Energy is a fundamental subject for Martian societies. It is not the most labor intensive sector, but certainly the one that attracts the most attention. Some essential points: civilizations on Earth developed from the exploitation of wood from forests, as fuel, but also as building material. It then moved on to the formidable fossil fuel reserves. The Earthlings have thus benefited from a colossal converter of solar energy, the Ecosystem, fruit of billions of years of evolution and stockpiling huge amounts of energy. However, on Mars, Civilization and a mature ecosystem can only emerge from a system of energy production ex nihilo.
Foundation was developed on the basis of a nuclear and solar energy mix. The low density of the atmosphere of Mars makes wind power uneconomical and no significant underground heat source has been found for geothermal energy to be developed on a City-State scale. Nuclear energy offers the possibility of a continuous supply of energy. The preferred technology is that of fast-neutron MSR (Molten Salt Reactor) with in-line fuel reprocessing. However, the absence of usable uranium deposits on Mars makes the planet dependent on natural uranium extracted from the oceans on Earth and imported at each synod. This departure from the rules of autonomy is made out of necessity, and has led to the creation of a strategic stockpile of ten years worth of nuclear fuel. Exploration continues in the hope of finding local uranium that could compete with solar energy.
Solar energy on Mars today ensures near complete independence from the Earth, but also between each location. The technology of inkjet printed perovskite photovoltaic cells dominates the field. They are installed in concentric strips approximately 5 m wide and up to several kilometers long, around central dedicated manufacturing plants. Specialized rovers print them, clean the surface of dust, move the strips when needed and recycle them if they are damaged.
Solar energy is sensitive to natural variations in sunshine: daily variations, seasonal variations (induced by the obliquity of the axis of rotation of Mars to which are added variations due to the ellipticity of the orbit of Mars, where the sunshine is more than 40% stronger at perihelion than at aphelion) and dust storms. These regularly plunge the settlement into the dark for long periods, with planet wide storms every six years and many smaller ones. Energy supply being the condition sine qua non of survival on Mars, these conditions make the management of energy stocks extremely strategic. To meet the challenge, Foundation uses three generic technologies: batteries for short-term storage, pumped storage hydroelectricity (PSH) for short and medium term storage when available, and a fleet of methanox thermal power plants for strategic ‘long-term’ storage.
The two main settlements observe the principles described above, but put into practice different energy mixes. Arkadia has a balanced energy mix of 45% nuclear and 55% solar (in energy produced), while the sunshine in Surya (combined with a fierce desire for independence) has enabled the implementation of a much higher fraction of solar. In addition, in Surya, a massive PSHstores energy (see bellow on this subject). The use of orbital mirrors has also increased the solar availability at Surya to near earth levels.
Energy consumption on Mars is 1600 GJ / year per person. This may seem huge versus 220 GJ / year per person in North America, or 120 GJ / year / person in Europe but it is, at least in part, an illusion: on Earth, a gigantic fraction of the required solar energy is hidden in agricultural production, which is not included in the balance sheets. On Mars, all the energy is counted and tabulated. Nothing is free.
Installed power
Arkadia Surya
Nuclear 17GW 8 GW
Solar 39 GW 53 GW
Batteries 2 GW 15 GW
Thermal (methane) 17 GW 15 GW
PSH 0 GW 5 GW
The city of Surya is located at the equator, in Nicholson crater. This crater offers elevation differences of over one thousand meters and has proven to be a prime location for the construction of a massive pumped storage hydroelectric(PSH) station of 5 GW and 200 GWh, partly dedicated to daily storage and partly to seasonal storage. The principle is as follows: Two lakes hold 300 million m3 of water each (4kmx3kmx25m and 3kmx2kmx50m). One is located at the bottom of the crater and the other in a natural hollow near the central summit. They are connected by pipes. To keep the water in a liquid state, the lakes are covered with hanging plastic sheets and maintained at a pressure of 0.1 bar. Thanks to the greenhouse effect and additional light provided by orbital mirrors, the temperature is kept above 5° Celsius. During the day, large fields of solar panels supply electrical energy to reversible turbines which bring the water up from the lower lake to the upper one. Depending on the needs, day and night, the water can run down the pipes and reverse the turbines, driving electrical generators.
Thanks to a maximum total flow of 2000 m3/s3and a cumulative elevation of more than 1000 meters, the electric power is potentially 5 GW (efficiency of 70%) and the storable energy is around 200 GWh.
Arkadia is surrounded by hundreds of square kilometers of strips of solar panels whose role is to provide local, abundant and cheap power. These are manufactured and maintained by autonomous factories which tirelessly roam the great expanses of Mars to extend the surface of energy collection. These robots are themselves manufactured in fully automated factories (which they call autofabs). I discover that Adhémar, for his part, works in one of the master factories that manufactures the components of these autofabs. After a 3-day petition and an expensive Hawaiian restaurant, Adhémar announces that he is taking me to see the solar panels. Joy!
Leaving early, he finishes his first rotation and picks me up around 11am at the “Domer” station. It's meal time and we'll start with the cafeteria. Like a foreigner recently arrived in Dodge city in the American Far West, I attract attention. I end up exchanging the usual banalities that bring strangers together. While we share a bowl of farmed salmon Poké, several workers ask me, in various ways, how I manage not be afraid, on Earth, without a protective enclosure above my head. I find that my answers remain unconvincing to them. Knowing me to be a journalist, Mayra, Adhémar's partner, pushes him to take me to see one of the roaming factories, something inaccessible for a lambda newcomer as it requires putting on a mechanical pressure suit. I struggle into the tight suit and we take off on a small wheeled vehicle. No walking this time! We three drive for many kilometers between the long strips, until we reach one of these famous roving factories. I feel very small at the foot of this huge quasi sentient machine, it’s bulk enhanced by an enormous roll of film which it carries on his back. A number of subunits wheel around, and the printheads slide back and forth over the strip. I contemplate the immense expanse of panels, while in the distance a wide rolling robot, rather like a linear irrigation machine, cleans the solar panels. Adhémar explains to me that this is how the inhabitants of Mars have managed to drastically reduce the price of energy, to the point that it is this same process, under Martian patent, which is currently implemented in some deserts on Earth. Confronted with this very real scene, an emotion overwhelms me without warning. I understand something essential here: What forests and fields do on Earth by converting sunlight into organic matter and multiplying by seeds is exactly what these replicating robots are doing on Mars: transforming rock into an environment favorable to the emergence of life. (From Lucie's notebook)
Orbital mirrors are used at Surya to increase average ground insolation. these convex mirrors are located in low Martian orbit, built from cheap local materials in the spirit of the Starlink communication constellations on Earth. Thousands of low flying mirrors in highly eccentric orbits focus light onto the Surya area, increasing the light levels to nearly those of the Earth. These light balloons, usually 150 m in diameter but just a few hundred kg in mass, are made of reflective Mylar sheets and provided with a minimum station keeping system. Their convex surface redirect solar illumination over a ground area five times larger than the mirror surface, and the rays from multiple mirrors create optimum growing conditions at very low cost. Martians SSTOs have found here a new market for their capabilities.
Geothermal energy is an option for Mars, but it is not obvious that it would succeed. Deep well geothermal might be required and this is notoriously expensive to realize. Geothermal energy is also very local, and in the project we simply excluded it from consideration. If nuclear power is very successful, other sources of energy might not develop. When the report was written it appeared that SpaceX was not trying to develop nuclear power sources but would use solar. If this remains true, then solar might become the main infrastructure on Mars using energy storage as backup. There may also be a role for wind power, that the report dismisses a bit quickly. A lot will depend on the mass required for wind turbines on Mars and the location of suitable windy areas.
Although thorium has been detected on Mars from orbit, the concentration is very low. Determining if usable concentrations are available awaits large scale geological exploration.
Marspedia references : Wind turbines - Solar power -Nuclear power - Geothermal energy
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