Sunlight

Worms and bugs are a viable sources of protein and food energy, they do not provide a balanced nutritional profile for a human diet, this becomes critical when you consider that you may be stuck with that diet indefinitely if you do not provide for alternate means of food production. True, insect and worm cultivation can be done without benefit of light. The little critters will dutifully convert biomass to useable food. Remember, all biomass energy comes ultimately from photosynthesis. If you cannot achieve photosynthesis your biomass reserves will become depleted! A biosystem that does not have energy coming in from somewhere is not sustainable, this is just an application of the second law of thermodynamics.

Consider the scenario. There may be little or no useable sunlight for decades. You have a biomass reserve to feed your little food critters. This reserve becomes depleted. You must travel farther and farther to acquire additional biomass. The environment where you live may be extremely hostile (high winds, torrential rain, temperature extremes, toxic air, ground and water, etc.). You will have to expend ever more resources to acquire biomass since it is your basic energy source without photosynthesis. The point to my argument is that you cannot expect to sustain an existence on biomass reserves indefinitely, you must have a way to photosynthesize, and if you expect to have an indefinitely sustainable biosystem, your capacity to photosynthesize must at least equal to your food energy needs, but in practicality will have to be much greater.

The organisms largely responsible for driving our biosphere are algae. Algae convert light to food energy ten times more efficiently than any other plant, even so, in nature this efficiency is less than 1%. There is no life without the sun. To sustain life the sun must be replaced, temporarily.

Offered by Steve