Abstract
The potential of algal biomass as a source of liquid and gaseous biofuels has been the subject of considerable research over the past few decades, with researchers strongly agreeing that algae have the potential of becoming a viable aquatic energy crop with a higher energy potential compared to that from either terrestrial biomass or municipal solid waste. However, neither microalgae nor seaweed are currently cultivated solely for energy purposes due to the high costs of harvesting, concentrating and drying. Anaerobic digestion of algal biomass could theoretically reduce costs associated with drying wet biomass before processing, but practical yields of biogas from digestion of many algae are substantially below the theoretical maximum. New processing methods are needed to reduce costs and increase the net energy balance. This review examines the biochemical and structural properties of seaweeds and of microalgal biomass that has been produced as part of the treatment of wastewater, and discusses some of the significant hurdles and recent initiatives for producing biogas from their anaerobic digestion.
Highlights
There has been significant research interest over the past 50 years in the use of algae as a source of biofuels due to the high potential biomass yield of algae and cultivation systems that do not compete for land or fresh water with terrestrial crops [1,2]
Ter Veld [52] found an EORI > 3 for biogas produced from microalgal biomass grown in high rate algal ponds (HRAPs) and concluded that microalgae-based biofuel sustainability was not set by areal productivity or lipid content in the algae but by the recovery of nutrients
This review will examine biogas from algal feedstocks grown in processes that minimise the demand for fresh water and nutrients; microalgae produced as part of the treatment of wastewater and seaweed cultivated or collected after growing in the ocean
Summary
There has been significant research interest over the past 50 years in the use of algae as a source of biofuels due to the high potential biomass yield of algae and cultivation systems that do not compete for land or fresh water with terrestrial crops [1,2]. Ter Veld [52] found an EORI > 3 for biogas produced from microalgal biomass grown in high rate algal ponds (HRAPs) and concluded that microalgae-based biofuel sustainability was not set by areal productivity or lipid content in the algae but by the recovery of nutrients. Another energy balance model for the production of biogas from microalgae grown on wastewater found energy returns on operational energy invested greater than 3 with the use of nutrients from wastewater being a crucial component in producing a positive net energy balance [53,54]. This review will examine biogas from algal feedstocks grown in processes that minimise the demand for fresh water and nutrients; microalgae produced as part of the treatment of wastewater and seaweed cultivated or collected after growing in the ocean
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have