Apart from the perspective of energy balance, economic feasibility, coupled with techno­logical innovations, plays a critical role in ensuring the successful production of algal biofuels on a commercial scale. Based on an ideal assumption that algae could grow at a very rapid rate (typically requiring less than 10 days to reach the stationary growth phase) and could accumulate a high lipid content (30-70%) inside the cells, the resulting algal biodiesel should be able to compete or at least be on par with the current petrol-diesel price.

A preliminary cost analysis conducted by Chisti (2007) revealed that oil recovered from algal biomass produced in closed photobioreactors cost approximately $2.80/L, assuming that the algal biomass contained 30% oil and the oil-recovery process contributed 50% to the total production cost. However, in comparison to the average petrol-diesel price of $1.20/L gross delivered in the year 2010 (McHenry, 2012), the estimated algal biodiesel price is still much too high for commercial use, unless the algal biomass contains 70% oil, which could further reduce the price to $0.72/L (Chisti, 2007).

In a recent algal technological road map reported by the U. S. Department of Energy, a more robust system of modeling and comprehensive techno-economic analyses for algal biofuels should be developed to reach the goal of commercialization in the next 5 to 15 years (Fishman et al., 2010). An economic breakdown of multiple algal processing units with dif­ferent integration systems could help address the techno-economic feasibility of algal biofuels before reaching the commercial scale (Amer et al., 2011). An in-depth understanding of the techno-economic feasibility of algal biofuels is required to not only maximize profits and minimize investment risk but also to stimulate the consideration of the "bigger picture" in identifying the critical problems for scaling up this process and recommending specific corrective measures (Davis et al., 2011; Delrue et al., 2012; Harun et al., 2011; Sun et al., 2011). The following sections describe some significant results from recent techno-economic studies of algal biofuels.