MANILA - The Philippine power grid operator warned on Wednesday of further outages on the island of Luzon, which is home to more than half of the country's 110 million people, after electricity supplies were hit by power plant shutdowns.

The electricity output capacity is projected to be 6% short of the requirement on Wednesday, marking a second day of shortfalls on Luzon, the National Grid Corporation of the Philippines (NGCP) said in an advisory.

It said available power capacity was expected to reach 11,260 megawatts, with peak demand seen hitting 11,976 MW.

Given the shortfall, NGCP said rotating outages were expected to continue in parts of Luzon, including portions of the capital region of metropolitan Manila.

Wednesday's 716 MW deficit is nearly four times bigger than the 185 MW shortfall on Tuesday, highlighting the precarious electricity supply position that is often felt by consumers at this time of year when demand peaks due to hotter weather.

The outages are another blow for the Philippine economy, which is recovering from a steep pandemic-induced recession, with metropolitan Manila alone accounting for around 40% of economic output.

The outages could also present a challenge for authorities to ensure steady power supply for COVID-19 vaccine storage facilities.

In a statement, the Department of Energy (DOE) said it has put the Luzon grid on "red alert" status during peak demand hours from 9 a.m. to 5 p.m., and in the evening until 11 p.m.

The DOE, which attributed the power deficit to several planned and unplanned power plant shutdowns, said the shortage should ease later on Wednesday when one of the plants hit by an unplanned outage comes back onstream, boosting supply by 647 MW.

An electricity price cap has also been imposed to protect consumers from possible price spikes, it said.

The DOE expects more than 3,000 MW of additional capacity to come onstream in coming years and is encouraging more investment in renewables and clean power technology after declaring a moratorium on endorsing greenfield coal power plants.

(Reporting by Enrico Dela Cruz Editing by Ed Davies) ((enrico.delacruz@tr.com))