New Delhi, Feb 15 (ANI): Chief Economic Advisor Arvind Subramanian on Sunday said that the country needed massive investment in clean energy to kick start economy. Subramanian made the remarks at the first Renewable Energy Global Investors Meet and Expo, Re-invest 2015 in New Delhi. Subramanian said that focus of renewable energy should be on major investment in greening coal. India is the world's third-largest greenhouse gas emitter and often acts as the voice of the world's developing countries in United Nations talks on everything from climate change to economic cooperation.