Recycling plants are expensive and there’s not a robust market in Hawaii for the products they’d produce, so all glass, plastic, paper and metal trash Honolulu residents want to recycle has to be shipped somewhere else.

Oahu residents Naomi Shigenaga, Scotty Anderson, Sally Mist and Diana Bonsignore all wanted to know how the carbon impact of shipping recyclables off-island compared to burning them for electricity.

Episode 4 of Civil Beat’s podcast “Are We Doomed? And Other Burning Environmental Questions” explores the greenhouse gas impact of both.

The City and County of Honolulu hasn’t analyzed the carbon impact of shipping 235,000 tons of plastic, paper, metal and glass to places like California, Alabama, Taiwan or Malaysia to be recycled into new items.

But Dan Rutherford, who studies marine transportation for the International Council on Clean Transportation, estimates the ships transporting Honolulu’s recyclables emitted 28,914 tons of CO2 into the atmosphere last year.

Rutherford stresses that this is an estimate as he had to make assumptions about the type of ships and what routes they took to the final destination.

Naomi Shigenaga, a Civil Beat reader, asked if Oahu’s carbon footprint would be smaller if all recyclables were sent to H-Power instead. The company’s 29-year-old trash incinerator in Kapolei burns about 700,000 tons of trash a year and generates 8% to 10% of the island’s electricity.

Pieter Matthews, a city contractor with an engineering firm who’s worked at H-Power for the last decade, said he’d welcome more paper and light plastics at the facility because they are “really easy to burn.”

H-Power employees have to layer the trash being fed into the fire so the temperature stays stable. Bigger items, like mattresses and heavy plastics, take longer to burn and have to be intermixed with lighter materials.

H-Power can’t burn metals or glass, so Matthews said those materials would still have to be shipped off-island for recycling, but more paper and plastics could help the operation run smoothly.

“We can use it here locally to displace foreign oil,” he said. “It actually makes a little bit more sense to take most of those recyclables and use them here as renewable energy than ship them someplace far away.”

But trash incinerators don’t produce truly renewable or clean energy, some experts say.

The U.S. EPA only considers about 40 percent of the facility’s carbon emissions when comparing it to other ways to generate electricity. That’s because it subtracts “biogenic CO2,” created from burning food waste, paper, sewage and other municipal waste, from the facility’s overall greenhouse gas emissions.

“So what it looks like on paper then is that waste to energy is really clean and low carbon,” said Nicole Chatterson, director of Zero Waste Oahu. “And when you dig into it a little bit more you’re like, ‘OK, that’s not actually the case.’”

In 2018, H-Power emitted 682,759 tons of CO2 into the atmosphere. Chatterson points out that the United Nations has recommended against classifying electricity from trash incinerators as renewable or green because “the atmosphere does not differentiate between a molecule of biogenic CO2 and a molecule of fossil-derived CO2.”

Chatterson said that while the carbon impact of shipping recycling off-island is troubling, it’s probably still better to continue recycling since more greenhouse gasses would be emitted to create new products that could otherwise be made of recycled material.

The conundrum of how to ethically deal with our trash is part of the reason she recently co-founded Zero Waste Oahu, a local coalition aiming to reduce all waste by 90%.

“We’re talking about redesigning systems so that people don’t have to work so hard to do the right thing,” she said.

But she said she’s encountered institutional barriers to cutting down on waste, mainly the City and County of Honolulu’s contract with Covanta, the company operating H-Power, which says the city must provide 800,000 tons of burnable material a year or pay the difference.

Honolulu fell about 49,000 tons short last year. The Department of Environmental Services said they paid Covanta $578,996.78 for “Lost Electrical Energy Revenue” for the shortfall.

“Are We Doomed And Other Burning Environmental Questions” is funded in part by grants from the Environmental Funders Group of the Hawaii Community Foundation and the Frost Family Foundation.