Using used cooking oil (UCO) to produce clean energy is an economically viable plan. Unlike fresh vegetable oils, like palm or soybean oil, UCO does not compete with the food supply and offers great environmental credits under global clean energy rules.
However, running a profitable used cooking oil biodiesel processing plant requires managing three main things: collecting enough oil, processing it efficiently, and using the energy wisely. Understanding the basic chemical process and power formulas is key to getting a strong used cooking oil biofuel Return on Investment.
How Used Cooking Oil is Turned into Biodiesel
Raw used cooking oil contains water and high amounts of Free Fatty Acids (FFAs) caused by heating during cooking. Using high-FFA oil directly to normal biodiesel production methods creates soap instead of fuel. This ruins the chemical reaction and wastes the oil.
To solve this, modern processing facilities use a simple 2-step process:
- Acid Treatment (Pretreatment): Mixing the oil with an acid catalyst and methanol to lower the FFA level below 1%.
- Base-Catalyzed Reaction (Transesterification): Mixing the oil with methanol and an alkaline catalyst (like KOH or NaOH) at warm temperatures (55°C to 65°C) to produce biodiesel (FAME, Fatty Acid Methyl Ester) and glycerol:
Raw Oil + Methanol —(Catalyst)→ Biodiesel + Glycerol
The final fuel must meet official standards (such as ASTM D6751 or EN 14214). The ester content is minimum 96.5%-mass based on EN 14214 standard.
Simple Real-World Example: Power Generation & Savings
To see how this works in practice, let’s look at a small-scale real-world example. In this setup, a local collection hub collects used cooking oil from food vendors to make a B30 fuel blend (30% biodiesel mixed with 70% regular diesel) to run on-site power generators.
Data:
- Total oil collected = 35.96 liters/day
- Frequency of cooking oil replacement = 2 (yield of biodiesel produced decreased with the increasing frequency of cooking oil replacement)
We want to know:
- How much pure biodiesel produced
- Daily electricity generated from B30
- Cost savings and carbon savings
Biodiesel Production
Output = 35.96 L/day × 83.92% = 30.18 Liters of pure biodiesel/day
The relationship between biodiesel produced and frequency of cooking oil replacement is below:
Electricity Production
Electricity = 30.18 L/day / 0.2606 L/kWh = 115.80 kWh/day
Based on one source, specific fuel consumption of biodiesel is shown below:
Carbon Emissions Reduction
Assuming emission factor of 0.87 kg CO2/kWh,
Saved CO₂ = (115.80 kWh/day × 26 days/month × 0.87 kg CO₂/kWh) / 1,000 = 2.62 tons of CO₂/month
Scaling this up to a commercial factory processing 5,000 Liters per day can generate over 420,000 kWh of electricity per month, bringing huge financial and carbon savings.
Engine Performance and Environmental Benefits
Using UCO biodiesel blends in generators and diesel engines offers practical benefits:
- Engine Power & Efficiency: Tests show that using B10 to B30 fuel blends maintains engine power and torque. The natural oxygen inside biodiesel helps the fuel burn completely.
- Lower Pollution: Running generators on B30 significantly cuts down on harmful exhaust gases like carbon monoxide (CO), unburned fuel particles, and black smoke compared to plain diesel—all without needing to modify the engine.
I hope you find this post useful!
References:
- Rahman, A., Suryawan, I. W. K., Sarwono, A., Zahra, N. L., & Faruqi, Z. M. (2020). Estimation of biodiesel production from used cooking oil of university cafeteria to support sustainable electricity in Universitas Pertamina. IOP Conference Series: Earth and Environmental Science, 591, 012013. DOI: 10.1088/1755-1315/591/1/012013.
- Ali, B., & Nugroho, P. A. (2017). Analisis Pemakaian Bahan Bakar High Speed Diesel dan Biodiesel (B30) Terhadap Konsumsi Bahan Bakar dan Emisi Gas Buang Mesin Diesel PLTD 1.4 MW. Presisi, 18(2), 30-41.