How much electrical energy does it take to make 100L of fresh water?
kWh per 100 litres is the most transferable performance metric for onboard watermaking. It converts freshwater production into the same units used to plan battery capacity, charging power, and daily electrical load budgets. That makes it straightforward to compare systems of different outputs on a like-for-like basis and to set realistic daily water targets that fit the yacht’s operating profile.
When you’re choosing a watermaker, the key is matching production to both water demand and electrical capacity. That’s why kWh per 100 litres is so useful: it converts output into an energy figure you can compare directly against the yacht’s available power - whether that comes from batteries, charging sources, generator power, or shore supply. The result is a clearer basis for specifying the correct unit size and output for your needs, rather than selecting on litres per hour alone.
In this post we apply the same calculation method across the Dessalator Cruise, Freedom, and DUO ranges to show the electrical energy required to produce 100 litres of fresh water.
Method
Time (h) = 100 ÷ Output (L/hr)
Energy (kWh) = Motor power (kW) × Time (h)
Convert W → kW using: kW = W ÷ 1000
Note on output: stated outputs are averages, production rate varies with seawater temperature.
Worked example (D100 Cruise)
Output = 100 L/hr
Time for 100 L = 100 ÷ 100 = 1.00 h
Motor power = 1100W ÷ 1000 = 1.10kW
Energy for 100 L = 1.10kW × 1.00h = 1.10kWh
From here, the same calculation is applied to every model in the table below.
Comparison: Electrical Energy to Produce 100L
(Using published output and motor power figures for Cruise, Freedom and DUO.)
| Range | Model / mode | Output (L/hr) | Motor power (kW) | Time (h) | Energy (kWh) |
|---|---|---|---|---|---|
| Freedom | D30 (DC) | 30 | 0.55 | 3.33 | 1.83 |
| Freedom | D60 (DC) | 60 | 0.55 | 1.67 | 0.92 |
| Freedom | D100 (DC) | 100 | 0.70 | 1.00 | 0.70 |
| Cruise | D60 (AC) | 60 | 0.75 | 1.67 | 1.25 |
| Cruise | D100 (AC) | 100 | 1.10 | 1.00 | 1.10 |
| DUO | D60 (DC motor) | 60 | 0.55 | 1.67 | 0.92 |
| DUO | D60 (AC motor) | 60 | 0.75 | 1.67 | 1.25 |
| DUO | D100 (DC motor) | 100 | 0.70 | 1.00 | 0.70 |
| DUO | D100 (AC motor) | 100 | 1.10 | 1.00 | 1.10 |
Converting kWh into battery Ah (12V and 24V)
To translate energy into battery capacity in a way that’s useful for system planning:
Ah = (kWh × 1000) ÷ V
| Range | Model / mode | Energy for 100 L (kWh) | Ah @ 12 V | Ah @ 24 V |
|---|---|---|---|---|
| Freedom | D30 (DC) | 1.83 | 153 | 76 |
| Freedom | D60 (DC) | 0.92 | 77 | 38 |
| Freedom | D100 (DC) | 0.70 | 58 | 29 |
| Cruise | D60 (AC) | 1.25 | 104 | 52 |
| Cruise | D100 (AC) | 1.10 | 92 | 46 |
| DUO | D60 (DC motor) | 0.92 | 77 | 38 |
| DUO | D60 (AC motor) | 1.25 | 104 | 52 |
| DUO | D100 (DC motor) | 0.70 | 58 | 29 |
| DUO | D100 (AC motor) | 1.10 | 92 | 46 |
These are energy-only equivalents; real-world battery draw will depend on whether the unit is supplied directly from DC, from AC, or via an inverter; not accounting for any losses.
What the numbers mean in real operating modes
A useful way to look at the table is as an energy budget for producing 100 litres, and that points to two typical operating modes.
Battery-led operation
The practical metric is kWh per 100L translated into Ah at system voltage. That single number tells you whether producing 100 litres is a light, repeatable daily load or something best aligned with specific charging windows. Lower-energy figures (for example 0.70kWh per 100L) are simply easier to carry alongside refrigeration and other continuous services, helping water production sit naturally inside a battery-first routine.
Generator- or shore-led operation
In generator/shore mode, kWh per 100L becomes a runtime-planning number. Once the generator is online, the watermaker’s electrical cost is predictable, and the selection focus shifts toward how you prefer to batch tasks: shorter, higher-output runs versus longer, lower-output runs. The key benefit of normalising to kWh per 100L is that it makes those runtime choices transparent and comparable.
Either way, normalising performance to kWh per 100L keeps specification tied to integration reality: battery capacity, charging power, and the operating profile you want the yacht to follow day-to-day.
Specify once. Run predictably.
Choosing between Dessalator Cruise, Freedom, and DUO comes down to matching the unit to how you actually use the boat. If you’d like a clear recommendation, get in touch; tell us how much water you want to make each day and a quick outline of your power setup, and we’ll point you to the right model and a straightforward way to run it.