In order to maintain a Colony on Mars, we will need to be able to provide consistent, safe, and sustainable power on the planet. The extremely cold temperature means that the need to maintain temperature in the habitat will require consistent power generation. What are the viable options for a Martian colony to provide this power?
Many life support and mission design questions have answers depending on scale: how large is the colony?
So far viable solutions discussed in Mars mission papers revolve around two major sources of energy:
- solar (photoelectric panels ) and
- nuclear (meaning conventional fission reactors on Uranium-235, most likely highly enriched)
Until now, we have faced several challenges as far as photovoltaics are concerned:
- dust accumulation
- the need to rotate the panels to track the Sun and corresponding unreliability of any mechanisms with bearings in Martian environment (even with human maintenance)
- PV decay with time
- seasonal variations of PV output
- the need to store energy for consumption at night and the refreshing idea of having to add extra mass to the deliverable goods and to watch out for any problems (including thermal ones) with the batteries (although flywheels will become more efficient as the colony scales)
Nuclear reactors with Brayton cycle turbines do not obviate the need for energy storage, but they have problems of their own:
- cooling requires large radiators (since they are vertical, no need to worry about the dust)
- siting (behind berms and in craters) due to the need to shield the colony from neutron flux
- the choice between refuelling (for large and long-term colonies) and replacement
- nuclear waste (and reactor) disposal
However, there are two other possible solutions for sufficiently large colonies:
- solar thermal power plants
- orbital solar PV power plants which send the energy through microwaves (thus, one doesn't need to provide aeroshields and all the other dead mass needed for landing the plant) - a rather scalable solution, I'd gather.
- a colony/habitat will need power generation and storage, no matter what
- reliability means diversity: for sufficiently large habitats, one would like to have both a reactor and a solar panel field, flywheels and batteries
- resupplying the colony is a pain due to the need to pinpoint land the cargo, so any energy solutions that don't require landing are really welcome
In my humble opinion, having a nuclear reactor as the main source of energy, flywheels for energy storage, and panels and batteries for backup would provide a conservative starting point for future designs. However, calculations are needed to refine the designs and choose between competing solutions.
A suggestion discussed in "Self-sustaining Mars colonies utilizing the North Polar Cap and the Martian atmosphere." (Powell et al. 2001) is that the colony should be near the northern ice cap, utilising any water ice - separating it into hydrogen and oxygen for power generation. The article suggests that this process could be initiated using nuclear reactors.
From the linked Abstract:
The colonies would be located on the North Polar Cap of Mars and utilize readily available water ice and the CO2 Martian atmosphere as raw materials to produce all of the propellants, fuel, air, water, plastics, food, and other supplies needed by the colony. The colonists would live in thermally insulated large, comfortable habitats under the ice surface, fully shielded from cosmic rays. The habitats and supplies would be produced by a compact, lightweight (~4 metric tons) nuclear powered robotic unit termed ALPH (Atomic Liberation of Propellant and Habitat), which would land 2 years before the colonists arrived. Using a compact, lightweight 5 MW (th) nuclear reactor/steam turbine (1 MW(e)) power source and small process units (e.g., H2O electrolyzer, H2 and O2 liquefiers, methanator, plastic polymerizer, food producer, etc.) ALPH would stockpile many hundreds of tons of supplies in melt cavities under the ice, plus insulated habitats, to be in place and ready for use when the colonists landed.