Biowaste to biofuels conversion simplified with new process

Researchers in Canada claim to have found a simpler, cleaner way to produce fuel from biowaste such as sewage.

Currently, biowaste is converted into biofuel with a two-step process. Biomass is converted into a biocrude oil with a chemical and thermal process. The second stage is refining, where hydrogen is added under high pressure and heat, serving to remove contaminants such as sulphur, nitrogen and oxygen.

According to a statement from the University of Calgary, this two-step process has a number of issues. Hydrogen is expensive, the processes are energy intensive, and carbon waste is left over in the form of char and CO2 emissions.

To solve this, the scientists from the University of Calgary have developed a process which “simultaneously produces and upgrades bio-oil in one step and without the need for high pressures,” according to Hua Song, an associate professor of chemical and petroleum engineering.

The process uses methane instead of hydrogen for the purification process. They used the methane directly in the crude stage, then removed the hydrogen from the methane during the purification process, as hydrogen is still required for removing impurities in the crude oil.

Key to the breakthrough is a catalyst the researchers developed at Canadian Light Source, which reacted with the methane, causing it to release hydrogen. The researchers then coated the catalyst, dubbed HZSM-5, with different materials to improve its ability to react with methane.

Initial tests with the new catalyst have apparently shown it is more efficient and lower cost method of producing biofuels from waste, which also leads to better quality, more stable biofuel with significantly lower greenhouse gas emissions.

"This puts biofuel closer to being a good substitute for fossil fuels," said Song, explaining the potentially huge significance of the findings.

Song and colleagues’ research has been published in the journal Fuel.