RED - Reverse Electrodialysis
For energy generation
Membranes: low resistance grade homogeneous anion and cation exchange membranes
How does it work?
The technology for which Fujifilm membranes are used, is called Reverse Electrodialysis (RED). RED is like Electrodialysis (ED) a DC voltage-driven membrane process. An electrical potential is used to move ions (salts) through a membrane. ED and RED depend on the following general principles: Most salts dissolved in water are ions, either positively charged (cations), or negatively charged (anions). Since two identical charged poles repel each other and two opposite poles attract, the ions migrate toward the electrodes with an opposite electric charge.
With RED technology energy can be generated from two electrolytic solutions with a different salinity gradient, for example seawater and fresh water. Both water streams are separated by ion exchange membranes in a number of cells, stacked between a cathode and an anode creating an electric circuit.
The ion exchange membranes allow only the charged ions to flow through. In salt water there are more positively and negatively charged sodium chloride (salt) particles than in fresh water. Under the influence of an electric field the fresh and seawater wants to balance out in ionic charge, therefore the ions will try to flow evenly across both feed-in water cells but need to pass the charged ion exchange membranes. Since the RED cell consist of a negative charge membrane and a positive charged membrane the salt will be split into negative ions on one side and positive ions in the other channel creating a partial difference over the cell and electric power can be generated.
A RED unit consist of several hundred cells bound together with electrodes, and is referred to as a stack. The more membranes piled in a stack, the more electrical power a stack can generate. Besides the difference of salinity gradient of both feed-in waters, also the flow rate of the water through the stack is of importance for increasing the power generated in the end.
Driven by salinity gradient difference like:
- Energy generation in river delta’s (salinity gradient river-sea water)
- Energy generation in mining areas (salinity gradient mining process water-river water)
- Energy generation from low grade waste heat (40 - 90 °C) in traditional power plants
Blue Energy project
a sustainable alternative energy source
Contribute to the global fight against climate change and to reach the strategic target of the European Union (transition to a low carbon economy with 27% renewable energy sources by 2030).
Blue Energy technology, based on Reverse Electrodialysis (RED), is a zero carbon emission energy source which is 100% sustainable and available 24 hours per day. It is complementary to other renewable types of energy such as wind, solar and biogas. With RED energy can be harvested from the difference in the salt concentration between seawater and river water. RED uses stacks of alternating anion and cation exchange membranes to generate electricity.
Blue Energy current status
Operated by projectpartners REDstack and Wetsus a pilot plant, powered by FUJIFILM membranes, is currently running in the Netherlands at the Afsluitdijk. Here seawater of the North Sea meets fresh water of the IJsselmeer. Further developments to improve the membrane performance (high power density generation) and cost effectiveness are ongoing.
Ambition for Blue Energy membranes
The Blue Energy project has won the “Dutch National Icon” title, as one of the projects for the best technological solutions for societal problems. Together with REDstack we strive to make Blue Energy technically and economically viable by developing high volume, cost effective membranes. Our ambition is to contribute to the development of alternative, environmentally friendly sources of energy.
A new research project, funded in the EU Horizon 20020 in the field of "Future Energy Technologies", with 4 scientific institutes and 2 companies. This project is focussed on the research and development of a novel energy technology to convert low grade waste heat (40 - 90 °C) in valuable electricity. It is targeted to add an unexplored sustainable energy source against low electricity prices.
project aims to contribute to overcoming the drinking water challenge via novel desalination. The goal is to produce safe, affordable and cost-competitive drinking water with significantly reduced energy consumption compared to state-of-the-art Reverse Osmosis (RO) desalination technology. The project comprises several systems and applications with 12 pilots in total, ranging from Electrodialysis (ED) small systems for off-grid brackish water desalination in developing countries to larger scale hybrid (RED/ED-RO) systems for sea water desalination.
FUJIFILM coordinates the whole project as well as supplies ion-exchange membranes for all systems and components developed in the project.
FUJIFILM also leads development activities of the brackish water desalination systems as well as development and field-demonstration activities of the tap-water softening systems with a particular focus on designing, manufacturing and testing of the dedicated stacks.
Use the slider bars to choose a salt concentration for feed stream 1, with a high salt concentration, and for feed stream 2, with a lower salt concentration. Use the third slider bar to define a feed flow rate between 0 and 500 m3/s and discover how much energy can be generated by reversal electro dialysis (RED) membrane technology.
A 200 m3/s flow rate at the Afsluitdijk, where water of the North Sea with circa 30 g/l salt meets the IJsselmeer with circa 1 g/l salt, would typically generate around 200 MW. This is enough to serve approximately 200,000 households. The calculation is based on a energy recovery rate of 70% and a coincidence factor of 1 kWh per household
Blue Energy, a Renewable Energy Source
Blue Energy is a promising renewable energy source for the future, producing electricity by harvesting the difference between salt water and fresh water. Blue Energy is an environmental alternative for energy. There is no emission of greenhouse gases and the feed streams are 24h per day available.
The 2 variables mentioned below are important for the energy recovery of the Blue Energy process:
Difference in Salinity
In order to obtain energy, two feeds of different salt concentration must be available. Such a salinity pair might be formed from sea water or industrial brines, coupled with a low concentration source as for instance river water. The higher the delta in salinity, the more electric power can be generated. The salt concentrations are given in g/l.
The electrical power that can be generated, linearly depends on the feed flow rate. Doubling the flow rate will also double the electric power. The flow rate is given in m3/s.