Molten lava from the erupting Kilauea Volcano on Hawaii’s Big Island crept onto a geothermal power plant site on Monday, as workers rushed to shut down the facility to prevent the uncontrollable release of toxic gases. Crews were working into the night to cap the 11th and final well at the Puna Geothermal Venture plant, which provides about 25 percent of the Big Island’s power, the county said in an alert. The race at the site marked the latest challenge facing authorities as they cope with what geologists rank as one of the biggest upheavals in a century from one of the world’s most active volcanoes.