MANILA, Philippines?Some 50 cities around the country have pledged to support Earth Hour on March 28?a Saturday?by shutting off electricity for one hour, an environmental group said Wednesday.

World Wildlife Fund campaign manager Yeb Saño also said they are targeting saving 100 megawatts for electricity during the shutdown.

?We are hoping to surpass last year?s 80 megawatts that was saved and we hope to involve around 10 million Filipinos. We believe all these are very doable,? he told the Philippine Daily Inquirer.

Earth Hour is a global effort of voluntarily shutting down electricity in homes, offices, public places and commercial establishments for one hour from 8:30 to 9:30 p.m. to raise awareness about the effects of climate change and global warming.

Saño added that over a hundred corporations, schools, public and private organizations have pledged support with the list growing.

Among the corporations who have pledged support for Earth Hour include Ayala Corporation, Bank of the Philippine Islands, Coca Cola, Energy Development Corporation, First Gen Corporation, Globe Telecoms, HSBC, Lopez Group, Manila Ocean Park, Meralco, Philips, Shangri-la Hotels, Shell, SM Group, Starbucks and Tetra Pak.

Institutional partners include the Archdiocese of Manila Ministry, Boy and Girl Scouts, CBCP, Department of Education, Earth Day Network, Gawad Kalinga, Habitat for Humanity, League of Corporate Foundations, National Electrification Administration, National Historical Institute, Outdoor Advertiser?s Association of the Philippines, Philippine Jaycees, Renewable Energy Coalition, Rotary Club and World Youth Alliance.

?The commitments of support grow with each day. We urge everyone to spread the word and join millions throughout the world by switching off lights from 8:30 p.m. to 9:30 p.m. on Saturday night, 28 March. This is our chance to show the world what our Bayanihan spirit can do, for only when we act as one will Earth Hour be successful,? said Saño.

Saño called on the public to join the event and spread the word to friends and members of their families.

In the country, Earth Hour is being held under the auspices of the World Wildlife Fund (WWF), the Department of Energy, Green Army Network and SWITCH Movement.

Earth Hour was launched in Australia on March 31, 2007 with over two million people and 2,100 businesses in Sydney turning off their lights for 60 minutes.

In 2008, 50 million people in 370 cities participated with lights going out in New York?s Times Square, Rome?s Coliseum and even the remote Casey Station in Antarctica.

The Philippines was the first Southeast Asian nation to pledge support. Last year, its flagship cities of Pasay, Manila, Parañaque and Makati observed a switch-off ceremony with darkness enveloping the entire Roxas Boulevard seaside strip in darkness. Popular landmarks such as the Cultural Center of the Philippines and Mall of Asia also joined the event.

?Our Earth Hour last year remains the country?s largest environmental action ever staged. Last year, total power savings amounted to 80MWh. 56MWh was saved in Luzon alone which is equivalent to shutting down a coal-fired power plant for one hour,? he said.

Worldwide, Saño said the target is for the participation of around 1 billion people in Earth Hour.