NNadir
NNadir's JournalSustainable Electrochem Extraction of Metal Resources from Waste Streams: From Removal to Recovery
The paper I'll discuss in this post is this one: Sustainable Electrochemical Extraction of Metal Resources from Waste Streams: From Removal to Recovery (Wei Jin and Yi Zhang, ACS Sustainable Chemistry & Engineering 2020 8 (12), 4693-4707)
This weekend, CSPAN history presented two academic lectures on the 1918 Flu Pandemic, where the strategies for containment, for better and for worse, were similar to what we are seeing 102 years later, in 2020.
They are here:
https://www.c-span.org/video/?465724-7/influenza-pandemic-world-war
https://www.c-span.org/video/?469755-1/1918-influenza-pandemic-public-information
Unless you are 102 years old or older, your entire life took place after that pandemic, which was very, very, very serious and which actually ended up killing more people than died in combat in World War I, which ended the same year as the pandemic began. Until now, what was extremely and overwhelming important probably garnered very little attention except in obscure academic treatises. I am not minimizing what we are seeing now - it's very possible Covid will kill me, as I am high risk, although if it doesn't something else will - but it behooves us to remember that there will be life on this planet when the pandemic is over, and major problems that were exigent before the pandemic will remain exigent afterwards as well.
The paper here is about one such exigent problem, the problem of both contamination by and depletion of various critical elements of the periodic table; many of which, while quite toxic, are also of high technological and economic importance. Our technology is structured so that these elements are isolate from dilute sources, usually ores, refined to high states of purity, and then re-diluted in the devices in which we use them. Not only are they diluted in these devices, but they are usually so diluted in a complex array of other elements, as well as a complex array of organic molecules, such as polymers, and insulating material and flame retardants of toxicological import. This nature represents chemical problems in separation and recovery.
For about five or ten years now, whenever I think of this problem, my mind turns to electrochemistry since the electron, which, because its energy is adjustable, is not only a flexible tool to reduce salts to their metals, but also is a tool for chemical separations. Much of my attention in this area has focused on the element uranium, which is an element that can save the world, and it's presence in various dilute matrices, notably seawater, natural formations and of course, as a side product of mining, not only uranium mining, but the mining of dangerous fossil fuels such as coal, oil and gas, all three of which, particularly in "fracking" settings, can result in uranium mobilization. Other means of distributing uranium in dilute but still potentially problematic forms include agriculture, since uranium is a constituent of many phosphate ores, and especially the mining of fossil and recharging ground water in regions where uranium is a natural constituent of soils and/or bedrock.
The removal of elements like uranium, and as we shall see, many other elements, results in the concentration in some device or substance. In the age of the waste mentality, sometimes these devices and substances are regarded as waste. Arguably however they are low grade (or even high grade) ores. As my generation has selfishly consumed almost all of the best ores of many elements in the periodic table, these kinds of ores may ultimately become very important sources of elements: I have argued this point about uranium many places on the internet.
This is why it is such a pleasure to see this paper in the most recent issue of ACS Sustainable Chemistry & Engineering.
This paper is a "perspective," essentially a review article, and it is not possible in this space to cover very much of it.
Nevertheless from the introductory text:
...Many technologies have been applied for efficient metal removal, such as chemical precipitation, adsorption/biosorption, and ion exchange.(11,12) However, they usually suffer from the drawbacks of secondary pollution generation, large reagent consumption, and high operating cost. Recently, electrochemical methods have attracted considerable attention for the remediation of metal-polluted water mainly owing to their advantages of environmental compatibility, high efficiency and versatility, operation feasibility, and cost effectiveness, via the employment of the green redox reagent “electron”...
The authors remark that many mine tailings contain valuable materials, noting that the Bayer process - the process that extracts alumina from bauxite - leaves between one and two and a half tons of "red mud," a highly caustic mixture of sodium hydroxide, iron oxide, titanium oxide and a host of other metals that might be considered as ores for iron, titanium and other compounds. The composition is given as "20−40 wt % Fe2O3, 10−25 wt % Al2O3, 3−10 wt % TiO2, and other metallic compounds." In theory, and sometimes in practice, all of these metals can be electrochemically recovered, iron and titanium in the FFC process, aluminum, enriched by the removal of the other elements, in the Hall process.
Historically, according to the authors, electrochemistry was utilized to purify water by removing heavy metals as spongey flocculents, largely consisting of metal oxides. The difference between historical approaches and the approach that the authors discuss is that these flocculents, particularly when used on a large scale, can be ores to recover metals for use.
Because the energy associated with an electron per unit of charge - the voltage - it is possible to make electrochemical adustments that not only remove and or collect metals but also separate them.
Here from the paper is a table of electromotive force (electrochemical or electrode potential) of a few elements in the periodic table:
In this table, those elements whose standard electrode potentials are negative require an input of energy to reduce them to metallic form, those with electrode potentials are positive require energy to oxidize them. Since these potentials all differ they can be separated by adjusting electrode voltages. While this a significant simplification, since other factors are involved, this is a well known strategy both on a lab scale and an industrial scale as well.
This cartoon from the paper shows an example of how it might work:
The caption:
It is as the authors make clear, not always the case that electrochemical approaches are appropriate for all situations. Much depends on concentrations, (which may be very low), economics, and the costs and supply of materials and/or reagents, as well as the cost of disposing (or, as the paper seeks to advance recovering) side products. This cartoon chart from the paper shows the various kinds of approaches:
The caption:
Note that the waste water, especially if it is concentrated in metals, can be further purified by electrochemical means with recovery of the materials.
The subsequent cartoon in the paper generalizes industrial material processing technologies, focusing on their relationship to the generation of wastewater:
The caption:
Taken together these options suggest many hybrid approaches. Consider the case of desalination. Worldwide, the main approach currently in use on an industrial scale is membrane driven (RO) approaches, as outlined in figure 3. To recover uranium - although the uranium already mined and isolated is sufficient to cover all of humanity's energy needs for centuries (in "breed and burn" reactors) if we pass the seawater being piped into a desalination plant with an appropriate resin (uranium capture resins are well known) we can recover uranium for future generations to utilize.
I personally believe that a better approach to desalination could and should be developed, albeit requiring some materials science advances. That process would involve heating seawater to supercritical water where two different phases would exist, one being relatively pure water, and the other brine. The energy required to this can be partially recovered by allowing the separated pure water phase to expand against a turbine, and allowing the saline phase to evaporate against a turbine. The advantage of this process would be to oxidize suspended micro and macro plastics, as well as algae and seaweeds and eutrophic biomass through a supercritical water oxidation procedure, producing hydrogen and carbon oxides, a mixture known as syn gas. Since seawater contains higher concentrations of carbon dioxide than does air, this will have the additional benefit of removing carbon dioxide from the environment for use. The resulting brines and dried salts might then be subjected to the electrochemical separations that the paper describes. An important element recovered in this process, depending on the location and nature of the seawater or water stream, is the element phosphorous, which has previously, in cleaner times, been cyclized from the sea to land by seabirds, with birds being organisms under chemical, mechanical, and climate threats. (As we build useless wind farms at sea in our misguided worship of so called "renewable energy" this pathway in the phosphorous land sea cycle may face threats. Birds matter.)
Another rich source of metals that ends up being pollution rather than being a resource is electronic waste.
Reference 24 in the review paper under discussion is this paper: A review of current progress of recycling technologies for metals from waste electrical and electronic equipment (Xu and Zhang, Journal of Cleaner Production,Volume 127, 20 July 2016, Pages 19-36). It too, is a review article.
That paper (Xu and Zhang) has a showing a graphic of a generalized composition of various types of electronic waste:
It also has some useful tables, again generalized:
A cartoon of one process to recover materials from electronic waste is given in the paper cited at the outset.
It would seem to me, off the top of my head, that melt processes are the best in those devices containing a lot of copper, for the recovery of precious metals like platinum, palladium, silver and gold. These elements are extractable into liquid copper which can then be solidified and dissolved in concentrated nitric acid. Under these conditions the platinum and gold will not dissolve, whereas the silver, copper, and some palladium, and the platinum and gold and residual palladium can be filtered. The silver can be removed by precipitation with hydrochloric acid; and the copper by electrolysis. The residual solids (Au, Pt, Pd) can then be dissolved in aqua regia and recovered by exploiting electrochemical means.
This is a slightly different approach than is described in figure 6 from the paper reproduced just now.
Although people like to prattle on and on about how "green" batteries are, this as a subtext to the mistaken idea that so called "renewable energy" is "green" these batteries can be and are recycled (albeit only partially) but this is not a risk free or necessarily clean process.
I have discussed this issue in other posts in this space:
Dealing with 11 Million Tons of Lithium Ion Battery Waste: Molten Salt Reprocessing.
Identity and Toxicity of Off Gases in Thermolysis Lithium Battery Recycling Schemes.
I won't therefore discuss the environmental issues nor the socio-political issues connected with the cobalt they contain, but will only note an interesting approach that is discussed in this paper, which is "slurry electrolysis" which is described in a graphic for lithium batteries that are cobalt free, utilizing lithium manganate electrodes.
The authors write:
A figure connected with this approach is found in the paper:
The caption:
I love that ruthenium plated titanium anode. I have reference 50 in my files and will check it out when I am done here.
This picture seems to show an ion selective membrane. These sorts of membranes are very useful for another area discussed in the paper, which is capacitive deionization. This type of deionization is utilized in Heather Willauer's scheme to electrolytically produce jet fuel from the carbon dioxide dissolved in seawater, a wonderful technology, but one that is assumed - since dumping dangerous fossil fuel waste is "free" - to be uneconomical while the price of the dangerous fossil fuel petroleum is low.
Here is a schematic for capacitive deionization, which is also discussed at length in this paper:
The caption:
Since I am not shy about expressing my enthusiasm for nuclear power as the world's last best hope to save the environment, it behooves me to post a graphic about nuclear fuel reprocessing from the paper, which is this one:
The caption:
I'm not sure about the precise details of this paper, but I muse often on electrochemical refining techniques for the recovery of valuable materials from used nuclear fuel, so called "nuclear waste."
I don't regard, as this graphic does, that fission products are "waste." In fact, I have convinced myself that they are all quite valuable.
In any case, this is an interesting paper, well worth going through. Someday our world will reopen, and when it does, this paper may be accessed in a good scientific library, or obtained now, via subscription.
Be safe, be well, and enjoy, as I am enjoying, the pleasure of being alive.
Eight days into her illness, my sister-in-law's COVID test results came back.
She's got it.
She's getting better though, after self isolating in a bedroom in her home, with her children and her boyfriend (who's recovering himself from major surgery) bringing things to the door.
We figured she had it, and we're very grateful that she is recovering.
Edit: I do want to thank all of the wonderful people at DU for their kind words and good wishes.
You people are just the best.
I wish everyone a safe and healthy outcome in these tragic times.
Covid patients can remain infectious following recovery.
The paper to which I will refer is this one from scientists in China, where they have the most long term knowledge of this disease: Chang, Mo, Wang et al., Journal of Respiratory and Critical Care Medicine, https://doi.org/10.1164/rccm.202003-0524LE.
It is a small study and its statistical power is unclear, but in the interest of safety, it may be wise to consider it.
The world's scientific publishing community has made all Covid related papers open sourced, and this paper is no exception.
in Table 1. The viral detection test was performed upon clinical presentation and repeated
every other day until the patient tested negative. The negative test was confirmed again
the next day. Upon confirmation of the negative test, the patient was asked to quarantine
at home for the next two weeks with a follow-up visit to the hospital after one week to
confirm the viral negative status. The incubation periods were estimated based on the
history of the patient’s travel or potential exposure. Our data show an incubation period
of 5 days (IQR 1-6 days) among the patients (except for patient 12 who had no specific
exposure). The mean duration of symptoms was estimated to be 8 days (IQR 6.25-11.5).
Most importantly, half (8/16) of the patient remained viral positive (a surrogate marker of
shedding) even after the resolution of symptoms (Median 2.5 days, range 1 to 8 days).
Some of our patients had other comorbidities, which included diabetes (2/16) and
tuberculosis (1/16), both of which did not affect the time course of the disease. Similarly,
the clinical course for the 3-year-old male did not significantly differ from the rest of the
patients.
Be safe and healthy.
One glass of alcohol per day...
Over in the science forum, I'm driven nuts by the failure to appreciate units and their meaning.
This is usually about the somewhat dubious practice - albeit widely used - of confusing a unit of power, the Watt, with a unit of energy, the Joule.
So apparently is one of my son's professors also gets pissed off about this sort of thing and sent this pic to his (now on line) students:
New Weekly Reading Record Established at the Mauna Loa Carbon Dioxide Observatory.
Somewhat obsessively I keep a spreadsheet of the weekly data at the Mauna Loa Carbon Dioxide Observatory, which I use to do calculations to record the dying of our atmosphere, a triumph of fear, dogma and ignorance that did not have to be, but nonetheless is.
I had the naive wishful thinking notion that restrictions on automobile traffic with all of the worldwide lock downs would lead to a slowing of carbon dioxide accumulations. Something quite different has been observed with the most recent weekly data.
The data from the Mauna Loa Carbon Dioxide Observatory:
Up-to-date weekly average CO2 at Mauna Loa
Week beginning on March 22, 2020: 415.52 ppm
Weekly value from 1 year ago: 411.24 ppm
Weekly value from 10 years ago: 390.77 ppm
Last updated: March 29, 2020
This week's reading, 415.52 ppm is the highest weekly average ever recorded at Mauna Loa.
As I often note in this space the readings are sinusoidal, superimposed on a steadily rising slightly less than linear axis, as this graphic, which I often reproduce, from the Mauna Loa website shows:
Every year, like clockwork, a new all time record is set in May.
Last year's highest ever recorded value, recorded on May 9, 2019, was 415.39 ppm
The increase over 1 year ago is 4.28 ppm. As of this writing, there have been 2,303 such readings of increases recorded going back to 1975. This is the 11th highest such recorded comparative reading over the period noted.
This is the first such reading in 2020 to break into the top 50. Every year in the last four has resulted in one or more readings penetrating the top 50: 2016 had twenty such readings, 2017, just one, 2018, one, 2019, seven, and as of this writing, now, 2020, one.
Of the top 50 such readings, 29 have taken place in the last five years, 36 in the last ten years, and 40 in the twenty-first century.
If the fact that this reading is 24.75 ppm higher than it was ten years ago bothers you, don't worry, be happy. Just repeat over and over and over and over, until it becomes a modern day Gregorian chant - "Renewable energy is great! Renewable Energy is Great! Renewable energy is great! Renewable energy is great!" Talk about Elon Musk and his cobalt laced electric cars.
Maybe you'll feel better.
I won't.
My impression that I've been hearing all about how rapidly renewable energy has been growing since I began writing here in 2002, when the reading on April 14, 2002 was 375.14 ppm should not disturb you, since it is better to think everything is fine rather than focus on reality.
In this century, the solar, wind, geothermal, and tidal energy on which people so cheerfully have bet the entire planetary atmosphere, stealing the future from all future generations, grew by 9.76 exajoules to 12.27 exajoules. World energy demand in 2018 was 599.34 exajoules. Unquestionably it will be higher in 2019 and in 2020.
10.63 exajoules is slightly over 2% of the world energy demand.
2018 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.)
According to this report, the fastest growing source of energy on the planet in the 21st century over all was coal, which grew from 2000 to 2018 by 63.22 exajoules to 159.98 exajoules.
If you think that unlike you, I am worrying and not being happy, you can always chant stuff about how "by 2050" or "by 2075" or "by 2100" we'll all live in a so called "renewable energy" nirvana powered by the sun and tooling around in Tesla electric cars.
I may be too jaded to be comforted, having heard this stuff my whole adult life - and I'm not young - but you could try. It's not results that count, but good intentions.
To those among us who are Christians, I wish you a Happy Easter holiday when our orange gnome in the White House will unilaterially declare that everything has returned to "normal," whatever in his weak minded distracted self congratulatory universe, "normal" might be.
Take whatever pleasure you can under the circumstances. Despite all this, there are still beautiful things worth saving. If something like a "normal" in the Trumpian age of abnormal celebrations of ignorance ever comes again, we ought to concentrate on such saving.
History will not forgive us, nor should it.
My youngest son's 21st birthday is today. I guess he'll always remember it.
I feel for him. He's working his ass off on his classes, far more difficult when on line, away from his beloved girlfriend, whose mother is a health worker on the front line treating Covid patients and in lockdown with his family, all of us working on line.
I trust he will live to be an old man and tell this story, and that in time, find something to laugh about it all, and remember his father's stupid jokes, as I remember my father's stupid jokes.
We bought him a big bottle of Corona beer by which to remember this day.
If nothing else, in these times we can really feel our love, and it's important to remember that, above all.
Trapped in the house with me, I feel for my wife and sons listening to me brag about my ACE2.
This morning, poking around in the scientific literature, I realized I'm probably a mutant. I found this out because many years ago, I started out my blood pressure treatment taking the ACE inhibitor lisinopril, which caused me to cough so much that I had to switch to another class of BP medicines represented by valsartan.
It turns out, on a little more digging, that people who cough when taking ACE inhibitors have mutant ACE2, ACE2 (angiotensin converting enzyme 2) being the protein that the SARS-Cov-2 (Covid-19) hijacks to weasel its Trumpian useless offensive ass into cytoplasm. I keep telling my poor wife and sons about my "genetically superior" ACE2, telling my boys that they would be very lucky to have gotten my superior ACE2 gene, rather than their mother's inferior ACE2 gene.
(Any supposed real advantage conferred by this mutation is scientifically very, very, very dubious by the way, but if I can annoy my sons by telling them their Dad is a mutant, it's worth it: A little genetic/protein humor is always a good time.)
A few hours ago, the joke may have been funny, but I'm a world class expert at beating a joke to death. I am now merely insufferable.
They've taken to telling me that it's not nice to taunt mother Nature and are now telling me about that asshole Preacher who called Covid a hoax and died from it.
I'm a very bad person.
If we don't want to cry, we should try laughing. Sometimes it works.
The Effect of Variable Generators, aka "Renewable Energy" on the Efficiency Of Fossil Fuel Plants.
In other news, another big problem for humanity is still climate change.
The paper I'll discuss in this post is this one: An Analysis of Thermal Plant Flexibility Using a National Generator Performance Database (Rossol et al., Environ. Sci. Technol. 2019, 53, 13486−13494)
One of the coauthors is Paul Denholm whose 2005 paper on the subject of compressed air energy storage (CAES) to convert the useless wind energy systems into base load power, certainly stimulated a lot of thought on my part, although initially I was interested and amused by the paper since it relied on the combustion of dangerous natural gas to "store" energy.
(Emissions and Energy Efficiency Assessment of Baseload Wind Energy Systems, Denholm et al., Environ. Sci. Technol. 2005, 39, 6, 1903-1911) To be fair, under these conditions, this idea was less noxious than other types of dangerous natural gas plants, but it was still reliant on the combustion of a dangerous fossil fuel to back up a so called "renewable energy" facility. In any case, the point is moot. Fifteen years later, the number of dangerous natural gas enhanced compressed air energy storage systems that have converted wind energy into baseload energy is essentially zero. In the week of January 16, 2005, the week during which Denholm's interesting paper was published, the concentration of the dangerous fossil fuel waste carbon dioxide in the planetary atmosphere was 378.13 ppm. In the week of March 16, 2020 it was 414.28. None of the endless prattling on about so called "renewable energy" in the intervening years has prevented the increase by more than 35 ppm in the concentration of dangerous fossil waste carbon dioxide.
That's a fact. Facts matter.
Even if the wind industry is useless in addressing climate change, everything that has been written about it is not. As I said, Denholm's paper certainly stimulated a lot of thought on my part, and to the extent that we attempt to store energy, compressed gases including, but not limited to compressed air, seems to offer several thermodynamic and environmental advantages, particularly if future generations attempt to clean up the mess with which we have left them in our contempt for them.
(The contempt for young people I hear expressed here, on a liberal website distresses me to no end, particularly because the Millennials I know are all very impressive people.)
The use of compressed gases for energy storage is certainly a superior option to all that potentially environmentally odious crap that's written about batteries. So thank you, Paul Denholm, for stimulating me to consider this idea!
It has seemed obvious to me that when you shut down a dangerous fossil fuel plant because so called "renewable energy" happens to be available because the wind is blowing and/or the sun is shining, that you decrease that dangerous fossil fuel plants energy efficiency, simply since these plants require heat to operate. If they cool, they need to be reheated. The result, I have argued based on this obvious assertion is to limit any advantage that inherently variable energy might provide with respect to climate. Moreover, the need to have a redundant system whose cost recoveries are limited, making them more expensive to exist, raises the costs of overall energy despite all the delusional crap we hear about how "the costs" of wind energy and solar energy are going down, down, down. There is a reason that the most expensive electricity in the OECD is in Germany and Denmark. That is because while the momentary production of solar driven electricity and wind electricity appears to be cheap, it drives up the costs of reliable energy. Fifteen years after Denholm's paper the back up for the trivial and useless solar and wind industry is dangerous fossil fuels, dangerous fossil fuels being the fastest growing source of energy on this dying planet.
The wind and solar energy facilities have not arrested this rise, the are not addressing it, and they won't address it.
Anyway, the paper cited at the opening of this post details where one can get data to support what I have regarded as the assertion that I have considered obvious that adding variable (and random and notoriously unreliable) energy to the grid reduces the thermodynamic and economic efficiency of the required back up systems.
From the introduction to the text:
...A key element of integration studies is understanding the capability of fossil-fueled thermal generators to turn off and on and vary output over multiple time scales.(5,8) This is partly because increased penetration of VG resources results in increased variability of net energy demand (i.e., normal demand minus the contribution of VG). As VG is added to the grid, thermal plants will produce less energy, reducing fossil fuel use and emissions. However, these plants operate at different efficiencies when operated at part load, and increased VG penetration results in greater thermal plant output variability.(3,6) The ability of thermal plants to respond to increased variability, and the impact of this variability on costs and emissions, is often a key element of VG integration studies, so it is important that the operational characteristics of power plants are well represented...
...In this work, we use historical data from the U.S. Environmental Protection Agency’s (EPA) Clean Air Markets (CAM) Division that captures about 71% of the U.S. thermal generation fleet (excluding nuclear) to demonstrate that most plants spend a large fraction of their operation at part load, including traditional baseload generators...
A note: Nuclear energy - which is the only environmentally and economically sustainable form of energy in my often stated opinion - can be excluded because it is everything that so called "renewable energy" is not, that is that it is reliable and dependable and is continuously available and because, as Denholm claimed in 2005, it's carbon cost is extremely low, as close to zero as one can get. (His figure was 10-25 g CO2/kwh for nuclear, compared to 67-104 gCO2/kwh for compressed air storage of wind energy over a 50 hour period.) (Op cit., Denholm, 2005, Table 1, page 1909.) Thermal Rankine cycle nuclear plants are not shut down because the wind is blowing and the sun is shining: It would be exceedingly stupid and damaging to the environment to do so. They do not require expensive redundancies to be base load. This said, I have convinced myself that an intelligent race - that may not be us in this generation - would build combined cycle nuclear plants which inherently involve (in the nuclear case) compressed gases, inasmuch as the Brayton component involves compressed gas. To the extent that the use of compressed air can play a role in these types of operations, the passage of air will allow for the removal of dangerous pollutants, including carbon dioxide, but not limited to it: Sulfates, higher nitrogen oxides, and ozone may removed. In the latter case, if the removal involves exposure of air to a high radiation field - desirable in my view - the ozone destruction may be accompanied by the destruction of dangerous organohalides, and other inorganic halides such as SF6 and NF3, and the very risky ozone depleting side product of agriculture, nitrous oxide.
Now let's turn to the energy efficiency discussed in the paper.
The hand waving fool Amory Lovins, in a delusional but regrettably famous paper filled with poorly referenced assertions that were rather Trumpian inasmuch as they just sprung out of his head and were not backed by any serious research, Energy Strategy: The Road Not Taken?, claimed in 1976 that energy efficiency and so called renewable energy would save the world. This is despite the fact that in the 19th century (1865) a fellow named Jevons stated "Jevons Paradox" which asserted that increases in energy efficiency increased the use of energy. The energy efficiency of this planet, as a whole has been rising throughout the 21st century, and indeed, for much of the latter part of the 20th century. In the year 1971, according to the 1995 edition of the World Energy Outlook published by the International Energy Agency, World Energy Consumption was around 5000 Million Tons Oil Equivalent (cf page 18, 1995 World Energy Outlook) which translates to about 210 exajoules in SI units. In 2018, according to the 2019 World Energy Outlook, energy consumption on the planet has risen to 599.34 exajoules.
The data suggests that Jevons was right. The data suggests that Lovins was and is a fool.
It turns out that to the extent the other leg of his waving 1976 ravings, the claim that so called "renewable energy" would save the world is also self defeating. Because of rants of uneducated anti-nukes of which Lovins is only one example, the use of nuclear energy has been arrested since 1990, and has remained fairly constant, roughly between 28-29 exajoules per year, which is still considerably more than all of the world's solar and wind plants combined produced in 2018, after decades of wild cheering, 12.26 exajoules.
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.)
As the paper shows, the presence of variable energy on the grid which is still backed up by dangerous fossil fuels decreases the efficiency (as well as the economics) of these redundant yet necessary plants.
Mind you, in the graphics from the paper, I am about to show here, there has been unwarranted kindness to these efficiency figures.
The interested reader (if there are such readers) is invited to check out the flow chart for data treatment found in the Supplementary Data, which is open sourced, figure S1 showing that the data involved with shut down and restart of the dangerous fossil fuel plants has been removed, even though this data is very real, and is very much involved with emissions and efficiency, since all of this energy is wasted and provides no value to humanity.
In these graphics from the paper please be aware of the units which are units of heat divided by units of electrical energy generated, formally, but not in the described axes, dimensionless numbers. This means that the higher values on the y axis reflect lower efficiency. These are for some sample plants in the EPA CEM data set:
The caption:
The caption:
In the case of these two plants, they clearly show the degradation of efficiency at low load.
The paper does not draw overweening conclusions, it is more of a procedure paper suggesting how to analyze data and does refer to the results of evaluating the data.
The paper may be accessed with a subscription or by access to a good university library, although right now these libraries - in my area at least - are closed, consistent perhaps, with our national celebration of ignorance. More frightening to me than anything connected with Covid-19 is the possibility that we are entering a dark age, like all dark ages, dependent on ignorance.
The authors are from the National Renewable Energy Laboratory, NREL, in Golden Colorado. Although I am personally appalled by the belief that so called "renewable energy" could or should save the world, I have great respect for the scientific integrity of the authors.
I hope, during this weekend that you will find the excitement and pleasure that we probably have neglected to feel in our previously hurried world, the mere joy of being alive.
Structural basis for the recognition of SARS-CoV-2 by full-length human ACE2
The paper I'll discuss in this post is this one: Structural basis for the recognition of SARS-CoV-2 by full-length human ACE2 (Yaning Li et al., Science (2020) Vol. 367, Issue 6485, pp. 1444-1448)
Although I downloaded the full paper using my subscription, it probably is open sourced: The world's scientific publications are making all Covid related paper open sourced free of charge.
While the paper is technical, interested readers with only a modicum of scientific training should be able to get the basic idea, which sketches out a pathway for the development of antiviral drugs, if not for this particular epidemic, then for similar outbreaks which may occur in the future. (These SARS type viruses seem to be pretty facile in carrying out evolution, which is not entirely surprising given that they are RNA viruses with low accuracy replication machinery, prone to errors, and thus quick to evolve.)
The paper focuses on how the virus binds to cells as the first step to entering them. As I've discussed in other posts here, this is an effect of the binding of the "S" (for Spike) protein to the ACE2 protein on the surface of lung (and other types of cells). ACE2 is "Angiotensin Converting Enzyme 2" which is responsible for the control of blood pressure.
From the text:
In the case of SARS-CoV, the spike glycoprotein (S protein) on the virion surface mediates receptor recognition and membrane fusion (3, 4). During viral infection, the trimeric S protein is cleaved into S1 and S2 subunits and S1 subunits are released in the transition to the postfusion conformation (4–7). S1 contains the receptor binding domain (RBD), which directly binds to the peptidase domain (PD) of angiotensin-converting enzyme 2 (ACE2) (8), whereas S2 is responsible for membrane fusion. When S1 binds to the host receptor ACE2, another cleavage site on S2 is exposed and is cleaved by host proteases, a process that is critical for viral infection (5, 9, 10). The S protein of SARS-CoV-2 may also exploit ACE2 for host infection (2, 11–13). A recent publication reported the structure of the S protein of SARS-CoV-2 and showed that the ectodomain of the SARS-CoV-2 S protein binds to the PD of ACE2 with a dissociation constant (Kd) of ~15 nM (14).
Although ACE2 is hijacked by some coronaviruses, its primary physiological role is in the maturation of angiotensin (Ang), a peptide hormone that controls vasoconstriction and blood pressure...
The authors have studied the structure of the ACE2 protein.
A picture:
The caption:
Other figures in the paper detail protein interactions leading to the behavior of the ACE2 protein itself, and more importantly, it's interaction with the S protein of the virus.
It doesn't, apparently take all that much evolution to change the nature of the virus. Apparently, according to this paper, comparison of the interaction of the SARS-COV-RBD (an older coronavirus) (RBD = receptor binding domain, i.e. the points at which the ACE2 protein interfaces with the viral "S" protein) varies only slightly from the far more pernicious SARS-COV-2-RBD, although the variations over 139 amino acid residues show an RMS deviation of about 0.7 Angstroms. An interesting comparison is noted where an interaction in the SARS-COV-RBD which involves a "greasy" amino acid, valine, at residue 404 is displaced by a hydrophilic residue, lysine, at residue 417 in SARS-COV-2-RBD.
The pictures are in the full paper. They should be open for perusal.
All of this is notable, according to the authors, because:
Regrettably there is a long way from these kinds of findings to a real drug. We should be aware that any agent interfering in this system may have severe hypotensive or hypertensive consequences, something only a careful clinical trial can reveal.
I wish that in this emergency, this weekend you will find some joy in the reflections that this unexpected change to your life may bring, the tragedy of it all notwithstanding.
Be safe; be healthy.
Chinese Retrospective Comparison Between RTPCR Covid Tests/Radiological Findings: False Negatives.
The paper I'll discuss in this post is this one: Correlation of Chest CT and RT-PCR Testing in Coronavirus Disease 2019 (COVID-19) in China: A Report of 1014 Cases
Earlier today, with reference to a post speculating on a shortage of instrumentation to conduct testing and lab staff, I remarked that I didn't think that was the case, based on general knowledge, since I assumed that the test was a PCR test and that there are a plethora of automated instruments that can do that. I stated that I believed the real issue with testing was more logistical and not related to equipment or even personnel at least to conduct the tests, since these devices are highly automated. (Interpretation is another matter, but even this can be streamlined with software.)
To confirm my suspicion, since I hadn't really looked at how the test works, I poked around briefly when I had a few spare minutes, something that doesn't happen that much while working from home.
The test according to the Chinese paper cited herein is in fact a PCR based test, which is not surprising, but if this paper is correct, the accuracy of the test is in question.
The normal regulatory pathway for a CLIA test - this is the class of tests that are approved for use in clinical settings - is actually quite rigorous in terms of acceptance. However nothing that went before is anything quite like Covid-19 and it is understandable that we go with what we can do rapidly based on an understanding of technology.
This paper however is a little disturbing. All the world's scientific publishers are working to make all Covid-19 related papers open sourced, so there is no need for me to discuss the details. The summary at the top of the paper is clear enough.
It reads:
■ The positive rates of RT-PCR assay and chest CT imaging in our cohort were 59% (601/1014), and 88% (888/1014) for the diagnosis of suspected patients with COVID-19, respectively.
■ With RT-PCR as a reference, the sensitivity of chest CT imaging for COVID-19 was 97% (580/601). In patients with negative RT-PCR results but positive chest CT scans (n=308 patients), 48% (147/308) of patients were re-considered as highly likely cases, with 33% (103/308) as probable cases by a comprehensive evaluation.
■ With analysis of serial RT-PCR assays and CT scans, 60% to 93% of patients had initial positive chest CT consistent with COVID-19 before the initial positive RT-PCR results. 42% of patients showed improvement of follow-up chest CT scans before the RT-PCR results turning negative.
A brief excerpt from the introduction with some added bold on my part:
In absence of specific therapeutic drugs or vaccines for 2019 novel coronavirus disease (COVID-19), it is essential to detect the diseases at an early stage, and immediately isolate the infected person from the healthy population. According to the latest guideline of Diagnosis and Treatment of Pneumonitis Caused by 2019-nCoV (trial sixth version) published by the China government (5), the diagnosis of COVID-19 must be confirmed by the reverse transcription polymerase chain reaction (RT-PCR) or gene sequencing for respiratory or blood specimens, as the key indicator for hospitalization. However, with limitations of sample collection and transportation, and kit performance, the total positive rate of RT-PCR for throat swab samples was reported to be about 30% to 60% at initial presentation (6). In the current emergency, the low sensitivity of RT-PCR implies that many COVID-19 patients may not be identified...
I thought it worth pointing out.
I am very, very, very, very sure that scientists are working their collective asses off to improve this situation. We have some very dedicated and knowledgeable people working late into the night to address these concerns, to validate methods, to get the materials in place to handle them. (I know this from the emails I receive at work from biological suppliers.)
But this is worth considering and represents an important safety point. Just because a person has tested negative while sick does not absolutely imply that it is something other than Covid-19
Keep it in mind.
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