Greenwire: Backers of algae-based biofuels tout the simplicity of their feedstock. Sunlight and water are all that’s needed to convert carbon dioxide into fuel. Now, some scientists are testing the notion that sunlight might be optional. Researchers at the Missouri University of Science and Technology are planning to grow algae for fuel in abandoned mines using light-emitting diodes, or LEDs. “About this time in the conversation, someone usually raises their hand and says, ‘But …