Beneficial Reuse of Industrial CO2 Emissions Using a Microalgae Photobioreactor: Waste Heat Utilization Assessment

Abstract

Microalgae are a potential means of recycling CO2 from industrial point sources. With this in mind, a novel photobioreactor (PBR) was designed and deployed at a coal-fired power plant. To ascertain the feasibility of using waste heat from the power plant to heat algae cultures during cold periods, two heat transfer models were constructed to quantify PBR cooling times. The first, which was based on tabulated data, material properties and the physical orientation of the PBR tubes, yielded a range of heat transfer coefficients of 19–64 W m−2 K−1 for the PBR at wind speeds of 1–10 m s−1. The second model was based on data collected from the PBR and gave an overall heat transfer coefficient of 24.8 W m−2 K−1. Energy penalties associated with waste heat utilization were found to incur an 18%–103% increase in energy consumption, resulting in a 22%–70% reduction in CO2 capture for the scenarios considered. A techno-economic analysis showed that the cost of heat integration equipment increased capital expenditures (CAPEX) by a factor of nine and increased biomass production costs by a factor of three. Although the scenario is thermodynamically feasible, the increase in CAPEX incurs an increase in biomass production cost that is economically untenable.

Techno-Economic Study of CO2 Capture of a Thermoelectric Plant Using Microalgae (Chlorella vulgaris) for Production of Feedstock for Bioenergy

“…In this study, it was established that the preculture was performed in a tubular photobioreactor, achieving a final biomass concentration of 1.5 g/L [65], which is then mixed with the culture medium and fed to the raceway pond. It has been reported that the cultivation of biomass in photobioreactors is more efficient in biomass production, but the energy consumption is higher in these systems [66][67][68]. In this case, the preculture consumes 44% of the total energy consumption for the cultivation of biomass, while the rest is associated with the raceway pond (56%).…”

Automation of the Photobioreactor Lighting System to Manage Light Distribution in Microalgae Cultures

“…As part of their research, microalgae biofuel scientists are focusing their attention on various indicators related to light distribution, such as colour, photosynthetically active PAR irradiance, and the ratio between light and dark periods. Findings from studies on the influence of factors on microalgae growth are used to develop optimal culture strategies under controlled conditions and to design modern photobioreactors [42,46,47]. Thus, different photobioreactor solutions can contribute to increased biomass productivity and optimal energy use for the production of valuable bioproducts.…”

The Follow-up Photobioreactor Illumination System for the Cultivation of Photosynthetic Microorganisms

“…As photosynthetic organisms consume carbon dioxide in the process of photosynthesis, algae breeding also presents a desirable side-effect of carbon sequestration [9,10].…”