Biogas Plant Upgrade to CO₂‐Free Technology: A Techno‐Economic Case Study

Abstract

A techno‐economic analysis was performed for a biogas plant with in‐built algae production. Degradation in the fermenter occurs under mesophilic conditions, to produce 605 Nm3t−1TS of biogas and 343 Nm3t−1TS of methane after 50 days. The biogas was combusted in a combined heat‐and‐power unit to produce heat and electricity. Cultivation of Chlorella vulgaris was done in co‐annular photo‐bioreactors, with an annual productivity of 107.5 t. For cultivation, both autotrophic and mixotrophic growth were assumed. Detailed mass and energy balances were done. For both conditions of algae growth, the results are approximately the same after a 30‐year payback period.

Techno-Economic Analysis of Macroalgae Biorefineries: A Comparison between Ethanol and Butanol Facilities

“…where C e is the cost of the equipment ($); a and b are cost constants, which value depends on the equipment being evaluated; S is a size parameter, obtained from the simulation that depends on the equipment that is being evaluated; and n is an exponent that also depends on the equipment. The values obtained from this method were estimated using carbon steel as a material to update this value and use it for stainless steel; this method has been previously used to evaluate biorefinery plants [36][37][38]. Using Equation (1), we estimated the inside battery limits (ISBL), which consider all the equipment used in the flowsheet, to estimate the outside battery limits (OSBL), wherein a factor of 0.5 of the ISBL was chosen.…”

“…However, they exhibit a strong dependence on the size of the plant, reaching a value even higher than the initial investment cost. H 2 O ($/m 3 ) 1.9 [37] NaOH ($/t) 400 [38] Ca(OH) 2 ($/t) 131.8 [36] Algae ($/t) 21 [39] With the estimation of the costs and revenues, it was possible to calculate the net present value (NPV) of the plant. This parameter has been widely used for the economic assessment of plant investments and was used in this study [42][43][44][45].…”

Influence of Walls in a Container on the Growth of the <i>Chlorella vulgaris</i> Algae

“…Open systems, which are cheaper to maintain, but less controlled, are most often used for energy purposes. Closed algae growing systems are more expensive to build and maintain [Singh and Sharma, 2012;Kutsay et al, 2020].…”