A hamburger grown in a laboratory costs about $330,000 to produce and tastes... well, only so-so for now. "The bite feels like a conventional hamburger,” one taster reported Monday, but the meat tastes “like an animal-protein cake.” Meh.

Still, environmentalists are hoping that lab-grown meat will keep getting better — and cheaper. The allure is powerful: Not only could we get burger patties without slaughtering cows, but we could also cut down on the greenhouse-gas emissions that are heating the planet.

As Ezra Klein pointed out, livestock accounts for 18 percent of global greenhouse-gas emissions — more than the world's entire transportation sector. (All those cows belch up lots of methane.) And one analysis found that getting meat from artificial cells grown in a lab and "fed" with algae could, in theory, produce 78 percent to 96 percent fewer emissions than getting the same amount of meat from an a cow. Sounds good, right?

But that's a best-case scenario. The reality might not be that simple. In an essay for Discover last year, synthetic biologist Christina Agapakis explained why she thinks that scaling up artificial meat production will be harder than people think:

Cell culture is one of the most expensive and resource-intensive techniques in modern biology. Keeping the cells warm, healthy, well-fed, and free of contamination takes incredible labor and energy, even when scaled to the 10,000-liter vats that biotech companies use.
In addition, even in those sophisticated vats, the three-dimensional techniques that would be required to grow actual steaks with a mix of muscle and fat have not been invented yet, though not for lack of trying. (This technology would primarily benefit our ability to make artificial organ replacements.) Add on top of that the fact that these three-dimensional wads of meat would have to be exercised regularly with stretching machinery, essentially elaborate meat gyms, and you can begin to understand the incredible challenge of scaling in vitro meat.

Agapakis also noted another big hurdle. At the moment, as Tom Philpott highlights, the artificial meat cells need to be nurtured with "fetal bovine serum," or blood derived from cow fetuses. That's not exactly ideal from an environmental or animal rights perspective — and it's massively expensive, with the serum selling for around $250 per liter.

So, as an alternative, some scientists hope that future meat cells could be fed with algae. That's an enticing idea. Algae are exceedingly efficient at photosynthesis, which is why researchers have often looked to the organisms as a way of minimizing the environmental footprint of food production. But it's never quite worked in the past:

[T]his isn’t the first time that algae has been proposed as a solution to an environmental crisis in food production. In the 1940s and 1950s, as the population exploded and conventional agriculture didn’t seem like it could keep up, enormous research efforts went into scaling the production of algae as a food product, a high-protein green paste to feed to increasing number of hungry people around the world. ...
Scaling, it turned out, killed these plans the last time we tried them. Scaling algae production in open ponds proved an enormous challenge, with the gains in efficiency fading as the controlled environment of the lab was traded for ponds where cells crowded and shaded each other while having to fight off infections and predators.

Now, this isn't an argument that artificial meat will never work — it'd be foolish to bet against all the smart engineers and scientists working on the issue. But there are more than just engineering hurdles to surmount. There are also difficult resource constraints.

Further reading:

--Alexis Madrigal has a fantastic post charting predictions about lab-grown meat that have been made over time. In general, forecasters have tended to underestimated the difficulty of producing the meat. "[T]he technology is advancing, but very slowly, and the commercialization horizon hasn't really gotten any closer over the last eight years. In fact, it may have receded."

--Agapakis has some more recent thoughts on the lab-grown meat tasting over at Scientific American. Key question: "Is controlling all the variables really possible when it comes to meat?"