Grantee Research Project Results
High Performance Membranes for Sustainable Production of Energy and Water
EPA Grant Number: FP917338Title: High Performance Membranes for Sustainable Production of Energy and Water
Investigators: Hoover, Laura A
Institution: Yale University
EPA Project Officer: Lee, Sonja
Project Period: September 1, 2011 through August 31, 2014
Project Amount: $126,000
RFA: STAR Graduate Fellowships (2011) RFA Text | Recipients Lists
Research Category: Academic Fellowships , Fellowship - Science & Technology for Sustainability: Green Energy/Natural Resources Production & Use
Objective:
This research aims to increase the efficiency of energy and water production in pressure retarded osmosis and forward osmosis, respectively, by reengineering the structure of the membranes used in these processes to diminish their generation of internal concentration polarization. Increasing the efficiency of these sustainable “engineered osmosis” technologies will make them more economically attractive and incentivize their commercial implementation.
Approach:
Internal concentration polarization (ICP) is a performance limiting phenomenon that reduces the osmotic pressure difference, the driving force of pressure retarded osmosis and forward osmosis, across the semi-permeable membrane. Literature has established that the severity of ICP can be reduced by enhancing mixing, by increasing the porosity of the support layer of an engineered osmosis (EO) membrane, and by decreasing the tortuosity and thickness of the support layer of an EO membrane. A novel fabrication technique called electrospinning can produce networks of nanofibers that have extremely high porosity, customizable thickness and the strength and flexibility that are required to make robust membranes. Electrospun fiber alignment also can be tailored to enhance mixing. This project aims to investigate the use of electrospun fiber mats and other novel materials in the fabrication of ICP-minimizing, high performance membranes for pressure retarded osmosis and forward osmosis. Furthermore, models will be developed to determine the dependence of EO efficiency on customizable membrane properties to identify optimal conditions for fabrication of membranes for specific applications.
Expected Results:
Successful completion of this research will produce high flux (water per area) membranes for forward osmosis and high power density (energy per area) membranes for pressure retarded osmosis. In addition, a more advanced model will be developed to guide optimization of membranes for specific applications with specific input streams, and previously underutilized streams, especially waste streams, will be identified that can become useful sources of energy and water through the application of engineered osmosis.
Potential to Further Environmental / Human Health Protection
Pressure retarded osmosis can provide clean energy from renewable resources and waste, replacing conventional methods of energy production that harm human and environmental health and use non-renewable resources. Forward osmosis can provide a low-energy desalination alternative to conventional seawater desalination technologies, and it can lower the energy requirements and rate of waste production for select industries, including food processing and wastewater treatment.