Algae-based biofuels: a review of challenges and opportunities for developing countries May 2009

Algae have recently received a lot of attention as a new biomass source for the production of renewable energy. Some of the main characteristics which set algae apart from other biomass sources are that algae can have a high biomass yield per unit of light and area, can have a high oil or starch content, do not require agricultural land, fresh water is not essential and nutrients can be supplied by wastewater and CO2 by combustion gas.
The first distinction that needs to be made is between macroalgae (or seaweed) versus microalgae. Microalgae have many different species with widely varying compositions and live as single cells or colonies without any specialization. Although this makes their cultivation easier and more controllable, their small size makes subsequent harvesting more complicated. Macroalgae are less versatile, there are far fewer options of species to cultivate and there is only one main viable technology for producing renewable energy: anaerobic digestion to produce biogas.
Both groups will be considered in this report, but as there is more research, practical experience, culture and there are more fuel options from microalgae, these will have a bigger share in the report.
In chapter 2, the different technological components that make up Algae Based Biofuels (ABB) are discussed: algae cultivation technology; processing to biofuel options; locations and carbon; light and nutrient inputs. Both land based and sea based applications are discussed.
In chapter 3, ABB sustainability is investigated in depth. First, existing biofuel sustainability standards are analysed for applicability, followed by a thorough analysis of the opportunities and risks of ABB sustainability. Secondly, sustainability is discussed in the context of potential and threats for developing countries.

By: Food and Agriculture Organization of the United Nations (FAO)