Lightning rod

Lightning rod

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Recipe
5 + 12 + 8 + 4 → 1
Total raw
8 + 6 + 8 + 4
Map color
Health	100 130 160 190 250
Resistances	Electric: 0/100% Fire: 0/90%
Stack size	50
Rocket capacity	50
Range	15 19.5 24 28.5 37.5 + Lightning reach
Efficiency	20% 26% 32% 38% 50%
Dimensions	1×1
Drain	150 MW (electric)
Energy capacity	500.0 MJ (electric)
Mining time	0.1
Buildable only on
Crafted only on
Prototype type	lightning-attractor
Internal name	lightning-rod
Required technologies
Produced by
Consumed by

Object description

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Space Age expansion exclusive feature.

The lightning rod is a building from Fulgora that protects an area from getting struck by lightning from the nightly storms. When struck, they generate power for a limited time. The peak power production is limited only by the demands of the connected electric system, but the internal storage is subject to a 150 MW drain in addition to the load from the electric system. It is unlocked by researching the Planet discovery Fulgora technology.

The lightning rod cannot be crafted on any planet other than Fulgora, as other planets lack the same strong magnetic field.

Normal-quality lightning rods in a square pattern can be at most 34 tiles apart, or every 35 tiles, while completely protecting the area between them. This is a density of 1 lightning rod per 35x35=1225 tiles. More tile efficient is a triangular pattern with an outside 42x76 rectangle with one rod in its center. This is a density of 2 lightning rods per 42x76=3192 tiles, or one per 1596 tiles.

To align with a 50x50 grid of roboports the quality needed is epic, as epic-quality lightning rods in a square pattern can be placed 54 tiles apart.

Net Efficiency

Lightning rods are ultimately energy storage devices which are recharged with lightning strikes and have unlimited power output potential. However the 150MW drain-to-ground means that they are very lossy storage devices which will rapidly dissipate their stored energy even if unconnected. The actual usable energy we get out of a lightning rod per lightning strike is thus less than strike energy times efficiency. This section provides an overview of this relationship.

Definition of Net Efficiency

Assuming a lightning rod is providing P MW of power whenever charged, the usable energy output by that lightning rod after a lightning strike is: time_charged x P. Time_charged can be calculated as:

(efficiency x strike_energy) / (150 + P).

So the total usable energy output after a lightning strike is:

P x (efficiency x strike_energy) / (150 + P).

Note how the drain reduces the available energy to below (efficiency x strike_energy). Since this expression has units of energy, ideally we would get this into a form of: f(p) x strike_energy where f(p) represents the "net efficiency" of the lightning rod outputting p watts. To do so, we just set them equal and solve for f(p). This yields:

net_efficiency = efficiency / (150/P + 1)

Since individual lightning rods are usually outputting only a fraction of base power needs, net efficiency is often significantly lower than the nominal efficiency listed. For example a 10MW base with 10 active common-quality lightning rods will mean each lightning rod outputs 1MW and has a net_efficiency of ~0.13%.

Implications

Because of the above dynamics, fewer lightning rods per unit area are better for capturing lightning energy as it increases the power draw per lightning rod. One can only achieve this with better packing (hexagonal placement is most efficient) or quality. This consideration can be important when one is dealing with beacons and modules that dramatically increase the power-density of the base or on small islands. It is also important for ensuring accumulators charge as soon as possible upon night falling and keep charging into the early morning as the lightning ends.

History

• 2.0.7:
  • Introduced in Space Age expansion.

See also

• Fulgora
• Lightning collector
• Electric system