The historic blackouts that left more than 670 million people in India without electricity this week revealed profound problems with a power network struggling to keep pace with one of the world’s fastest growing economies, experts say. While it’s unclear what specifically triggered this week’s massive grid failures, which knocked out power in 20 Indian states, government officials accused several northern states of drawing more power from the grid than their allocated amounts. Another factor may have been increased electricity usage caused by unusually high water pumping for irrigation as a result of weak monsoon rains. Experts say the blackouts reveal a fundamental gap between supply and demand in a nation that aspires to be a global economic leader. While India has increased its power capacity more than 35 percent in the last five years, a peak-hour electricity shortfall of about 10 percent exists and hundreds of millions of people in rural areas have no access to electricity. As much as two-thirds of India’s electricity comes from the burning of coal and some plants are struggling to meet demand because of a coal shortage.