Can a Refrigerant Be "Natural"?

 

The other evening my wife and I went to a new ice-cream shop in town, and while I was having my usual cup of vanilla I happened to glance at a refrigerated glass-front cabinet where the employees kept decorated cakes for sale.  Way down on the lower left corner of the front was a green label that read "NATURAL [followed by a leaf symbol] Refrigerant." 

 

That got me curious.  I knew the "natural" label has great consumer appeal these days when applied to food and maybe clothing, but refrigerants?  So I did some digging and discovered that there is quite a history behind the various refrigerants that have been used since mechanical refrigeration was developed in the nineteenth century.

 

For readers who need a review of how mechanical refrigeration works, here's the brief version.  When you compress a gas, it gets hotter, and that heat comes from the work you expend in compressing it.  If you then remove the heat somehow (that's what the condenser unit does outside every air-conditioned building), and the gas is suitable for use as a refrigerant in the system designed for it, it will turn into a liquid when it's cooled down enough.  If you then send the liquid through a small opening into a place where the pressure is lower, it will evaporate back into a gas, and get a lot cooler than it was before.  That's what happens in the evaporator inside an air-conditioned building.  It's the same basic principle that makes you feel cooler when you're sweating on a hot day and a breeze comes up:  water evaporates from your skin and takes some heat with it.  Run this process around and around again with the same substance, and you have a mechanical refrigerator. 

 

All right.  When large-scale mechanical refrigeration systems operated by steam power became available in first Europe and then the U. S. in the 1880s, they used ammonia gas.  The bottled liquid we call ammonia is just a solution of pure ammonia gas (NH₃) in water.  The gas itself condenses to a liquid at atmospheric pressure at a temperature of -28 F (-33 C), but under moderate pressure it can be persuaded to condense at or above room temperature, and it carries a good amount of heat away when it re-evaporates at lower pressure. 

 

Nineteenth-century ammonia was about as natural and organic as you could get.  It was obtained mainly from the waste urine from packing houses, by distillation, and it was therefore fairly expensive.  It got a lot cheaper when the Haber-Bosch process for making it from hydrogen (obtained from natural gas) and nitrogen (obtained from air) was perfected in the early 20th century.  But leaks in refrigeration machinery were common and ammonia gas is nothing you want to get loose around customers.  So the industry sought a non-toxic, non-corrosive substitute, and along came a General Motors chemist named Thomas Midgely Jr.

 

Midgely was largely responsible for the development of leaded gasoline, which in the 1920s was viewed as vital to the efficient operation of gasoline-powered vehicles.  Fresh from this first long-term environmental disaster, Midgely devised a new chemical that used carbon, hydrogen, and fluorine to make what at the time appeared to be the ideal refrigerant, which was trade-named Freon.  It became wildly popular, but in the 1970s, just when we were phasing out Midgely's first brainchild, leaded gas, it was discovered that the original type of Freon destroyed ozone in the atmosphere, at a rate that promised to leave us unshielded from the harmful ultraviolet rays that are normally absorbed by the naturally-occurring ozone layer. 

 

Somehow, the world's engineers cooperated in 1987 to agree to the Montreal Protocol, which committed the signatories to replace ozone-destroying refrigerants with some that are less harmful to the atmosphere.  Since then, the overarching question asked about new refrigerants is whether they hurt the atmosphere, and if so, by how much?  So it turns out "natural" in the context we're talking about means "less harmful to the atmosphere," and not necessarily something that occurs only in nature.

 

For example, on a website that sells restaurant equipment, I found an article that rates many current types of refrigerant with red (Not Eco-Friendly), yellow (Somewhat Eco-Friendly) and green (Eco-Friendly) labels.  Something called R-450A has a green label, and may be what's keeping the ice-cream shop's cakes cool.  It's made of a chemical called hydrofluoroolefin (HFO), which is anything but natural in the sense that it's a highly engineered artificial compound.  But if it gets loose in the air, the nature of its chemical bonds makes it turn into a reactive acid that gloms onto something or other fairly quickly and leaves the air, never making it into the stratosphere where it could bother the ozone layer. 

 

If you want "natural" to mean "naturally occurring," there is the old standby ammonia, which is still used in large-scale industrial refrigeration where its toxicity and flammability can be kept safely under control.  Propane and isobutane, which are distilled from natural gas, can also be used as refrigerants, but they can burn and have to be used in carefully sealed systems for consumer applications.  And the bad boy of the climate-change movement itself, carbon dioxide, can also be used as a refrigerant, although it doesn't condense unless the pressure is raised to over sixty times atmospheric pressure, necessitating very sturdy compressors and containment pipes. 

 

As historian Jacques Barzun pointed out in his monumental From Dawn to Decadence, the notion that nature knows best about a wide variety of things has a life of its own, and was one reason the "natural" tribes discovered in North America were of such interest to the Europeans who eventually overwhelmed them.  In the context of refrigeration, it looks like a more accurate label than "natural" would be "eco-friendly," but the PR people know what words look good in public view, and they picked "natural." 

 

It's only pedants like me who would even think to quibble with what the word actually means.  Without rolling the cabinet out from the wall and looking at the nameplate, I couldn't tell exactly what refrigerant was being called natural.  And my curiosity has its limits—it was good ice cream, and I didn't want to cause a scene and get barred from the shop forever.  I'm just glad that once we found problems with the refrigerant that at first glance looked ideal, we changed course and developed a whole spectrum of other ones.  That's the way engineering should work, and in this case, it has.

 

Sources:  I referred to the website https://www.webstaurantstore.com/article/474/refrigerant-types.html?srsltid=AfmBOorPfBjgu4ChyoyuSMDiNc9uETNLojxoiL_gL91XRkUgPKAPtlym

for the list of eco-friendly-graded refrigerants, and to the Wikipedia articles on HFOs and Thomas Midgely Jr. 

The Downside of Manufacturing: The Givaudan Factory Explosion

 

A theme of the recent election was to bring good jobs back to the U. S.  One type of job that many regard as good is manufacturing:  the work is usually steady, often no advanced degree is required of most manufacturing employees, and anything from a factory in the U. S. can be labeled "Made in the U. S. A."  Combine such jobs with the all-natural theme that has run through so much of Western history—the notion that natural ingredients are better than artificial ones—and you would think that employees of the Givaudan Sense Color factory in Louisville, Kentucky, which made natural caramel coloring for a variety of foods and beverages, were some of the most favored in the country. 

 

And perhaps some of them were, until an explosion at the plant last Tuesday, Nov. 12, killed two of them, injured 11 more, and wrecked a good part of the factory. 

 

This is the second fatal accident at the plant in the last three decades.  In April of 2003, an ammonia tank which was moved from another facility without its safety pressure-relief valve exploded, killing one person and releasing 26,000 pounds of ammonia solution, according to the Wikipedia page on D. D. Williamson, which company owned the plant until it was sold to the Swiss multinational corporation Givaudan in 2021.  Investigators are still looking into last week's explosion, which apparently did not release significant quantities of hazardous chemicals.

 

The D. D. Williamson firm dates to 1865 and specialized in caramel coloring for malt liquor, soft drinks (think Coca-Cola and Dr Pepper), and other food products.  Anyone who has burned cookies in a stove has encountered the process that turns sugar brown.  To control the process and end up with a water-soluble product, one must start with a sugar solution and add acids or alkalis.  The alkali favored by the Williamson plant was evidently aqua ammonia, a solution of ammonia gas in water.  Nearby residents complained of odors from the plant ranging from a burnt-sugar smell to an ammonia smell, all of which stands to reason. 

 

So until the plant blew up, except for the minor odor nuisance it seemed to be a good place to work.  But any time heat and pressure are applied to materials at an industrial scale, there are hazards, and the price of freedom from such hazards is eternal vigilance.  Such vigilance requires a culture of safety and a kind of rigor that is not easy to sustain these days.  But it was evidently sustained adequately at the Givaudan plant until last week, when something went horribly wrong.

 

Such accidents are one reason that many average citizens do not favor the idea of a manufacturing plant being built in their own neighborhood.  This is the famous NIMBY problem ("not in my back yard"), which not only makes it hard for new manufacturing plants to be built anywhere there are people, but leads to building and zoning laws that essentially put huge swathes of the U. S. off limits for certain types of manufacturing. 

 

Of course, some types of manufacturing are nicer than others, at least in the public eye.  Here in Central Texas, we have hosted the construction of several huge new manufacturing facilities in the last decade.  The developers of the so-called Tesla Gigafactory in southwest Austin broke ground in 2020 and began making cars in it only a year later.  I drive by it every time we take the eastern turnpike around downtown Austin, and there's new construction at the site all the time.  Northeast of Austin, Samsung is building a clone of one of their giant Korean semiconductor plants, which is expected to be completed soon. 

 

Neither one of these plants was in anybody's back yard, as they were sited in semi-rural areas, but close enough to Austin and its suburbs so that commutes from populated areas are not too arduous.  And if history is any guide, residential communities will spring up nearer the plants, which compared to a factory using a 100-year-old caramelization process are pretty clean and modern. 

 

I'm not aware of any major accidents involving either car manufacturing or semiconductor manufacturing, but I'm sure there have been some.  There are plenty of materials in any semiconductor plant that would kill dozens of people really fast if they got loose.  But the fanatically fussy nature of semiconductor manufacturing—the "seven-nines" (99.99999%) type of purities required, the exacting care every step requires—more or less bakes in safety procedures as well, or at least it should. 

 

The other major manufacturing enterprise that Texas is known for is oil production and refining, and for insurance reasons refineries have to be fanatical about safety.  Such efforts are not always successful, and the factory town of Deer Park outside Houston has suffered two fatal accidents just this fall, as referred to in this blog.  An oil refinery is something that my adult self would hesitate to invite into my neighborhood, although I confess to a youthful industrial-romantic phase in which I thought the sight of giant flares illuminating the mudflats of Houston for miles around was beautiful.  Then I found out how much cancer and other chronic diseases show up in people who live their lives near chemical plants, and that took some of the bloom off the rose.

 

As long as people still want new stuff, someone is going to have to make it, and I see no reason that we in the U. S. shouldn't be able to make our fair share of stuff and sell it both here and abroad.  But the visions of so-called autarky, in which a country becomes completely self-sufficient, are either harmless fantasies that have no chance of being realized, or cruel malignant visitations on the citizenry of a dictator who actually tries to put it into practice, as Castro did in Cuba and as Kim Jong Un still does in North Korea. 

 

The Givaudan caramel factory in Louisville may be rebuilt, or its new owner may conclude that the effort isn't worth it and close it down, as a 100-year-old wax plant in Barnsdall, Oklahoma was closed last summer after being wrecked by a tornado.  But if the Givaudan plant closes, Kentuckians can hope for someone to come along and build a new factory making cleaner-smelling stuff more safely.  It's happened in Texas, and it can happen there too.

 

Sources: I referred to an article on the Dayton Daily News website at https://www.daytondailynews.com/nation-world/2-dead-in-explosion-at-kentucky-factory-that-also-damaged-surrounding-neighborhood/ZCCWLCJIBJGDFHRPPX4VAKVIRA/.  I also referred to the Wikipedia pages on D. D. Williamson, caramel color, and Tesla's gigafactory.  My blogs on the Deer Park accidents are at https://engineeringethicsblog.blogspot.com/2024/09/deer-park-pipeline-fire-raises-questions.html and https://engineeringethicsblog.blogspot.com/2024/10/deadly-hydrogen-sulfide-accident-puts.html. 

Get Real with Vaclav Smil

 

The headline doesn't really rhyme, because Professor Smil's last name is pronounced "smill" to rhyme with "will."  But getting real is what Vaclav Smil does in his latest book, How the World Really Works.  And the reality that he presents, with incontrovertible evidence in the form of wide-ranging statistics and little-known but vital processes and connections among global economic flows, show that the highly-touted future of a fossil-fuel-less economy in ten or even thirty years is a pipe dream.  Not that it shouldn't happen—Smil tries to avoid the familiar political grandstanding beloved by both sides of the climate-change issue, with fairly good success.  What he excels in is showing in great but fascinating detail how essential but little-known industries such as ammonia synthesis play critical roles in sustaining the eight billion or so people on the planet, and that realizing a global zero-carbon economy any time soon would cause mass starvation.

 

Who is Vaclav Smil?  In reading his columns in the professional journal IEEE Spectrum, I wondered that myself while admiring his unorthodox but always fact-based take on various technical issues of the day.  He recently retired from a distinguished professorship in the Faculty of Environment at the University of Manitoba.  He is the only academic I have come across recently who can lay some claim to being a Renaissance man, having published in areas as disparate as population demographics and energy policy.  In whatever field he chooses to write about, however, he likes to start from the facts.

 

For example, if you were asked what are the four material pillars of modern civilization, what would you say?  Silicon, because it's used in virtually all computers and information technology?  Glass, because it forms the material backbone of the Internet?  Smil would disagree.

 

His choices for the four pillars are steel, concrete, plastics, and—the oddest member—ammonia.  Why ammonia?  Because ammonia synthesized from nitrogen in the air and natural gas is the source of the vast majority of chemical fertilizers used throughout the world.  German chemist Fritz Haber figured out how to do that by 1911, and the Haber process still provides most of the world's supply of nitrogen fertilizer, without which you get things like the recent collapse of Sri Lanka, which was caused largely by an out-of-touch government ordering all the nation's farms to switch immediately to non-chemical-fertilizer farming.  But the Haber process needs hydrogen, which comes from natural gas.

 

Plastics, the second pillar of modern society, are made mostly from petrochemicals or sometimes what used to be called "coal-tar derivatives."  Either way, they come from fossil fuels.

 

Concrete, without which we couldn't build most of the large-scale built infrastructure we have, is made with Portland cement, which in turn has to be manufactured with large amounts of coal, or sometimes natural gas.  Anyway, you need fossil fuels to make cement.

 

And steel is made in blast furnaces fired with coke, which is derived from coal.

 

Besides these four pillars, which have to remain in place if the six billion or so people who live less-than-average-income lives hope to improve their lot, all airplanes and nearly all ships burn fossil fuels.  Battery-powered planes or ships to carry even a small fraction of the vital international trade on which modern society depends will not be available for many decades, if ever.  So for the foreseeable future, we are stuck with using fossil fuels for a wide variety of essential processes and products without which most of us would have to crawl away somewhere and die of starvation. 

 

So what do we do, just give up on fighting climate change and get used to wearing bathing suits in the winter?  No, Smil says there are some practical things we can do.  Conservation is a big one.  A surprisingly large fraction, on the order of 40%, of food worldwide is simply wasted—spoiled somewhere along the transportation chain, or simply not used before it goes bad.  And there are tons of opportunities to conserve energy around the world, starting with displacing coal-fired plants (which China is still building like there's no tomorrow) with natural-gas-fired ones, going to smaller cars rather than SUVs and electrics where possible, and building more solar and wind-generation facilities.  But here is Smil reacting to claims that we could decarbonize at least 80 percent of the global energy supply by 2030:  "Alas, a close reading reveals that these magic prescriptions give no explanation for how the four material pillars of modern civilization . . . will be produced solely with renewable electricity, nor do they convincingly explain how flying, shipping, and trucking (to which we owe our modern economic globalization) could become 80 percent carbon-free by 2030; they merely assert that it could be so."

 

Smil's book is full of cold-shower moments like that, but he is also refreshingly free of the tendentious us-versus-them tone that dominates most public pronouncements on these matters by politicians and other leaders.

 

He does not deny that global warming, or climate change, is happening.  In fact, he shows how the essentials of the connection between carbon dioxide content in the atmosphere and global temperature were worked out over a century ago, long before it became a contentious political issue.  When he sees global leaders convening an endless series of summits and proclaiming unrealistic and unreachable goals while letting things just go on as usual, he gets irritated that no one is working toward a more systematic and engineering-driven approach to the problem. 

 

What is needed, and what is so often lacking, is the wisdom to choose the right path, or combination of paths, and the courage to put the decisions into action.  That is the real problem Smil portrays in his book:  the fact that a truly global issue—climate change—will have to have a truly global solution.  And we haven't figured out how to do that yet.

 

Sources:  Vaclav Smil's How the World Really Works was published in 2022 by Viking.