For the past century, the energy sector has been dominated by fossil resources. Concerns regarding limited availability of fossil resources and increasing emission of greenhouse gases (GHG), however, have grown interests for advancement and implementations of alternative renewable energy conversion process such as wind turbines, photovoltaic devices, and concentrated solar power plants. Among these alternatives, solar energy conversion processes are prominent as solar energy is the only energy source that can independently meet all human energy needs due to its abundance. Yet its intermittencies and land availability constraints pose as the grand challenges for solar conversion process and demand high conversion efficiency and synergistically integrated solutions.
Our group focuses on developing and optimizing novel systems/processes to provide the energy requirements in the desired forms (transportation fuel, fertilizer, chemicals, electricity, heating) using solar energy. The fact that fossil resources will be in place for another century is not ignored in our studies and transition solutions using renewable energy sources and fossil resources in tandem are also considered.
- Baseload Power Cycles from Solar Energy: Power generation is among the fastest growing sector and accounts for major stationary source (~40%) of global CO2 emission. Photovoltaic cells and concentrated solar plants (CSPs) are the two main power generation processes from solar energy. Existing CSPs remain far from its thermodynamically achievable efficiency limit. We investigated solar thermal water power cycle and discovered opportunities by identifying exergy losses, analyzing different heat integration techniques, and possible amalgamation with other chemical processes.
- High Density, Efficient, Grid-Level Energy Storage from Renewable Energy: Due to the intermittency of renewable energy, energy storage is indispensable for providing continuous power. The current use of non-hydro renewable energy source is limited to peak shaving instead of baseload applications. In order to provide GWh-level continuous power from renewable energy, high storage efficiency and low storage volume are highly desirable for an efficiency energy storage. Our research focuses on chemical-based energy storage cycles, such as carbon storage cycles (CSCs) and hydrogen water storage cycles, that convert solar energy into different forms of energy.
- Biofuel Production from Biomass: Petroleum derived liquid hydrocarbons have been the predominant fuel for the transportation sector. Concerns in green house gas (GHG) emission and scarcity of petroleum resource pushed for advancement for fuel production from alternative carbon sources such as biomass. However, supply of sustainably available (SA) is limited and standalone biomass-derived liquid fuel production is relatively low (30-40%). We investigated opportunities to increase biomass carbon conversion to liquid fuel by using supplemental non-carbon energy, such as solar energy.
- Biomass Processing and Integrated Biorefineries: More than 90% of the commodity chemicals produced in US are derived from fossil resources. Fossil fuel usage for energy and chemical production is a large contributor to the generation of GHG emissions. Substitution of fossil resources with biomass is one of the most promising alternatives for GHG reduction because carbon is withdrawn from the atmosphere via photosynthesis during feedstock growth and then is released upon combustion. In a more general sense, a biorefinery is a processing facility or a cluster of processing facilities that transform biomass into various value-added chemicals and forms of energy. Determining processes for a biorefinery design has been limited to heuristic approach and the entire biomass conversion reaction system is not well understood. Our research in this area focuses on developing a holistic approach to identify, create, evaluate new production routes and integration opportunities.
- Process Design, Synthesis, and Discovery: We pursue the systematic development of new processes which meet the specified performance criteria of maximize carbon efficiency, energy efficiency, and minimum cost or maximum profit. Our approaches are based on an optimization framework where discrete and continuous decisions are modeled explicitly and we also utilize process simulation software such as AspenPlus. Our research focuses on (i) simulation, design, synthesis,and optimization of novel reaction networks for processes converting biomass to commodity chemicals and transportation fuels, (ii) design and optimization of processes that convert solar thermal into electricity, hydrogen, clean water, and fertilizer.
- Macroscopic Systems Analysis and Integration: The grand challenges of a solar economy are highly intertwined. Considering the varying constraints in land availability and renewable energy intermittent nature, it is inevitable that the energy landscape of the future will not be dominated by a single source. Therefore, in order to enable a sustainable economy, we pursue to fully understand and appreciate the integrated nature of various energy resources and processes. Our research focuses on systematic analysis of the energy landscape to determine the limitations of different energy resources and assess their impacts to the existing and future energy demands.
- Mathematical Modelling, Computational Optimization, and Analytic: Modeling process synthesis and problems in reaction engineering result in mixed-integer linear and nonlinear optimization formulations. We have studied modeling issues in process superstructure, heat integration, and reactor based systems.