(4ol) Energy-Efficient Carbon Sequestration in Achieving Net-Zero Emissions By Biobased Fuel, Chemicals and Materials

Greenhouse emissions from intensive fossil energy use have caused global warming, and net-zero emissions are globally admitted to mitigate climate change. Transportation and industrial sectors account for over 50 % of greenhouse gas (GHG) emissions. Biofuels, biochemicals, biomaterials, and energy-efficient industrial technologies can significantly reduce GHG emissions and assist the United States in aching the goal of net-zero GHG emissions by 2050 [1]. Therefore, my research group will focus on the sustainable and renewable biomanufacturing of bioenergy/biofuel, biochemicals, and biomaterials in the first 3-5 years: 1) sustainable energy-efficient ultrasonic bioprocessing in separation, purification, and extraction, 2) biomanufacturing of biokerosene, aviation fuel, biolubricants, and biochemicals from lipids derived from crops, algae, and lignocellulosic sugar fermentation.

1. Sustainable energy-efficient ultrasonic bioprocessing in liquid separation

Distillation is ubiquitous for liquid separation and purification in the chemical and process industry, and the separation depends on the substances' boiling points. The temperature can be significantly varied along the height of the distillation column based on the boiling points of the distillate and bottom product (Fig 1). The second law constrained the heat exchange between the vapor and liquid inside the column in each tray/stage and resulted in low efficiency, about 10 to 15 %. In addition, significant energy is required to heat the reboiler and cool the condenser. Over 40,000 distillation columns are used in the United States and account for about 95 % of energy consumption in the separation and about 6 % of total energy consumption (⁓ 6 quadrillions of BTU) in the United States. Moreover, azeotropic mixture separation is a challenge for regular distillation. Therefore, efficient separation technologies, such as ultrasonic bioprocessing in separation [2], are desired to replace distillation.

Unlike distillation, ultrasonic bioprocessing in separation depends on the substances' viscosities and surface tension. The electrically charged piezoelectric transducers generate high-frequency vibration, resulting in cavitation to form atomized droplets. Cavitation can result in certain chemicals becoming enriched on the surface of the cavitation bubbles, but other chemicals become depleted on the cavitation bubbles' surface. Our previous study has shown the enrichment or depletion of some substances in ultrasonic separation. Therefore, ultrasonic separation can enrich chemicals in mist or concentrate chemicals in bulk solution. With electricity becoming wholly renewable from wind, solar, and biomass in the future, ultrasonic separation can drive the liquid separation to achieve net-zero GHG emissions. In addition, our previous research funded by DOE (DE-EE0007888) and NSF (16-24812 I/UCRC IA) has shown that ultrasonic separation can bypass the azeotrope point [3,4], which the regular distillation process cannot achieve. Moreover, ultrasonic separation is a nonthermal process without heating, and the fully electrified ultrasonic transducer will be a cleaning process without increasing carbon emissions. According to this concept, we are invited to submit the full proposal to DOE Industrial Efficiency and Decarbonization Office (IEDO) FY23 DE-FOA-0002997 with the concept of the bioethanol purification from ethanol fermentation broth and sucrose concentration from sugar canes or beets to replace the distillation and evaporation process. In addition, I also applied ultrasonic separation to obtain biobutanol from acetone-butanol-ethanol (ABE) broth to test the feasibility of ultrasonic separation in the complicated system, and this concept was submitted to USDA this year. In addition, ultrasonic separation is advantageous in the food industry for heat-sensitive materials separation, such as concentrating milk before spray drying, separating flavor and color, etc. Another promising application of ultrasonic separation is in biomanufacturing sustainable aviation fuel (SAF) since it can replace energy-intensive distillation in fractionating the products into renewable diesel, SAF, etc. Moreover, ultrasonic separation can be used in wastewater treatment, desalting, water purification processes, etc.

2. Sustainable biomanufacturing of biofuel, biochemical, and biomaterials from plant-based oils

Utilization of bioenergy, biochemicals, and biomaterials can significantly reduce GHG emissions. Lipids are highly promising feedstocks that can synthesize these products. Unlike crude oil, the carbon chain lengths of fatty acids in fats/oils have a narrow range, and over 90% of fatty acids have carbon chain lengths of 16 and 18 [5]. The significant difference in the carbon chain length makes it challenging to transfer from a petroleum-based economy to a bioeconomy. Thermal cracking, catalytical cracking, and hydrocracking are generally used in the crude oil refining process, but they are not favored by sustainable bioeconomy for the high temperatures (400 to 900 ^oC), expensive catalysts and regeneration maintenance, and expensive renewable hydrogen. Sustainable energy-efficient technology is desired in reforming/refining oils/fats into various functional products. With fractions of unsaturated components ranging from 60 to 90%, the crude oil cracking/reforming can form aromatic chemicals unfavorable to use as diesel and aviation fuel because the combustion of aromatics can result in emission problems, such as PM. Here, ozonolysis is proposed to perform the cracking of oils/fats or the derivatives (such as fatty acids and fatty acid esters) to cleavage the carbon-carbon double bonds to short-chain and middle-chain fatty acids as the feedstocks to synthesize the biofuel, biochemicals, and biomaterials (Fig 2). The lipids could be obtained from crops, algae, and lignocellulosic sugar fermentation. The proposed technology has advantages in 1) room temperature cracking process, 2) high yields of targeted products (>99%), and 3) the electronization process for decarbonization to mitigate climate change.

I have collaborated with Dr. Nathan Mosier from Purdue University on the concept, and it was funded by Indiana Soybean Alliance as a seed grant since 2022. Our preliminary results showed that the resulting products, such as biofuel, biolubricants, and biomaterials, exhibited excellent qualities in their categories. I worked as the lead PI and collaborated with Dr. Mosier from Purdue University and Dr. Ignasi Palou-Rivera from RAPID at AIChE to submit the integrated project to USDA this year with the involved areas in research, extension, and education. I also obtained support from my industrial partners, such as Dow Chemical Inc., Exxon Mobil Inc., John Deer, the Andersons Inc., Lubrizol, Shell gamechanger, Indiana Soybean Alliance, etc. Fig 3 exhibits an example of the sustainable bio-economy based on soybean oil through ozone cracking to produce biofuel, biolubricants, and biopolymers, but it can apply to other oils or fats, such as corn oil, sunflower oil, beef tallow, etc. In addition, the ozonized products can also be the feedstocks for other types of essential materials in various applications, such as MOFs as catalysts.

I will assign the budget to support postdocs, graduate students, and undergraduate students. I prefer various levels of personnel involved in the research to provide vital education and research experience for their future success. I am eager to extend my previous research and continue with programmatic research related to sustainable and renewable materials. Furthermore, I am convinced we will significantly affect society using advanced technologies, sustainable/renewable energy, and chemicals. These research areas are good topics for USDA, NSF, DOE, etc.