Aug 02 2021

Farming Microbes

In 1968 Paul Ehrlich wrote the controversial book, The Population Bomb, in which he argued that we had lost to battle to feed the world and would soon face massive starvation. He also argued that overpopulation was the number one threat to the environment. In a 2018 review, Smithsonian Magazine argues that Ehrlich’s book, in addition to being clearly wrong in its predictions, had a large effect on the environmental movement itself, moving it toward believing that overpopulation was their most urgent issue. This in turn also lead to a host of repressive and abusive policies around the world, especially toward women.

Even today, whenever I blog about related issues such as organic farming, it is common for someone in the comments to essentially argue that we need to allow millions or billions of people to starve to death in order to control population, which is the single most important thing. The “overpopulation purists” are following in Ehrlich’s legacy.

Ehrlich, however, was completely wrong in his predictions because he missed the green revolution, the remarkable ability for technology to be leveraged to increase the productivity of an acre of farmland several fold. We are now facing a similar situation, with scientists warning that the world population will likely increase to about 10 billion people by sometime around 2050. Yet, we are already exploiting most of the available arable land, so simply expanding farmland is not a great option. Any further expansion will extend into progressively less productive land, or into forests or occupied land. Further, land use is the greatest impact that farming, and in fact humans, have on the environment. If anything we should be looking for ways to return land to a natural ecosystem, in order to minimize extinctions due to loss of habitat.

Just because I disagree strongly with the overall position of the overpopulation purists, that doesn’t mean they don’t have somewhat of a point. It is probably a good idea to stabilize the human population on the Earth at some point. Fortunately, we know from experience how to do this – when we lift people out of crushing poverty and grant basic rights to women, then populations stabilize (without having to starve anyone). These are things we should be doing anyway, and we have an extra incentive to do so.

But in the meantime, we do have the challenge of feeding as many people as possible with the smallest footprint, both carbon footprint and land use and overall environmental impact. There are multiple methods we can use to accomplish this. One is leveraging GMOs, which have the potential of increasing productivity and minimizing inputs. A second I wrote about recently – hydroponics. Vertical hydroponic farming can potentially increase the productivity of land by hundreds of time, while reducing the use of fresh water to a pittance, and minimizing things like fertilizer runoff. Further, you can build a hydroponic farm almost anywhere, so you don’t have to use up valuable arable land.

There is yet another way to significantly increase food production – farming microbes. I a new study published in PNAS, scientists model (based upon published basic science) a system for growing microbes as a source of protein and other nutrients. They write:

Here, we analyze the efficiency associated with using solar energy for converting atmospheric CO2 derived from direct air capture into microbial biomass that can feed humans and animals. We show that the production of microbial foods outperforms agricultural cultivation of staple crops in terms of caloric and protein yields per land area at all relevant solar irradiance levels.

The system would use solar photovoltaics for power in order to grow microbes, like bacteria, in vats. Proteins can then be harvested from the microbes and dried. The dried protein can then be converted directly into food for humans or be used as feed for animals. This system would have many of the same advantages as hydroponic farming. The most important number is perhaps this – their simulation estimates that such a system could produce ten times the protein per unit of land, and at least twice the caloric output, as even the most efficient crop, soybean. Further, this would be a closed system, with minimal impact on the environment. And, such microbe farms could be built anywhere, even in the desert. This does not mean zero environmental impact – any land use by humans will displace natural ecosystems. But with a tenfold increase in protein output per unit of land, and the ability to choose locations which will maximize productivity while minimizing environmental effects, this is a dramatic improvement over traditional farming.

With such an increase in output, it would actually make sense to use the product as animal feed. This would at least partly erase the land-use disadvantage of raising animals for food, vs just growing crops, while maintaining the advantages of animal use. Animal protein is higher quality than plant-based protein, and including meat in a diet can be important to overall nutrition and is essential in some parts of the world. Further, about half the crops in the world are fertilized with manure. Where do you think all that manure comes from? This way the nitrogen in that manure which eventually feeds crops would be ultimately sourced from growing microbes in vats using solar power. Further analysis will be necessary to see, from a systems approach, the relative efficiency of using microbial protein directly as food vs as animal feed.

One important caveat, their study reports:

Our model includes photovoltaic electricity generation, direct air capture of carbon dioxide, electrosynthesis of an electron donor and/or carbon source for microbial growth (hydrogen, formate, or methanol),

Using methanol is obviously suboptimal. Most methanol is currently made from natural gas. Formate is made from CO2 and H2. Hydrogen is currently mostly produced from fossil fuels. Scaling up this system, therefore, without being dependent on inputs from fossil fuels probably requires a method for sustainably producing large amounts of hydrogen. Of course, the ability to do so would have lots of uses, and this could be one more. This is also an area of active research.

We also still need to actually build such a facility and make sure that it works. But the recent study does make it sound plausible, at least enough to justify building a test farm as proof of concept. It’s too soon to predict how much of an impact this exact method will have in 10-20 years. The same is true of hydroponics. Perhaps we will dramatically increase microfarming of insects for food. The bigger point is that we should not make the same mistake that Ehrlich made, underestimating the potential for scientific advancement to change the game. This won’t happen automatically, we likely have to focus our research and resources on the specific problem (unless we just get really lucky, but we shouldn’t count on that). But these are examples of potential ways for humans to increase our food production many fold, even beyond the significant increase we have already produced.

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