Energy storage

The availability of energy is one of the vital requirements for a settlement on Mars. Solar power and wind turbines are subject to changing weather conditions, especially during the Martian night, which makes energy storage necessary.

Nuclear power has been considered as the preferred energy source for most plans for medium- to long-term human expeditions to Mars. However, this is scarcely an option for an autonomous colony due to the vast effort of the nuclear enrichment process.

Compressed-air

Compressed-air storage is a recently upcoming technology to store large amounts of energy. Natural Martian caves can be used as a pressure accumulator.

Chemical

Flow battery

Electrical energy can be stored in a flow battery. The capacity depends on the size of the tanks and can be easily extended.

Nickel–iron battery

While the nickel–iron battery is rather heavy, it is very robust and durable, making it a good candidate for a stationary energy storage in a Martian settlement. It does not require poisonous substances.

Hydrocarbon fuel

Hydrocarbons have an inherent amount of energy, which can be used as stored energy. Excess electric energy can be used to produce hydrocarbons out of carbon dioxide and water. The hydrocarbons can be stored in large tanks. In periods of energy deficiency the hydrocarbons can be oxidized to produce heat (heating station) or electricity (fuel cell), with carbon dioxide and water as reaction products.

Some companies have already developed the technology to store excess electricity in methane.

Management of production processes

Another way to store excess energy is a sophisticated management of production processes. Energy consuming production processes can be carried out during periods of available energy (e.g. daylight), such as the production of liquid hydrocarbons out of atmospheric carbon dioxide. At night the exothermic production processes are carried out, such as some recycling processes.

Heat

A substantial amount of energy is required for heating the settlement buildings and greenhouses. Materials with a high heat capacity inside of buildings, combined with an excellent insulation on the outside, help to keep the inside warm during the night.

Scorching heat can be stored in a big block of concrete, which is used to turn water to steam. The steam powers a turbine and finally produces electricity. The concrete block has a big heat capacity and can store the heat for many hours.

Other

Most conventional schemes (e.g. batteries and flywheels) are practical on a small scale, but do not scale up very easily.