Materials for Energy and Environment
Cross-disciplinary researchers at Boston University are exploring materials that can help produce cleaner and more efficient sources of energy. Clean energy conversion, hydrogen generation and storage, fuel cells, green manufacturing and biofuels/metabolics are all subjects of active research.
Research in this area of involves faculty from various departments within the College of Engineering and College of Arts and Sciences. Scientists in this group share facilities, have collaborative grants, and publish their scientific findings jointly.
The Materials for Energy and Environment thrust area addresses education and research activities that deal with generation and efficient use of clean and/or renewable energy. Research in these areas is expected to address much of our present energy-related concerns and steer us to a better future. Based on the current strengths and activities, Boston University is well positioned to steer the course of this important field and participate in the tremendous growth opportunity it presents. Examples of current activities in this area are described below:
Fuel Cells and Renewable Energy: Power limitations, life time, environmental impact, fuel flexibility and cost are challenges facing portable and large-scale energy conversion devices. These critical issues are being addressed by developing new materials and optimizing processing methods. This research combines materials processing (Pal, Gopalan), characterization (Basu, Ludwig, and Smith) and modeling (Zhang and Lin) of materials and structures, ranging from nanometer to meter length scales, thereby creating new possibilities. By combining progress made by the PIs of this proposal in fabricating ceramic thin-film multilayer structures, 3D printing of submicron ceramic lattice-like networks, synthesis of mixed-phase ionic and electronic oxide composites structure, micro and nano-scale characterization, new architectures are being created to offer a test bed for investigating novel and model materials and structures, their integration, and their electrochemical performance. The fundamental understanding gained from such electrochemical systems (see Figure 1) are also applicable to other clean energy technologies, such as primary and rechargeable batteries, biological, thermo-chemical, photo-electrochemical, and electrolytic processes for energy production.
Figure 1: Illustration of the microscopic processes taking place in a fuel cell cathode.
Hydrogen Generation and Storage: Hydrogen is considered as a potential future energy carrier. The material challenges and the associated processes addressing hydrogen generation, storage and use (see Figure 2) are currently being addressed (Pal, Gopalan, Sarin, Swan and Mohanty). High energy-density hydrogen storage material that can be reversibly cycled is required. Research work is on-going on modeling materials and structures at the atomic level (Grinstaff) that have the property to reversibly bind and de-bind with hydrogen. Metal and Complex hydrides along with micro and nano porous materials are being researched as possible candidate materials in terms of high volumetric density (Kg H/m3) and mass density (mass % H) for hydrogen storage.
Figure 2. Technologies and challenges for Hydrogen Economy
Bioenergy: Research is also being conducted in engineering microbes to synthesize fuels, electricity and materials. Advanced genomics technologies are being developed and applied to optimize the metabolism of microbes for fuel or electricity production (Segrè and Collins). Micro-fabricated devices are being developed to enable electricity production directly from microbes, see Figure 3. This technology would be applicable to microelectronics powered by raw biomass or the bloodstream.
Figure 3: Electrochemical cell for Bio-energy Conversion
Advanced coatings for Clean Energy Generation: Higher temperature operation of gas turbines improves efficiency. This can be achieved by improving the performance of thermal barrier coatings (TBCs). Research enabling engineering of the micro-crack density in these TBCs to minimize the thermal conductivity without sacrificing lifetime is ongoing (Basu, Gevelber). Introduction of Si-based ceramics into turbines can also significantly raise the operating temperature, but require the development of hot-corrosion and recession resistant environmental barrier coatings (EBCs). Research on developing functionally graded EBC systems is ongoing (Basu, Sarin, Murray).
Solid State Lighting: The goal of our research in solid-state lighting is to produce energy-efficient lighting for a variety of applications and eventually replace the incandescent and fluorescence light sources for general illumination. Research in this area addresses the formation and study of Ultraviolet and Visible Light Emitting Diodes (LEDs) using the family of Nitride Semiconductors (Moustakas). These light sources are used to produce white light either by mixing the three primary colors (red, green and blue) or by combining UV LEDs with a tricolor phosphor, see Figure 4. The Department of Energy estimates that the overall savings in United States alone will be in the $20-30 billion per year.
Figure 4. BU’s Phosphorless White LED based on textured Nitride Multiple Quantum wells.