Difference between revisions of "Electricity"
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Revision as of 13:10, 21 June 2022
Electricity is the general term used to describe a number of electrical phenomena, such as Electrical power, electrical current and electric potential. It is associated with magnetism. It plays an important part in almost every modern technology. Electrical power can be transmitted easily a distance via conductors, such as metallic cables. A settlement on Mars cannot be imagined without an electrical distribution system. An energy infrastructure and eventually power facilities will be required.
Contents
Primary Generation
Electrical power can be generated from a number of energy sources.
Electricity can be produced locally or centrally, or in a mixture of the two systems. Solar energy tends to be distributed, while nuclear energy tends to be centralized. Solar energy efficiency is independent of the size of the installation, and has lower losses when the user is close to the source. Nuclear energy efficiency depends on the temperature of the nuclear core and require minimum amounts of nuclear material to go critical and produce energy. Secondary systems for nuclear reactors, such as turbogenerators are more efficient when they are larger.
Solar energy
Photoelectricity is the direct conversion of photons to electricity. On Mars, this has already been used extensively for most of the solar probes and rovers. Photo electricity produces DC power. Power electronics can be used to convert to AC, if needed.
Nuclear energy
Nuclear reactions in nuclear materials produces heat, that can be converted into electricity either directly or using thermal processes and mechanical energy. Turbo-alternators in nuclear power stations produce AC power.
Thermoelectric generators
A thermoelectric generator produces electricity from differences in thermal energy between two or more areas.
Photovoltaics from very hot cores (fourth generation nuclear)
This is the same process as photo-electricity from the sun but gets its photons from a very hot nuclear reactor core that liberates most of its energy in the form of photons.
MHD generators
Magnetohydrodynamic generators use the passage of a hot conducting gas in a magnetic field to generate an electrical current. MHD generators are generally considered as a topping stage to conventional turbo-generators.
Turbo-generators
A combination of a turbine and a generator, usually an alternator, to produce electricity. The generator uses the interaction between magnetic fields and conductors to generate an electrical current. A Dynamo can be used as generator for DC current. However, this requires a mechanical commutator that is subject to wear. Most turbo-generators are turbo-alternators and produce AC power.
Piezoelectrics
Piezoelectricity is the generation of electricity as a direct result of mechanical deformation. They are generally very small systems, used in a large range of applications from speakers to sensors.
Secondary generation
Electrical energy can be converted into other form of energy for storage, or stored directly in magneto electrical fields in inductance and capacitance. See Energy storage. It can then be produced in a number of ways; electrochemically or mechanically.
Distribution and transportation
Electrical energy can be distributed using either Alternating Current (AC) or Direct Current (DC). On Earth AC current is used for most large scale systems, such as power grids and general electrical distribution. DC current has seen renewed use after the development of power electronics, that have led to the construction of DC power lines and DC converters for inter grid connections.
Electrical distribution on Earth makes extensive use of the concept of grounding, as the Earth is generally considered a good conductor due to the presence of water in the soil. On Mars, however, the soil conductance is not necessarily good and separated grounding systems may be required. To avoid uneven buildup of electrical charges, the buildings will probably need to be connected together by grounding wires. Some kind of grounding device might be required for astronauts after an EVA.
The Martian atmosphere is a poor insulator. Hi tension lines will not be possible in the same way as on Earth, and probably all power lines will be electrically insulated. This would add significantly to their cost, and probably again favor DC over AC for a Martian power grid.
Uses of Electricity
Electricity can be directly used to produce:
- Heat through electrical resistance of conductors.
- Light using a number of different system, from resistances to fluorescent tubes to LEDs.
- Motors and other electric actuators using electromagnetic fields.
- Electronic circuits, computers and the joys of civilization.
- Sensors and instruments.
- Hydrogen, oxygen, aluminium and many other metals and gases through electrolysis.
Significance for a Martian colony
Inevitabilities
For some settlement applications electricity cannot be avoided. This is true for radio link and night time lighting. Propellant production requires electrolysis, that is an electrical process. Electronics, and the corresponding knowledge and control systems, require electricity. A thermal nuclear society might be possible, but does not seem very robust in the long run. A passive thermal martian settlement may also be possible, but again will have difficulty in producing propellant, maintaining control systems and may have a very low productivity level that could compromise viability.
Alternatives
Electricity is an excellent energy distribution system. However, there are alternatives that can replace it in some situations.
- Rocket propulsion is best done using chemical energy, although electrical engines have some applications in space probes and future transportation systems.
- Energy storage using hydraulics or pneumatics may be more economical than electrochemical storage.
- Thermal conduction is more practical when the energy levels are low.
- Waste heat should be used whenever possible rather than using electricity directly for heating.
Some Mars settlement designs use artificial lighting for greenhouse operations. In such cases it can be said that all energy for the settlement is electrical in some sense, as the two main energy uses, propellant production and food production, are dependent on electrical energy.
Storage of electricity is a challenge. However, a martian settlement should grow at the same time as its energy storage systems grows.
