Emre Gençer

A synergistic biorefinery based on catalytic conversion of lignin prior to cellulose starting from lignocellulosic biomass

Current biomass utilization processes do not make use of lignin beyond its heat value. Here we report on a bimetallic Zn/Pd/C catalyst that converts lignin in intact lignocellulosic biomass directly into two methoxyphenol products, leaving behind the carbohydrates as a solid residue. Genetically modified poplar enhanced in syringyl (S) monomer content yields only a single product, dihydroeugenol. Lignin-derived methoxyphenols can be deoxygenated further to propylcyclohexane. The leftover carbohydrate residue is hydrolyzed by cellulases to give glucose in 95% yield, which is comparable to lignin-free cellulose (solka floc). New conversion pathways to useful fuels and chemicals are proposed based on the efficient conversion of lignin into intact hydrocarbons.

Round-the-clock power supply and a sustainable economy via synergistic integration of solar thermal power and hydrogen processes

Significance Diminishing fossil fuel resources and increasing atmospheric greenhouse gases present a compelling case for transitioning to a sustainable economy where all human needs can be met by using abundant solar energy. In this paper, we introduce “hydricity,” a paradigm that proposes synergistic coproduction of solar thermal power and hydrogen. We realize hydricity by judiciously integrating solar water power cycle, solar thermal hydrogen production techniques, and turbine-based hydrogen power cycle and by suitably improving each one for compatibility and beneficial interaction. The proposed hydricity concept presents a potential breakthrough solution for continuous and efficient power supply and also an exciting opportunity to envision and create a sustainable economy to meet all the human needs—namely, food, chemicals, transportation, heating, and electricity. We introduce a paradigm—“hydricity”—that involves the coproduction of hydrogen and electricity from solar thermal energy and their judicious use to enable a sustainable economy. We identify and implement synergistic integrations while improving each of the two individual processes. When the proposed integrated process is operated in a standalone, solely power production mode, the resulting solar water power cycle can generate electricity with unprecedented efficiencies of 40–46%. Similarly, in standalone hydrogen mode, pressurized hydrogen is produced at efficiencies approaching ∼50%. In the coproduction mode, the coproduced hydrogen is stored for uninterrupted solar power production. When sunlight is unavailable, we envision that the stored hydrogen is used in a “turbine”-based hydrogen water power (H2WP) cycle with the calculated hydrogen-to-electricity efficiency of 65–70%, which is comparable to the fuel cell efficiencies. The H2WP cycle uses much of the same equipment as the solar water power cycle, reducing capital outlays. The overall sun-to-electricity efficiency of the hydricity process, averaged over a 24-h cycle, is shown to approach ∼35%, which is nearly the efficiency attained by using the best multijunction photovoltaic cells along with batteries. In comparison, our proposed process has the following advantages: (i) It stores energy thermochemically with a two- to threefold higher density, (ii) coproduced hydrogen has alternate uses in transportation/chemical/petrochemical industries, and (iii) unlike batteries, the stored energy does not discharge over time and the storage medium does not degrade with repeated uses.

Strategy to synthesize integrated solar energy coproduction processes with optimal process intensification. Case study: Efficient solar thermal hydrogen production

Abstract The development and implementation of alternative energy conversion techniques using renewable energy sources is critical for a sustainable economy. Among renewable energy sources, solar energy is prominent due to its abundance. Towards a sustainable economy, this paper presents a process design concept to synthesize Solar Electricity, Water, Food and Chemical (SEWFAC) processes. The proposed approach entails systematic synthesis of energy efficient, synergistic processes incorporating process intensification for optimal utilization of resources. The objective is the development of coproduction processes around the clock on an as-needed basis. A general strategy and detailed analysis to synthesize efficient solar thermal hydrogen production processes through solar thermal power cogeneration. Process simulations and optimizations are performed using an integrated MATLAB and Aspen Plus modeling environment. The proposed process designs are evaluated based on the various metrics introduced. Process designs are estimated to achieve 11% higher exergy efficiency compared to the traditional processes.

Directing solar photons to sustainably meet food, energy, and water needs

As we approach a “Full Earth” of over ten billion people within the next century, unprecedented demands will be placed on food, energy and water (FEW) supplies. The grand challenge before us is to sustainably meet humanity’s FEW needs using scarcer resources. To overcome this challenge, we propose the utilization of the entire solar spectrum by redirecting solar photons to maximize FEW production from a given land area. We present novel solar spectrum unbundling FEW systems (SUFEWS), which can meet FEW needs locally while reducing the overall environmental impact of meeting these needs. The ability to meet FEW needs locally is critical, as significant population growth is expected in less-developed areas of the world. The proposed system presents a solution to harness the same amount of solar products (crops, electricity, and purified water) that could otherwise require ~60% more land if SUFEWS were not used—a major step for Full Earth preparedness.