Diy nitrate fertilizer from the sun.

 **This is a DIY adaptation of the historical Birkeland-Eyde (or plasma arc) nitrogen-fixation process to make dilute nitric acid from air, followed by neutralization with limestone (CaCO₃) to produce calcium nitrate (Ca(NO₃)₂) solution or crystals as a liquid or solid fertilizer.** 

The listed items exactly match a low-tech, off-grid setup: the aquarium air pump moves air through the system, plumbing connects everything, solar panels (with a 12 V battery or charge controller) power the low-voltage side, the car ignition system (coil + basic interrupter/switch) generates the high-voltage electric arc/sparks needed to combine atmospheric N₂ and O₂ into nitrogen oxides, blue plastic barrels serve as absorption and reaction vessels, limestone provides the calcium source, and water absorbs the gases. 

**Efficiency is very low** (a few percent at best; expect dilute ~5–15% HNO₃ after many hours of running), but the method works in principle and has been demonstrated in numerous home-experiment videos using similar components (ignition coils and cheap aquarium pumps). 

**Critical safety warnings before starting**  

- NO₂ gas is toxic and reddish-brown; run everything outdoors or in a well-ventilated area with wind blowing away from you.  

- Nitric acid is corrosive — use gloves, goggles, and acid-resistant clothing.  

- High voltage from the ignition coil (10–30 kV) can kill; work only when powered off and use proper insulation.  

- CO₂ is released during neutralization; no explosion risk but keep area ventilated.  

- Do this only if you are experienced with high voltage, acids, and basic chemistry. Scale is small and purely experimental.

### Step-by-Step Setup and Process

1. **Prepare the power system (solar + car ignition)**  

   Wire one or more solar panels (any 12–20 V panel, ~50–100 W total) through a charge controller to a 12 V battery or directly to the primary side of a standard car ignition coil.  

   Use the coil’s normal low-voltage trigger (points, simple 555 timer circuit, or manual switch with ballast resistor) to create repeated sparks or a continuous-ish arc. The high-voltage secondary output (from the thick wire) will go to your electrodes. This is the classic cheap way to get plasma without expensive neon-sign transformers.

2. **Build the arc / plasma reactor chamber**  

   Use a short section of PVC or heat-resistant glass/plastic pipe (4–6 inches diameter) as the reaction chamber.  

   Insert two electrodes (spark-plug tips, tungsten rods, or stout nails) spaced 3–10 mm apart inside the pipe and connect them to the ignition-coil high-voltage output.  

   Seal the ends with end caps and fittings so air can only enter and exit through plumbing ports.  

   Mount the chamber on or inside one blue plastic barrel for stability if desired.

3. **Air flow and oxidation section (aquarium pump + plumbing)**  

   Connect the aquarium air pump (standard 12 V or AC model powered from the same solar setup) to push ambient air into the bottom of the arc chamber.  

   Run the hot exit gas through 10–20 feet of coiled PVC or garden hose (the “oxidation chamber”) — this gives time for NO to combine with extra O₂ to form NO₂ (the reddish gas you want).  

   Use standard plumbing elbows, T-fittings, and hose barbs to connect everything gas-tight.

4. **Absorb the NO₂ into water to make nitric acid (blue barrels)**  

   Route the gas line into the bottom of the first blue plastic barrel (filled ~⅔ with plain water). Use an aquarium air stone or perforated pipe at the end of the hose so the NO₂ bubbles up through the water.  

   For better absorption, chain 2–3 barrels in series (gas exits top of first barrel and enters bottom of next).  

   The reaction is: 3 NO₂ + H₂O → 2 HNO₃ + NO (the NO recycles when more air is present).  

   After several hours or days of continuous running you will have a dilute nitric acid solution (pH ~1–2, yellowish). The more barrels and the slower the bubbling, the stronger it gets. Top up water as needed.

5. **Neutralize with limestone to make calcium nitrate fertilizer**  

   In a separate (or the same, after emptying acid) blue plastic barrel, slowly add crushed/powdered limestone (CaCO₃) to the dilute nitric acid while stirring (use the aquarium pump or a simple paddle).  

   Chemical reaction:  

   **CaCO₃ + 2 HNO₃ → Ca(NO₃)₂ + CO₂↑ + H₂O**  

   You will see vigorous fizzing (CO₂ bubbles). Keep adding limestone until fizzing stops and pH reaches ~6–7 (test strips). Excess limestone simply settles.  

   The resulting liquid is a calcium nitrate solution — exactly the fertilizer you want (provides both calcium and nitrate nitrogen).  

6. **Finish and use the product**  

   Let solids settle, decant or filter the clear calcium nitrate solution through cloth or a coffee filter.  

   You can use it directly as a liquid fertilizer (dilute 1:100–1:200 with water for plants).  

   For solid form, pour shallow trays of the solution in the sun (solar evaporation) until crystals form, then dry them.  

   Store in sealed plastic containers away from moisture.

### Typical Running Tips  

- Run the arc and pump during daylight when solar is strongest.  

- Expect very slow production — a few liters of weak acid per day with a small setup.  

- Dry the incoming air slightly (silica gel in a tube) for slightly better yield, though not essential.  

- Monitor temperature — the arc chamber gets hot; add a small fan if needed.  

- Scale: one or two 55-gallon blue barrels for absorption + a third for the final neutralization step is common for backyard setups.

That’s the complete closed-loop process using only the exact items you listed. The solar panels keep it off-grid, the car ignition coil provides cheap high voltage, the aquarium pump + plumbing moves the air and gas, the barrels contain the chemistry, and limestone + water turn the acids into usable fertilizer. It’s inefficient compared to commercial production but demonstrates the chemistry beautifully with scrap materials. 

If you build it, start tiny and test outdoors first. Enjoy the mad-science fertilizer project!