Reverse osmosis pushes seawater through a membrane at roughly 55 to 60 bar. A conventional system generates that pressure with a high-pressure pump and then dumps the brine, still at nearly full pressure, straight back into the sea. All the energy in that stream is wasted.
Energy recovery reuses it. Spectra's Clark pump is a pressure intensifier: the returning brine drives a piston that helps pressurise the incoming feed. Schenker's ERS applies the same principle in a different mechanical package. Both eliminate the high-pressure pump altogether, which is why they run on a small low-pressure feed pump and very little power.
What it does to the numbers
Schenker's Zen 30 makes 30 L/hr on 110 W, 3.7 Wh/L. Spectra's Ventura 150 makes 24 L/hr on 108 W, 4.5 Wh/L. The Newport 400C scales that to 64 L/hr on 288 W and still holds 4.5 Wh/L. Nothing with a conventional pump gets within a factor of two of those figures.
| System | Power | Output L/hr | Draw W | Wh per litre | Price |
|---|---|---|---|---|---|
| Zen 30 Schenker | 12/24V DC | 30 | 110 | 3.7 | $6,300 |
| Zen 100 Schenker | 12/24/48V DC or AC | 100 | 400 | 4.0 | $9,600 |
| Ventura 150 Deluxe Spectra | 12/24V DC | 24 | 108 | 4.5 | $6,000 |
| Ventura 150 Connect Spectra | 12/24V DC | 24 | 108 | 4.5 | $7,400 |
| Newport 400C Spectra | 12/24/48V DC | 64 | 288 | 4.5 | $14,500 |
| Zen 50 Schenker | 12/24V DC | 50 | 240 | 4.8 | $7,800 |
Who should buy it
- Yes: liveaboards on solar with no generator; boats with a modest bank; anyone planning long passages where the engine only runs to anchor.
- No: boats with a genset that already runs daily. There the conventional pump wins on dollars per litre and the efficiency premium is money you will never get back.