Microbial fuel cells are considered a source of sustainable energy. Why? 1. They use living organisms as catalysts to generate electricity from certain substrates. 2. They use a variety of inorganic materials as substrates. 3. They can be installed in waste water treatment plants to cleanse water and produce electricity. Which of the statements given above is/are correct?

To meet its rapidly growing energy demand, some opine that India should pursue research and development on thorium as the future fuel of nuclear energy. In this context, what advantage does thorium held over uranium?

With reference to technologies for solar power production, consider the following statements: 1. 'Photovoltaics' is a technology that generates electricity by direct conversion of light into electricity, while 'Solar Thermal' is a technology that utilizes the Sun's rays to generate heat which is further used in electricity generation process. 2. Photovoltaics generates Alternating Current (AC), while Solar Thermal generates Direct Current (DC). 3. India has manufacturing base for Solar Thermal technology, but not for Photovoltaics.

With reference to two non-conventional energy sources called 'coalbed methane' and 'shale gas', consider the following statements: 1. Coalbed methane is the pure methane gas extracted from coal seams, while shale gas is a mixture of propane and butane only that can be extracted from fine-grained sedimentary rocks. 2. In India, abundant coalbed methane sources exist, but so far no shale gas sources have been found.