"Microalgae are the only option," says Yusuf Chisti, a professor of biochemical engineering from the Massey University in New Zealand. Chisti says biorefineries with multiple value chains will be the most viable way forward for a commercial industry - facilities that can produce high-value products such as biodiesel, ethanol and proteins, while by-products like biogas, solid biomass and fertiliser are recycled into the production of algae.