved in the same kind of work, the probability that you will die as a result of Chernobyl is roughly comparable to the probability that you will win the Powerball lottery. The probability that you will die from air pollution, or a car accident, or the effects of eating cows - if you do eat them - is five or six orders of magnitude higher.
Maybe you couldn't care less; maybe you think Chernobyl is the worst thing that ever happened. I disagree. There are, in my mind, hundreds of thousands of things that were worse. For me, since I'm in the unusual position of actually giving a shit about future generations, climate change is much, much, much worse. With respect to nuclear reactors, Chernobyl and Fukushima type events are easily engineered away, just as we engineer away aircraft failures, which by the way, have killed way more people than nuclear reactors have in the last 60 years.
I hope you're having a pleasant Sunday morning.
Extraction and Separation of Lanthanides Using Hydrophobic Ionic Liquids.
The paper I'll discuss in this post is this one: Synergistic Enhancement of the Extraction and Separation Efficiencies of Lanthanoid(III) Ions by the Formation of Charged Adducts in an Ionic Liquid (Hiroyuki Okamura et al. Ind. Eng. Chem. Res. 2020, 59, 1, 329-340).
The importance of the lanthanide elements to modern technology cannot be over estimated. Among many other systems, their importance to so called "renewable energy," particularly the wind industry, is dependent on access to these elements since the wind industry depends on the use of permanent magnets, which are in turn, dependent access to the elements neodymium and dysprosium. The majority of these elements are obtained in China, often under appalling environmental and health and safety conditions.
I'll jump here to the text of the paper which has a nice summary of the value of these elements:
Recently, ionic liquids (ILs) have attracted considerable interest in green and sustainable chemistry and engineering(10,11) and in applications such as functional materials,(12,13) catalysts,(14?16) and pharmaceuticals.(17)Typical ILs are composed of an asymmetric and bulky organic cation and a halide-containing inorganic or organic anion. The ILs consist entirely of ions, and their properties, such as extremely low vapor pressure and incombustibility, are thus quite different from those of molecular diluents. The physicochemical properties of ILs uniquely depend on both the cation and anion.(18) Thus, the polarity, hydrophobicity, and miscibility can be tuned by varying the constituent ions. These unique features offer ILs great potential as functional extraction media for solvent extraction.(19,20)...
The authors discuss, with references, to some of the complexing agent classes that have been utilized in the current organic solvent technology that is currently used in this technology, and looks at some different members of this class for use in their ionic liquid.
The structures of these components are shown:
The caption:
The "Htta" reagent, (2-thenoyltrifluoroacetone) is an acidic reagent, and as such, its properties vary with pH. It has been widely utilized in the extraction chemistry of europium, a feature to which I'll allude below. "TOPO" is trioctylphosphine oxide.
The authors discuss their approach using these reagents.
Some experimental details:
Some results are shown graphically:
Since the DU editor no longer allows exponents, and because the captions are quite busy, captions for figures 4 through 7 are posted as graphics objects. A cubic decimeter (dm^(-3) is a fancy word (a bow to SI units) for "liter.”
The caption for the above figure:
The caption for the above figure:
The caption for the above figure:
This next graphic is a 3D representation of the synergistic effects of the two extractant agents TOPO and htta-
The caption for the above figure:
Of course the interesting thing about this system is that not only can it extract the lanthanides, but can do so in an environment which also allows for their separation.
This graphic shows an example:
The caption:
The structure of the complexes was investigated, and showed, for europium, that a
The lower lanthanides, from lanthanum up to and including gadolinium are also components of used nuclear fuels, and the fast separation and recovery of these elements is desirable. The high energy density of nuclear fuels means that the amount of these elements obtainable from nuclear fuels is low compared to natural sources, but they still have economic value, and those which retain significant radioactivity over relatively long periods of time, significantly samarium and europium, may have particularly high value to accomplish certain environmentally important tasks, owing to this activity.
It is interesting to note that samarium and europium, along with cerium are the lanthanides which exhibit multiple oxidation states. Europium has a well known +2 oxidation state, stable in aqueous solution, samarium a +2 oxidation state in the solid phase and non-aqueous solution, and cerium a +4 oxidation state under a wide variety of conditions, making it useful for thermochemical water and carbon dioxide splitting among many other redox situations, including self cleaning ovens. These three elements are also the three lanthanides in nuclear fuel whose radioactivity remains for appreciable periods of times, samarium for a few centuries owing to its 151 isotope (t(1/2) = 88.8 years), europium for about a century owing to its 152 isotope (t(1/2) = 13.5 years) and 154 isotope (t(1/2 = 8.5 years), and cerium for less than a decade (t(1/2) = 284.9 days). The quantities of samarium and europium isotopes are generally low because of the high neutron capture cross sections of the isotopes of these elements. (Pure non-radioactive europium can be obtained by allowing samarium 151 isolated from used nuclear fuel to decay into this stable daughter nuclide.) Although europium is a valuable element, and tends to be somewhat depleted in many lanthanide ores, the small amounts possible to isolate from decayed samarium-151 is small, and not likely to have tremendous economic value.
It is not clear how this system might operate in the separation of used nuclear fuels to recover the valuable constituents. The radiation stability of ionic liquids has been extensively studied, notably by a scientist whose work I follow quite closely, Jim Wishart, at Brookhaven National Lab and also by his frequent co-author, Ilya Shkrob at Argonne National Labs. The imidazolium ions are known to degrade in radiation fields, albeit (as Wishart has noted) not necessarily at a rate that effects its performance as a solvent, apparently because of the ability to solvate electrons. (I became familiar with Dr. Wishart when attending a lecture of his on electron solvation.) In some systems, degradants of the widely used TBP (tributyl phosphate) extractant in existing nuclear fuel reprocessing schemes can give rise Zr and Pu (and other metals) upon degradation. The TOPO reagent is sort of an analogue, although TBP is a phosphate and TOPO is a phospine. Htta has been used as an extractant for other metals as well.
However, the wonderful thing about ionic liquids is that their composition is tunable to fit purposes. There is an entire class of ionic liquids that use phosphinium ions as cations, by the way. Another feature is that, being ionic, they are useful for the performance of electrochemistry. Owing to the aforementioned variable oxidation states of cerium, samarium, and europium, it is possible to imagine very fast facile separations of these elements by exploiting solubility differences between oxidation states, as well as extraction into liquid metal cathodes or deposition on solid electrodes.
This paper is certainly not the last word in these types of separations, but it's a lovely paper along a route to a sustainable world.
I hope you're enjoying your weekend.
Fiber Supported Amino Acidate Functionalized Ionic Liquid Gels for Direct Air CO2 Capture.
The paper I'll discuss in this post is this one: Hollow Fiber-Type Facilitated Transport Membrane Composed of a Polymerized Ionic Liquid-Based Gel Layer with Amino Acidate as the CO2 Carrier (Hideto Matsuyama et al. Ind. Eng. Chem. Res. 2020, 59, 5, 2083-2092)
This paper caught my eye because it has in its introductory text a "by 2100" statement that's quite different than all those I've been hearing my whole adult life about so called "renewable energy." I first started hearing these when I was effectively a child - since I was a gullible sort well into my twenties - about how "by 2000" we'd live in a renewable energy nirvana.
We don't.
The fastest growing source of energy on this planet in this century has been coal, despite all the "coal is dead" rhetoric that flies around among the other distortions one hears in these times of the celebration of the lie, Trumpian and otherwise. So called "renewable energy" remains what it has been since the early 20th century (when its abandonment was nearly complete), a trivial form of energy.
One doesn't see much blunt realism, even in the primary scientific literature, but this paper has it. To wit, from the introductory text:
I have put in bold the realistic statement.
It's realistic because we are no where near close to doing anything effective to address climate change. We'd rather prattle on endlessly about Fukushima - without recognizing that almost all of the people in the area of the failed reactors who died were killed by seawater and not radiation - than we would have a serious discussion of what the destruction of the entire planetary atmosphere might mean.
980 ppm sounds reasonable to me. In my lifetime, I've seen an increase of over 100 ppm, and despite the trillions thrown at so called "renewable energy" the rate of increase (the second derivative) is rising and accelerating (the third derivative).
I have been studying and thinking about direct air capture for sometime to dream that something will be available for future generations to clean up the mess we left for them because, well, we need our cars, and we need our vacations, and we need our suburbs, etc, etc.
Fugettaboutit.
The technical stuff from the paper:
The introduction continues thus:
However, CO2 desorption requires high temperatures, which increases equipment costs and energy consumption. On the other hand, the membrane technology does not require high temperatures for CO2 separation, and energy-efficient processes can be established. In particular, facilitated transport membranes (FTMs) are suitable for capturing CO2 from gases with low CO2 concentration, such as those found in closed spaces (0.5–0.6% of CO2) as well as flue gases (approximately 10–15% of CO2). Therefore, FTMs are suitable for DAC applications.
FTMs are functional membranes that contain a chemical compound called a CO2 carrier.(8?24) The CO2 carrier can selectively and reversibly absorb CO2 by a chemical reaction. Therefore, FTMs have an extremely high CO2 permeability, even at low CO2 partial pressure.(8?12,16?24) Sarma Kovvali et al. reported that FTMs consisting of polyamidoamine in a porous hydrophilized polyvinylidene fluoride flat membrane showed CO2 permeability of 4100 barrer [1 barrer = 1 × 10–10 cm3 (STP) cm/(cm2 s cmHg)] at a CO2 partial pressure of 0.26 cmHg for completely humidified CO2/N2 mixed gas at room temperature.(10) Chen et al. also reported that FTMs containing glycine–Na–glycerol had CO2 permeability of more than 3000 barrer at CO2 partial pressure of 0.5 cmHg under relative humidity exceeding 70% at room temperature (23 ± 2 °C).(8)...
What follows is a number of references to publications in which various scientific groups discussed the utility of amino acids for CO2 capture.
The authors not however, that the thickness of layers and the viscosity of amino acid solutions are a limitation. They here suggest a supported membrane consisting of hollow fibers to support an amino acidate (an ionic amino acid species). (This is, by the way, sort of similar to what goes on in biological systems for transporting CO2. Biological systems are quite good at CO2 capture from the air.)
The authors write:
Ionic liquids are comprised of organic ions that are positively charged and organic ions that are negatively charged. (Sometimes one of the ions will not be organic, but most often they are.) These are not entirely new compounds. Stable organic ions have been known for a very long time. Brains, among other organs, function because of the organic ion choline, which is positively charged, and many choline based ionic liquids are known. These ionic salts are remarkable because, as the name implies, they can be liquid at, below or slightly above room temperature. They are a positively huge area of research.
Some pictures from the text to illuminate the authors approach in which they polymerize a fairly well known class of organic cations, alkyl imidazolium cations, and then do ion exchange with the resulting resin, exchanging a bromine ion for a glycinate anion, derived from the simplest amino acid, glycine:
The caption:
The caption:
The caption:
The caption:
The separation between nitrogen and carbon dioxide - the important point since air is mostly nitrogen - as a function of gel layer thickness is shown:
The caption:
(A GPU is a unit of gas permeance that has a unit of volume of a gas at standard temperature and pressure (STP) per unit of surface area of the permeating surface, per second per unit of pressure). The unit is sometimes denoted the "Barrer." )
Subsequent diagrams will make better sense with this bit of text:
The caption:
The molecular weight distribution was determined by old fashioned GPC (Size exclusion chromatography) and not something like MALS. (Multiangle light scattering) It's good as a first approximation.
Some results of the dialysis:
The caption:
The caption:
The caption:
And now the important stuff, the selectivity:
The caption:
The conclusion:
These are dark times, and in dark times, sometimes it relieves the pain to recognize that for all that is, there are also things - good things - that are possible.
We have left our children nothing but disaster, except, in the cases like the work of scientists like these, perhaps some tools that they might use to dig out of the graves we have dug for them.
Have a nice TGIF day tomorrow.
Someone here in the Lounge introduced me to Yuja Wang's piano playing.
My wife and I saw her live tonight at Princeton's McCarter theater.
It was simply unbelievable.
I can't remember who posted about her, but whoever it was...
...a big THANX!!!!
Structural Variations of Lignin Macromolecules from Early Growth Stages of Poplar Cell Walls.
The paper I'll discuss in this post is this one: Structural Variations of Lignin Macromolecules from Early Growth Stages of Poplar Cell Walls (Sun et al, ACS Sustainable Chem. Eng. 2020, 8, 4, 1813-1822)
When I moved into my house about 24 years ago, there was a small tree in the front yard that was growing out of a hedge, a little taller than I am - I'm a short fat white bald guy. Despite being a member of a problematic demographic, I rather like trees, and didn't cut the thing down, even though it was growing in the middle of a hedge. I'd estimate that it is now about 10 or 15 meters tall, at the base more than half a meter in diameter. It's survived several major droughts, a few hurricanes, the sucker just grows and grows and grows.
It's tulip poplar, a very fast growing tree, quite remarkable.
In recent years, I've become very interested in the chemistry of wood, which is composed of three biopolymers, one quite regular, cellulose, one somewhat irregular, hemicellulose, and the other a remarkably irregular polymer, or co-polymer, lignin.
(Disclaimer: About 20 years ago, I briefly worked for a company that manufactured, albeit not in the department in which I worked, lignosulfonates, which are used as binders in concrete. They are a side product of the wood pulp industry - the paper industry - and when used in concrete, they represent sequestered carbon - carbon sequestered from the air. I actually didn't like that job, and didn't stay at it very long, but at the time, I was less interested in climate change than I am now. At the time I had no interest in lignin, which is sad, because the chemistry of lignin turns out to be quite fascinating. I wish I'd paid more attention.)
The structure of lignins is evoked by the cartoon introducing the paper:
I enjoyed the paper because of the wonderful analytical and biochemistry in it, and whether or not anyone cares, I thought I'd write about it to fix it in my mind. A fast growing tree, albeit one which is rather water hungry, might well prove to be an important tool for future generations to clean up the planetary atmosphere that we've been so enthusiastically wrecking for them in our sybaritic exercise in self indulgent ecstasy.
From the paper's introduction:
...With regard to the structural features of lignin, the relative abundance of interunit linkages and chemical composition differs among plant cell types, tissues, species, and growth stages. Besides the common units (H, G, and S), hydroxycinnamic acids (p-coumarate and ferulate) and tricin were found to be attached to wheat lignin.(11) Furthermore, the visualization of the plant cell wall is capable of providing important insights into the lignin distribution and accumulation in the plant cell wall.(12) Raman microscopy is an ideal technique for in situ visualizing the lignin distribution in plant cell walls...
...Poplar is a deciduous tree that has been naturalized in different areas of the China especially in northern China, which is a desirable lignocellulosic feedstock for pulping and papermaking as well as biorefinery industries due to several attractive features, including short growth period, high production yield, and wide adaptability. Poplar biomass constituents vary in abundances among the different species,(23) and characteristics the of these chemical constituents are closely associated with the biofuel conversion of poplar.(24) Although structural characteristics of lignin from poplar during different pretreatments have been studied, structural variations and evolution of the lignin macromolecule during different growth stages were rarely investigated. In the present study, the poplar (Populus tomentosa) woods with three different growth stages (3, 6, and 18 months) were selected to reveal structural variations of lignin macromolecules, and elucidate microscopic distribution and dynamic accumulation of lignin in different poplar cell walls. Herein, DEL samples were isolated from different poplar woods; 2D-HSQC NMR, 31P NMR, gel permeation chromatography (GPC), and pyrolysis GC/MS techniques were applied to delineate its structural characteristics during the early growth stages. In addition, confocal Raman microscopy (CRM) was adopted to monitor the dynamic and microcosmic distributions of lignin macromolecules in plant cell walls. Furthermore, CP/MAS 13C NMR spectroscopy was also performed to characterize the structural features of different poplar woods.
There is a nice description in this introduction, of separations of lignin from cellulose, both industrially and for analytical purposes. There's this nice little intriguing note:
I'm curious about that; after I'm done here I'll check out reference 19, which is surely in my files, and hopefully remember to pick up references 18 and 20.
Anyway, the authors did some cool analytical chemistry to get at the structures of lignins in different growth stages of poplar, as described in the final excerpt of the introduction above.
Some generalized composition of the wood at different points of the growth is shown in this table:
The following figure shows the Raman image of the lignins at different growth stages.
The caption:
The next figure shows spectra (with structural cartoons) that utilizes a type of two dimensional NMR known as HSQC (Heteronuclear Single Quantum Coherence) spectroscopy, which utilizes magnetic coupling between protons (which have a strong magnetic moment) to rare isotopes of either nitrogen (15N) or carbon (13C) which are also magnetically active. In the present case, 13C, was the coupled nuclei.
The figure:
The caption:
A DEL is a "double enzyme lignin" which results from separation of the wood by repeating an enzymatic isolation step twice.
The make up of the lignins was elucidated by derivatizing the free phenol hydroxyl functional groups with a standard phosphorylating agent, 2-Chloro-4,4,5,5-tetramethyl-1,3,2-dioxaphospholane, and running 31P NMR.
Other figures show other HSQC experiments.
The most interesting figure is that showing structures of the lignins at various growth points.
The caption:
A technique known as pyrolytic GC was utilized to thermally decompose, in the absence of oxygen, the lignin into monomeric species.
The following table shows some of the compounds obtained from this process:
Of particular interest are the "G" type phenolics.
4-vinylguiacol is commonly found in many flavored foods and is partially responsible for the taste of some wines, beers, cloves and other foods. It is a precursor to synthetic vanillin, as is the 4-methylguiacol. Interestingly, vanillin can be converted in a few chemical steps, demethylation, acetalization with formaldehyde and a few other steps to the illegal street drug MDA, known as "ecstasy."
Of the S type, one, syringaldehyde can be converted in three chemical steps to the illegal street drug mescaline.
I don't know how or why I know these things, but somehow I do. (There was a time in my life, too long ago, when I couldn't look at the structure of simple molecules without thinking how they might be synthesized. Life is very beautiful, and then you die.)
Trivia in a trivializing time, the self destruction of the United States by the installation of a criminal in its leadership.
Anyway. In a time in which we regret the wooden heads of our pResident and his minions of cowardly co-conspiratorial Senators, there is, great wonder it turns out, in wood, despite this.
Have a nice day tomorrow.
Seven million people die each year from air pollution.
The answer to your question is contained in whether or not one believes that any death from radiation is worth a million deaths from stuff we ignore.
Chernobyl was 34 years ago. The immediate death toll was 31 people; over the long term, perhaps a few thousand people will ultimately have their lives shortened significantly.
Let's say that the death toll of air pollution averaged, over the last 34 years, five million people per year, a lower rate than what is currently understood.
That works out to 170,000,000 deaths from air pollution in the 34 years since Chernobyl.
Of course, the fact that we don't pay attention to one, and microexamine the other makes no difference in the actual numbers.
And then there's climate change. Do you grasp how serious, how much death and destruction will be involved in comparison to Chernobyl?
Here are some things that have killed more people than 60 years of nuclear operations: Automobiles, aircraft, fatty foods, water, house fires...
Do we routinely assume that cars, aircraft, fatty foods, water and houses are "too dangerous?" Do we say any of these things should be phased out? (For the record, I do believe that cars should be phased out, but that's just me.)
I'm a scientist. I am trained to think critically. In general this means rejecting journalistic impressions, which are often geared at making people not think critically but rather in emotive and/or sensationalist terms.
Look at politics. "But her emails..."
I look at journalism about nuclear energy in exactly the same way, "...but her emails..."
You know what the difference between so called "nuclear waste" and dangerous fossil fuel waste is? Fossil fuel waste kills people.
If you're serious about energy and the environment - and I claim I have done the work to show I am - the first step is to think clearly and critically.
Nuclear energy need not be perfect; it need not be without risk, to be vastly superior to everything else. It only needs to be vastly superior to everything else, which it is.
Here is the comprehensive list of causes of mortality on this planet, published in the prestigious medical journal Lancet, part of a series updated about every 4 years:
Global, regional, and national comparative risk assessment of 79 behavioural, environmental and occupational, and metabolic risks or clusters of risks, 1990–2015: a systematic analysis for the Global Burden of Disease Study 2015 (Lancet 2016; 388: 1659–724) One can easily locate in this open sourced document compiled by an international consortium of medical and scientific professionals how many people die from causes related to air pollution, particulates, ozone, etc.
It's open sourced. Anyone can read it. Feel free to let me know how many deaths derived from all the bugaboos raised by anti-nukes. Then come back and tell me what "safe" is.
Speaking only for myself, I think there are a lot of things more scary than Chernobyl. Climate change is among those:
Death toll exceeded 70,000 in Europe during the summer of 2003 (Plus de 70 000 décès en Europe au cours de l'été 2003) (Robine et al Comptes Rendus Biologies
Nuclear energy saves lives: Prevented Mortality and Greenhouse Gas Emissions from Historical and Projected Nuclear Power (Pushker A. Kharecha* and James E. Hansen Environ. Sci. Technol., 2013, 47 (9), pp 4889–4895)
An Interesting Lecture on the Technological Coding of Racism Is Now Online.
I saw it live a few weeks ago, and found it rather inspiring and informative. I originally posted about it in the science section.
It's worth watching:
It is here: Science on Saturday: Dr. Ruha Benjamin: Will Robots Save Us or Slay Us?
Electrolytic reduction of carbon dioxide to yield multicarbon products
The paper I'll discuss in this post is this one: CO2 electrolysis to multicarbon products at activities greater than 1 A cm^(?2) (F. Pelayo García de Arque al, Science, Vol. 367, Issue 6478, pp. 661-666).
There is a growing, and frankly delusional, belief that electricity is "green," i.e. that is inherently sustainable and clean. This is pure nonsense. First of all, except possibly in the case of lightening which is not utilized to charge Tesla cars, electricity is not primary energy. Since it must be made from a source of primary energy, it is therefore, by appeal to the inviolable laws of thermodynamics, a degraded form of energy: Whenever electricity is generated, irrespective of how it is generated, some energy is lost to entropy. Moreover, electricity must be either used when it is generated, or stored, with additional thermodynamic loses, as chemical energy, usually in the form of batteries, batteries representing a rising threat to the environment whether we get it or not.
This pernicious fantasy which helping to push the planetary ecosystem over an abyss that we cannot even remotely imagine, is based on an unsubstantiated bit of nonsense that pretends, in Trumpian contempt for reality, that electricity is, or soon will be, generated by another pernicious, but popular, fantasy, so called "renewable energy." In turn, so called "renewable energy" is not clean and is not sustainable. Even it it were, despite all the cheering, it is largely ineffective at producing energy, and the two trillion dollars per decade squandered on it - the current rate - will not change that fact. In this century the growth in the use of so called "renewable energy" has been dwarfed by the increases in the use of dangerous coal, the use of dangerous petroleum, and the use of dangerous natural gas. This is true in every area of energy use, but it is equally so in the case of electricity generation.
The International Energy Agency puts out, every year, along with the World Energy Outlook, to which I often refer, a document called "Electricity Information." Here is a link to the 2019 Edition: Electricity Information 2019: Overview
Here is a graphic from it:
Coal remained, as of 2017, the world's largest source of primary energy used to generate electricity.
A similar graphic, in the same document, on the same page, shows the actual primary energy generated by all fuels:
Both graphics show how successful, for all the cheering, and the trillions of dollars thrown at it, so called "renewable energy" has been in displacing dangerous fossil fuels, which is to say not all. None of this experimental data, however, will prevent advocates of this scheme to turn our remaining (and vanishing) wilderness areas into industrial parks for wind turbine and solar farms, for no meaningful result. The use of dangerous fossil fuels, not just to produce electricity, but for all purposes, is rising, not falling.
On page II.4 of the EIA Electricity Information Document, is a rather large table (Table 1.0 of section II of the report) relating to energy use in general and what proportions of it involves the generation electricity.
The table contains some interesting information about the use of coal for purposes other than generating electricity or heat, with three categories, steel production, non-ferous metals, and non-metal mineral processing (probably mostly representing concrete production) - the demand for all three will rise in the worst case scenario, where the world continues to expand so called "renewable energy" - amounted to about 23.3 exajoules of energy. Other ancillary uses for coal also require prodigious amounts of this rather unsustainable material.
I won't reproduce the table here, but note that, with some calculation - which I have done - one can obtain the thermodynamic efficiency of all the major forms of energy utilized to generate electricity, as well what fraction of the total generation derives from a particular source of primary energy. The following table is the result of my calculations from Table 1.0 of section II.
To the extent that CHP, combined heat and power, is present, suggests that, at least in Winter months, not all of the entropy (heat) losses are truly wasted, but the fact is that overall, for all types of plants that produce electricity - clearly these tables ignore transmission losses, since otherwise hydroelectricity would not be recorded as 100% efficient - the energy efficiency is 42.31%.
(In fact, no system for generating electricity can actually work at 100% efficiency, as is stated in this table for hydroelectricity. The "100%" figure ignores that the system is inefficient when the primary energy to drive the hydroelectric turbines is actually gravitational energy associated with the mass of water that falls through the turbine. It is probably too painful to calculate, and so we have this somewhat disingenuous 100% figure. With this in mind, we should not that the 42.31% figure is clearly too high, since hydroelectricity produces about 15% of the world's electricity. In any case, we are almost fresh out of major rivers to destroy with hydroelectric plants. The less than 100% efficiency for so called "renewable energy" is difficult to explain in the same terms - except for geothermal - and may reflect the fact that it is often required to dump so called "renewable energy" because of saturated grids, where there is too much wind and solar with the result that every energy system on that grid, including so called "renewable energy," is economically useless to the owners of the plants. It also may reflect the use of batteries. Who cares? So called "renewable energy" is best at generating not energy, but rather at generating evidence of its uselessness.)
The point is, overall, that electricity is a degraded form of primary energy. The highest efficiency for a thermal system, belongs to dangerous natural gas fuels, a point to which I will return briefly in the summary of this post, since although dangerous natural gas is in no way a sustainable or acceptable fuel - it must be phased out in its entirety - one can certainly learn from how it is used to achieve higher thermodynamic efficiency than other systems.
Therefore, when one stores electricity in a chemical form - a practice in itself that is never 100% efficient, one further degrades the energy efficiency of the system. That is true for batteries, and it is true for the electrochemical reduction of carbon dioxide described in the paper referenced at the outset of this post.
The paper begins with the typical rote obeisance - found in almost all energy storage papers these days - to so called "renewable energy."
In these reactions, water-based electrolytes act both as a proton source and as the ion conductive medium (10). However, the solubility of these gases in water is limited, leading to constrained gas diffusion as gas molecules collide or react with their environment (11). The diffusion length of CO2 can be as low as tens of nanometers in alkaline aqueous environments (12). This has limited the productivity of catalysts in aqueous cells to current densities in the range of tens of milliamperes per square centimeter due to mass transport (13–16).
In a gas-phase electrolyzer, catalyst layers are deposited onto hydrophobic gas-diffusion layers so that gas reactants need to diffuse only short distances to reach electroactive sites on the catalyst surface (Fig. 1A) (17–19). Gas reactant diffusion in the catalyst layer becomes the mass transport–limiting step in the cathode, as observed in the oxygen reduction reaction (ORR) in fuel cells. To improve ORR performance, fuel-cell catalyst layers are designed to balance hydrophobicity to help expel water and hydrophilicity to maintain sufficient ion conductivity.
In contrast with oxygen reduction, which generates water as a product, CO2 reduction requires water as a proton source for hydrocarbon production. Thus, the catalyst layer is hydrophilic and fully hydrated during the reaction. In this configuration, CO2 electrochemical reactions occur within a gas-liquid-solid three-phase reaction interface (Fig. 1B) (20). This volume, in which gaseous reactants and electrolytes coexist at catalyst electroactive sites, decays rapidly into the electrolyte, particularly at the high pH used in alkaline electrolysis. The decay is further increased at high current densities because of local OH? generation (21). A large fraction of the catalyst is in contact with electrolyte in which CO2 availability is limited by its solubility (<2 mM at pH 15). Because hydrogen evolution is a competing reaction with CO2 reduction in a similar applied potential range, the large fraction of catalyst surface area exposed to CO2-depleted electrolyte promotes undesired H2 generation (Fig. 1C). Whereas recent advances in gas-phase CO2 reduction have led to partial current densities for CO2 reduction of ?100 mA cm?2 (12, 22, 23), other liquid-phase electrochemical technologies such as water electrolysis achieve multi-amperes per square centimeter (24, 25).
Figure 1:
The caption:
(A) Flow-cell schematic. Reactant gases are fed through the back of a gas diffusion–electrode catalyst, facing an aqueous electrolyte. An anion-exchange membrane (AEM) facilitates OH? transport from cathode to anode. GDL, gas-diffusion layer. (B) In a gas-diffusion electrode (GDE), catalysts are deposited onto a hydrophobic support from which gas reactants [G] diffuse. (C) The volume in which gas reactants, active sites, and water and ions coexist determines the maximum available current for gas electrolysis. Catalyst regions with limited reactant concentration promote by-product reactions such as hydrogen evolution. (D) When gas and electrolyte (water and ion source) transport is decoupled, the three-phase reaction interface can be extended so that all electrons participate in the desired electrochemical reaction. (E and F) Modeled gas reactant availability along the catalyst’s surface for standard (E) and decoupled (F) gas transport into a 5 M KOH electrolyte, assuming an in-plane laminar gas diffusivity of D‖/DKOH = 1000 for the latter, where D‖ is gas diffusivity parallel to catalyst surface. Depending on the gas diffusivity within the gas transport channel, gas availability dramatically increases. L‖, distance parallel to catalyst surface; L?, distance perpendicular to catalyst surface. (G) Modeled maximum available current density for CO2 reduction. D/DKOH manipulation enables entrance into the >1–A cm?2 regime for CO2R. See methods for details on gas transport and reaction simulations.
This is a gas phase system, which involves gas phase water (steam), and thus involves high temperatures which can only be provided by wind and solar so called "renewable energy" via an electricity intermediate, again, thermodynamically degraded energy:
Here, we present a hybrid catalyst design that, by decoupling gas, ion, and electron transport, enables efficient CO2 and CO gas-phase electrolysis at current densities in the >1–A cm?2 regime to generate multicarbon products. We exploit an ionomer layer that, with hydrophobic and hydrophilic functionalities, assembles into a morphology with differentiated domains that favor gas and ion transport routes, conformally, over the metal surface: Gas transport is promoted through a side chain of hydrophobic domains, leading to extended gas diffusion, whereas water uptake and ion transport occur through hydrated hydrophilic domains (Fig. 1D). As a result, the reaction interface at which these three components come together—gaseous reactants, ions, and electrons—all at catalytically active sites, is increased from the submicrometer regime to the several micrometer length scale.
The system that the authors design is a functionalized type Nafion based system of electrodes. Nafion is a fluoropolymer. In general, fluoropolymers, while extremely useful, are a source of the intractable fluoroalkane (PFOS, PFOA) contamination issue that has become recently an area of increasing environmental concern.
Figure 2 of the paper:
The caption:
(A) Schematic of metal catalyst deposited onto a PTFE hydrophobic fiber support. A flat ionomer layer conformally coats the metal. (B) Perfluorinated ionomers such as Nafion exhibit differentiated hydrophilic and hydrophobic characteristics endowed by –SO3– and –CF2 functionalities, respectively. Laminar Nafion arrangements have been reported depending on its thickness and substrate (37, 40). (C and D) SEM images of ionomer-coated copper catalysts. (E to G) Cryo-microtomed TEM cross-sections of catalyst and ionomer revealing a laminar conformal overcoating. (H) WAXS spectra for reference and ionomer-modified catalysts. These reveal features at 1, 1.28, and 2 A?1, associated with various PFSA and PTFE-support phases. (I) Raman spectra of reference and ionomer-modified catalysts revealing distinctive features of ionomer –CF2 and –SO3? groups (table S5).
Figure 3 shows limiting currents for these systems:
In the caption, "RR" stands for "reduction reaction" and "ORR" stands for "oxygen reduction reaction," CORR for "carbon monoxide reduction reaction" and CO2RR to "carbon dioxide reduction reaction." CIPH refers to "catalyst:ionomer planar heterojunction" which refers to the type of electrodes the authors have developed in this paper.
The caption:
(A) ORR showing a 30–mA cm?2 limiting current (Jlim) for Ag reference catalysts as opposed to 250 mA cm?2 for a CIPH configuration. RHE, reversible hydrogen electrode. (B) For CO2RR, standard Ag catalysts yield a Jlim of ?54 mA cm?2 (remaining current used for hydrogen evolution). This is in stark contrast with CIPH samples, which retain a FE above 85% for CO2 reduction (CO2R) to CO up to ?500 mA cm?2. (C) This trend is maintained for Cu CIPH catalysts and hydrocarbon production: Jlim toward ethylene (dominant product) is 50 mA cm?2 at ?0.7 V versus RHE for bare Cu but increases beyond 0.5 A cm?2 for CIPH (peak FE of 61% at 835 mA cm?2). (D) For CO reduction (COR), Jlim ? 64 mA cm?2 for standard Cu, whereas CIPH achieves a maximum 340–mA cm?2 current for the same reaction; H2 by-product generation is restrained below 15% FE at all currents. (E and F) Partial pressure COR studies in CO|N2 mixes for CIPH (E) and standard (F) catalyst show that only at partial pressures below 60% is Jlim observed for CIPH, whereas a sharp, steady decrease is observed for reference samples. At all partial pressures, CIPH exhibits an order of magnitude larger Jlim. Both reference and CIPH samples exhibit comparable resistance and double-layer capacitance. Electrochemical experiments were carried out in 5 M KOH electrolyte with a 50–cm3 min?1 CO or CO2 feedstock (in the case of 100% partial pressure).
The unusual, and important point about this technology is the fact that it produces ethylene, which is the monomer utilized to make the polymer polyethylene, and is also a useful intermediate for the production of many other types of polymers and chemicals, including, but certainly not limited to, ethanol. As such, the technology allows for the elimination of the use of dangerous fossil fuels in the manufacture of this intermediate, thus eliminating their contribution to climate change - which is not to say we give a rat's ass about climate change; clearly we don't. If we did, we'd stop carrying on about so called "renewable energy" - since it has been experimentally determined to be useless at addressing climate change.
Some interesting stuff about the catalyst morphology is shown in figure 4:
The caption:
(A) Schematic representation of metal-ionomer bulk heterojunction catalysts on a PTFE support. (B) Cross-sectional SEM of the CIBH catalyst. (C and D) TEM image of a cryo-microtomed CIBH (C) and elemental mapping of Cu and C revealing CIBH nanomorphology (D). (E) Partial current density for total CO2RR reactions, with C2+ and C2H4 at maximum cathodic energy efficiency. The total CO2R current saturates at 1.3 A cm?2 before cathodic energy efficiency drops for CIBH thicknesses beyond 6 ?m. CIBH samples achieve more than a sixfold increase in partial current density at cathodic energy efficiencies >40% (fig. S30). Each sample and operating condition ran for at least 30 min. (F) Performance statistics of the highest partial current configuration for eight Cu CIBH catalysts. The box plot corresponds to Q1 to Q3 interquartile range, median, and average. The error bar represents ?5.4 standard deviations. EE1/2, half-cell (cathodic) energy efficiency. (G) Performance of the best CIBH catalyst in an ultraslim flow cell consisting of a 3-mm-wide catholyte channel. A full-cell energy efficiency of 20% for C2+ products is estimated at 1.1–A cm?2 operating current. All CIBH electrochemical experiments were carried out in 7 M KOH with a 50–cm3 min?1 CO2 feedstock.
The authors conclude their article with a discussion of efficiency and of course, evocation of the wonder word "renewable:"
The product distribution for optimal CIBH catalysts at different current densities in 7 M KOH electrolyte reveals that H2 generation remains below 10% from 0.2 to 1.5 A cm?2 (fig. S29). At the highest current operation, optimized catalysts exhibited a maximum productivity toward ethylene with a FE in the 65 to 75% range, a peak partial current density of 1.34 A cm?2 at a cathodic energy efficiency of 46 ± 3% (Fig. 4F and figs. S31 and S32). We implemented the best CIBH catalyst in an ultraslim flow cell (with no reference electrode and a minimized catholyte channel of ?3 mm, with water oxidized at a Ni foam anode), leading to an estimated full-cell energy efficiency toward C2+ products of 20% at 1.1 A cm?2 without the benefit of iR compensation (i, current; R, resistance) (Fig. 4G). CIBH catalyst current and FE remained stable over the course of a 60-hour initial study implemented in a membrane electrode assembly configuration (fig. S33).
Although CO2 reduction kinetics improve with increasing temperature, alkaline electrolyzers manifest worsened CO2 availability as temperature increases, and this fact curtails reaction productivity. We explored the effect of temperature on planar CIPH metal:ionomer catalysts and observed that CIPH catalysts require lower overpotentials to attain similar FE, in contrast with planar reference catalysts (fig. S34), when operated at 60°C. This effect translates into 3D CIBH catalysts, which show improved performance arising from the combination of accelerated CO2 reduction kinetics and extended mass transport through the ionomer layer with increasing temperature (fig. S35). As a result, CIBH catalysts achieve ?1 V reduced overpotential and more than a 50% increase in C2 productivity when operated at industrial electrolyzer-relevant temperatures of 60°C in a full-cell configuration, compared with the case of room temperature operation (fig. S36).
The phenomena described herein showcase catalyst design principles that are not constrained by prior gas-ion-electron transport restrictions. The CIBH catalyst paves the way to the realization of renewable electrochemistry for hydrocarbon production at operating currents needed for industrial applications, as has been achieved with syngas for solid oxide electrolyzers (48, 49).
The cathodic efficiency comes from the efficiency of converting electricity - thermodynamically degraded energy - into these products. It does not include the thermodynamic cost of separating the four products, although the separation of ethylene gas is something of a no-brainer.
I don't believe for a New York second that this technology is applicable in an economically or environmentally acceptable fashion to so called "renewable energy." The economics of any production system depends very much on its capacity utilization. Since the capacity utilization of the mass intensive so called "renewable energy" industry is low, and decoupled intrinsically from demand loads, it follows that the capacity utilization of these systems in so called "renewable energy" systems will be even lower. Thus for long periods, the capacity built to construct such a system will be generating zero value to an investor, and moreover, the return on investment will be unpredictable.
Nevertheless may be useful in limited applications, depending on the design of a power grid, for continuous operation systems. The power grid in most places is uneven. Generally peak loads on grids occurs in the early evenings and late afternoons. If the output of so called "renewable energy" systems in places where they have foolishly represent a large portion of the grid sources is momentarily high, all power sources return nothing to their investors, and for systems that are reliable but uneconomical at random points, to be available for those times when the sun is not shining and the wind not blowing, to survive they must recover their costs in the periods in which they are required to operate to prevent blackouts. This is why Denmark and Germany have the highest retail electricity prices in the OECD.
Nuclear power plants operate best at close to 100% capacity utilization. As the table above shows, they operate at unacceptably low thermodynamic efficiency, about 33%. The reason for this is that the basic technology under which they were built was to produce electricity; they were designed to be coal plants without the coal. They operate overwhelmingly (with some exceptions) on Rankine (steam) cycles.
We know from the much discussed events at Three Mile Island and Fukushima - events that garner far more attention than 70 million deaths from air pollution every decade - (and of course from engineering and science courses, were we interested in taking them) that nuclear fuels can produce heat that is much higher than the boiling point of water. It is possible to use these high temperatures to skip the thermodynamically degraded electricity intermediate to increase thermodynamic efficiency by simply proceeding directly to chemical storage using heat. Thermochemical cycles to do this are well known and widely studied. In fact, they can be operated synergistically with electricity production, for example using a modified Allam cycle, a heat engine cycle I discussed elsewhere in this space.
It is the use of two heat engine cycles in tandem that accounts for the high thermodynamic efficiency of gas plants: They have Brayton cycles (of which Allam cycles are a subset) coupled to Rankine cycles, using the waste heat from the high temperature cycle, the Brayton cycle, to drive the lower temperature cycle, the Rankine cycle. Their are other possibilities to go beyond these, thermochemical cycles (which represent stored energy as fuels or materials) coupled to Brayton cycles (with a carbon dioxide working fluid) driving a Rankine steam cycle, with high efficiency thermoelectric devices and or Stirling engines being possibly added in the temperature reduction line. This would have the added advantage of reducing the water demand for cooling of such plants, although it is also possible to put a desalination scheme somewhere in the line. There is a world of better ways to do things.
All of these high temperature high efficiency schemes are dependent on access to continuous reliable energy that is also clean and sustainable. This limits the choice to one source of primary energy, nuclear energy.
As for the electrochemical reduction of carbon dioxide, it might be utilized, in the limited setting of preventing the waste associated with spinning reserve, depending on the economic cost of the entire system and its relationship to capacity utilization. Spinning reserve is the amount of power that is generated to cover fast and short term and unexpected surges in demand on the system without producing brown outs. To the extent that this energy, when not in demand, is utilized to drive the electrochemical reduction of carbon dioxide to ethylene, it's certainly worth consideration.
I wish you a pleasant and productive workweek.
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