Using Water-Reactive Metals to Power Seawater Desalination

Technology

The technology employs an increase in pressure to propel fluid through a semi-permeable membrane, a process known as "reverse osmosis." It comprises multiple chambers accommodating both gas and liquid. In desalination, seawater is driven through the membrane to produce desalinated water. Seawater serves as the "feed liquid" in one chamber, while gas occupies another. The feed liquid is driven through the membrane to create “permeate,” which in the case of desalination is the desalinated water. An actuator separates these chambers and allows for volumetric changes. The gas is heated, expanding its chamber, followed by the actuator causing a reduction in the liquid chamber's volume. This reduces the liquid chamber's volume, increasing pressure on the feed liquid beyond a specific threshold, compelling it through the membrane. Consequently, the collection of permeates becomes feasible. Methods for heating the gas to drive reverse osmosis include a chemical reaction where heat is generated, using water and a metal like aluminum as reactants, and inducing a liquid-to-gas phase change in the second chamber, possibly employing solar energy.  

Problem Addressed

Following a disaster, access to drinking water is often limited, especially in coastal regions where there may be an abundance of saltwater but a scarcity of freshwater. Most current desalination processes rely on mechanical pumps, which may not be readily available after a disaster, particularly in resource-constrained areas. This membrane-based approach to fluid treatment without the need for mechanical pumps addresses this challenge, making it a valuable solution for coastal disaster relief efforts in regions with limited resources.

Advantages

• Does not require use of mechanical pumps to drive reverse osmosis process.
• Suitable for disaster relief efforts in resource-deficient regions. 
• Utilizes the abundance of saltwater on Earth to provide much-needed drinking water to growing populations. 
• Pressurized hydrogen is a byproduct of this invention which can be used for running a stove, heating, or powering a generator and that the aluminum fuel used in this can be easily made from scrap aluminum, often found as waste debris as a consequence of a natural disaster.

Publications

Godart, Peter, et al. "Hydrogen production from aluminum-water reactions subject to varied pressures and temperatures." International Journal of Hydrogen Energy 44, no. 23 (May 2019): 11448-11458. © 2019 Hydrogen Energy Publications LLC.