Fueled by Flowers

A creative approach to biosolids conversion


A field of golden sunflowers stretches along the Neuse River Greenway in Raleigh, North Carolina. Their faces shift, following the sun’s path overhead.  

“Right now it looks like a sea of gold,” Tim Woody, superintendent of the Neuse River Resource Recovery Facility, told North Carolina Public Radio.

The flowers—one of several crops grown on facility land—are part of an initiative to convert biosolids, the nitrogen-rich organic materials produced by the wastewater treatment plant, into energy.

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Neuse River’s initial sunflower planting was 27 acres in 2010, funded by a $100,000 grant from the Biofuels Center of North Carolina to test the potential for crop-based biodiesel. The team added canola in 2011, and today the crop has expanded to 72 acres.

Sunflower and canola seeds contain oils that can be processed into biodiesel. The seeds produced on Neuse River land are harvested and converted to biofuel that can be mixed with diesel to help balance the facility’s energy use.

The first sunflower crop provided 29,700 pounds of oilseed that was used to produce 1,258 gallons of biodiesel—a total of 46 gallons per acre, at a cost of $2.35 per gallon. Replacing 10–20% of the 25,000 gallons of diesel fuel that the plant uses each year with biofuel will support the plant’s generators along with the backup generators at each pump station.

The seeds are currently processed off-site but in the coming years, Woody and his team plan to install the processing equipment on-site. Once the seeds are crushed, “making the biodiesel at that point is relatively easy,” he explains.  “You don’t have to do a lot to the oil. A typical recipe includes sodium hydroxide [lye], alcohol [methanol], heat, and the oil.”

We’re inspired by this creative solution. What methods of converting biosolids to energy has your organization explored? WE_bug_web


  • Rick Laughlin, APLD.

    Hi Laura Sanchez…let me say that I have been following you for several years and consider reading your column(s) every single week…high quality, right on and to the point Laura…I blog once every week for 2 3/4 years…

  • Beth Burnam.

    Nice blog; the river is the Neuse , not Neuce–spellcheck gone rogue?

    • Laura S.

      Good catch! Yes…a case of spellcheck gone rogue. 🙂
      We’re correcting it.

  • Bradford Whitty.

    The river is spelled “Neuse”, at least the 20 years I lived on the river. I have been gone 30 years now, so maybe they changed it to “Neuce”. Great idea to turn land into productive land, even more so when it is a renewable resource.

  • kwblair.

    Not to be a downer, but once the $100,000 has been depleted, Is this going to be a profitable venture for private sector? Sounds like a sizable investment of equipment / workers planting 72 acres to produce only 1,258 gallons at a end value of only $3,000. Does it pencil out when you consider labor costs, seed costs, trucking costs, not to mention diesel used by trucks for hauling oils to / from plant, oil storage tanks, piping to generators, etc.

    • Laura S.

      These are all valid questions. I’m not certain of the specifics. Perhaps we should do a follow up question and answer piece with the Neuse River Resource Recovery Facility. Thanks for the inspiration!

  • James.

    How was the cost of $2.35/gallon calculated? Does it include the farming, harvesting and processing and waste treatment costs? I’d like to see a breakdown if you have one. Thanks.

    • Laura S.

      That’s an excellent question, Mr. Yates. I don’t have access to a breakdown of the cost calculations. It may be worth reaching out to the team at the Neuse River Resource Recovery Facility to inquire.

  • Edward Couch.

    More profit and better served by just harvesting and selling seed for cash and purchasing fuel at the local 7/11….lots of wasted time, effort and energy !! Sorry for the bubble burst !

    • Laura S.

      Not to worry! It’s no bubble burst at all, Mr. Couch. We’re just interested in learning about different approaches to energy and water efficiency that organizations are exploring today.


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