Technology Will Reduce Waste, Greenhouse-Gas Emission

Ethanol plant in Brazil
This refinery in Minas Gerais, Brazil, produces ethanol (ethyl alcohol) from sugarcane. Ethanol is used worldwide mainly as biofuel additive in gasoline.

By Edwin L. Aguirre

Biofuels — liquid fuels such as ethanol and biodiesel derived from organic materials (biomass) or their waste products — can supply our energy needs in transportation and electricity generation while significantly reducing the emission of planet-warming gases. Among the scores of researchers worldwide who are developing new processes to make biofuels and evaluate their performance are mechanical engineering Asst. Prof. Hunter Mack and chemical engineering Asst. Prof. Hsi-Wu Wong.

“Since fossil fuels are a finite resource, it is important that we identify alternative renewable fuel sources,” says Mack. “First-generation biofuels like ethanol, which is made from corn or sugar cane, are an adequate first step, but we need solutions that do not disrupt the food supply or the environment while remaining clean and sustainable.”

Mack is developing quick, reliable methods for testing the potential of new biofuels for use in existing internal combustion engines and gas turbines. Additionally, he is investigating novel thermodynamic cycles to increase the efficiency of engines and turbines and cut emissions significantly.
Profs. Wong and Mack in the lab
Asst. Profs. Hsi-Wu Wong and Hunter Mack examine the reactor used in creating biofuels in the lab.

“Preliminary research has shown that by using noble gases such as argon, xenon or krypton as the working fluid in gas turbines, we can increase the turbines’ thermal efficiency by more than 20 percent,” he explains. “For domestic turbine power plants fueled by natural gas, this efficiency translates to a reduction in the amount of natural gas burned by 13.5 billion cubic feet, resulting in 1.6 billion pounds less carbon dioxide emissions.”

Mack is working with graduate student Martia Shahsavan and is collaborating with researchers at the University of California at Berkeley, the National Renewable Energy Laboratory, the Lawrence Livermore National Laboratory and the Colorado School of Mines.

Discovering New Reaction Pathways

Wong’s research, meanwhile, focuses on the recycling of solid wastes, which he says is “one of the most critical environmental issues today.”

“Discoveries of new chemical reaction pathways, or processes, to convert wastes into alternative fuels and green chemicals will enable new technologies to manufacture next-generation renewable and sustainable fuels and products,” he says.
Prof. Wong's setup in the lab
In Wong's reactor setup, a sample of biomass-waste mix in a glass tube is heated without oxygen in a furnace to 500 degrees Celsius to pyrolize (break down) the mix into biofuel, which then collects in a steel cylinder.

Wong’s goals include producing biofuels from plastics and biomass-waste mixtures, synthesizing high-value commodity products from biomass-derived feedstocks (raw materials) and generating energy from the co-processing of fossil fuels like coal and shale gas with biomass.

Assisting Wong in the lab are Ph.D. students Melisa Nallar and Peng Yu and master’s student Wilbur Zuo. Wong is also collaborating with researchers at MIT, the University of California at Santa Cruz, NASA and Aerodyne Research, Inc.

“Converting waste to energy and/or products is particularly promising, since we are cutting down waste and producing renewable energy or high-value chemicals at the same time,” he says.