Trees grown from wastewater to fuel our cars

Almost 4000 pongamia trees have been planted at two sewage treatment plants in the towns of Boonah and Toogoolawah, Queensland, where they will be irrigated by treated wastewater as part of an Australian-first trial to produce biodiesel.

The trial is being run by Queensland Urban Utilities, which planted the trees on four hectares of unused land around the sewage treatment plants. The plan is to extract oil from the seeds of the trees and convert it into biodiesel.

“We hope to harvest enough seeds to yield at least 12,000 litres of biodiesel every year — that’s enough to run approximately 24 cars for a year,” said Queensland Urban Utilities spokesperson Michelle Cull.

The trial has been commended by the University of Queensland’s Professor Peter Gresshoff, who described it as “an exciting advance from university-focused research to practical application”.

“The advantage of growing this particular type of tree is that their seeds produce a higher quality and quantity of oil than other biodiesel crops,” Professor Gresshoff said. He noted that biodiesel is better for the environment than fossil fuels because it’s a sustainable source of energy that emits fewer greenhouse gases into the atmosphere.

According to Cull, the sewage plant component is “just the first step” of the trial.

“In the next stage of the trial, we’ll be establishing a research facility where we’ll test using wastewater to irrigate other crops,” she said.

“It’s all part of our renewable energy plan, which aims to reduce our carbon footprint and keep costs down.”  

Top image caption: Queensland Urban Utilities’ Michelle Cull and the University of Queensland’s Professor Peter Gresshoff.