One Hawai'i facility, the coal-fired AES Hawai'i power plant at Campbell Industrial Park, is a leading example of "clean" power because it uses low-sulfur, low-mercury coal and an advanced filtration system that results in reduced mercury-containing emissions.

"This is what's called a clean coal plant. We have a multiple-emissions-control system," said plant manager Matthew Riel.

Environmental Protection Agency head Mike Leavitt last month said the EPA plans to regulate mercury emissions for the first time. But the U.S. Public Interest Research Group said the EPA's proposed regulations are far too weak. Among the strictest of proposed alternatives is a 30 percent cut by 2008 in the 48 tons of mercury that U.S. power plants now emit into the atmosphere each year. The Public Interest Research Group says the technology exists to have a 90 percent cut by 2008.

"The Bush administration now seems content to let big energy companies dictate what should be a common sense decision to protect our children's health," said Moira Chapin, the organization's field organizer for Hawai'i and the western states.

Mercury can cause brain and nervous system damage, particularly to children. The Hawai'i Department of Health last year issued mercury warnings for certain fish species and recommends that top predators such as 'ahi, ono and opah be eaten no more than once every two weeks.

Ken Rubin, an associate professor in geology and geophysics at the University of Hawai'i, said atmospheric mercury can enter the ocean, where it accumulates in fish and other species. Because it is readily taken in by animals, "mercury has a harder time flushing out of systems than other metals," Rubin said.

Rubin said Hawai'i is a comparatively small source of mercury on an international scale, but Chapin noted that Hawai'i has six power plants listed on the EPA's 2002 Toxic Release Inventory for mercury air emissions. The biggest mercury generator — Hawaiian Electric's oil-fired plant at Kahe Point — is No. 184 on that list, and all the others are much lower.

Among the states, Hawai'i is 37th on the list of mercury generation from electric utilities, even though most of the Islands' electricity is produced from mercury-containing fossil fuels. But these numbers may not be useful for comparison. Many other states use a great deal more electricity, but also produce much of their power from other sources, such as hydroelectric and nuclear.

Natural gas, a fossil fuel not used for power generation in Hawai'i, is used on the Mainland and has much lower mercury levels than oil and coal, said Nolan Hirai, supervisor of the engineering section in the Department of Health's Clean Air Branch.

Chapin said that coal-fired power plants are the worst mercury polluters on the Mainland, but Hawai'i's largest coal-fueled power plant, the 180-megawatt AES Hawai'i plant, in the 2002 inventory pumped far less mercury into the atmosphere than is attributed to oil-fueled power plants.

AES Hawai'i's Riel said he believes the low mercury emissions are the result of low-mercury coal from Indonesia and a plant built in 1992 that uses comparatively new technology. The plant injects limestone dust into its furnace to capture sulfur dioxide and ammonia to take nitrogen oxides out of the emissions. Furthermore, all emissions are processed through a fabric filtration system to remove solid particulates. He said the filtration system is probably catching most of the mercury as well as other materials.

Mercury statistics are reported for the state's oil-fired power plants, but the actual mercury emissions of those facilities are not known because they are not calculated or measured, said Jose Dizon, an engineer with Hawaiian Electric. Since neither the EPA nor the Department of Health has mercury standards, there is no requirement to test for the substance.

Dizon said the figures in the EPA's Toxic Release Inventory are simple calculations based on the amount of fuel burned, multiplied by a standard factor supplied by the EPA. The EPA multiplier does not take into account that Hawaiian Electric burns low-sulfur fuels, Dizon said.