While overly wordy and negative, most of the premises of dissent seem to be well founded. The article's own summary:

> *For cultured meat to move the needle on climate, a sequence of as-yet-unforeseen breakthroughs will still be necessary. We’ll need to train cells to behave in ways that no cells have behaved before. We’ll need to engineer bioreactors that defy widely accepted principles of chemistry and physics. We’ll need to build an entirely new nutrient supply chain using sustainable agricultural practices, inventing forms of bulk amino acid production that are cheap, precise, and safe. Investors will need to care less about money. Germs will have to more or less behave. It will be work worthy of many Nobel prizes—certainly for science, possibly for peace. And this expensive, fragile, infinitely complex puzzle will need to come together in the next 10 years.*

More snippets below

Note that GFI refers to the optimistic analysis/factory proposal and Humbird is the author of the pessimistic analysis commissioned by Open Philanthropy.

> The single, hypothetical facility described by GFI would require nearly a third of <the entire capacity of the biopharmaceutical industry today>, just to make [.0002, or one-fiftieth of one percent, of the 100 billion pounds of meat produced in the U.S. each year.]

... If cultured protein is going to be even 10 percent of the world’s meat supply by 2030, we will need 4,000 factories like the one GFI envisions, according to an analysis[link] by the trade publication Food Navigator. To meet that deadline, building at a rate of one mega-facility a day would be too slow.

Each of those facilities would also come with a heart-stopping price tag: a minimum of $1.8 trillion, according to Food Navigator.

> Humbird’s analysis ... represent the lowest prices companies can expect. ... The final product would be a single-cell slurry, a mix of 30 percent animal cells and 70 percent water, suitable only for ground-meat-style products like burgers and nuggets. With markups ... [this] becomes $40 at the grocery store—or a $100 quarter-pounder at a restaurant. Anything resembling a steak would require additional production processes, introduce new engineering challenges, and ultimately contribute additional expense.

... “The requirements for return on investment need to be set much lower than common practice in commercially motivated investments,” the authors [of GFI] write. ... It will likely need public [subsidies] or philanthropic support to be competitive.

> In cell culture, sterility is paramount. Animal cells “grow so slowly that if we get any bacteria in a culture—well, then we’ve just got a bacteria culture,” Humbird said. ... "The culture has no immune system. If there’s virus particles in there that can infect the cells, they will. And generally, the cells just die, and then there’s no product anymore. You just dump it.”

... It may not matter if governments end up allowing cultured meat facilities to produce at food-grade specs, critics say—cells are so intensely vulnerable that they’ll likely need protection to survive.

... According to Humbird’s report, those economics will likely one day limit the practical size of cultured meat facilities: They can only be big enough to house a sweet spot of two dozen 20,000-liter bioreactors, or 96 smaller perfusion reactors. Any larger, and the clean room expenses start to offset any benefits from adding more reactors. The construction costs grow faster than the production costs drop.

For comparison, GFI’s hypothetical plant would have 130 fed-batch reactors and 430 perfusion reactors—a facility that could easily cost over a billion dollars if Humbird’s specs and prices prove to be accurate.

> In Humbird’s projection, the cost of amino [acids] alone ends up adding about $8 per pound of meat produced—already much more than the average cost of a pound of ground beef. GFI’s study, on the other hand, reports that the cost of aminos may eventually be as low as 40 cents per kilo.

Why the discrepancy? ... the price figures for macronutrients are largely based on a specific amino acid protein powder that sells for $400 a ton on ... Alibaba.com. That source ... is not likely not suitable for cell culture. ... Because they’re not intended for human consumption, they may include heavy metals, arsenic, organic toxins, and so on. ... foreign substances that aren’t consumed by the cells—or that don’t kill them outright—likely end up inside the cells.

Currently, global production of individual amino acids is far too low to support cultured meat production, even at a modest scale. ... “There can be no cultured meat scale-up without concomitant and dramatic scale-up of amino acid production,” Humbird’s report concludes.