Energy Used
We calculated the total amount of CO2 produced to make one batch of biodiesel 20 L (18.3 kg).
Step 1: Find current/amperage (I) and voltage (V) of equipment used at each unit operation. Assume 120 V from wall outlet. Calculate power (P), in Watts, as:
P = IV
*If wattage of a piece of equipment is given, P = IV is not needed.
Step 2: calculate kilowatts, as:
kW = P (in watts) / 1000
Step 3: Calculate kilowatt hours (kWh), as:
kWh = P (in kW) x time equipment is used for a unit operation (in hours)
Step 4: Convert kWh to CO2 emissions:
1 kWh = 0.39 kg CO2 (US) = 0.31 kg CO2 (North Carolina)
Results = CO2 emissions to make 20 L of biodiesel
Water Washed Biodiesel
8 kg
Water Washed Biodiesel
8 kg
Additionally:
20L of biodiesel produces 7.2 x 10^8 J of energy when combusted, as:
= 9427 cal/g (4.184 J/cal) x 18,300 g
And, the total electrical energy used to make 20L of biodiesel can be calculated as: J = W/s, and there are 3600 sec/hr.
Energy ROI = energy return on energy invested = J “to burn” / J “to make”
Biodiesel energy by calorimetry
9427 cal/g
Total energy in 20 L biodiesel
7.2 x 10^8 J
Total energy to make 20 L biodiesel
(water washing to finish)
7.3 x 10^7 J
Total energy to make 20 L biodiesel
(distilling to finish)
1.6 x 10^8 J
Energy ROI (water wash)
9.9 x
Energy ROI (distillation)
14.5 x