Solar Panels
The old site recorded a steep fall in panel prices. That historical change made photovoltaic desalination practical in more locations; this archive does not make a new price forecast.
Renewable Desalination
Reverse Osmosis Powered By The Sun
For more than fifteen years, Sisyan LLC designed and optimized seawater photovoltaic reverse-osmosis plants in Baja California Sur, Mexico.
This site is a record of that work: the pilot systems, the engineering drawings, and Yan Kunczynski and Ben Burger's original paper on demand-response desalination.
The work is presented as a technical archive, not as an active sales or project-development program.
The original case
The Need for Renewable Desalination
A 40% gap between freshwater supply and demand was predicted by 2030, and the stress on natural water systems could already be seen in every part of the world.
In addition to water recycling and conservation, new sources would be necessary. Seawater is the only source that is drought-proof and virtually inexhaustible.
Purifying seawater is also the most energy-intensive way to provide freshwater. The white paper reported that desalinated water typically cost four to eight times more to produce than other sources, with energy often accounting for more than half of operating cost.
Three claims in the paper
Why the water-energy problem mattered
40%projected freshwater gap by 2030
0%100%
4-8×cost of desalinated water versus other sources
0×10×
>50%energy share of operating cost in many cases
0%100%
Language and figures in this section come from page 2 of Demand Response Desalination (2015). They are retained as the paper presented them, not recast as current projections.
Water Energy Nexus
As climate change contributes to water shortages, fossil fuels are not part of the solution.
The economics, as the original site explained them
Price Trends
Energy Storage
Lead-acid batteries once accounted for around 60% of the cost of off-grid solar desalination. Storage was therefore a central design and cost constraint.
Reverse Osmosis
RO had achieved steady efficiency improvements, but further gains were approaching limits imposed by physics.
Grid Energy
Renewable generation was getting less expensive, while the electric grid still required substantial adaptation and investment.
From the original white paper
Further energy reductions are limited
Figure A places the historical fall in reverse-osmosis power consumption beside the thermodynamic minimum at different salinities and recovery rates. It is reproduced from the paper rather than redrawn from estimated data.
The technology
Some of the technologies Sisyan employed
UF
Membrane pretreatment
Membrane-based pretreatment (0.03-micron ultrafiltration) protects and extends the life of the RO components, and allows brine streams to be blended — significantly reducing the salinity of what returns to the sea.
VFD
DC-native variable frequency drives
Unique to this application, the variable frequency drives accept DC current directly from the solar array and batteries — eliminating expensive inverters and creating a naturally flexible, dispatchable load.
APP
Axial-piston high-pressure pump
The most efficient positive-displacement high-pressure pump available — light, low-maintenance, and well matched to variable solar input.
APM
Pressure-recovery motor
An axial-piston motor recovers the pressure still held in the brine stream after desalination and applies it directly to the torque of the pump shaft — one of the first uses of paired APP/APM energy recovery.
RO
Reverse osmosis
A purely mechanical process that pushes fresh water through a semi-permeable membrane while the cross-flow of brine carries dissolved solids away — no heat, no phase change.
The central proposal
Demand Response Desalination
The paper proposed replacing large pressure centers with a multitude of relatively small, fully integrated RO modules.
The plant could coordinate production with energy prices by automating the number of modules in operation. The design grew directly from Sisyan's off-grid pilot, where modules switched on and off in response to battery voltage and available sunlight.
Reverse-osmosis plants are suited to flexible operation because they are not labor-intensive, seawater is continuously available, and treated water can be stored. The claim was specific: make the electrical load adjustable without asking water demand to become adjustable.
Read the paper onlineThe grid problem
Load, net load, wind and solar do not move together
The paper used this CAISO simulation to show the steep ramps a high-renewable grid must follow. It does not claim that desalination output traces an invented hourly curve.
Power inexpensive or surplusMore modules operate
Power expensive or constrainedFewer modules operate
Water demand continuesStored permeate supplies it
Off-grid pilot documented in the paper
- 18 million gallons
- 68,000 m³ of permeate over more than twelve years
- 3 × 3 hp
- fully integrated modules sharing intake, treatment and storage
- 18 kWp
- photovoltaic array connected directly to the battery bank
About
Yan Kunczynski and Sisyan
Yan was the founder and creative force behind Sisyan, with more than fifty years of experience designing, manufacturing, and deploying original machines.
He was a licensed California contractor “A” from 1963 and filed more than twenty patent applications. Before turning his attention to water, he was best known for his contributions to aerial tramways and automatic people movers.
The clearest account of how he worked is his own: define the objective, think independently, prototype and test, then simplify.
Read Yan's points on design