Column: Plasma arc gasification could solve Oahu’s landfill problems

Waste management on Oahu has always been a challenging endeavor, and if recent events have taught us anything it is that we need to have more financially and environmentally sustainable infrastructure. The question is: What does Oahu need? Does Oahu need to perpetually struggle with deciding where to locate new landfills and suck up precious land use, or would they adopt a new technology if it came their way?

Oahu generates some 800,000 tons of nonrecyclable waste each year that is currently disposed at Waimanalo Gulch Landfill (WGL) and Honolulu Program of Waste Energy Recovery (HPOWER). HPOWER currently operates at 2,000 tons/day capacity and supplies Oahu with approximately 8.5% of the island’s electricity demand.

However, HPOWER cannot handle all of the waste generated each year, and produces its own fly ash and residue that need to be disposed, such that 340,000 tons of waste still need to be placed in WGL and another landfill each year, increasing with population growth.

The question we must ask is: Are we fed up of landfill discussions and landfill politics? If you want real environmental sustainability, then plasma technology is clearly the choice. Plasma arc gasification (PAG) heats water to temperatures of 15,000°C, vaporizing all salts into their elemental ions. This is a more effective method of handling waste and it produces fewer emissions when compared with HPOWER.

Sulfur dioxide and mercury emissions are reduced by half; nitrogen oxides reduced to a fifth; and dioxin furans are made absent. Any type of non-nuclear waste can also be processed, removing the necessity of having to ship hazardous waste off island. The broken-down municipal waste is separated by PAG into synthetic gas that drives a turbine for electrical energy and coarse slag aggregate that can be used in concrete and asphalt.

An economic study conducted at the University of Hawaii determined that building two PAG 1,000 ton/day facilities would shrink WGL’s footprint down to 2% of its current footprint, and eliminate the need for new landfills on Oahu. Further, the city can make money off of electricity and slag aggregate sales, which can then be used to improve the lives of Oahu’s residents.

In 2012, Honolulu’s mayor tasked a committee to find additional landfill locations on Oahu. The committee located 11 possible sites and estimated that a new landfill project will be needed by the year 2028 and construction would last 10 years. But that is not what we need.

With PAG technology, we can mine waste in WGL and handle new waste generated each year at a rate such that we do not need a new landfill and we also reduce the size of WGL. This spares the island from unnecessary construction and zoning.

Moreover, PAG can generate an additional 7% of clean energy toward Oahu’s total electricity demand. This renewable energy means lower pollution levels — and lesser disease, global warming or plant damage.

Lastly, if implemented correctly, using right-sized PAG facilities, Oahu has the potential, along with HPOWER, to generate plenty profits that can be used for conservation, health, education, disaster relief, roads, storm water or whatever Oahu residents need. The capital cost? About $385 million to slow down WGL growth to 3% of its current level and generate $72 million/year in profits by adding one PAG plant; $770 million to eliminate the need for another landfill altogether, reduce the present footprint of WGL to 2% its present size, and generate $206 million/year in profits by adding two PAG plants.

The future is in our hands. It is time that Oahu develops new technologies to better the lives of her residents and push the world towards a cleaner tomorrow.

Amarjit Singh is professor and Bailey Hopkins a graduate research assistant in the Department of Civil and Environmental Engineering, University of Hawaii-Manoa. The authors have no conflict of interest in recommending PAG, and the opinions presented are their own.