Codex Energy Molten Salt Store

Molten-Salt Store

The Molten-Salt Store keeps heat, not energy. It takes process heat from a neighbouring source through its Heat Ports and gives it back to a neighbouring consumer when needed, for example a boiler at night when the solar field is dark. Thermal Salt holds a lot of heat but must stay molten; Thermal Concrete is cheaper, holds less and never freezes.

How it works

1. A heat source next to a Heat Port of the store (a Solar Receiver, an Electric Heater, the Heat Port of a tokamak …) pushes heat in.
2. The heat warms the filling; Heat Exchanger Tubes inside limit how fast heat goes in and out.
3. A consumer next to a Heat Port (a boiler, a foundry …) takes heat back, up to the output limit you set.

See Process Heat for how heat moves between plants.

Building

Shown size: 4 wide, 4 high, 4 deep (adjustable: Width 4–16, Height 3–16, Depth 3–16).

One example of many: within the rules on this page, size and arrangement are up to you; the Build Projector shows the plan in every allowed size.

	Key	Block	Count
	A	Salt Tank Casing	50
	D	Thermal Salt	7
	B	Industrial Sight Glass	3
	E	Heat Port	2
	C	Heat Exchanger Tubes	1
	0	Molten-Salt Store Controller	1

Step by step

Each picture adds one layer, from the bottom up; the newest layer is bright. The controller wall faces you on the left.

Step 1: Layer 1

Parts in this step: Salt Tank Casing (A) ×16

Step 2: Layer 2

Parts in this step: Salt Tank Casing (A) ×8, Thermal Salt (D) ×3, Heat Port (E) ×2, Heat Exchanger Tubes (C) ×1, Industrial Sight Glass (B) ×1, Molten-Salt Store Controller (0) ×1

Step 3: Layer 3

Parts in this step: Salt Tank Casing (A) ×10, Thermal Salt (D) ×4, Industrial Sight Glass (B) ×2

Step 4: Layer 4

Parts in this step: Salt Tank Casing (A) ×16

Rules

• Size: at least 3 × 3 × 3, at most perf.maxStructureSize (default 16, allowed 5–32) in every direction.
• Edges and corners: only Salt Tank Casing.
• Walls, floor and roof: Salt Tank Casing, Industrial Sight Glass, Inspection Hatches, Heat Ports and the controller.
• Inside: only Thermal Salt, Thermal Concrete and Heat Exchanger Tubes. No air.
• Needed: at least one Heat Exchanger Tube and at least one block of salt or concrete.
• Ports: only Heat Ports. Each one takes heat in and gives heat out on its outer face.

Salt and concrete

Filling	Heat per block and °C	Usable from	Full at	Loss
Thermal Salt	2,000 HU	290 °C	565 °C	about 1 % of the heat per minute
Thermal Concrete	800 HU	20 °C	400 °C	about 2.5 % of the heat per minute

In a mixed store the heat capacities add up; the usable range and the loss are averages weighted by the heat capacity of salt and concrete.

Important

Salt starts frozen A new salt store is at 20 °C: the salt is solid and gives no heat. It first has to be heated to its freezing point; every salt block takes 2,000 HU for every degree on the way. Concrete is usable from the start.

Operation in depth

• Transfer limit: tubes × 100 HU per tick, separately for heat in and heat out.
• Usable heat = (temperature − lowest usable temperature) × heat capacity.
• Room for heat = (full temperature − temperature) × heat capacity. A full store takes nothing more.
• Output limit: the store gives at most this much per tick to its consumers (and never more than the tubes allow). Set it with -/+ in steps of 50 HU per tick; at first it is as high as the tubes allow.
• Losses through the shell grow with the temperature above 20 °C.

The screen

• Lines: Status and Salt (the state of the filling).
• Values: temperature, usable heat, room for heat, heat (in), heat output, output limit, tube limit, salt blocks, concrete, tubes, heat loss.
• Buttons: -/+ for the output limit.

Salt	Meaning
Solid (heat above 290 °C first)	The salt is frozen; heat it before it gives heat.
Molten	Ready: it takes and gives heat.
Full	It takes no more heat.
Ready (concrete never freezes)	A store with concrete only.

Automation

• Put a heat source and a consumer each against a Heat Port. One port can both take and give, so a single port between a source and the store works as well.
• A Sensor Module reads temperature, heat stored and heat output.

Error messages

Message	What to do
The controller must sit in a wall, front facing out	Put the controller into a wall face, front outwards, with the inside behind it.
Structure too small (…)	At least 3 × 3 × 3.
Wrong block at … (expected: Salt Tank Casing)	Only Salt Tank Casing on edges and corners.
Wrong block at … (expected: Thermal Salt, Thermal Concrete, Heat Exchanger Tubes)	Fill the whole inside; no air.
Missing parts: Heat Exchanger Tubes ×1 / Thermal Salt ×1	Add at least one tube and at least one block of salt or concrete.
Port not allowed here: …	Only Heat Ports work on the store.

In the world

The salt glows behind the glass, with more embers the fuller the store is.

Tip

Size the tubes The tubes, not the salt, decide the power: a store with lots of salt and one tube charges and discharges only 100 HU per tick. Add a tube for every 100 HU per tick your boiler needs.