Community Research and Development Information Service - CORDIS


CAPMIX Result In Brief

Project reference: 256868
Funded under: FP7-ENERGY

Salinity gradient provides green energy

European scientists are investigating a source of clean renewable energy that can be extracted from the mixing of fresh water and salt water.
Salinity gradient provides green energy
The amount of energy potentially available from the difference in the salt concentrations of seawater and river water around the world is 1.4–2.6 terawatts (TW), or about 20 % of local electricity consumption. This natural process does not produce carbon dioxide (CO2) or any other polluting combustion emissions, nor does it result in thermal pollution.

An EU-funded project titled CAPMIX was established with the aim of developing an innovative technology for the extraction of salinity gradient energy. The concept is based on producing electricity directly from the difference in salt concentrations between fresh and saltwater.

CAPMIX stands for capacitive mixing and is a new way of harvesting salinity gradient energy. The main advantage is that electricity generation is directly linked to the mixing process without any intermediate steps, so no expensive and complex converters like turbines or electrochemical reactions are required. Therefore, the technology promises to provide a cost-effective and environment-friendly form of renewable power.

Project partners are using capacitive electrodes to directly convert the salinity gradient energy into electricity and are investigating two types of capacitive energy extraction. One type is based on capacitive double-layer expansion (CDLE), while the other is based on capacitive Donnan potential (CDP). To date, the consortium has successfully characterised both CDLE and CDP in mathematical models and identified the parameters that must be optimised to improve performance.

Scientists have also identified new materials for electrodes and studied new cell designs that experience almost no voltage drop over time. Researchers have also investigated the fouling of CDP ion-exchange membranes. A demonstration cell was designed to enable the general public to witness capacitive energy extraction by simply dipping the cell successively from sea water to river water. In addition, an international workshop on salinity gradient energy was organised, the outcomes of which are available online.

The success of CAPMIX offers a new and exciting form of clean technology for the generation of an untapped source of renewable energy that can be applied throughout Europe and the rest of the world.

Related information

Record Number: 90491 / Last updated on: 2013-02-21
Domain: Energy