Research at the University of Illinois to convert swine manure into oil has expanded to include more efficient technologies that use a variety of materials to produce hydrocarbon fuels.

Now human, animal, and food processing waste, as well as algae, are being used in a process called hydrothermal liquefaction (HTL). During HTL, high moisture biowaste is subjected to elevated temperatures and pressures in order to break down and reform the biowaste into a crude oil. The conversion mimics the natural geological processes that produced our current fossil fuel reserves and allows for the conversion of a wide range of feedstocks.

Yuanhui Zhang, a professor in Agricultural and Biological Engineering, said after the biowaste is converted, the resultant wastewater still contains nutrients, such as nitrogen and phosphorus, that can be used to grow algae. The algae are then fed back into the HTL reactor, as a sole feedstock or as an additive, to be converted into additional crude oil.

Synergistic process

"This synergistic process is extremely advantageous," said Zhang, "because it brings together two rivals, energy production and environment protection, to complement rather than compete with one another. We clean the waste water, we capture the carbon and we convert it into biomass and produce more crude oil. That's why our research theme is called E2 Energy — Environment Enhancing Energy. We can produce the energy, and at the same time, enhance the environment."

Zhang said they are also studying the chemistry of HTL. "We can convert biowaste into oil, but we want to better understand the fundamental mechanisms of HTL. What are the pathways of each reaction? We are looking deeper. At the same time, we are still engineers, so we are working on developing new types of continuing reactors.

"Biowaste and algae have the potential to completely replace petroleum," Zhang concluded. "Anyway, that is the grand goal."