Sunday, August 30, 2020

A Song For Masking

Daniel Kahn brings a century old Yiddish song about the plagues which beset us then and now

Eli, as part of the target group, would like to have a word about masks. Now the Eli is not a virologist or a statistician, or a medical type, but the Bunny does have some opinions.

TL:DR: Masks protect you and those near you

The first part requires explanation, but it's actually quite simple.

We know a few things about the coronavirus 2 [SARS-CoV-2]) and similar viruses

1.  Infection by viruses require a minimum dose. A single or a very small number of virus particles are not infectious.  No one knows what the minimum effective dose is and, of course, this will vary from person to person. There is evidence that the severity of the disease depends on the initial viral load

2.  Hospitals and other places where there people seriously shedding the virus are extremely dangerous and those working in such places require extremely good Personal Protective Equipment including N95 masks.

3.  Places where there is good ventilation (e.g. outdoors) are much less dangerous as long as infectious people are not within some small radius

Points 2 and 3 follow directly from Point 1 and there is good direct and indirect evidence for all of them.

4. People are the vector and reservoir for spreading the disease which is why lockdown, social isolation and masking can eliminate the disease at least locally. That's the old fashioned way of dealing with plagues. At worst it buys time and that is vital as treatments improve with time as the decreasing death rate shows, and like Sartre we are waiting for vaccine.

5, The size of the virus is small (of the order of 100 nm) and the disease can be spread directly as well as in droplets emitted in breath which are a few microns. The latter have a very short lifetime in the air, a few seconds, the former a much longer time.

Now Eli needs to talk a bit about masks. It's well established that they can protect others against you, if you have COVID 19 by capturing droplets as you cough and breath. The question is can they protect you from when others are sharing. Turns out, it's not a one way thing, but the protection is asymmetric.  OTOH, if the amount of viral aerosol is low, non-perfection is better than nothing.

Masks can be extremely simple, a piece of cloth, or very complex, multi-layer engineered devices. The most sophisticated such as surgical masks and N95 ones have a layer with an electrostatic filter that can attract and hold small aerosol particles.  You can also get inserts for cloth masks with electrostatic filters.

Frankly this surprised Eli, but multiple layers in any mask will provide a tortuous path for the particles to pass through so the efficiency of multi-layer masks is much higher than just their pore size would indicate.

Before the last six months or so there actually is not very much information on mask efficiency for various size materials and composites beyond N95 and surgical masks because there was not much need, but, of course, recently, a tsunami. Unfortunately a lot of the tsunami are simply reviews of the tsunami and not so much new work.

Perhaps the best earlier work was Testing the Efficacy of Homemade Masks: Would They Protect in an Influenza Pandemic? Anna Davies, Katy-Anne Thompson, Karthika Giri, George Kafatos, Jimmy Walker, and Allan Bennett, Disaster Med Public Health Prep. 2013 Aug; 7(4): 413–418. which anticipated the need for cloth masks when N95 and surgical mask supply was exhausted by an epidemic. They said, ok, better than nothing against virus and bacteria.

Bacteriophage MS2 is a 28 nm RNA virus, so really small, B atrophaeus is much larger a rod shaped bacterium.  Just looking at the Bacteriophage MS2 results shows that even  single layers of cloth can provide some protection. They conclude that a surgical mask might be 2 or 3 times as effective as a tea towel.  Eli takes this to mean that even simple masks offer some protection in situations where there is not a lot of a virus and can limit infection to below the minimum critical amount. 

Among the new work, the most interesting is maybe Filtration Efficiencies of Nanoscale Aerosol by Cloth Mask Materials Used to Slow the Spread of SARS-CoV-2 Christopher D. Zangmeister*, James G. Radney, Edward P. Vicenzi, and Jamie L. Weaver ACS Nano 2020, 14, 7, 9188–9200. So that's in July.  They find that 3 layers (blue line) of a simple cotton poplin cloth had a minimum efficiency of ~40% at 200 nm, but was over 50% efficient for smaller and larger particles.  Weave and mixtures of fabrics didn't appear to make much of a difference, but the number of layers did, They and Eli note that it would not be easy to breathe with more than three layers.


There is also Aerosol Filtration Efficiency of Common Fabrics Used in Respiratory Cloth Masks Abhiteja Kondra et al.  CS Nano 2020, 14, 5, 6339  6347 acs nano but it had a fatal flaw because it measured the airflows established in the apparatus before placing the mask materials. This limited the flow to below the normal breathing rates and there is a correction but there are also 109 citations in 4 months since publication.  Zangmaeister et al found a lot of other problems with the conclusions of that paper. This illustrates the problem of pre-existing post normal science publications where the rush leads to errors that persist on Twitter

So in conclusion fabric masks even simple ones provide some protection (not 100% but what is) to the user where the concentration of virus aerosols is low  even given the Rabett's native skepticism of hot results.

TL:DR: Masks protect you and those near you

Wednesday, August 26, 2020

What T1J says about cancel culture



It's not helpful that Republican leaders have now added to the repertoire that "social media criticism of Republicans = cancel culture", but just because they're being brainless doesn't mean we should act similarly.

T1J's, somewhat muddled, middle-of-the-road position kind of matches my own, so here it is.

The one thing I'll disagree with is that he attempts a crisp definition of "cancelling" to be completely silencing someone or getting them fired. I think it's broader than that, but also not necessarily a bad thing. JK Rowling still has a platform, but she doesn't have the same ability to reach out and communicate on LGBTQ issues that she did before - and she doesn't deserve the same platform she had before. Richard Dawkins also has less reach, but in his case I'm not so sure the cancelling is deserved.

It's complicated. Anyway, T1J is right, saying people shouldn't be jerks and that should guide their behavior.

(Adding here that the above is Brian's opinion - Eli and John may feel differently on cancelling, the Harper's letter, etc.)

Thursday, August 20, 2020

Dispatchable hydropower versus pumped storage, Round 2

I've been meaning to return to this concept of dispatchable hydropower and distinguishing it from pumped hydropower storage. The tweet above shows how one example of it being used in practice. We could do much more, somewhat to help in energy crises similar to what's happening now in California, and more to smooth out renewable power-based systems generally.

Sammy Roth publishes some great work about climate and energy, and recently published eight low-carbon solutions to variability in renewable power. Pumped hydro was one of them, while dispatchable hydro was not. Glen Canyon Dam suggests it should've been.

Dispatchable hydropower is (mostly) distinguishable from pumped hydro storage in that it makes use of existing dams and reservoirs, and (mostly) doesn't build new infrastructure like pumped hydro does. Its focus is a change in how hydropower is used and released from baseload power that's used constantly, first in line to satisfy demand, to dispatchable power that - subject to other constraints that require release - is conserved and then released when needed.

I previously had some documents that I'll try to dig up from my local Community Choice Energy Aggregator that showed essentially no 24-hour variation in the hydropower they received, and that's the type of baseline use that could be saved, somewhat, for the late afternoon and evening hours when demand is up and solar is down.

I also want to distinguish this from Mark Jacobson's Wind Water Solar system for replacing all fossil fuels. He's proposing something gigantic, I'm discussing something much smaller and therefore able to be implemented much sooner. In particular, what I had read a while back was that he wants to quadruple the dispatchable power from existing dams by rebuilding their outlets. I don't know how well that would work, but I do know it would require dewatering and then mostly or entirely rebuilding the dams themselves. I'm not talking about that.

These ideas do shade into each other a bit. You can't fully turn off and turn on water from dams, they have ecological and water supply reasons for running as well. Some construction might also be helpful for dispatchable hydropower, particularly an afterbay below a dam that stores a tiny percent of the total water, maybe a day's worth or more, and can modulate the downstream releases from the main dam. The expense would be small though compared to other massive projects, or you can just not do it and still use some limited flexibility in water releases to time them for dispatchability.

Using that power in this manner could help in the shortages California is facing now, and maybe elsewhere too, along with batteries and everything else we can do to reach 100% carbon free economies.

Saturday, August 15, 2020

Renewables up, gas down, and coal at less than half capacity

Interesting report by think tank Ember on state of energy transition, comparing the first half of 2020 to 2019 and also looking back to 2015. Over five years, solar and wind doubled worldwide from 5 to 10 percent of generation, and coal's share unsurprisingly decreased by 5 percent in that period.

Comparing first halves of 2020 and 2019, solar and wind generation rose 14% despite decreasing electricity demand due to covid, while gas decreased 1.6%. This is an especially early indicator of renewables starting to outcompete and reduce gas generation, not just coal, even without fully pricing carbon. I say "especially early" because I assume gas will bounce back for 5-10 years as electricity demand recovers and gas has more opportunity to replace coal. But as renewables rise into the range of 15-25% of the total, they'll take out some gas generation.

Coal took the biggest hit in generation in 2020, falling 8.3% compared to 2019, again unsurprising that in a period of reduced demand, the most expensive operating-cost input would decrease the most. With that, already somewhat-idle coal plants dropped to now using 47% of their capacity.

Plants straining at 100% capacity are probably not the most efficient, but neither are plants that are mostly unused. In a free market a lot of these plants would probably be closed down permanently. Most places don't have a free market, but they still are influenced by economic forces. If demand for coal doesn't go up after covid, and it's doubtful it will outside of Asia, then I'd expect to eventually see shutdowns.

So good news globally, although as the report says, this decline still isn't fast enough to keep warming to 1.5C. We're really going to have to work on carbon-negative policies.

In the US specifically, a mixed bag: coal's taken a huge hit, generation down 31% and capacity at 32%. OTOH gas generation increased 7% - not as much as solar/wind's 16% but more in overall watts, for now. Still not a bad result with an anti-science, pro-coal administration. Let's look forward to January 2021, hopefully.

Note BTW that I used "renewable" and solar/wind interchangeably for purposes of this discussion although renewables is a bigger/more amorphous category. Also some wags might point out that solar/wind typically operate at significantly less than 47% capacity, but the difference is that they are designed and priced at the level of generation compared to capacity, and coal is not.

Friday, August 14, 2020

Who's Next

 Brian and MT hav already taken some free whacks at Michael Shellenberger, but Eli would a couple too. In a truly deranged article at Forbes Shellenberger goes fully insane 

Who Are We To Deny Weak Nations The Nuclear Weapons They Need For Self-Defense?

Now Eli knows that foresight was never the Breakthrough Institutes forte, given their inability to go beyond the bright shiny thing they see in the candy store window, but Michael Shellenberger needed to grow up sheltering under his desk.

Of course one could put together a carefully reasoned replies to this, but why bother when it has been done 50 years ago, and with rhythm. Going back to the old days of the nuclear arms race Tom Lehrer put it well

and as to the other side there will be universal bereavementfor Shellenberger an inspiring achievement, we will all go together when we go.

Shellenberger has always been a boy playing with toys, not able to figure out that sticking his finger in an electrical socket is not a great idea. As Oliver Cromwell put it, Dear Michael, in the name of God, go. there is more, but it fits so well