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Biobased Chemicals

Reactions: Issues with biomanufacturing and a firsthand experience with ball lightning

May 16, 2024 | A version of this story appeared in Volume 102, Issue 15


Letters to the editor

Biomanufacturing for commodity chemicals

A C&EN cover showing a chemical plant next to a cornfield that is mostly in shadow.
Credit: C&EN

The article “Biomanufacturing Isn’t Cleaning Up Chemicals” in the April 15/22 issue of C&EN (page 26) failed to mention the two largest fermentation processes for commodity chemicals that benefit from metabolic engineering. The 1,3-propanediol (PDO) process developed de novo by DuPont and owned by Covation has been commercial for 20 years, and the starch-to-ethanol process uses strains engineered for better functionality variously by Novozymes, DSM, and Genencor/International Flavors & Fragrances. This doesn’t alter the fact that target identification is the most important part of any industrial research project. In hindsight, the field got ahead of its headlights, especially by going after fuels (other than ethanol, which had a dramatic natural head start) in the heady aftermath of the announcement of the PDO process in the early 2000s. As the article states, this was, in part, because of influence from investors and senior management looking for a quick hit.

Mark J. Nelson
Newark, Delaware

“It was the biological equivalent of trying to break the sound barrier,” a former vice president of R&D programs at Amyris says in the article “Biomanufacturing Isn’t Cleaning Up Chemicals.” Indeed, two technical issues exist with biomanufacturing and affect its economic viability. These issues are mass balance/stoichiometry and product properties.

It is beyond the scope of a letter like this to detail property issues, but in any case, it can be a major pitfall if the properties of the biomanufactured product are not exhaustively determined before beginning work on (large scale) production and shown to be fully competitive with the existing petroleum-derived product.

The mass-balance issue when using sugar as feedstock to make hydrocarbons (such as farnesene) for fuel purposes on a large scale is that the numerous oxygen atoms in sugar are not used. Thus, a significant amount of mass (in glucose, C6H12O6, more than half the mass!) does not contribute to the product. That also means that the feedstock and the production process need to be extraordinarily cheap to compete economically with petroleum-derived hydrocarbons. Otherwise, only a valuable coproduct or, perhaps, legislative or regulatory measures might help offset this problem (as alluded to in the article). Thus, focusing on higher-value, nonfuel products seems advisable from the outset unless an offset exists.

Gerhard Knothe
Peoria, Illinois


A firsthand experience with ball lightning

Re “Ball Lightning: Reality or Myth?” (C&EN, April 15/22, 2024, page 20):

In August 1984, while working outdoors near Indiantown, Florida, I observed the formation of ball lightning firsthand. The thunderstorm developed rapidly, exhibiting many large bolts of whitish-blue lightning, which were accompanied by a very hard rainfall. As I was making my way to shelter, a large bolt of lightning hit the antenna atop my laboratory roof, knocking it down. The lightning bolt then proceeded to condense into a basketball-size fireball of energy, which bounced from the antenna and then proceeded to travel about 6 m, hitting me square on top of my head. This ball of fire hit me with considerable force. The kinetic energy it carried was enough to knock my hat off and knock me flat on my back from a standing position. Fortunately for me, I was wearing heavy rubber boots and rain gear, which protected me from any electrical shock the ball may have had. As you can imagine, I will never forget this experience.

Paul Scinto Sr.
New Bern, North Carolina


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