Agence France Presse: The world’s top economies pledged Tuesday to work together to improve efficiency of electricity-guzzlers from televisions to cars, hoping to eliminate the need for hundreds of power plants. Senior officials from economies making up more than 80 percent of global gross domestic product agreed on a slew of projects to promote clean energy, belying the prolonged stalemate in negotiations on a new global climate treaty. US Energy Secretary Steven Chu voiced hope that the 11 …