How Long Will Biodiesel Last?
The shelf life of biodiesel depends on storage conditions, fuel quality, and blend level. In general:
- Pure biodiesel (B100): ~ 6 months
- Blended biodiesel (e.g., B20): ~ 6–12 months
- Under ideal storage conditions, it may last up to 1 year, but quality can start degrading earlier.
Why Biodiesel Has a Limited Shelf Life
Biodiesel is more sensitive than petroleum diesel because it:
- Oxidizes easily
Exposure to oxygen causes chemical breakdown, forming acids and sediments. - Absorbs moisture
Biodiesel is hygroscopic (attracts water), which can lead to:- Microbial growth
- Fuel contamination
- Corrosion
- Breaks down under heat and light
High temperatures and sunlight speed up degradation.
Storage Conditions That Affect Shelf Life
1. Temperature
- Best storage: Cool (below 20°C / 68°F)
- High heat accelerates oxidation.
2. Light Exposure
- Store in dark containers
- UV light degrades fuel faster
3. Air Exposure
- Minimize air space in tanks
- Use tightly sealed containers
4. Water Contamination
- Keep tanks dry
- Regularly drain water from storage tanks
Signs Biodiesel Has Gone Bad
- Darkened color
- Cloudy appearance
- Sour or rancid smell
- Sludge or sediment formation
- Engine performance issues (clogged filters)
If fuel shows these signs, it should not be used.
How to Extend Biodiesel Shelf Life
- Add antioxidant stabilizers
- Store in clean, dry, airtight tanks
- Use stainless steel or aluminum containers (avoid copper, brass, zinc)
- Rotate stock (first in, first out)
- Regularly test fuel quality if stored long-term
Comparison with Petroleum Diesel
- Petroleum diesel: 12–24 months (with proper storage)
- Biodiesel: 6–12 months
Biodiesel degrades faster because it is derived from natural oils and fats.
Quick Summary
| Type | Typical Shelf Life |
|---|---|
| B100 (Pure biodiesel) | ~6 months |
| B20 blend | 6–12 months |
| With stabilizers & ideal storage | Up to 1 year |
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