Difference between revisions of "Power for Settlements"

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==Power for Lunar Settlements==
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Here are some considerations for the power systems used in our lunar settlement stories.
 
Here are some considerations for the power systems used in our lunar settlement stories.
  
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The first small scale bases on the Moon will either use solar power or nuclear power (or both).  
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The first small scale bases on the Moon will either use [[Solar Power]] or [[Nuclear Power]] (or both).  
  
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===Solar Power===
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==Solar Power==
  
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An attractive source for power on the Moon is the Sun.  Solar is particularly inviting in the polar regions where mountain tops are available that have solar views 75% to 99% of the time. The sun light is not diminished by an atmosphere and is never blocked by clouds.  It is harsh and unrelenting.
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This topic is discussed in detail on the [[Solar Power]] page.
  
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From the surface of the Moon, the Sun appears to move slowly across the sky making a full cycle every 29 days.  On rare occasions it is eclipsed by the Earth for a few minutes.
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==Dumping Heat==
  
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At the poles, the Sun simply circles the sky very near the horizon.  At its lowest point it may be blocked by mountain tops.  Other times it may be blocked by local instillations such as other power collectors.
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One of the hardest things to do on the Moon is to get rid of large amounts of waste heat.  In any power generation system you must have both a source power and a sink for waste heat.  This is basic thermodynamics and there is no way out of this requirement. 
 +
Most space missions simply dump waste heat to deep space.  On the surface of the Moon, this is not so simple.  Half of your view is exposed to the cold of deep space, with
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the other half occupied by the Moon itself which is radiating at a moderately high temperature during the daytime.
  
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Near the lunar equator, the Sun is visible only one half the time.  The 14 day lunar nights are a major problem for power generation and are a major factor in setting a polar location for the first lunar settlement.
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As per spacecraft, shades will be needed to prevent the exposure to the hot spot Sun and a warm spot Earth.
  
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There are basically two types of solar power, [[Solar Dynamic]] (SD) and [[Photovoltaic]] (PV).
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At the pole the average lunar surface temperature will be around 0 C and does not change drastically during the day.  Here simple heat radiators can be used as they only need to avoid exposure to a slow moving Sun.
  
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SD uses a heat cycle to drive a piston or a turbine which connects to a generator or dynamo.   Two popular cycles for Solar Dynamic are [[Brayton Cycle]] or [[Stirling Cycle]].    Solar Dynamic systems employ a large reflector to focus sunlight to a high concentration to achieve a high temperature for the heat cycle to operate at highest possible efficiency.
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At the equator there is a completely different story.  The surface of the Moon rises to about 200 C by mid lunar day. It will be very difficult to dump waste heat at this time, so it will be difficult to keep the living areas cool and do major industrial operations.  Equatorial housing may need to be buried extra deep for thermal reasons.
  
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PV uses semiconductors (e.g. Silicon or Gallium Arsenide) to directly convert sunlight photons into electric potential.  Commonly know as “Solar cells”
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==Power Storage==
  
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====Comparison of PV versus SD====
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===Flywheels===
  
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=====PV Problems=====
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See [[Flywheel]].
  
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The main problem with solar power is that PV conversion efficiency is only about 20% efficient, for rather high priced PV cells. Plus PV cells are rather heavy to ship from Earth and to soft land on Luna is very expensive.
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===Big Battery Power===
  
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=====SD Problems=====
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Batteries are used for power storage, they are  not  a primary source of power.
  
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SD has a much more severe pointing requirement than PV because it needs to maintain an accurate optical focus.
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There are at least three separate technologies promising a times-ten improvement in rechargeable batteries currently demonstrated in the laboratory.  They are all based on some version of the super capacitor.  The value of such a battery for electric cars on Earth alone will be in the hundreds of billions.  The only problem is developing mass production techniques.  The race is on.
  
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If a PV array drifts off a few degrees, the power level drops a few percent.
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By the time of our stories, it is reasonable to expect really good batteries will be available for use in space.  These will give a lunar rover a range of at least 500 kilometers.  They will also be able to power reasonable amounts of electronics and modest life support equipment through a 14 Earth day lunar night.  They will not allow large industrial operations for this length of time.
  
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If a SD array drifts off a few degrees, the power level drops off to zero.
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More convential batteries that can use local materials are iron/air, aluminum/air and iron salts and water. The first two need little imports the last needs more but the bulk is local.
  
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====Space Based Solar power====
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[https://www.researchgate.net/figure/Discharge-curves-of-ALFA-cell-a-Normal-type-Aluminium-air-battery-b-ALFA-cell-c-1_fig2_264858519 AL O]
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[https://en.wikipedia.org/wiki/Aluminium–air_battery AL O]
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[https://formenergy.com/technology/ FE O]
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[https://essinc.com FE Salt]
  
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Until [[ISRU]] manufacturing is online, [[Solar Power Satellites]] (SPS) represent a more economic means of supplying large scale basebar power on the Moon in the early days.
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===Solar Thermal===
  
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Compared to PV or SD systems, an SPS rectenna by itself is lightweight and has a conversion efficiency of over 90%.
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Heat energy collected from the Sun could be stored via molten salts in insulated containers and made available throughout the Lunar night. Salts in a molten state holds tremendous amount of energy which could be converted to both mechanical and electrical power through the use of a steam turbine or Stirling cycle engine.
  
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Let us assume a PV array is 10 times heavier per watt than a rectenna.
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Reflectors, salts and insulating containers could all be fabricated from materials on Luna, requiring little or no supplies to be shipped from Earth.  
  
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That means we can get 5*10 = 50 times as much power per kilogram for a rectenna than for a PV array. That means a rectenna will be at least 50 times cheaper per watt of useful power than PV array. "At least" because the manufacturing cost of a rectenna will be much cheaper than for PV array.
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==Nuclear Power==
  
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Soft landing hardware on to the Moon is very expensive, so weight is at a premium.
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Two common type of nuclear power, [[Nuclear Fission|nuclear fission]] reactors, or [[RTG]]s.
  
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The distance from L1 to Luna is about the same as the distance from Earth to a geostationary satellite.
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During early stages of lunar exploration, some instruments can be powered by [[Radioisotope Thermal Generators]] ([[RTG]]).  The [[radioisotopes]] needed to make them are manufactured at only a few places on Earth and only in small amounts.
  
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So one could put an SPS at lunar-L1 and beam microwaves from there to supply one or more rectennas on the Moon as a very efficient way to provide energy to a power hungry moon base.
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In the longer term it may be useful to establish small [[Nuclear Power|nuclear power]] stations on the Moon, particularly in non-polar locations.  These will mainly provide power during the long [[lunar night]].  Their daylight operation will be limited by their ability to dump [[Lunar Radiator|waste heat]].  They will be expensive to build.    [[Solar Power Satellites|SPS]] [[rectennas]] would probably be cheaper for larger power requirements.
  
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The sun angle across PV arrays on the lunar surface constantly changes, and is usually less than the 1,360 w/m^2. To maintain constant max power the PV array must have
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There has been a suggestion that Low Energy Nuclear Reactions [http://futureinnovation.larc.nasa.gov/view/articles/futurism/bushnell/low-energy-nuclear-reactions.html LENR] could be a solution to energy problems on the moon and on Earth.  If this technology develops confirmed positive results, use on the moon would be enhanced if the necessary elements are found to be common in regolith.
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expensive and heavy steering equipment.  Whereas a rectenna does not need to be steered, and always gets maximum power.
 
  
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The ideal site for the lunar rectenna would be in [[Sinus Medii]] at the Lunar 0-Longitude point on the Lunar Equator, in the middle of the side which faces the Earth.
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==Story Power==
  
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1) Because it is directly below the L-1 point,
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In our stories, solar will be the major power source.  RTGs can be used for small science stations.  Big batteries may be used for electronics and life support.
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2) it is the closest point on the lunar surface to the L-1 point,
 
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3) Because at that point the lunar surface is at right angles to
 
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the incoming microwave beam.
 
  
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All these factors permit the smallest rectenna at that location.
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Stories set some what farther in the future, may have nuclear power stations.  It is reasonable to assume that if Helium 3 from the Moon is an important element of Earth side power generation, then small safe lunar nuclear power plants are a likely possibility.
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Without making any modifications at all to that very SPS, it could easily be maneuvered from L1 to GEO to feed a terrestrial ground based rectenna. The antenna design for L-1 to Luna will work equally well from GEO to Earth
 
−
 
 
−
 
 
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===Dumping Heat===
 
−
 
 
−
One of the hardest things to do on the Moon is get rid of large amounts of waste heat.  In any power generation system you must have both a source power and a sink for waste heat.  This is basic thermodynamics and there is no way out of this requirement.
 
−
Most space missions simply dump waste heat to deep space.  On the surface of the Moon, this is not so simple.  Half of your view is exposed to the cold of deep space, with the complication of a hot spot Sun and a warm spot Earth.  The other have of your views sees the surface of the Moon itself.  At the pole the average lunar surface temperature will be around 0 C and does not change drastically during the day.  Here simple hear radiators can be used as they only need to avoid exposure to a slow moving Sun.
 
−
 
 
−
At the equator there is a completely different story.  The surface of the Moon raises to about 200 C by mid lunar day.  It will be very difficult to dump waste heat at this time, so it will be difficult to keep the living areas cool and do major industrial operations.  Equatorial housing may need to be buried extra deep for thermal reasons.
 
−
 
 
−
 
 
−
===Big Battery Power===
 
−
 
 
−
There are at least three separate technologies promising a times-ten improvement in rechargeable batteries currently demonstrated in the laboratory.  They are all based on some version of the super capacitor.  The value of such a battery for electric cars on Earth alone will be in the hundreds of billions.  The only problem is developing mass production techniques.  The race is on.
 
−
 
 
−
By the time of our stories, it is reasonable to expect really good batteries will be available for use in space.  These will give a lunar rover a range of at least 500 kilometers.  They will also be able to power reasonable amounts of electronics and modest life support equipment through a 14 Earth day lunar night.  They will not allow large industrial operations for this length of time.
 
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−
 
 
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===Nuclear Power===
 
−
 
 
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During early stages of lunar exploration, some instruments can be powered by Radioisotope Power Generators (RPG).  These devices provide only about 100 watts and are difficult to come by.  The short lived radioisotopes needed to make them are manufactured at only a few places on Earth and only in small amounts.
 
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In the long term it may be necessary to establish small nuclear power stations on the Moon, particularly in non-polar locations.  These will mainly provide power during the long lunar night.  Their daylight operation will be limited by their ability to dump waste heat.  They will be expensive to build and difficult to maintain.
 
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−
 
 
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===Story Power===
 
  
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In our stories, solar will be the major power source.  RPGs can be used for small science stations.  Big batteries may be used for electronics and life support.
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==External Links==
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*[http://climateprogress.org/2009/04/23/arizona-csp-solar-thermal-storage/ Solar Thermal Energy Storage]
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Stories set some what farther in the future, may have nuclear power stations.  It is reasonable to assume that if Helium 3 from the Moon is an important element of Earth side power generation, then small safe lunar nuclear power plants are a likely possibility.
 
  
 
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[[Category:Stories]]
 
[[Category:Stories]]
 
[[Category:Architecture]]
 
[[Category:Architecture]]
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[[Category:Life Support (Power Supply)]]
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[[Category:Power Supply]]

Latest revision as of 00:30, 11 June 2022

It is requested that a fork of this article be installed to Scientifiction.org.



Here are some considerations for the power systems used in our lunar settlement stories.

The first small scale bases on the Moon will either use Solar Power or Nuclear Power (or both).

Solar Power

This topic is discussed in detail on the Solar Power page.

Dumping Heat

One of the hardest things to do on the Moon is to get rid of large amounts of waste heat. In any power generation system you must have both a source power and a sink for waste heat. This is basic thermodynamics and there is no way out of this requirement. Most space missions simply dump waste heat to deep space. On the surface of the Moon, this is not so simple. Half of your view is exposed to the cold of deep space, with the other half occupied by the Moon itself which is radiating at a moderately high temperature during the daytime.

As per spacecraft, shades will be needed to prevent the exposure to the hot spot Sun and a warm spot Earth.

At the pole the average lunar surface temperature will be around 0 C and does not change drastically during the day. Here simple heat radiators can be used as they only need to avoid exposure to a slow moving Sun.

At the equator there is a completely different story. The surface of the Moon rises to about 200 C by mid lunar day. It will be very difficult to dump waste heat at this time, so it will be difficult to keep the living areas cool and do major industrial operations. Equatorial housing may need to be buried extra deep for thermal reasons.

Power Storage

Flywheels

See Flywheel.

Big Battery Power

Batteries are used for power storage, they are not a primary source of power.

There are at least three separate technologies promising a times-ten improvement in rechargeable batteries currently demonstrated in the laboratory. They are all based on some version of the super capacitor. The value of such a battery for electric cars on Earth alone will be in the hundreds of billions. The only problem is developing mass production techniques. The race is on.

By the time of our stories, it is reasonable to expect really good batteries will be available for use in space. These will give a lunar rover a range of at least 500 kilometers. They will also be able to power reasonable amounts of electronics and modest life support equipment through a 14 Earth day lunar night. They will not allow large industrial operations for this length of time.

More convential batteries that can use local materials are iron/air, aluminum/air and iron salts and water. The first two need little imports the last needs more but the bulk is local. 

AL O
AL O
FE O
FE Salt

Solar Thermal

Heat energy collected from the Sun could be stored via molten salts in insulated containers and made available throughout the Lunar night. Salts in a molten state holds tremendous amount of energy which could be converted to both mechanical and electrical power through the use of a steam turbine or Stirling cycle engine.

Reflectors, salts and insulating containers could all be fabricated from materials on Luna, requiring little or no supplies to be shipped from Earth.

Nuclear Power

Two common type of nuclear power, nuclear fission reactors, or RTGs.

During early stages of lunar exploration, some instruments can be powered by Radioisotope Thermal Generators (RTG). The radioisotopes needed to make them are manufactured at only a few places on Earth and only in small amounts.

In the longer term it may be useful to establish small nuclear power stations on the Moon, particularly in non-polar locations. These will mainly provide power during the long lunar night. Their daylight operation will be limited by their ability to dump waste heat. They will be expensive to build. SPS rectennas would probably be cheaper for larger power requirements.

There has been a suggestion that Low Energy Nuclear Reactions LENR could be a solution to energy problems on the moon and on Earth. If this technology develops confirmed positive results, use on the moon would be enhanced if the necessary elements are found to be common in regolith.

Story Power

In our stories, solar will be the major power source. RTGs can be used for small science stations. Big batteries may be used for electronics and life support.

Stories set some what farther in the future, may have nuclear power stations. It is reasonable to assume that if Helium 3 from the Moon is an important element of Earth side power generation, then small safe lunar nuclear power plants are a likely possibility.

External Links

Retrieved from "https://lunarpedia.org/index.php?title=Power_for_Settlements&oldid=116761"