Techno‐economic assessment of heterotrophic microalgae biodiesel production integrated with a sugarcane bio‐refinery

Abstract

The use of diesel fuel in crop and transportation operations is responsible for one third of the carbon emissions in sugarcane biorefineries. A possible solution is to replace it with biodiesel from lipids, directly produced from sugarcane by highly productive heterotrophic microalgae. In this study a heterotrophic microalgae biodiesel plant, integrated with a typical Brazilian sugarcane bio‐refinery, was designed and evaluated. Molasses, steam, and electricity from sugarcane processing were used as inputs for microalgae production. For a non‐integrated plant, the production cost of the microalgae biodiesel was estimated at 2.51 and 2.27 $/liter for fed‐batch and continuous processes, respectively. Equipment for cultivation and carbon sources was the highest cost affecting the financial feasibility of the proposed design. For the integrated plant, at present ethanol and biodiesel selling prices, the profitability would be lower than a first‐generation sugarcane bio‐refinery using fossil diesel fuel for its operations. However, the CO2 emissions would be reduced by up to 50 000 × 103 kg per year at a cost of $83 10−3 kg−1 CO2‐eq. If carbon credits are considered, the process becomes economically profitable even at present fuel prices. © 2020 The Authors. Biofuels, Bioproducts, and Biorefining published by Society of Chemical Industry and John Wiley & Sons, Ltd

Microalgae Commercialization Using Renewable Lignocellulose Is Economically and Environmentally Viable

“…However, we note that producing only biofuel using microalgae obtained through the Cel-HC process would not be economically feasible based on current projections, due to the negative NPVs under all of the three scenarios. Similar conclusions have been drawn by other TEA studies focusing on either phototrophic or heterotrophic algal production. ,, Combining the production of biofuels with other high-value-added commodities could provide a feasible alternative. In this case, a complete biorefinery, i.e., allocating biomass components to different markets, could maximize the revenue, considering a total biorefining cost of 3000–4800 USD/t .…”

“…Similar conclusions have been drawn by other TEA studies focusing on either phototrophic or heterotrophic algal production. 10,35,66 Combining the production of biofuels with other high-value-added commodities could provide a feasible alternative. In this case, a complete biorefinery, i.e., allocating biomass components to different markets, could maximize the revenue, considering a total biorefining cost of 3000−4800 USD/t.…”

“…Thus, numerous studies are focusing on utilizing lignocellulose from different sources for algae cultivation in recent years, 31−34 and successful scale-up cases have already been reported. 35,36 Nevertheless, there is still lack of investigations to reveal whether cellulosic hydrolysate-mediated heterotrophic cultivation is competitive with conventional phototrophic cultivation for microalgae commercialization.…”

“…The application of lignocellulose-derived carbon sources, such as cellulosic hydrolysate, for heterotrophic algae cultivation could potentially overcome the limitations associated with using commercial glucose, , therefore providing a potential opportunity for algal biomass production on a large scale. Thus, numerous studies are focusing on utilizing lignocellulose from different sources for algae cultivation in recent years, − and successful scale-up cases have already been reported. , Nevertheless, there is still lack of investigations to reveal whether cellulosic hydrolysate-mediated heterotrophic cultivation is competitive with conventional phototrophic cultivation for microalgae commercialization.…”

Viability of non‐edible oilseed plants and agricultural wastes as feedstock for biofuels production: a techno‐economic review from an African perspective

“…[161][162][163][164][165][166][167] Scown et al, 165 for instance, describe TEA as a starting point for process design and simulation of conventional biofuels processes. The use of a self-coded computer program or commercial software packages such as Aspen Plus, 168 Honeywell's UniSim Design Suite, 156 and SuperPro Designer 169 have made it easier to manage, comprehend, and optimize the complexities of biofuel process design and simulations. 170 The integration of TEA on the one hand and software packages on the other streamlines the procedures for analyzing the technical performance and economic feasibility of a proposed bio-refinery plant, hence assisting investment decisions at the lowest cost possible.…”