The world's first lab grown hamburger has been create and eaten. It has received support from PETA and many in the sustainable-food movement (including some vegetarians). Amongst the unsupported claims are that lab grown meat has a much smaller environmental footprint than animal-grown meat, and that lab grown meat does not depend on cruelty to animals.
To examine the ecological and animal-ethics issues around lab grown meat we have to look at the full supply chain. Sure growing meat in a dish looks on the surface to require less land, and be more energy efficient; but really the costs are just better hidden earlier on in the process. Because you can't just take a bunch of cells off an animal (cow in this case) and put them in a plastic dish and expect them to grow.
If you stop and think for a second you'll realize that in order to grow cells need food. Mammalian cells also need to be held at a temperature close to the body-temperature of the animal they came from. They need water. They need to be protected from infections and parasites.
When the cells were in the cow, the cow was able to supply all these needs itself. The cow's immune system took care of infections, the cow's digestive system turned grass or other vegetation into the right kind of food for cells, the cow's circulatory system transported the cell-food and oxygen to the cells and took away the waste. When you remove cells from the cow and put them in the dish you have to take over these functions as well.
To compensate for the immune system you have to keep the area you store the cells and everything that comes in contact with the the cells as clean and sterile as possible and even then you have to put antibiotics on the cells because some bacteria always get through (its also not unusual to have to throw away a bunch of lab-grown cells because they were contaminated with a virus or other parasite). To compensate for the cow's digestive system you have to supply
specially formulated "media" (either liquid or jelly-like) with
precisely the right balance of already digested food molecules for the
type of cells you are growing. So far we don't have a good way to compensate for a circulatory system so instead you can only grown small amounts of cells at a time in separate containers so all the cells have contact with the air as well as change the media periodically.
To top it all off, unless you genetically modify the cells to be "immortal" (aka turn them into cancerous cells) the cells will only grow a little bit before getting stuck, requiring you to go get a new sample from the animal and start the process over (again introducing more risk of contamination).
The Environment & Problems with Media
Leaving aside the other issues for a moment, let's focus on just what is media? and why it means it lab grown meat is environmentally unsound. For those who are interested more information is available here.
Media is a mixture of amino acids, salts, refined pre-digested sugars, vitamins, proteins, hormones, water and antibiotics. Most of this stuff is providing nutrition for the cells as well and creating a hospitable environment similar to the being inside the original animal. Proteins and hormones are necessary to signal to the cells to grow and/or differentiate into the desired cell type (in this case muscle cells). Since it is such a complicated mixture the most common standard media contains 10% animal serum (ideally fetal bovine serum but can include a mix of others) which already contains most of the necessary components as well as extra stuff which makes the culture less sensitive to any change. Serum is what is left over after you take out all the blood cells and clotting factors from blood, and is currently relatively cheap and plentiful since it is a by-product of the meat industry. But this means that even if all meat was replaced with lab-grown meat there would still be a need to raise large numbers of livestock (cows) in order to supply the serum to make the media to grow the cells. So minimal environmental benefit over just eating the cows directly.
If you then consider the energy required to harvest and purify the serum, plus the energy to incubate the cells at cow-body temperature in all likelihood lab-grown meat will be worse for the environment than animal-grown meat.
Although, there is another option it is not as good a serum-containing media but several serum-free medias have been developed. But before you all start jumping for joy, I will point out that there is still no such thing as a free lunch. The proteins and vitamins and hormones and the other 20+ chemicals in serum-free media still have to be produced and refined. A minority can be chemically synthesized chemically from oil-derived products, but most would have to be purified individually from some living system (eg. hormones can be produced in genetically modified microbes - which themselves require a more simple media to grow -, vitamins and amino acids can be purified from plant matter, salts can be mined and refined, etc...). I find it hard to believe (and the price tag would suggest I'm right) that the farmland & energy required to produce the raw materials to make the media required to feed the cells to produce a kilo of meat will ever be less than the farmland required to feed the cows to make the equivalent amount of meat.
Cell Culture and Animal Cruelty
Serum-based media usually involves killing the animal before harvesting the serum. Harvesting serum without killing the animal is pretty ethically dubious as it would involve regularly removing as much blood as safe from the animal which is almost certainly going to be stressful for the animal.
In addition, even with serum-free media cells would have to be frequently extracted from a donor animal to provide the initial cells to grow due to the natural growth limits on cells - and the potential health & safety issues (as well as ick factor) in selling immortalized cells for human consumption. Since we are growing muscle cells it is likely this would involve frequent muscle biopsies which are not painless procedures. To minimize environmental impacts the number of donor animals would have to be kept to a minimum which means many many biopsies per animal.
To top it all off, to hold cells in place while they are growing, often the plates are coated in collagen (connector tissue) extracted from some mammal (currently usually the tails of rats since they are often handy in science labs) so there is no guarantee this lab-grown meat would be death-free.
To summarize large scale production of lab grown meat is unlikely to be better for the environment than animal-grown meat and would not be an improvement when it comes to animal cruelty. Plus since it must be grown in a sterile environment without exposure to the full complement of proteins and chemicals in a living animal it will never taste the same as animal grown meat. So I have no intention of ever eating it. (OTOH grasshoppers or insects I'd be willing to try).
