Most energy efficient food production for sustainable human life support

Question

Say you want to build a base at a place where conventional food deliveries from Earth would be very expensive. What will be the most energy-efficient food production process that could feed humans, both at the beginning of the mission and in the long term (years)? Will people grow calory-rich plant(s) first and try to transition to a more complicated ecosystem later as that may have better energy efficiency due to more sophisticated biological cycles (plants, insects, waste recycling, etc.)? Will the more complex ecosystems better use the nutrients and also provide a more diverse range of foods to humans? Or, will it be easier to "brute force" the food production with enough power (solar, etc.) as I don't expect that creating a stable ecosystem will be simple?

There is a very interesting question on the possible power requirements for food production where answers deal with corn but I actually would not expect corn to have a high "input energy"/"produced calories" ratio since the higher plants may be less efficient (at least in oxygen production).

Answer 1

To answer this question, we first need to consider what is needed to sustain people in space. If we assume that we can't limit our crew to keto eaters, then (according to a presentation by Bryce Meyer given in the Space Settlement session of the International Space Development Conference in 2023) some examples of ideal foods for space travel will include:

• Bell peppers
• Rice
• Vegan, min processing (e.g. roasting peanuts, etc.)
• Vegan, heavy processing but no peanuts (e.g. includes fermentation)
• Vegan, processed foods and peanuts
• Seafood proteins (kosher, non-kosher, etc.)
• Insect proteins
• Birds (kosher, non-kosher, etc.)
• Rabbits

These plants and animals reproduce quickly, which is good for efficiency. On the other hand, almonds, cashews, pecans, and larger livestock do not reproduce as quickly, and are therefore examples of foods that would be inefficient - at least in the short term.

Plants in space provide not only food, but also oxygen generation, carbon dioxide removal, and support mental health. Duckweed, for example, can even be used for purifying water. When determining efficiency, it's advisable to consider all of the ways plants are beneficial when selecting the right mix of flora for a base. Multi-purpose plants may be more efficient overall than plants that are very good at doing just one thing.

The resiliency of your ecosystem is also important. For example, algae are size-efficient due to doubling time and photobioreactor size; however, the tank may be more susceptible to failure than a robust plant-based crop. (Note: This scenario was used as a plot device in the 2021 Movie Stowaway.)

On Mars, it may be more efficient to grow plants in lava tubes under artificial lighting than to use greenhouses, even after the cost and efficiencies of solar panels and LEDs are factored in. But, in space, crop selections may be influenced by the plant's susceptibility to oxidative stress induced by space radiation (Oxidative stress is defined as excess production of reactive oxygen species (ROS) relative to antioxidant defense.)

There are lots of factors that go into engineering a biosphere and there is lots of active research in this exciting field. Many researchers have theories on what the best solutions might be, and several experiments are underway at universities, such as the University of Arizona, to try to verify these theories. There are even some startups, such as InterstellarLab, that are attempting to commercialize solutions to these kinds of problems.

(Note: The author is not affiliated with UofA or InterstellarLab.)

Answer 2

Human nutrition is a very complex subject And the dynamics of food production on Mars will take decades to be developed and optimized. So it is not possible to do anything other than provide a few pointers. Being calorie rich is just a small part of ensuring human health. Many minerals and vitamins are needed as well as proteins that include all required amino acids and fat including the essential fatty acids.

Food production won’t be the primary issue at least initially. First will be the politics around thousands of good well paid technical jobs, votes and monetary costs here on Earth. After that assuming there is the political will the next two things would be power (nuclear and solar) and a reliable ground proven water source capable of providing thousands of tonnes of water / year for an extended period.

After all of that yes food production from local resources would become a priority and there would probably be a range of technology demonstration units followed by small scale vegetable and perhaps grain production. But initial production would be unlikely to meet all of the crews needs. So the initial set up can’t be fully closed (excess wastes).

Over time (probably decades) more systems and modules would be introduced to help reduce the reliance on imports. Perhaps live fish might be included and insects as well as fermented products and more.

Ultimately the types of plants used would depend on experiments on Mars and what works best. In the more distant future there might be attempts to introduce a full ecosystem and integrate food production with air purification and water recycling, but I predict it will take a very long time to optimize.

Final thoughts the speed of development in food production on Mars would depend on how successful it was, on what emphasis was placed on reducing costs and what emphasis was placed on growing the size of the base v making the existing base more self sufficient. Food of some sort (chocolate etc) will probably continue to be sent from Earth almost indefinitely.

Answer 3

Highly efficient food production can be unsafe and subject to blight and crop failiure, mixed crops complement each other for maximized resource use and protect each other and provide more food security. Hydroponics is pretty efficient for some crops but it not a source of very good food. If you want to efficiently produce bad food then you can just use chemistry to produce protein, carbs, sugars, even lab meat.

Fish and vegetation are a good known closed biomes to cultivate food, so you can use the fish and water to produce nitrogen and to filter the toxins through microbial maps inside aquaculture, also growing plants in the water.

The bigger a biological system, the more resilient it is to changes in temperature and microbial blooms and other changes.

The best way to keep everything contained on another planet is to dig big tunnels in impermeable rock and guarantee it is impermeable, use it as a large filtration lake for whatever agriculture you would want to do.

As technology advances very sophisticated microbiology and macro ecology strategies can be devised, food production remains the biggest barrier to extended terraforming.

As the rover has proven, it's easier to send an army of robots to do all kinds of things on far away planets because they survive for years in ambient conditions.

For robots are necessary to do nearly everything that a human could do on another planet, efficiently, including digging giant tunnels that humans could live in later, and fabricating buildings.