**4. Summary and outlook**

The world faces serious challenges from climate change, growing population, and increasing industrialization. The demand for food skyrockets, as does the desire for energy and various products. The capacity of the world's oceans to supply fish and of the world's fields to provide feed and food is limited, and measures to boost productivity have partly been exhausted. Prominent footprint calculations show clearly that the rate with which resources are consumed surpasses the regeneration by a factor of more than 2. Earth exhaustion day is advancing from year to year.

It is well-understood that the current meat production is not sustainable. Cultured meat obviously still needs significant development time to become costcompetitive [177]. Aquaculture can provide fish to the world's plate despite overfishing, but it needs fodder, which today is often taken from oceans—fish meal and fish oil, or soy, which has its own sustainability issues. Plant-based protein for food is not necessarily sustainable either, considering the large land areas that are required, besides fertilizers, pesticides, etc.

There is an urgent need for large-scale and cheap protein sources that are independent of land use. This has re-sparked interest in microbial protein production, which does not need but very little land and water—feeding microbes sugar or starch virtually perverts any attempts for sustainability: Methane can be a very valid option here. Øverland et al. argued: *"In recent years, the increasing global demand for sustainable protein sources, independent of marine origin, agricultural land use, and climatic changes, has led to renewed attention on the potential of microbial protein for use in animal production. Focus has been on methane, the main component of natural gas, which is found widely in nature* [28] *as an attractive substrate for bacterial protein production. The abundant supply, cheap transportation, and reasonable cost of natural gas indicate that protein production from natural gas could be realistic on a large scale. Using methaneoxidising bacteria as an amino acid source in animal nutrition may* spare over-exploited sources of protein suitable for direct human consumption" [65].

Protein from natural gas might, in the unfortunate event of a global food catastrophe, be a vital protein source for several years. As Allfed states: *"Human civilization's food production system is unprepared for global catastrophic risks (GCRs). Catastrophes capable of abruptly transforming global climate, such as supervolcanic eruption, asteroid/comet impact, or nuclear winter, which could completely collapse the*

*Value-Added Products from Natural Gas Using Fermentation Processes: Products… DOI: http://dx.doi.org/10.5772/intechopen.104643*

*agricultural system. Responding by producing resilient foods requiring little to no sunlight is more cost-effective than increasing food stockpiles, given the long duration of these scenarios (6–10 years)"* [169]. The preliminary techno-economic analysis revealed that bacterial SCP can be ramped up fast for global food production when needed [169]. Also, bacterial SCP might play a pivotal role in the energy transition, by providing suitable storage capacity for excess renewable energy in a Power2protein setup [178].

We see strong market dynamics in natural gas fermentation these days. This can be inferred from trends in scientific publications, patent applications, and commercial activities, such as pilot or manufacturing plant establishments by several market incumbents. It can be expected that the interest in this set of technologies will be even more in the near and medium-term future, as the key enabling technology for scaling up bioplastics production, protein manufacturing, and chemicals synthesis in a sustainable way, decoupled from agricultural operations.
