Oahu’s Construction Waste Could Become Food For Crops At A New Kapolei Facility
An innovative recycling plant also hopes to provide a process to turn invasive weeds and grasses into something more useful.
Joelle Simonpietri and her crew are clearing invasive flora, concrete detritus and derelict concrete-making machinery from a property in Kapolei that they hope will eventually close the loop on a significant portion of Oahu鈥檚 unrecycled waste.
The site is slated to become the Aloha Sustainable Materials Recycling and Fertilizer Facility, a $40 million project that would make biofuel and bioenergy from construction and demolition waste and transform invasive plants and grasses into biochar, an increasingly popular and climate friendly form of fertilizer.
In 2022, a quarter of Oahu’s 1.6 million tons of waste came from construction and demolition; 11% was not recycled.
Most of the island’s waste goes to Honolulu’s H-Power plant but much of the construction and demolition waste — treated or painted woods, for example — is dumped.
Like H-Power, Simonpietri Enterprise’s proprietary technology will convert about 200 tons a day of that waste into power and gas and ash but in a low-emissions, air-starved process called pyrolysis.
“It’s more like pressure cooking,” Simonpietri said.
The gases harnessed in the process will be used to create biofuels and only ash — about 10% of the total mass originally fed through the equipment — will need to be thrown away.
Biochar follows a similar process but the black residue produced by burning organic material is prized by farmers.
Simonpietri has received hundreds of thousands of dollars in federal grants, the latest aimed at the biochar work.
The Kapolei project was initially intended to focus on the construction waste. But community input over the last two years made it clear there was also a need to dispose of invasive grasses and plants that are proliferating in Hawaii.
“Fast forwarding to now, we鈥檙e planning for our plant to have two different waste streams coming in,鈥 Simonpietri said.
Invasive species have long been a concern for Hawaii. The issue has gotten even more attention since the Aug. 8 wildfires on Maui because non-native African grasses were shown to be particularly problematic in helping fuel those fires. They’re prone to fire and occupy about a quarter of Hawaii’s land.
Guinea grass collected on Oahu has already been converted into biochar and syngas at the U.S. Department of Energy’s National Center for Hydrogen Technology, in the first phase of Simonpietri’s research.
A Native Hawaiian plant nursery and landscaper, , harvested that grass as part of a wildfire mitigation project and the biochar created at the USDE center is now being tested on crops by the University of Hawaii.
Biochar could become a viable alternative to the fertilizers shipped in from the mainland, which have been subject to price hikes for years.
“Everybody loves the idea of biochar but there’s really not that much supply,” Simonpietri said.
The biochar facility will take just about any organic material. That includes green waste that could harbor invasive pests such as coconut rhinoceros beetles and little fire ants, which will be incinerated at 1,500 degrees along with the other green waste.
Simonpietri says the new facility may also help farmers find new revenue streams.
“Right now we have hundreds of thousands of pounds of chicken manure imported every year,” she said. “Meanwhile, we have all these poultry farms with no ability for that manure to be used because there’s no certified processing facility.”
That manure, along with much more, can become biochar.
The Legislature is also trying to deal with the issue of Oahu’s construction and demolition waste this year.
Sen. Maile Shimabukuro introduced two measures aimed at diverting construction and demolition waste from landfills by incentivizing the use of cleaner, more environmentally materials.
Oahu’s landfills, both on the Westside, would benefit from more recycling and waste diversion, according to Shimabukuro. The drier Leeward Coast is also more prone to wildfires due to the climate and prevalence of invasive grasses.
Shimabukuro’s bills have failed in the Senate although a companion bill in the House is still alive and would create a working group to address many of those issues.
“Maybe that will for the next session be a starting point,” Shimabukuro said. “Other states have been successful in recycling a lot of their construction waste and that’s all the advocates are hoping for.”
“Hawaii Grown” is funded in part by grants from the Stupski Foundation, Ulupono Fund at the Hawaii Community Foundation and the Frost Family Foundation.
