Made with some breadcrumbs (GMO no doubt), egg, and 20,000 lab-grown cow muscle cells, the world’s first lab-grown burger made its debut last year.

It was a proof of concept, evidence that you can make meat in lab. The technology is too difficult and expensive to show up grocery stores any time soon.

In the future, however, proponents hope so-called cultured meat will get cheaper. If it does, making beef from stem cells could be an environmentally friendly alternative to, you know, killing animals for food.

Raising cattle takes up a lot of arable land and water and creates greenhouse gas emissions. Engineers working on in vitro meat hope their creations will be less harmful on the environment. But will they ever get there?

One new paper, published yesterday in the journal Trends in Biotechnology, aimed to find out. It outlined a new method for growing ground beef in a lab, different from both the technique used in last year’s burger and the 3-D printing that other researchers have proposed. It also crunches some numbers on how much this animal-free beef would cost. Growing meat in lab is resource-intense and expensive, it turns out. One of the biggest costs? Feeding the little beasties.

Like the techniques that made last year’s burger, bioengineer Johannes Tramper’s proposed method starts with a small number of stem cells taken from an animal. After that, however, they go into a big, cylindrical bioreactor, like the ones used in the pharmaceutical industry today. In contrast, the burger was grown from small pieces in dishes in lab and made just a few burgers. So Tramper’s idea brings meat-growing to a bigger scale. So far, so good.

Trends in Biotechnology, van der Weele et al.

One bioreactor could make 25,600 kilograms (56,400 pounds) of meat a year, Tramper, a professor at Wageningen University in the Netherlands, calculates. His numbers take into account how big cells are, how fast cells reproduce, and how many batches a bioreactor processes in a year. Assuming a person eats 10 kilos of meat a year—enough for 968 burgers—one bioreactor could feed 2,560 people.

How much would it cost to grow a kilo of this stuff? About 391 euros ($534), Tramper calculates. That’s how much it takes to buy growth medium, the liquidy stuff that cells must grow on. After all, cells are living things. They have to eat, too. In fact, although one of the benefits of lab-grown meat is that it’s not supposed to harm any animals, for now, growth medium requires animal products to make.

Research could lower the cost of growth medium to 8 euros a kilo, or about $5 a pound, Tramper thinks. That’s still not competitive with cow-grown ground beef. Plus, it doesn’t take into account other costs of running a bioreactor, such as hiring three or four well-trained people.

“Competition with normal meat is still a challenge,” says Cor van der Weele, a Wageningen University bioethicist who worked with Tramper on the new paper. “We are not especially optimistic about that, in the short term.”

In the future, perhaps conventional meat will rise in price, van der Weele says. That will help close the gap between in vitro and in vivo.

Both van der Weele and Tramper think it’s important to study cultured meat to try to bring down its price, but that it’s not a guaranteed solution to the problems of world’s appetite for animals. “It’s not certain that this is going to succeed,” van der Weele says. “We do believe it is necessary to develop alternatives.”

“Cultured meat is one such alternative, but [so are] textured vegetable protein or even whole insects,” Tramper wrote to Popular Science in an email.

Beyond price, there’s one comparison many have missed, says a Texas-based science communicator who goes by the name Dr. Ricky. Dr. Ricky, who prefers to go by his pseudonym, has written and given public talks about the drawbacks of cultured meat. It’s not clear yet that cultured meat is—or will be—more environmentally friendly than meat cut from cows. Dr. Ricky doesn’t think it will be.

“We’re talking about feeding cells, running the bioreactor, sterilizing the area, the facilities we need to do all that,” he says. “This form of biology factory is hilariously inefficient, relative to the input.”

Without numbers like those Tramper calculated for the price of lab meat, Popular Science can’t say whether Dr. Ricky is right. While many scientists have calculated the environmental footprint of beef, no one has done that for stem cell burgers.

Updated May 22, 2014: Reader Jay pointed out there is at least one analysis of the environmental footprint of cultured meat. Know of any others? Let us know and we’ll write about farmed vs. cultured meat footprints soon.

Written by Francie Diep and published by Popular Science, May 21, 2014.

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