Flower Power

Sustainable Raleigh Spotlight Feature

News posted Jul. 01, 2016 - 6:00 am

If you walk along the Neuse River Greenway Trail this weekend, you’ll see more than 50 acres of sunflowers saluting the sun. The sunflowers do more than just brighten the trail, however. Come harvest time, they’ll become biodiesel for the City of Raleigh’s diesel trucks.

Sunflower seeds have a high oil content, and are an ideal source for biofuel, which burns cleaner than fossil fuels.

“We do a lot of hauling,” said Resource Recovery Division Superintendent Tim Woody, “so anything to reduce the cost of our fuel helps.” Woody and his staff at the Neuse River Resource Recovery Facility (NRRRF) manage the project.

They also grow corn, soybeans and wheat on their 1,000-acre farm, where they’ve had to get creative with the sludge produced every day in the fast-growing region. One of the ways they distribute these products is by producing a highly stabilized product known as biosolids, which serves as a nutrient-rich soil amendment.

The NRRRF produces 2,000 tons of sludge a day as part of the wastewater treatment process and the plant uses chemical and biological processes to stabilize the solid waste into a resource.

“We’re not your typical City Department,” said Woody, “We do some unique things out here. We’ve got our own farm and we can produce our own fuels. And we embrace that.”

The staff also irrigates the fields with recycled water to keep the sunflowers and the other crops happy, which in turn makes the staff happy, according to Woody. “They are a great morale boost,” he said.

After harvest in September the team will convert the seeds into biofuel with their very own biodiesel processor. The department, with help from the Office of Sustainability, received a grant in 2009 to turn a 46-foot trailer into a biodiesel manufacturer on wheels.

The processor crushes and converts sunflower seeds into biodiesel. A thick, cakey meal is left behind, and can be used for compost or animal feed.

Assistant Superintendent Jeremy Blackmon said he likes the simple efficiency of the process. “The sludge comes in, we turn it into biosolids, we fertilize the crops, and then we convert the crops into fuel,” he said. “It’s pretty neat.”

The biodiesel processor can convert any vegetable oil into fuel, including soybeans, which also grow on the farm. It can even process cooking grease, and Blackmon suggested using the process for waste vegetable oil collected from household kitchens.

Meanwhile, the sunflower harvest could produce up to 35 gallons of biodiesel per acre. “If the deer will stop eating the sunflowers,” said Blackmon.

Woody and Blackmon have other energy projects in the works. “There are all kinds of ways for the wastewater industry to couple with alternative energy production,” Woody said. “Sometimes it’s just a matter of expanding your thoughts a little bit and getting outside the box.”

The waving sunflower heads nod their approval. And if you miss their blooms, never fear; Blackmon said another batch will bloom in early fall. Stay tuned for more cool energy projects from the Resource Recovery Division.

This Sustainable Raleigh Spotlight is one in a series of City of Raleigh sustainability stories.

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