HILO » A bill aimed at prohibiting enhanced geothermal power systems has received initial support from the Hawaii County Council.

The Council voted 7-0 Wednesday in support after amending the legislation to increase penalties. The Council must vote on the bill one more time, the Hawaii Tribune-Herald reported.

With enhanced geothermal systems, fluids are injected deep in the earth to widen cracks and increase the flow of fluids through the ground. That allows more underground heat sources to be reached.

The bill was drafted to prohibit enhanced geothermal systems, but it would apply to all forms of hydraulic fracturing, or fracking. Fracking involves injecting water, and sometimes chemicals, deep underground to break apart rock to access hard-to-reach resources like natural gas and oil.

No geothermal companies have publicly stated an intent to use enhanced geothermal in Hawaii, but bill supporters say the ban is needed to err on the side of caution. They’re concerned that the practice would contaminate groundwater and increase earthquake activity.

Kau/South Kona Councilwoman Brenda Ford, who introduced the bill, called it "pre-emptive."

One concern some have is that enhanced geothermal might unlock underground heat sources away from the isle’s active volcanic rift zones, which could potentially lead to expansion of geothermal power.

Supporters say expanding geothermal power offers a way to provide affordable, renewable energy, but critics say the technology isn’t safe or reliable.

More than a dozen people spoke in favor of the bill at the Council. Many were from Puna, the district hosting the state’s only geothermal power plant.

Ormat Technologies, which runs Puna Geothermal Venture, finished an enhanced geothermal project earlier this year in Nevada.

Spokeswoman Heidi Bethel said in an email the company doesn’t plan to use enhanced geothermal in Hawaii.