Dutch company Redstack is seeking to establish its first pilot project in India, targeting integration of its reverse electrodialysis (RED) technology with desalination facilities in coastal regions.
The firm's technology generates electricity from differences in water salinity and could eventually supply round-the-clock renewable power to hydrogen and ammonia projects located near ports.
Argus spoke with Redstack India director Geeta Singh about project development, the path to commercialisation and opportunities for integration with hydrogen projects on the sidelines of the S&P Global Horizons Clean Energy Expansion India 2026 conference. Edited highlights follow.
What are Redstack's plans for India?
We have been seeking to establish an Indian pilot project for more than three years.
Our preferred route is to integrate with an existing desalination facility because that would involve fewer regulatory approvals than developing a project directly at a river-ocean confluence. We are discussing opportunities with potential partners and remain open to locations across India's coastline. At this stage, we do not have a preferred state or site.
How close is RED technology to commercial deployment in India?
We are still some distance from full commercialisation. Our immediate objective is to establish a first pilot project in India that can demonstrate the technology and show that it is ready for larger-scale deployment.
The pilot would showcase the full process flow required for future megawatt-scale implementation. One advantage of RED technology is that scaling up is relatively straightforward because capacity can be expanded without requiring a large horizontal footprint.
What economics do you expect from the first commercial RED projects?
We estimate that a first commercial-scale project could produce electricity at around 18 Indian rupees/kWh ($0.19/kWh).
As membrane costs decline and membrane technology improves, we expect costs to fall over time. With continued innovation, we believe generation costs could eventually decline to around Rs5/kWh over a period of roughly 10 years from the first commercial project integration.
How does RED compare with batteries and pumped hydro storage?
We do not view RED as directly competing with solar, wind, batteries or pumped hydro. These technologies have already been deployed commercially at scale and have decades of operating history.
Our technology is still at a stage where it must demonstrate commercial viability. We see RED as a complementary power source that can generate stable, round-the-clock renewable electricity without requiring battery energy storage.
What are the main limitations on deployment?
The key requirement is access to two different water sources. Projects need to be located near the coast where seawater is available, while also having access to freshwater, treated wastewater from sewage treatment plants or desalination-related water streams.
Apart from that, we do not see major technical limitations. Power generation can be controlled through water flows within the system, allowing stable electricity output.
How large could the Indian market become?
Based solely on locations where rivers meet the ocean, we estimate a potential market of around 19-20GW in India.
As more desalination projects are developed, we believe the market opportunity could become significantly larger.
Could RED support hydrogen and ammonia production projects?
Yes. One potential application is supplying renewable electricity to hydrogen and ammonia projects located near ports.
If a project already has access to seawater and desalination infrastructure, electricity could potentially be generated close to the point of hydrogen production rather than being transmitted from distant renewable energy projects. We believe this could help support renewable hydrogen developments that are looking for dedicated sources of renewable electricity.
What policy changes would have the biggest impact on deployment?
Marine-based renewable energy projects are subject to multiple regulations and charges.
One issue is that various cess and water-related charges may apply even when water is not consumed and is simply passed through the RED system.
A clearer regulatory framework for technologies such as RED, tidal and wave energy could help accelerate deployment.
What will determine the pace of commercial deployment in India?
We do not believe site availability will be a major constraint because India's coastline offers numerous potential locations.
We also believe financing should become easier once the technology gains broader acceptance. The more immediate challenge is educating stakeholders about the technology and establishing the ecosystem needed for commercial deployment.
What milestones would demonstrate the technology is commercially viable?
We already believe the technology is ready for larger-scale deployment, which is why we are pursuing projects in India.
We currently operate two pilot projects in Europe. One is located in the Netherlands at the confluence of the Rhine River and the North Sea and is the largest RED project developed to date. The second is in Spain, where desalination wastewater is combined with treated wastewater streams.
