The input category refers here to any product or service required at some point of the microalgae culture or transformation. It includes the materials used to build cultivation sys­tems, fertilizers and chemical reactants, production of electricity, and heat required at the facil­ity. Almost all the publications consider these inputs in exhaustive ways, except:

• Jorquera et al. (2010). Fertilizers are not taken into account.

• Clarens et al. (2010, 2011). Infrastructures are not taken into account.

• Sander et Murthy (2010). Only flows that contribute to more than 5% of the total mass, energy, and economy are taken into account.

The energy and the fertilizer are the most influencing inputs on the final environmental performance and energy balance.