How Methanol is Fueling a Food Revolution

A Google Earth image of fields and roads.

Of the worlds total land area about 36% is used for food production from plants or livestock[1]. Producing food from methanol has been suggested to be extremely land use efficient[2]. But what makes methanol special? There are two main aspects. First, methanol can be produced by combining water, electric power and a carbon source. Second, naturally occurring bacteria can use methanol as their primary food source. Here, I will first explain how to produce methanol and afterwards how to turn it into food by using microbes.

Methanol Production

The renewable way to produce methanol is to first take water (H2O) and split the oxygen off using a process called electrolysis. Electrolysis requires electric power, which can be provided by solar panels and wind turbines to stay renewable (or hydro or geothermal). Getting from lonely hydrogen atoms to methanol requires CO2 hydrogenation. Methanol is just CH3OH after all. In practice the reaction is CO2 + 3H2 → CH3OH + H2O. If the CO2 used in this process comes from the air, this process is carbon neutral. CO2 is taken out of the atmosphere to produce methanol and released back into the atmosphere when methanol is used. That is good because CO2 is a greenhouse gas that causes global warming and there is a large effort to develop carbon neutral processes. There are however caveats.

Demand for methanol (today almost entirely in the chemical industry) reached 85 million tons[3] and virtually all of it is produced from fossil gas and is thereby non-renewable. The non-renewable process causes global warming because it takes CO2 from fossil gas that would otherwise stay underground, turns it into methanol and then releases the CO2 to the atmosphere when the methanol is used. The non-renewable method is cheaper than the renewable method for now. The time point where that changes depends largely on the future fossil gas and CO2 price as well as the price of renewable power generation and electrolysis.

A complicating factor in the renewable process is that atmospheric concentrations of CO2 are relatively low, which means that to capture significant amounts requires additional energy (this the case for any kind of carbon air-capture process). Therefore, people have suggested that carbon for methanol production could be captured where it is emitted at high concentrations, such as coal- or gas-fired power plants. That would make renewable methanol production cheaper but it does not make the process carbon neutral, because underground carbon still ends up in the atmosphere. To be carbon neutral, it would need to be stored back underground after capture (carbon capture and storage, CCS) and not end up in methanol.

Because of its higher price, renewable methanol production is not commonplace yet but renewable production is projected to grow and become cheaper[4]. So let’s look at ways to turn methanol into food using bacteria.

From Methanol to Food

Bacteria are single-celled organisms that are all around us, inside us, and our food. They mostly use compounds with multiple carbon atoms (such as sugar) for food. Methylotrophs, however, can eat single carbon compounds like methanol. Some methylotrophs can grow with methanol as their sole carbon and energy source. One such bacterium is Methylobacterium extorquens and it occurs naturally in soil, air and water[5]. For bacteria to grow and multiply, they mainly need to incorporate the carbon from methanol into amino acids, which are the building blocks of proteins. Two more ingredients are required to build amino acids and bacterial cell walls: nitrogen and phosphor.

With that, bacteria have all the ingredients to grow. They can then be harvested and turned into protein rich products. Essentially, instead of growing and harvesting plants, this process grows and harvests bacteria. The end product is not too different from tofu, which is made from soy plants. Like plants, bacteria have been an integral part of food production for a long time, for example in cheese. But the process of harvesting bacteria is quite different from harvesting plants. It requires large bioreactors where bacteria have ideal biochemical conditions to grow.

This industrial process has many advantages over plant based agriculture. Not only does it have the potential to be carbon neutral, it is estimated to require far less land[3]. The amount of land required depends mainly on our ability to convert solar power into electricity something we have become extremely good at. In a renewable energy system, harvesting bacteria could be a food revolution.


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