Island solution

The Hawaiian Islands are known for their beaches and a rich blend of American, Asian and Polynesian cultures. They may be a slice of paradise, but that doesn’t make them immune to the same waste management issues that face any other state or municipality in the U.S. In fact, Hawaii has its own unique challenges that its mainland counterparts don’t have to worry as much about.

Depending on which island you are on, landfill space could be nearing capacity. The trash can’t be shipped to another state that has the room and lower tipping fees. Recycling isn’t always profitable or the best option for the environment if in order to recycle, commodities are shipped thousands of miles away.

Lori Kahikina, director of environmental services for the City and County of Honolulu explains on the mainland, “when someone says they are able to accomplish no landfill, what they are really doing is trucking it out of their city limits to someone else. We don’t have that luxury. We are in the middle of the Pacific. I can’t just pick up my trash and take it to California.”

Instead, the City and County of Honolulu, which makes up the island of Oahu, has another method to get rid of its waste: waste-to-energy (WTE). Kahikina says it is the best option to divert as much material from the landfill as possible. In fact, thanks to H-Power, the landfill in Honolulu has about 40 years of useful landfill life left and, with a host of other potential materials that can be diverted at H-Power, the city and county hope to stretch its life out even further.
 

History lessons

Honolulu constructed a refuse-derived fuel incinerator in the early 1980s for $150 million. The city and county invested an additional $40 million to provide scrubbers for the facility. The RDF facility was sold to Ford Motor Co., Dearborn, Michigan, in 1986 for $312.5 million and through a lease-back agreement, the city and county bought the facility back 17 years later at a residual value of $18 million. The city and county then invested another $50 million in air pollution control improvements, which were completed in 2009.

“Ongoing, we are spending $48 million to refurbish the system and construction should be complete in 2017,” says Kahikina.

H-Power also has a mass-burn unit that was conceived of in the mid-2000s. Kahikina says that part of the facility was constructed for $320 million using general obligation bonds and was completed in August 2012, “four months ahead of schedule and on budget.”

Morristown, New Jersey-based Covanta operates the facility. The combined plant has a $100 million operating budget, which includes ash disposal and debt service. H-Power generates $45 million per year in tipping fees, $70 million per year in electrical revenues and $5 million per year in recycled ferrous and nonferrous metals, leaving about $20 million in net revenue per year for the city.
 

Combining forces

The facility employs 170 people from Covanta. The RDF side of the facility processes 2,000 tons per day of municipal solid waste (MSW) for steam and electricity. The mass-burn side of the facility does not require any preprocessing and goes straight into boilers to produce electricity. It has a capacity of 1,000 tons per day. The combined plant has an annual capacity of 900,000 tons; however, only about 700,000 tons are currently going through the facility.

The city and county provide trash, recycling and once-a-month bulky waste pickup free of charge to residents. Bulky waste, municipal solid waste (MSW) and tires with and without rims are all going to H-Power.

Materials bound for the RDF side of the facility are shredded. H-Power uses two shredders to process MSW on the RDF side. A primary shredder shreds all incoming MSW and a secondary shredder shreds material that is still greater than 5 inches after the first shred. The RDF facility also has drum magnets to recover ferrous metals both pre- and postcombustion. For nonferrous metals an eddy current separator is used postcombustion by both the RDF and mass-burn facilities. The mass-burn facility does not require prepossessing and uses a crane to load materials from the pit into the boilers. The water wall boilers incinerate the waste at 2,000 degrees Fahrenheit and generate 850 pounds per square inch (psi) of steam to drive the steam turbine generator.

H-Power sells its electricity to Hawaiian Electric Co. (HECO) for about 20 cents per kilowatt hour. The facility has a 20-year power purchase agreement with HECO and is currently producing 400,000 megawatt-hours of electricity per year.

Eearning recognition

H-Power has earned recognition from the Solid Waste Association of North America (SWANA), Silver Spring, Maryland, for its operation. It earned a silver award in 2013 and took home the top honor Gold Excellence Award in 2014 in the WTE category. Kahikina says it is the only facility that currently has both RDF and mass-burn technologies operating side-by-side.

The mass-burn facility features very-low nitrogen oxide (VLN) technology designed to remove excess air from the boiler while increasing boiler efficiencies. A recycled water system and irrigation reduce the facility’s potable water use.

“We have practically eliminated what is going to the landfill. We are in the 90 percent diversion range,” says Kahikina.

The materials currently going to the landfill are nonrecyclable/noncombustible materials, ash residue and wastewater sludge, but that soon may change. By summer, the city and county plan to begin incinerating sludge. The city has contracted with Covanta to build a sludge intake station. Kahikina says H-Power will be one of the first WTE facilities to use wastewater sludge as feedstock.

“Now, if ever in our industry someone finds some way to reuse the ash with the EPA and Department of Health’s blessing, we would be golden,” Kahikina says. “We would have barely anything going to the landfill.”

An intake station will allow the sludge to be injected directly into the boiler where it will be mixed in with other waste. The intake station is expected to be completed by May 2015. If tests go smoothly, the sludge will begin to be incinerated this summer.

The facility also is looking at other materials it can use, including auto shredder residue (ASR) and medical waste. H-Power also accepts green waste contaminated by the coconut rhinoceros beetle. When the U.S. Department of Agriculture finds an infested tree, it cannot be composted so it goes to H-Power.
 

Challenges

H-Power’s operation is not without challenges. Ferrous and nonferrous prices are down, which also affects profits. H-Power also competes with the coal industry, which is less expensive for HECO to use than the electricity H-Power produces. The recycling program, which is contracted out, also costs the city money.

On the mainland, recyclable commodities can be trucked to nearby facilities that use the material. Such is not the case in Hawaii.

“Even though we are recycling paper, plastics, metal and cardboard, we are still shipping it to the mainland,” explains Kahikina. Even with the expense and challenges, recycling is not a program she is willing to take away from residents.

“If we stopped our recycling, we would be criticized heavily by the community. They want to recycle. When you look at it from the global perspective, it makes sense,” Kahikina says. “We are saving trees and plastic, but we are still burning fossil fuel to send it to the mainland.”

Kahikina says she is a huge proponent of H-Power. “I would love to just burn it all, but I understand there are emotional issues involved,” she says. “People want to do recycling and composting, so however we can, we are trying to divert as much as we can from the landfill.”

The author is managing editor of Renewable Energy from Waste and can be reached at ksmith@gie.net.