The interest in toxic trash also is driven by a city requirement that the expensive waste converter not cost taxpayers more than they pay to bury their trash in a landfill. Hanneman said he doesn't believe that can happen without taking the higher-value hazardous wastes, effectively subsidizing the high-tech disposal of municipal trash.
"They are going to have to look at electronic waste, tires and medical wastes so that they can charge a higher fee to put it into the system," Hanneman said of the developer, U.S. Science & Technology of Sacramento. USST maintains that the proposal pencils out on household wastes alone - at least 500 tons a day - given current revenue forecasts for electricity sales.
William Ludwig, the company's chief executive officer, said his company is exploring hazardous wastes not out of necessity but in order to possibly increase the revenue it could share with the city.
"Whether we can provide an additional premium, we don't know yet," Ludwig said. "We're going after the stockpiles of tires. We're going after (electronic) waste."
On Feb. 26, the City Council approved the project in concept and authorized staff members to negotiate exclusively with USST for up to 90 days.
Four council members interviewed Tuesday said they would consider toxic and infectious waste so long as the developer could demonstrate the safety of its transportation, storage, handling and processing.
"Those are going to be very hard questions," said Chuck Dalldorf, special assistant to Mayor Heather Fargo. Councilwoman Lauren Hammond said, "The idea of finding new revenue sources for the city intrigues me, but they've got to prove to us it will work."
The city manager's office has touted the project as an environmentally superior alternative to land-filling household garbage. The city spends $8 million a year to haul about 146,000 tons of residential trash over the Sierra to a landfill near Sparks, Nevada. Potential sites under discussion for a garbage-to-energy plant include Aerojet's rocket manufacturing complex in Rancho Cordova, the Sacramento Recycling & Transfer Station on Fruitridge Road and Sacramento County's Kiefer Landfill.
Adding hazardous materials to the plant's waste stream would require more environmental analysis and invite greater public scrutiny.
"There is more public opposition when they talk about these more hazardous feedstocks," said Robert Williams, a UC Davis research engineer who has evaluated waste-to-energy technologies for state regulators. The proposed power plant would use a process called plasma gasification, which disintegrates materials using an electrified gas, or plasma, torched to temperatures approaching those at the surface of the sun. Organic wastes are vaporized, producing a synthetic gas - "syngas" - that can be burned to run a turbine to generate electricity for sale.
Metals and other inorganic materials emerge as lava and cool into carbon-black slag resembling obsidian stone, which can be sold for construction materials. Gold, copper and other precious metals also are recoverable.
Westinghouse Corp. developed plasma gasification in the 1960s to destroy polychlorinated biphenyls - PCBs - toxic cooling compounds used in electrical transformers. Its application to municipal solid waste is relatively new. No commercial-scale plasma gasification plants exist in the United States, although license-holders of the technology have approached several cities that are short on landfill in the United States and abroad.
InEnTec Medical Services appeared well on its way toward building a medical waste plant on the outskirts of Red Bluff five years ago when a San Francisco environmental group, Greenaction for Health and Environmental Justice, began asking questions.
Several residents grew irate over the prospect of infectious surgery room wastes being trucked into town daily. Citizen appeals and lawsuits ensued, but InEnTec's Tehama County permits ultimately were upheld. The company has not announced whether it will proceed with construction. California hospitals have no alternative but to incinerate their hazardous wastes, which include diseased organs, body parts, chemotherapy wastes and expired pharmaceuticals.
But the closest furnaces are in Utah and Texas. Disposal costs range from $300 to $1,100 a ton, said Ludwig. Ludwig said his company also is exploring the disposal of Aerojet's rocket manufacturing wastes.
"Aerojet suggested that they had some spent fuels," Ludwig said. "We can take almost everything as long as there's enough BTU (British thermal unit) value to generate the right amount of syngas and electricity."
Aerojet officials said discussions concerning the proposed Sacramento plant have been limited to the siting of the plant.