Category: Environment

Post #1942: Microplastic, some more targeted questions.

 

In my last post, I pinned down what I did and didn’t know about microplastic.  And, while I don’t (yet) think this spells the end of civilization, what I learned has given me pause.

With the just-prior post as background, I spend this post homing in on the questions that I should be asking.

They are:

1)  What are my likely sources of greatest exposure?

2)  How does this stuff break down?  What is the half-life of microplastic, particularly fibers, in various environments (including human tissue).

2B)  Are we seeing this topic frequently in the popular press because microplastic has been building up in the environment (that is, it’s now a much greater hazard than in the immediate past), or because we’re looking for it and/or we now have the means to find it?

3)  Are nano-scale (really tiny) fibers a particular concern?

I’m only going to address the first question, in this post.

Understand my background as a health economist.  Surgeons have been implanting chunks of plastic and metal into people for more than 70 years.  (The first pacemaker implant took place in the late 1950s.  Modern metal-and-plastic hip replacements go back somewhat further.)  So the right materials, properly chosen, won’t interact with the body at all.  OTOH, there’s a long list of materials that were tried and rejected, because they were not so inert.

So my prejudice is that incorporating random bits of plastic into your body is probably a bad idea.  The only question is, how bad is it?  And can you avoid it?

Wall-to-wall paranoia

The first question to ask for any environmental health hazard is, 1)  What are my likely sources of greatest exposure?

For airborne fibers, if I walk through it logically, my greatest source of exposure almost certainly has to be the wall-to-wall carpeting in my home.  It’s indoors, it contains a huge amount of fiber, it’s clearly synthetic fiber, and it is constantly being abraded by walking on it.  And it’s “clipped”, that is, every strand of carpet yarn has been sheared off, so that it’s an entire floor surface consisting of the cut ends of synthetic yarn.  In my house, every floor surface save bathroom, kitchen, and foyer is covered in the stuff.

For me, it’s a big, fiber-generating surface that I shuffle my feet across, every time I change locations within my house.

Reading up on it, I’m guessing it has maybe 60 ounces of carpet pile per square yard, a.k.a., “face weight” 60 carpeting.  Doing the math, that means my house contains somewhere around 700 pounds of carpet fibers.  In the form of short pieces of yarn, with their cut ends exposed, for me to walk on.  I’m pretty sure that outweighs all other cloth in this household, by a wide margin.  True, on any given day, most of it just sits there.  But so does most of the clothing in my closet.

I can only think of two things arguing against this being my greatest source of airborne synthetic fiber exposure.

The first is that, whatever it’s made of (I have no clue), it’s made to resist abrasion.  It was here when we moved into this house in 2007, and it looks about the same now as it did then.  (To within my ability to tell.  What I mean is, no obvious new wear spots have developed in the past 15 years.)

The second is a potential “inverse-square-law” for inhaled fiber concentrations.  That is, for a given rate of fiber shedding, the closer you are to the source of the airborne fibers, the more of them you may be likely to inhale.  If that’s true, then the fibers shed from stuff that’s right under your nose — shirts, sweaters, scarves, coats — might matter more than the fibers shed at your feet.

And if I put all that together, I come up with the obvious conclusion that crawling around on wall-to-wall carpet may not be smart.  Not that I’m planning to do that any time soon, if I have any say in it.  But the point being that having infants crawl around on your wall-to-wall carpeting might require a rethink.  Putting that differently, if you’re not worried about your kids crawling around on wall-to-wall carpet, I don’t see much point in being worried about this topic at all.  Because, outside of a factory, it’s hard for me to imagine where you could get a higher concentration of inhaled artificial fibers than in crawling across modern wall-to-wall carpeting.

We have met the enemy, and he is us.

In my case, I’m going to start by trying to figure out what my carpet is made of.  It was here when we moved in, and I have no clue what the fiber is.  Nylon is a good guess, and everything I read says that nylon, in particular, is a fiber that you’d like to avoid breathing in, owing to what it produces as it slowly breaks down.

And I may be a little more diligent in vacuuming.  Given that the vacuum (in theory) has a HEPA-level filter on it, that (in theory) couldn’t hurt.

Conclusion:  What to do when you’re flying blind

From the prior post, it was absolutely clear that routinely inhaling a lot of nylon fiber is bad for you.  There’s even a name for the resulting condition — flock worker’s lung.

But so what?  Inhaling high levels of almost any fiber or powder is bad for you, be it coal dust, silicon dust, cotton dust, copier toner, wood dust, or what have you.

It’s still an open question as to whether or not there are identifiable health effects from absorption of microplastic at levels commonly found in the environment.

But, from my own perspective, given how picky medical device manufacturers are about the materials they will use for implantable medical devices, it’s a pretty good bet that inhaling and ingesting random plastic bits and fibers is probably not good for you.  How bad, exactly, we can argue about.  But almost surely not a good thing.

My first thought, in a situation like this, is to test for it.  Measure it.  See what my exposure is.

But I don’t think that’s possible, practically speaking.  I already have a “PM 2.5” meter, bought in response to the Canadian forest fires of 2023.  That almost uniformly shows lower airborne particulate levels inside my house than outside.  And that responds to all kinds of particulates, of which the tiny minority is likely to be microplastic fibers.

So this is a case of flying blind.  I can’t tell how much I’m exposed to and I have no clear idea what harm that exposure might do, anyway.

In that case, I can at least try to identify the easily-avoidable sources of microplastic, and so reduce my exposure until better information develops.  I might even go so far as to change what I buy, to avoid funding the production of even more items that shed microplastic.  (E.g., avoid synthetics in my next batch of shirts).  But I’d want to look at the full implications of that first.

So I’m stuck at the “identify my exposures” stage.  My water filter appears to take care of most of the microplastic that might make it into my tap water.  (Though I have no idea what it does with the very smallest particles).  And for airborne fiber, my biggest exposure has to be wall-to-wall carpet.  But this house was built for it, and replacing the existing wall-to-wall with hard-surface flooring would be ludicrously expensive.

Time to step back and let this percolate a bit.

Post #1941: Microplastic, some initial questions.

 

Intro:  Not a lot of answers in this post

Seems like every week I read another story about microplastics. 

At some point in all that reading, it dawned on me that I didn’t actually know what microplastic is.  Sure, micro meaning small, and plastic, meaning plastic.  But that’s as deep as my understanding went.

Turns out, there are good reasons for my confusion.  The term “microplastic” is used for everything from shreds of plastic you can see, down to nano-scale bits that you’d need an electron microscope to see.  From the plastic chips left over from recycling, down to aerosol-sized microscopic fibers.  The microplastic in your tap water (fibers, mostly polyester) really isn’t the same stuff as the microplastic in your bottled water (particles, mostly bits of PETE or HDPE plastic).

Let me narrow down my interest to microplastic in my tap water.  Or maybe, microplastic in the air I breathe.

What’s that all about?  What is it, exactly?  How much is there?  Will my water filter remove it?  How about an air filter?  Is it harmful in the concentrations I’m routinely exposed to?

Weirdly, for something that seems to be in the news a lot, I could not find out much in the way of hard facts.  In this post, I at least begin to pin down why I’m not finding answers to those basic questions.

Other than the fact that my Brita water filter promises to remove most of it.  Whatever it is.  I think.

Source:  Brita.com, data for the “elite” filter, not their standard filter.

First stop:  A mother lode of click-bait

The popular press on this issue yields a coherent if superficial story about the environmental danger of microplastic.

It’s invisible.  Municipal tap water, for example, typically contains bits of plastic that are too small to be seen with the naked eye. It is not present in enough density to give the water a cloudy or turbid appearance.  Nor does it affect the smell or taste of the water.

It’s everywhere.  These bits are too small to be filtered out completely by typical municipal water plants.  And once you start looking for it, you can find some amount of microplastic almost everywhere.  Not just tap water, but: Bottled water.  Bottled soda.  Even in things that are bottled in glass bottles.  Animal tissue.  Breast milk.  Rivers.  The oceans.  Fish.  The soil.  The air.  The clouds.

(Ah, yeah, in addition to eating and drinking it, you breathe it in the form of floating dust particles.)

It might be bad for you.  I haven’t yet come across hard evidence one way or the other, at levels seen by the average U.S. resident, but the most common analogy is with asbestos.  Exposure to asbestos fibers is associated with cancer presumably because the fibers were small enough to enter cells and perturb DNA replication.  A lot of microplastic is in the form of fibers, some of which are likely small enough to enter cells.  So this is a plausible if unproven concern.

And that combination makes it hard to sort fact from fiction.  Look at the phrases in red above.  In the internet-driven world, you know what means.  It means that “microplastic” is an ideal and practically inexhaustible source of  click-bait.  Between the people who make their living out of scaring you, and the people make their living out of mindlessly repeating stuff they gathered off the internet, let’s just say that the facts appear thin on the ground.

On top of which, everybody hates on plastic.  Even as we, collectively, use vast amounts of it.  So you’ve got some degree of  axe-grinding dressed as fact-finding, thrown into the mix.

To be clear, I’m not dismissing this as a threat.  This, even though our public health authorities don’t seem to have any handle on it.  But that has happened before (think, leaded gasoline).  Sometimes widespread harm is only understood well after-the-fact.

Three things

Three things make me hesitate before I freak out over microplastic.

Thing 1:  It’s not as if plastic is a new thing.  We’ve been using lots of plastic, for a long time, here in the U.S., and world-wide.  Whatever-it-is that microplastic does to you, chances are that it’s been doing that to you, to a greater or lesser degree, all your life.

Up until COVID, U.S. life expectancy had been increasing consistent with its historical trend.  So whatever it is that plastic in the environment is doing to us, it’s small enough not to perturb that trend.  It doesn’t mean it has no effect, it just strongly suggests that the population-level health effects, at typical exposure rates, are likely small.

There needs to be one major caveat there:  Assuming it isn’t just slowly accumulating.  And we’re only now beginning to reap what we’ve been sowing for the past N decades.  Haven’t stumbled across any evidence suggesting that, so far.

Thing 2:  It’s not as if having harmful material in your air or drinking water is new, either.  For example, Virginia requires that all public water supplies are tested, and that those test results be made public.  So I know there’s lead in my drinking water, but the 90th percentile of water samples in my town showed 1.5 parts per billion, lead.  That’s low enough that I cross it off my list of things to worry about.  (Source: 2022 water quality report testing 2021 water, Town of Vienna).

Thing 3:  This is a newly-recognized potential health hazard, and that means that there are no answers to even the most basic questions.  This really wasn’t on the public-health radar screen a decade ago, near as I can tell.

Suppose, for example, you wanted to see the equivalent of the report shown above, but for the microplastic content of your local tap water.  How much is there, in parts-per-million or parts-per-billion, and does that exceed some safety threshold?   You would discover that:

  • No, they don’t measure it that way (PPM or PPB).
  • No, nobody routinely monitors for it.
  • No, it’s not reported in the State-mandated drinking water reports that my Town must publish.
  • No, there is no accepted safety threshold.
  • No, there’s no hard evidence one way or the other for impact on human health.
    • Yet.

 

Boiling down the basic background.

Believe it or not, I don’t get paid by the word.  So let me just state some key facts that I think I’ve learned, without citation as to sources, then cut to the chase regarding health effects.

  1.  There is no standard definition of microplastic.  You’ll see that used for pieces of plastic that are anything from dime-sized to nano-scale bits (fractions of a micron).  But most research focuses on stuff that’s around the same size as aerosol air pollution, PM 10 (particles 10 microns or smaller) or PM 2.5 (particles 2.5 microns or smaller).   (Recall that a human hair is about 70 microns thick, and that aerosol particles — those that can remain suspended in the air for long times — are conventionally taken as those that are 5 microns and smaller).  The most common cutoffs I’ve seen for “microplastic” are 10 microns or smaller, or 1 micron or smaller.
  2. There are no quantitative measures of it similar to “parts per million” for drinking water.  Instead, for liquids, they run the liquid through a fine filter and count whatever gets caught.  So the most common measure of quantity is “counts per liter”, as in, the count of microplastic bits found, per liter of water poured through the filter.  Big bits, small bits, chunks, fibers — it’s all the same in that measure.
  3. It takes sophisticated equipment to determine how much plastic and what type of plastic is there.  Infrared spectroscopy, for most studies that I’ve seen.  Different types of plastic have unique infrared “signatures”.  Typically, certain distinct strong peaks in IR reflection or absorption are associated with specific common plastics.  At root, it’s the same process that your plastics recycler uses to sort plastic.  And the amounts in question are small enough that careful studies need to net out the residual or background amount of microplastic that’s found on everything, including everything in the labs that test for this stuff.
  4. In water, it’s mostly fibers.  And those fibers are mostly polyester.  But that’s not because polyester is uniquely bad among synthetic fibers.  In fact, acrylic cloth and yarn shed microplastic fibers at a much higher rate than polyester.  But polyester shows up as the main contributor because we use so much of it.
  5. The presumption is that this mostly enters the waterways from laundry effluent, but it may enter via deposition from the air as well.  Clothing sheds fiber as it is washed and dried, and it sheds as you wear it.  Plausibly, wearing it generates a much larger volume of shed fiber than washing it.  Some of that fiber remains suspended as dust in the air, which eventually settles and is then deposited in waterways via runoff.
  6. Typical municipal water processing removes most but not all of it.  Of what I recall, raw water might typically have on order of 200 CPL (counts per liter) of microplastic, and the finished water might have on order of 5 CPL.
  7. You also get little chunks of plastic that are not fibers.  Those also count, and my reading is that when you hear about microplastic in bottled water, for example, that’s what you’re hearing about. It’s not even clear that anybody knows where that comes from, but the presumption is that these are residues of some factory production process.
  8. There’s enough of this in the environment that labs have to net out their background level of microplastic when they test for it.   Just as they would have to do if (e.g.) measuring radiation, because every place on earth is slightly radioactive.  The readings you see in most studies are not the “raw” counts, they are the counts from the samples tested, less the counts found on control samples, presumably reflecting the background level in the lab doing the counting. Any human-occupied environment — laboratory, factory, office, whatnot — is going to have some ambient level of microplastic fibers, as long as the people in it are wearing clothes, and those clothes contain synthetic fibers.
  9. Most of it passes right through you.  At least, the larger fibers do.  That’s my takeaway from studies of fish that are fed materials containing microplastic fiber.  Mostly it just passes right through them.
  10. But some does not.  The concern centers around the tiniest fibers (fractions-of-a-micron), that are presumably small enough to pass through the gut, into the blood stream, and then into your tissues.
  11. I did not find research on what mechanisms the body has for breaking down or otherwise removing microplastic that make it past the gut/lungs.  So once you’ve absorbed some of this stuff, I have no clue how (or even, whether) you get rid of it.  That said, research seems to indicate that nylon fibers, in particular, produce some toxic byproducts when they break down in the body.
  12. Jury remains out on whether or not microplastic cause significant harm to humans.  At typical environmental concentrations.  In a dust-filled factory, you bet that synthetic fiber dust causes lung injury.  My take on it is that there’s almost literally no credible research on the likely level of harm at typical environmental concentrations of microplastic, because this has only recently (past decade or so) come to the attention of public health authorities.

A few observations.

First, taken as a whole, this likely explains why nobody routinely tests tap water for it. There’s no standard definition of it.  There’s no hard evidence of human harm, let alone some agreed-upon maximum threshold for safety.  It takes specialized equipment and techniques to measure.  And there’s a good chance of contamination from the testing lab.

Second, there’s some obvious potential for mischief in reporting the presence of microplastic in (fill-in-the-blank), in that this stuff is everywhere.  That is, there’s going to be a background level of microplastic in any testing lab.  If you don’t net that out, you’ve got the potential to report finding microplastic in pretty much anything you care to test.

Where to start:  Is there a synthetic-fiber analog of brown lung?  Answer:  Yes.

That is, do factory workers get sick from breathing in high levels of synthetic fibers?

Historically, workers in cotton mills suffered from a high incidence of brown lung.  This was the result of chronic exposure to high levels cotton dust, or to the dust of other organic fibers (jute, hemp, and so on.)

Is there anything to suggest that the same thing happens with chronic exposure to high levels of fragments of synthetic fibers?

Short answer: Yes, starting with Flock Workers Lung (.pdf).  This was recognized around the year 2000, in workers in Massachusetts plants that produced nylon flocking for use in producing velour-type fabrics.  In those plants, long nylon fibers were chopped into short lengths.  Inhaling airborne nylon fiber fragments led to inflammation, reduced lung function, and asthsma-like symptoms.

Whether polyester fiber fragments increase risk of lung cancer in factory workers is still an open question.  One study of a quarter-million female textile workers in Shanhai, China found no association between synthetic fiber exposure and cancer (reference).  By contrast, a study of one large industrial plant in France found that greater exposure to fiber dust was associated with increased risk of developing lung cancer (reference), but the dust was from a mix of fibers, including asbestos.

The upshot of this is that heavy exposure to large amounts of airborne synthetic fibers can mess up your lungs fairly badly.  This is definitely true for nylon, and may be true for other synthetic fibers.  (Several studies suggest to me that nylon fibers are particularly noxious, for reasons that appear related to what they release as they break down.)

This should come as no surprise, as chronic exposure to large amounts of almost any type of dust causes lung problems.  Sometimes the diseases have names, such as black lung for coal dust, mesothelioma for asbestos, siliconiosis (sp?) for silicon dust, and so on.  Sometimes, fiber will damage the lungs, but there is no specific name, for example, damage caused by breathing wood dust in a woodworking environment.  Name a dust, and an excess probably causes problems.  Toner?  Yep.  Fiberglass?  Yep.  And so on.

Is there any epidemiological evidence for the effect of lower levels of exposure?

No.   Not that I found. 

First, it’s a good bet that most people will have some microplastic in their lungs.  One small study in London (reference), using lung tissue samples that had been removed from people for various reasons.  It looks like they found a small number of microplastic particles in every sample they tested, although the number was not hugely higher than the background rate in the test lab.  By contrast, another study (reference) found 24 microplastic fibers total, in a sample of about 100 bits of lung tissue, but those fibers were more likely to be found in tumors than in normal lung tissue.

But in terms of linking population-level exposure to disease rate, I haven’t seen much.  And the studies of factory workers suggest why.  Where there appears to be an association between synthetic fiber exposure and cancer, say, we’re talking about modest increases (50% higher risk) for relatively rare cancers.  If the massive exposure you’d get from working in a textile mill has only a modest impact, you may not be able to see much impact from the vastly lower exposure of the general population.

That said, there are some hints.  There was a nice in-vitro study where polyester fibers inhibited the healing of lung “organoids”.  And one of the studies of lung tissue found that plastic fibers were more likely to be found in lung tumors than in healthy lung tissue.

Addendum:  Water filtration versus air filtration.

This is just a note-to-self that I now need to look up how water filtration works.

With COVID, I got up to speed on how air filters and N95 masks filter out aerosols. It’s not at all obvious, and it’s nothing like passing material through a fine-mesh filter.

For example, the hardest particle to capture is about 0.3 microns.  That’s why N95 masks are rated as producing a 95% reduction in 0.3 micron particles.  They actually produce a greater reduction in particles both larger and smaller than 0.3 microns.

I’m pretty sure that water filtration cannot possibly work the same way.  For example, 3M Filtrete material takes advantage of Brownian motion of particles in the air, in order to bring the most difficult-to-capture particles (0.3 micron) into contact with the electrostatically-charged filter material.  Well, that’s not going to work in a dense fluid like water.  Brownian motion won’t move particles far enough.

But I just plain don’t know.  For example, the Brita filter at the start of this posting is rated for capturing particles in the 0.5 to 1.0 micron (micrometer) range.  Is this like an air filter, so I can be assured that it captures even higher percentages of particles larger and smaller than that?  Or does that mean it simply doesn’t capture particles below 0.5 microns?

I just have a hunch that if you poured water through an N95 mask, it wouldn’t filter the water.  But I need to get up to speed on the basic science.

 

Post #1938: Psychrophilic bacteria for winter composting, total failure

 

This is a quick followup to post #1921, where I dumped some winter pond maintenance bacteria into one side of my tumbling composter, to see what would happen.  The question was whether or not that would keep my composter working in the cold of winter.

Now, one month later, the short answer is, not.  There is no detectable difference in the level of (un-decomposed) compost, between the treated and un-treated sides.

The upshot is that the only way I’m going to be able to keep that composter working throughout the winter is to heat it.  A little passive-solar-heated shed didn’t do the trick.  These cold-loving bacteria didn’t do the trick.  And having an electrically-heated outdoor composter is a total non-starter, for me.

At this point, I give up.  I just won’t compost kitchen scraps over the winter.

Post #1936: What if this is as good as it gets?

 

Source:  Data are from U.S. DOE, Sources: U.S. Energy Information Administration, Form EIA-860, Annual Electric Generator Report. U.S. Energy Information Administration, Form EIA-861, Annual Electric Power Industry Report. U.S. Energy Information Administration, Form EIA-923, Power Plant Operations Report and predecessor forms.

When technology produces big leaps in energy efficiency, it’s pretty easy to make meaningful reductions in your carbon footprint.  Just buy newer stuff.

But as a long-term observer of this issue, it seems to me that technology-driven gains in energy efficiency are hitting their limits.  There are a lot of important areas — cars, fridges, lighting, and even electrical generation itself — where any further reductions in carbon footprint look a lot more difficult.

What I’m trying to say is, looks like technology has already grabbed the low-hanging fruit.

I’m not going to belabor the societal implications of this.  For me, this means that once I’m driving an EV and living in a house with an efficient heat pump and LED lights, there are no more easy reductions in my household carbon emissions.  Nor are there likely to be, for the foreseeable future.  Lifestyle changes, yes.  Effortless reductions in emissions, no.

Maybe this is as good as it gets.

Continue reading Post #1936: What if this is as good as it gets?

Post #1931: Custom oil candle base for the Luminiser TEG lantern

 

This is the third (and, I hope, last) in a series of posts about the Luminiser thermo-electric-generator lantern.  This device makes light by converting the heat of a candle to electricity, then using that electricity to run some LEDs.

The claimed output of the Luminser is 200 lumens, or about one-quarter as bright as a “60 watt” light bulb.  It’s an impressive piece of technology for $20, and an impressive amount of light from the heat of a single tea-light-sized candle.

But it has a couple of problems.  It’s not very stable (sitting on four spindly plastic legs, as shown above), and it uses a disposable, proprietary oil candle as the preferred power source.

I happened to notice that the base of the Luminiser lantern is almost exactly the same size as a U.S. standard wide-mouth canning jar.  Which then immediately suggested a solution.

I’ve now fixed both of those issues by converting a standard wide-mouth mason jar into a custom oil candle, just the right size to be used to stabilize and power this lantern.  My Luminiser now rests securely on the mason jar, with the candle flame at the same height, and of the same size, to replace their proprietary disposable oil candle.

Here’s the final product, below, where I’ve removed the flimsy plastic legs, and used a low-profile pint (500 ml) canning jar as the base.  Plenty of light to work a crossword puzzle with no eyestrain.  All that, powered by a flame about the size of what you’d get from a tea light candle.

Directions in brief

Overview

Start with a wide-mouth canning jar (mason jar, Ball jar), pint or half-pint size.  Drill a little hole through the metal lid.  Stick a little piece of copper tubing through that.  Run a piece of cotton kitchen twine through that tube, to form the wick.  Fill the jar with lamp oil, screw on the lid, and that’s your oil candle.

(N.B., canning jars come in two formats in the in the U.S., regular and wide-mouth.  Wide-mouth is the right choice here, as that fits nicely into the base of the Luminiser.)

That’s the finished oil candle, shown above.  This now fits neatly against the bottom of the Luminiser, and replaces the proprietary oil candle.

NOTE:  You must also drill a small pressure-relief hole in the lid in order to use this safely.  That’s really the only part of this that isn’t obvious.  That little pressure-relief hole is a standard safety feature on oil lamps.  It is important that you include it in this oil lamp.  Even if you skip all the rest of the directions, read that part, in red, below.

Materials:
  • Pint or half-pint wide-mouth canning jar, with band and lid (a.k.a., two-piece metal lid).  If you’ve read this far, I probably don’t have to tell you, but don’t use a plastic lid.
  • 1/8″ rigid copper tubing (sold in 1′ pieces at ACE Hardware, $2, reference below).
  • A foot or so of cotton twine, ~2.5 mm diameter, sometimes sold as  “butcher twine” (the stuff you’d use to “truss a chicken”, see below for brief discussion).
  • For attaching the copper tubing to the lid:
    • A few drops of superglue  OR
    • Optional:  A small amount of two-part epoxy OR
    • Crazy optional:  Torch and solder.

Tools:

  • Razor-blade knife (Skil knife) or single-edge razor blade.
  • A bit of sandpaper.
  • Drill, with bits:
    • 1/8″ drill bit (to drill hole in lid for wick-holder tubing)
    • 1/32″ (or tiny) drill bit (to drill air relief hole in lid).
  • Metal paper clip (to push cotton twine wick through the copper tubing).

Part reference:  The only “exotic” piece of material here is the thin copper tubing.  My local ACE Hardware sells that, shelved with hobby supplies, for $2 each.  It’s “K&S 1/8 in. D X 1 ft. L Utility Copper Tubing“.  The metal does not make any difference — copper, brass, or aluminum would all be fine.  But the dimension is fairly critical.  Don’t go larger, you’ll get too big a flame.

Cotton twine:  The cotton twine needs to be small enough to fit through the copper tube, but must fit snugly inside the copper tube.  The theoretical internal diameter of that 1/8″ O.D. copper tube is .105″ or 2.667 mm.

You may have to eyeball this, as it’s hard to find twine marked as to diameter, or even as to twine gauge, in the hardware store. Ideally, the cotton twine would run about 3/32″ or 2.5 mm in diameter when lightly twisted.  The twine I used was not quite as thick as two U.S. dimes, as shown in the pictures below, thicknesses in millimeters.

What will work:  You want 2.5-ish mm cotton twine.  Of what I saw on the shelf at my local ACE Hardware recently, this product, labeled butcher’s twine, looked about right.

What might work, but I haven’t tried it:  In theory, purpose-made 2.6mm oil candle wicking on Amazon should work, but I can’t say that I’ve tried it, and it’s expensive.  If it works, it’ll be a tight squeeze.  Separately, a lot of cotton kitchen twine, package-wrapping twine, and general-purpose twine will be too small unless you double it or triple it up before feeding it through the copper pipe.

What won’t work:  Material sold as 1/8″ round oil lamp wicking is way too large for this use.  Any twine or wicking sold as 3 mm or larger is too large.  Wicking or twine sold as 2 mm or smaller would likely be too small.  Anything with a “twine gauge” or “size number” in the 10s or 20s (e.g., #12 twine) will be much too small unless you double it up or triple it up.

Finally, you can’t (or, at least, shouldn’t) use twine made of synthetic materials for this purpose,  Whether you could use other natural materials (e.g, jute), I have no idea.

Directions in some detail.

1:  Prepare the wick holder.

Cut 1.5″ off one end of the copper tube.  The simplest way to do this is to place it on a flat surface, place the Skil knife blade or single-edge razor blade on top, and roll it back and forth until the knife edge cuts through the thin copper tubing.  Remove the burr around the cut edge by sticking the paperclip in and working it around until you’ve opened cut end back up to the full diameter of the original copper tube.

2:  Prepare the wicking.

Cut a foot or two off the roll of cotton twine. 

Thread the cotton twine through the 1.5″ piece of copper tubing.  First, bind one end of the twine using superglue.  Hold the tightly-twisted cotton twine in one hand, put a few drops of superglue near the end, and let it set up.  Once set, snip off the little bit of twine past the super-glued part.  If you did it right, you end up with a nice, tight, rigid section of super-glued twine that you can then poke into the copper tubing.  (Same concept as an aglet, or shoelace-end.)  Once you have that started, use the paperclip to push it all the way through.

3:  Prepare the metal canning lid.

Sand the plastic coating off a square inch or so of the interior of the lid, right at the center.  This is to help whatever glue/solder you use to stick the wick holder to the lid.

Drill a 1/8″ hole in the center of the lid.  Wallow it out just a bit.  Sand it to remove any burrs.

Drill a tiny hole (1/32″ or so, smaller is better) well off-center, but not covered by the screw-on band that holds the lid in place, to provide air pressure relief.  You must provide this pressure-relief hole in order to operate this safely.  If you do not do this, and you screw the lid on tight, the oil candle will enter “runaway” mode when you use it.  Oil and air expand as they warm up.  If you do not provide a pressure relief hole, that will force oil up and out of the wick, resulting in an ever-increasing flame, and possible fuel spill beyond the top of the candle, and a fire.

This tiny vent hole is a standard safety feature on oil lamps, it’s just typically placed so that you don’t notice it on store-bought oil lamps.  You may see directions for mason-jar oil candles, or even commercially-offered mason-jar oil candles, that skip this step.  The resulting products are decorative objects, not working oil lamps.  If you actually want to burn this candle safely, include the air vent, just like a real oil lamp.  You may think to yourself, oh, I’ll always remember to leave the lid a bit loose, or some such.  But at some point, either you or somebody else will forget to do that.  Do your future self a favor and drill that pressure relief hole when you drill the main 1/8″ hole for the wick holder.

4:  Assemble.

Poke the copper tube through the lid, so that the long “tail” of wicking is on the under-side of the lid.

Adjust the copper tube until the top of the copper tube protrudes 15/16″ from the top of the lid.  This adjustment puts the flame in the correct position.  Take the time to get this right.

Super-glue the copper tube in place, front and back, and allow to set.  (This is not great technique, but it’s fast, and it mostly works.  A more secure method would apply a small amount of two-part epoxy to the back of the lid, around the tube.  Or would use a torch and solder to affix the copper tube to the metal jar lid).

Cut the bound end off the cotton twine/wicking, and adjust the cotton twine so that it barely protrudes beyond the end of the copper tube, about 1/16″ to 3/32″ or so.  Something under 1/8″.  This small amount of exposed wicking will generate a flame that’s the right size.  If you leave too much exposed, you will get an unusably large flame, and you’ll have to go back and adjust the wick once it’s wet with lamp oil.  You want just a tiny bit of exposed wick.

5:  Fill, light, test.

Add lamp oil.  To reduce the total amount of oil present, you may want to put some heavy inert filler in the jar, such as marbles, glass weights, clean rocks, or similar.  DO NOT OVERFILL.  As with any oil lamp, leave space at the top of the jar, to allow for easy expansion of the oil as it heats up.  A good rule-of-thumb from canning is, when in doubt, allow a 1″ headspace.  Don’t fill it closer than 1″ from the rim.

Insert the tail of the wick in the oil, put the lid on top of the jar, screw the band on to hold the lid into place.

Wait a few minutes for the lamp oil to saturate the wick.

Light and observe.  You want a flame that’s maybe 3/4″ tall.  Let it burn for 10 minutes to be sure that the flame height remains steady.

Note that the top of the tube is just shy of 1″ above the metal canning lid, and the flame is under 3/4″ tall.

Place the Luminiser over the mason-jar candle and observe another ten minutes to make sure the flame height remains steady.

Below is the final version, using a shorter jar, with the folding legs removed.  To remove the legs, take a Skil knife (utility knife) and slice the inside “rim” off the split plastic pegs that hold the legs on.  You can then pull those plastic pegs out of holes that hold them to the body of the lantern.  Toss the flimsy plastic legs, as they will no longer stay attached to the lantern after you do this.

Never leave the lit Luminiser unattended.

6:  Main drawback:  Awkward wick adjustment.

A simple oil candle like this lacks the “wick riser” mechanism of a real oil lamp.  (That’s the little wheel that you turn to raise or lower the flame.)  For this oil candle, you have to adjust the wick height by tugging on the wick and/or pushing on the wick.

As long as you don’t let the wick burn down to a nub, you should be able to grab it with pliers (or maybe even large tweezers) and give it a little tiny pull to lengthen it.

If you overdo that adjustment, you can either stuff the wick back down the tube, using a paperclip, or you can take the top off the jar and pull the wick back down.  If you let the wick it burn too far, so you can’t grab it from the top, you have to take the top off and use a paperclip to push the wick up.

It works, but it’s awkward.  Luckily, you don’t have to adjust the wick often, once you achieve the right flame height.

If it weren’t for the fact that a wide-mouth mason jar works so well as a stable base for the lantern, I’d probably have bought a commercial lamp mechanism for a mini-oil-lamp, and worked from there.  Just to get an easily-adjustable wick.  As it stands, the awkward wick adjustment is a minor annoyance I can live with.

7:  Eventually, deal with the lantern legs.

The pieces of perforated black plastic in the photo above are the flimsy lantern legs, folded up.  At some point, I’ll either remove them, or cut them so that they will fit over the final (likely, half-pint) container, and so hold the lantern firmly to the mason-jar base.

It works fine as-is.  Its mostly that those folded-up legs spoil view a bit.  Fixing that is optional.

Edit:  Done.

Conclusion

The end result is a heavy, solid base for the Luminiser lantern, along with an oil candle that could hold a several-week-supply of lamp oil.  This avoids the relative unsteadiness of the original design, and allows you to fuel the lantern cleanly without using the proprietary disposable oil candles sold by the manufacturer.

The fit between the standard wide-mouth mason jar and the Luminiser is so good that it almost looks as if this were made for it.   It’s like having an oil lamp with a chimney.  Except that the chimney puts out twenty times as much light as the oil lamp itself.

Replacing the pint wide-mouth mason jar with a half-pint would make this more stable, and more difficult to knock over.  (The only reason I made this with a pint is that I didn’t have a wide-mouth half-pint available.  I plan to replace my pint jar as soon as I can lay hands on a half-pint.) Edit:  I have now replaced it with an even better choice, a low-profile pint jar, as pictured near the start of the post).  If you desire stability beyond that, epoxy the mason jar to a suitable base, such as a piece of marble or wood.

Finally, let me emphasize the general safety precautions.  Don’t run this unattended.  Don’t run it with a flame bigger than about 3/4″.  (If the flame is too big, pull or push the wick down further into the tube.)  Drill that tiny pressure relief hole before you use this, to avoid a runaway lamp situation.  For indoor use, burn only lamp oil or kerosene (e.g.,”Klean Heat”).

That said, you do this at your own risk.  This is, after all, quite a bit of easily flammable material, all in one place.  As with any candle or oil lamp, you always need to keep in mind that you are playing with fire.  There is an inherent risk in doing that, and to do it safely, you need to acknowledge that, and take all reasonable precautions.

Post #1930: Luminiser lantern, much cheaper to run than a flashlight using disposable batteries.

Above, the Luminiser lantern being powered by a candle (left), and that candle alone, right.

In my just-prior post, I worked out the basic efficiency numbers for the Luminiser candle-powered electric lantern.  It’s vastly more efficient than, say, a mantle-based oil lamp, such as an Aladdin (r) lamp.

I was so struck by how well the thing worked …

Scratch that.  I was so struck that the thing worked, at all, that I neglected to show any numbers on  operating costs.  Let me fix that now.

If you are “on the grid”, nothing is as cheap as plugging an LED lamp into the wall.  No surprise there.  Not by a longshot.

But suppose that, as a moral issue, you would not allow the general use of electricity in your home.  You live in a home that is not merely “off the grid”, but one that is purposefully and thoughtfully un-electrified. For the sake of argument, let’s say you would selectively allow battery-powered devices, when useful and necessary.  A flashlight, for example, might be OK, but a battery-powered television would not.  But you had to use disposable (alkaline) batteries, for such devices, because there’s no place to charge your rechargeable batteries.

That’s all by way of setting up the comparison.  How would the operating cost of this candle-powered lantern stack up against that of a standard battery-operated lantern or flashlight using cheap, disposable AA alkaline batteries?

Turns out, depending on what you burn in your Luminiser, it’s either vastly cheaper or merely a lot cheaper, than producing the same amount of light with disposable AAs.

I didn’t expect that, and I find it kind of interesting.   Despite the seemingly Rube Goldberg nature of this device — you use the heat of a little oil lamp (“oil candle”) to run a thermo-electric generator, to power some LEDs — the running cost of this is vastly lower than using disposable AAs in a flashlight.

Here are the results of my cost calculation.  Assuming I haven’t slipped a decimal point somewhere, the Luminiser powered with ordinary gas-pump K1 kerosene costs about 3% as much to run as a battery-operated lantern powered with disposable batteries.

Description of the calculation follows.

A few key details

This calculation assumes the following prices, current as of January 2024:

  • 33 cents per AA battery, based on a box of 60 currently at Home Depot.
  • $5/gallon for K1 kerosene (roughly the U.S. national average right now).
  • $15/gallon for Kleen Heet deodorized kerosene (Home Depot price).
  • $30/gallon for paraffin oil (the finest fuel for flat-wick oil lamps), based on the current ACE Hardware price.

For the output of the Luminiser, I’m just accepting the manufacturer’s specs of 200 lumens, for 8 hours, using one 44 milliliter oil candle.

The only hard-to-pin-down unknown is how many lumen-hours you can squeeze out of the typical disposable alkaline AA battery.   This is hard to pin down from manufacturers’ published data for many reasons, not the least of which is that they’ll lie.  But in addition, modern flashlights contain circuits that will turn down the brightness if they are left on.  And, they’ll get dimmer as they run, in any case.  Manufacturers tend to publish data on maximum brightness, and then on run time, where (unstated) the run time is mostly at some much lower brightness.  This means you can’t just multiply published lumen numbers by published run time numbers.  That will typically vastly overstate actual light output.

In my post on candles and lanterns I used an example of a real-life device that produced about 300 lumen-hours per AA battery.  That was a marine distress signal, and likely had been optimized for long battery life.  Similarly, this Nitecore flashlight works out to about 250 lumen-hours per AA battery, on low.

The figure of 300 lumen-hours for a typical AA alkaline battery is consistent with a typical AA alkaline battery capacity of 3 watt-hours of energy, and an overall energy efficiency of LED/driver circuit of 100 lumens per watt.  The AA alkaline capacity figure is pretty much a known, and the lumens-per-watt figure is at the high end of the current crop of off-the-shelf hardware-store lights.  (E.g., 90 lumens per watt for these LED bulbs (Home Depot reference).

Close enough for this kind of calculation.

Addendum:  Re-using/replacing the oil candle.

Edit 1/22/2024:  One day later, and this is obsolete.  See next post for making the permanent refillable replacement for these.

Above:  Original oil candle, 3/16 twist drill, glue syringe, and tiny drill (for air hole).

Below:  Luminiser burning with factory-original candle, and with refilled candle.

The key to operating this cheaply is to use some sort of re-fillable oil lamp to power it.  As shipped, the device comes with a small disposable oil lamp (“oil candle”).  That’s engineered to work correctly with this device, but is an expensive way to produce light.  To run it cheaply, you need to a way to use off-the-shelf kerosene or lamp oil to power this.

I did the obvious thing and demonstrated that I can, in fact, refill the little disposable oil lamp that comes with the light.  At least once.  Drill a hole just big enough for a glue syringe, drill a second smaller hole for to release air, fill the syringe with lamp oil, and inject in into the oil candle.

That works fine.    Light might be a touch dimmer, consistent with using lamp oil (paraffin oil) for the refill, which by reputation will not burn as hot as kerosene.  But if it is dimmer, it’s not dimmer enough to matter.

Lamp oil and kerosene have high flash points, so I’m not terribly worried about the little open holes in the shoulder of the oil candle.  Other than as a spill risk.  Pretty sure the plastic enclosure (and the plastic oil candle itself) would melt before it got hot enough to flash over the raw lamp oil.

But the wick on these disposable “oil candles” does not appear to be adjustable.  Or, at least, not without a lot of effort.  So this looks like it may work once or twice, but not indefinitely.

In the long run, I’m probably going to adapt one of my small (night-light-sized) oil lamps for this purpose.  These lamps are just a few inches tall, and take a round cotton-cord wick instead of a traditional flat oil-lamp wick.  They can produce a flame that’s about the size of the flame produced by this oil candle.  So, by inference, they should be just about exactly hot enough to run this device as the oil candle does.

The Luminiser seems like a robust device, in terms of fuel source.  People have run it successfully using a variety of setups for candles, for example.  Separately, I got it to run by simply sitting it on top of the chimney of one of those miniature oil lamps.  It’s no surprise that refilling the disposable oil candle with lamp oil works well. 

At this point, I’m sure I can find a setup that is both convenient and works well.  But I need to work up something a little more permanent, and a little less hazardous, than any of these makeshift solutions.  I should probably also muck about with the electrical side a bit.  For example, see if I could I gin up a USB charger circuit, and splice it into this.  But that’s for another day.

I’m not usually one to fawn over technology.  But I am reminded of Arthur C Clarke’s dictum:  Any sufficiently advanced technology is indistinguishable from magic.  I mean, I know how it works — as discussed in the last post, it’s a TEG.  But at a gut level, you feed this gizmo a little tiny candle flame, and it spits out enough light to read by.  Not magic, but it sure looks like it.

Post #1929: The caveman wants his fire, or, better to light one candle.

 

I just bought a candle-powered electric light, on Amazon.  The Luminiser, for $20.

What attracted me to this device, aside from the low price, is that it seems like such an irredeemably stupid concept.  Perfect for the headlights on your horse-drawn EV.  Or perhaps to replace the light bulb inside your ice-powered electric fridge.

It’s almost as if some nerds took steampunk literally, glommed up a bunch of money via Kickstarter, and created this pseudo-retro-techno-thing.  Which is, in fact, how this was developed.

But all that aside, a) it works like a charm, b) the underlying tech is pretty interesting and mostly, c) it’s a vastly more efficient light source than the candle that drives it.  And d), I’ve been wanting to own a device of this type for quite some time.

In fact, in terms of in-the-home, fossil-fuel-fired lighting — oil lamps, candles, Coleman lanterns, Aladdin lamps, gas-mantle lamps, and all of that — this is by far the most efficient one you can buy.

So chalk one up for steampunk, as I sit here typing by the light of that lantern, warmed ever-so-slightly by the candle flame in its heart.

In any case, I’m going to use this new toy as my excuse for running the numbers on the entire range of lighting — from candles to LED lights — that I have in my home.

But I’m leaving the deeper moral question for another day.  Would the Amish accept this?  At root, this two-step light generation process is no different from a mantle-type oil lamp, which is a technology generally acceptable to the Amish.

Continue reading Post #1929: The caveman wants his fire, or, better to light one candle.

Post #1926: A Prius driver takes a pass on Chevy Bolt “one-pedal driving”.

 

Do electric vehicles (EVs) get rear-ended more often than conventional cars do?

They certainly should.

That’s my conclusion after trying out the “one-pedal driving” mode on my new (used) 2020 Chevy Bolt.   And working through the logical consequences of it.

The practical bottom line of this post is that you should think twice before you tailgate an EV in traffic.  Because the chances are good that they can stop a whole lot faster than you can.   And may give you less warning when they do.

Not convinced?  Keep reading the parts in red, below.

Words do not do it justice: An accurate description of one-pedal driving mode.

Source:  Yeah, I know it’s a front-wheel-drive car.  The Gencraft AI doesn’t, though.  Almost all pictures here are courtesy of Gencraft.

Here’s your typical bland one-sentence description of one-pedal driving mode:  “With one-pedal driving, the car has enhanced regenerative braking, and will begin to slow as soon as you ease up on the gas (accelerator).”

Before I bought a Bolt, my reaction to that was, big deal.  Almost all modern cars do that, to a degree.  Anything with an automatic transmission slows when you take your foot off the gas.  All hybrids use regenerative braking, that is, they slow down by generating and storing electricity, reserving the friction brakes (pads pressing on rotors) as a last resort.

Some EVs can now do it more?  Whoop-te-doo.

Now that I own a Bolt, I know that description is missing a key word:  Abruptly.  Or, rapidly. Or, with great force.  Take your pick.

Taking your foot off the gas in “one-pedal” mode is nothing like taking your foot off the gas in a normal or hybrid car.  You don’t coast, at all.  You stop, pronto.  Not quite a wheels-locked panic stop.  But far faster than I normally stop, and far faster than anyone would reasonably expect me to stop in traffic.  In the Bolt, in one-pedal model, take your foot off the accelerator and you pull a few tenths of a G worth of deceleration.  Enough to pull you forward in your seat.  Enough that there’s no way I would engage that mode in snowy or icy roads.  Enough that I’d think hard about it before I turned one-pedal driving on in a driving rain.

Enough, already.  You get the point.  Here’s a more accurate description of one-pedal driving mode:

The act of lifting up on the accelerator, in one-pedal driving mode, is equivalent to pushing the brake pedal.  Hard.  Your (lack of) accelerator pedal is your brake pedal.  It’s not 100% as much force as you can get, if you actually do mash down the brakes.  But it’s an appreciable fraction of it.

You may again think, so what?  So you can, in effect, actuate the brakes, without hitting the brake pedal.  What’s the big deal?

Keep reading.

Brake lights?  We don’t need no stinkin’ brake lights.

But wait, it gets better.

Prior to mid-2023, some EVs would do that — stop fairly abruptly, in one-pedal mode — without turning on the brake lights.  And no, I’m not kidding about that.  (Reference).

The worst of those were fixed via software update, so now, all EVs on U.S. roads will now show brake lights, at some point, during some level of deceleration, in one-pedal driving mode.

As an afterthought.  Does that make you feel better about it?

But even now, an EV manufacturer’s decision on when, exactly, to show brake lights, during rapid braking in one-pedal driving mode, is entirely voluntary, and entirely up to the manufacturer, here in the U.S.A.  And for all of them, those lights turn on after the car has started slowing down.

Oddly enough, if you see this brought up on-line, you’ll see nothing but apologists for it.  Ah, cars have always had ways of slowing down without showing brake lights.  Let off the gas, in an automatic-transmission car.  Downshift in a manual.  Or, if you’re a jerk, hit the parking brake to stop, to fake out the folks behind you.

But those events were either mild in nature (automatic transmission), or rare and mild (nobody in the U.S. drives a manual these days, and nobody in the last 50 years has been dumb enough to wear out their clutch rather than brake pads by routinely slowing the car by downshifting).  Or required outright malice, like using a hand brake to stop.

Now, by contrast, you’re putting out a whole fleet of cars, for Joe and Jane Driver, all of which are designed to be driven without touching the brakes.  Designed to allow for substantial rates of deceleration without using the actual brake pedal.  And for which the decision about whether, or when, to turn on the brake lights at some point during that one-pedal deceleration, is an option for the manufacturer to decide. 

Let me offer a clear contrast to what you are used to, in a traditional gas car.  There, the brake lights are designed to light the instant you rest your foot on the brake pedal.  Brake lights are actuated by a switch that typically sits directly above the metal bar holding the brake pedal.  That switch has a fine adjustment on it.  You literally fine-tune-it so that the tiniest movement of the brake pedal closes the switch.  Even the lightest possible braking pressure will turn on your brake lights.  Properly adjusted, you literally turn on the brake lights before the brake pads make contact with the rotors.

So we now have a mixed fleet of cars on the road.  For 99% of them, the brake lights illuminate as soon as the driver puts on the brakes.  For the remaining 1%, the lights may come on at some point, after the driver has “put on the brakes”, assuming the rate of deceleration exceeds the manufacturer-specified threshold.

Yeah, what could possibly go wrong with that?

Braking distance versus stopping distance.

Definitions:  Both terms apply to panic stops.  Braking distance is how far your car travels, from the moment that you’ve firmly stomped on the brakes, until you reach a complete stop.  Stopping distance, by contrast, is that, plus the distance you travel during your “reaction time”, that is, the time it takes to say “oh shit”, move your foot off the gas, and hit the brakes.

Honking the horn is optional, but highly recommended here in Northern Virginia.

Now for just a bit of math.

1:  It takes about three-quarters of a second to lift your foot off the gas, and put it on the brake, in a panic stop.  That’s in addition to the initial reaction time — the time it takes you to realize you need to stop quickly.  (Estimates vary, that’s my reading of the literature on the subject.)

2:  At 30 miles per hour, in that amount of time, a car moves about two car lengths.  (Calculated as (30 MPH *5280 FT/MI *(0.75/(60*60) HOURS) = ) 33 feet.

3:  EVs in one-pedal driving mode can initiate an abrupt stop without moving their foot to the brake pedal.

My takeaway from all that is that EVs in one-pedal driving mode should be able to panic-stop somewhere around a couple of car lengths shorter than traditional cars.  That’s not due to better brakes, or better drivers.  That occurs because they begin to brake rapidly before they even move their foot to the brake pedal.

Yeah, what could possibly go wrong with that?

Summary

Shorter stopping distance is just dandy if you’re driving an EV in one-pedal mode.  But maybe isn’t such a plus for the person in a standard vehicle, tailgating an EV in one-pedal mode.

If you are in traffic, behind an EV in one-pedal mode, and the EV in front of you makes a panic stop, you need to be aware that, compared to a conventional car or hybrid:

1: That EV is inherently capable of stopping faster.

2: That EV will give you less time to realize it is stopping.

And nothing about that car will give you the faintest hint that those two factors are in play.

You’ve been warned.

Background:  Regenerative braking the Toyota way, or why Bolt one-pedal mode does me more harm than good.

We changed the brake pads on my wife’s 2005 Toyota Prius sometime around 140,000 miles.  Up to that point, the brakes hadn’t needed any attention.

The crazy thing is, that’s not even brag-worthy.  Going 100K miles between brake jobs is normal for any car with regenerative braking.

The Prius has regenerative braking.  To the greatest extent possible, the car slows down by turning itself into an electric generator.  It converts the forward momentum of the car to electricity, which then charges the traction battery.  Cars with regenerative braking routinely go 100,000 miles between brake jobs.  So says the U.S. DOE.

No material efficiency gains — for me.

The reason for the low brake wear in a Prius is that almost all the braking energy is done electrically.  In an ideal gentle stop, the friction brakes only kick in below about 5 MPH.  (If your rotors have surface rust, and your windows are open, you can hear that happen until you knock the rust off the rotors.)

In an idealized stop from 30 MPH to zero, you can easily calculate the fraction of braking “power dissipation” accounted for by electrical generation versus friction brakes.  Kinetic energy goes as the square of the speed, so, in a hypothetical gentle stop from 30 MPH to 0 MPH, where the friction brakes only handle the part below 5 MPH, the fraction of braking energy is:

Friction fraction of braking energy = 5-squared/30-squared = 25/900 = ~3%

Electrical Fraction of braking energy = 1 – friction fraction = 97%.

In other words, with a reasonably gentle stop, in typical suburban traffic, regenerative braking (Toyota-style) converts about 97% of the car’s forward momentum to electricity.  You don’t get to keep all of that, because there are losses in the electric motor/generators, the wires and charging electronics, and in charging the battery.  Maybe you keep 80% of that, or so.

One rationale offered for EV one-pedal driving is that it improves efficiency by recapturing more of the potentially available energy from braking the car.  That’s because you can literally bring the car to a full stop, and so, in theory, capture 100% of the car’s forward momentum and convert it to electricity.  Of which, again, you might be able to keep and use maybe 80%, after all the relevant losses are factored in.

And that’s the main reason that Bolt one-pedal driving does more-or-less nothing for my driving efficiency.  Because, despite what you may read, the Bolt’s regenerative braking does more-or-less the exact same thing as the Prius, during moderate stops.  In normal (not one-pedal) driving, when I take my foot off the gas, the car begins to recapture energy through regeneration.  And when I push gently on the brake, it begins to capture even more energy through regeneration.  Just like a Prius.  (All you have to do is look at the dashboard, as you brake, to see that this is true.)  And in a normal, gentle stop, with rusty rotors, you can hear the Bolt friction brakes engage at about the same speed as the Prius — about 5 MPH.

I guess if you drive like a bat out of hell, regenerative braking can improve your efficiency somewhat.  Plausibly, those who routinely make quick stops can benefit from converting more of the stop to electricity, before the friction brakes kick in.

But my driving habits were formed during the Arab Oil Embargoes/energy crises of the 1970s.  And I’m cheap, to boot.  So I try to avoid rapid stops.

My gut reaction, from reading about this, is that the real fan-boys for one-pedal driving are, in fact, those who want to drive like a bat out of hell.  They like it for the “sporty” feel, and how it lets them zip around all that much faster.  Which, to me, makes the whole “efficiency” argument kind of silly.  If you drive that way, clearly efficiency isn’t your goal.  You’d get more miles per KWH by not trying to drive the Bolt like a sports car.

So, from my perspective, as far as efficiency goes, one-pedal driving provides a marginal improvement in efficiency, for those with habitually inefficient driving styles.  Turning that around, if you’re a laid-back driver by nature, you ain’t going to get much additional efficiency out of one-pedal driving, beyond what you get from regenerative braking in “normal” driving mode.

Extras for experts, 1:  There is one weird final twist on this, in that, in a hybrid, regenerative braking doesn’t much matter.  It might typically add just 2% to the vehicle’s overall efficiency.  That’s from a combination of factors.  First, even with the efficient Atkinson-cycle engine of a Prius, you start off by wasting 60% of the energy in the gasoline.  Second, with relatively small electric motor/generators, and most importantly a relatively small battery, the amount of regenerative braking force — the amount of current you can safely generate and squeeze into the battery, without damaging anything — is highly limited.   So for the U.S. EPA drive cycle, with its extended periods of fast stop-and-go driving, you tend to show only a modest amount of energy recapture, as a fraction of the total energy used by the vehicle.

In an EV, by contrast, regenerative braking is a much higher contributor to overall vehicle efficiency, as the Federal government measures it.  First, unlike a hybrid, all the inefficiency in converting fossil fuels to electricity is “off the books”, so to speak.  That occurs at your local utility, not in your car.  The calculation of overall car efficiency starts with charging it, so as a whole the vehicle appears to have vastly less total wasted energy, than a hybrid does.  Second, with large motors and much larger battery, you can safely put more current into the battery.  Thus, in a hard stop, an EV can likely capture more of the energy than an hybrid can, prior to applying the friction brakes.

Old dog, new trick — look ma, no brakes!

The first thing about Toyota-style regenerative braking is that it’s absolutely seamless.  In the best case, you wouldn’t even guess that the car had this feature.  Only if you listen very closely, and brake very slowly, can you discern the point at which the friction brakes are engaged.

The second thing about Toyota-style regenerative braking is that hybrids with regenerative braking behave exactly the same as any non-hybrid car with automatic transmission.  Take your foot off the gas, and the car begins to slow just a little bit, just like any other automatic-transmission car (then) on the road.  The harder you push on the brake pedal, the more braking force you get.

Regeneration in the Bolt, by contrast, feels nothing like a normal car in this regard.  It is far more aggressive, even in normal (not one-pedal) mode.  Take your foot off the gas in a Bolt, and you slow much faster than you would in a standard car with automatic transmission, or in a typical hybrid.  I have already had to break myself of the long-learned habit of lifting my foot from the gas when I see a red light ahead.  On the roads around here, If I were to do that in a Bolt, I’d come to a dead stop long before I make it to the light.

But I can live with that.  I lift my foot, eyeball the dash, and look for the something close to zero KW going into or out the battery.  It’s hardly a life-changing difference in driving technique.  Not after I had to re-learn driving for the Prius Prime, and its preference for constant-power (instead of constant-force) acceleration (Post #1618:  There ain’t no disputin’ Sir Isaac Newton).

But switching to one-pedal driving has one potentially life-changing difference:  You may lose the instinct to put your foot on the brake.  If you never need to panic stop, you can literally drive the car in one-pedal mode and never touch the brake.   (Some one-pedal fans brag about doing exactly that.)

So do I, as a 65-year-old guy, now want to train myself to drive in one-pedal mode?  This, when the approach to driving is so different from our other car (a Prius).  And this, where driving in this new style means basically to ignore the brake pedal.

Short answer, no.  Sooner or later, in NoVA traffic, I’m going to have to do a panic stop.  And when that happens, that panic stop happens on instinct.  It took me close to 20 years to get used to ABS, and to lose the instinct to release the brakes in response to a skid, and just keep my foot mashed to the floor.  I really, really don’t want to lose the instinct that tells me to hit the brakes in an emergency-stop situation.

So, it’s not that I couldn’t learn this new trick.  It’s that I probably shouldn’t.  Not with driving two different cars.  And not with my recent entry into geezerhood.  Better to leave sleeping dogs lie.

The Prius Gene

This is a true story.  We bought our first Prius in 2005.  The same week that we bought ours, hundreds of miles away, with no communication between us, one of my brothers also bought his first Prius.

We’re now a two-Prius family.  I think my brother and his wife have been a three-Prius family, with one going off to Prius heaven as a result of a freak highway accident.

My brother says the exact same thing about his Prius, as I say about ours:  It pushes all my buttons, in just the right way.  From the super-smooth acceleration with no gear shifts, to the dashboard feedback on mileage, pretty much everything about the car says “relax, chill, enjoy the drive”.

Maybe we both like that because that’s pretty much the way my dad drove.  Maybe we inherited the genes that give us that bent.  In any case, it seems to run in the family.

It takes some work to drive a Bolt as if you were puttering along in a Prius.  But for whatever reason, by golly, that’s how I choose to drive it.

So, no one-pedal mode for me.  It’s insufficiently Prius-like.

Post #1925: Bolt EV, party like it’s 1999.

 

The last car that I bought, before buying a used Bolt a) had a manual transmission, b) had a CD player, c) had no USB ports, not even for charging, and d) could only communicate with the outside world via the OBD-II port, as God and the U.S. EPA intended.

And, needless to say, ran on gasoline.

Continue reading Post #1925: Bolt EV, party like it’s 1999.