Desalination Energy Calculator Formula

Understand the math behind the desalination energy calculator. Each variable explained with a worked example.

Use the Desalination Energy Calculator

Formulas Used

Daily Energy Required

daily_energy = daily_kwh

Daily Energy Cost

daily_cost = daily_kwh * elec_rate

Annual Energy Cost

annual_cost = annual_kwh * elec_rate

Cost per 1000 Gallons

cost_per_1000_gal = kwh_per_1000_gal * elec_rate

Variables

VariableDescriptionDefault
volume_galDaily Water Volume(gallons)100000
kwh_per_1000_galEnergy per 1000 Gallons(kWh)12
elec_rateElectricity Rate(USD/kWh)0.1
daily_kwhDerived value= volume_gal * kwh_per_1000_gal / 1000calculated
annual_kwhDerived value= daily_kwh * 365calculated

How It Works

How to Calculate Desalination Energy

Desalination removes salt from seawater to produce fresh water, requiring significant energy.

Formula

Daily Energy = Volume (gal) * Energy Rate / 1,000

Energy Requirements (kWh per 1,000 gallons)

  • Reverse osmosis (RO): 10-15 kWh
  • Multi-stage flash: 20-30 kWh
  • Multi-effect distillation: 15-25 kWh
  • Forward osmosis: 8-12 kWh (emerging)

    • Worked Example

    A small RO plant producing 100,000 gal/day at 12 kWh/1000 gal with $0.10/kWh electricity.

    volume_gal = 100000kwh_per_1000_gal = 12elec_rate = 0.1
    1. 01Daily energy: 100,000 * 12 / 1,000 = 1,200 kWh
    2. 02Daily cost: 1,200 * $0.10 = $120
    3. 03Annual cost: 1,200 * 365 * $0.10 = $43,800
    4. 04Cost per 1,000 gal: 12 * $0.10 = $1.20

    Ready to run the numbers?

    Open Desalination Energy Calculator