Microalgae cofiring in coal power plants: Innovative system layout and energy analysis

Highlights

Integration of an algal farm with a coal-fired power plant is studied in terms of energetic performance, CO2 emissions, LCOE.

Flue gases are exploited as both CO2 source and heat source for biomass drying thus reducing the amount of energy consumed.

Component assumptions are derived from a thorough literature review thus offering a set of data useful for further studies.

The net energy ratio (1.92) and CO2 emissions reduction enlighten how the proposed cofiring system is environmental friendly.

LCOE from algae (554.4 € MWh−1) underlines how this solution is far from being competitive with traditional technologies.

Abstract

This paper investigates the smart integration of a 500 ha microalgae culturing facility with a large scale coal power plant (758.6 MWe): a fraction of the CO2 contained in the coal plant flue gases is used for the algal cultivation, a fraction of the low-temperature flue gas heat available is used for the biomass drying, finally the produced biomass is co-fired in the coal plant. The produced algal biomass represents approximately 1% of the boiler heat input.

Through the solution of energy and mass balances of each plant component, the overall system performances in terms of net energy ratio (NER) and CO2 emissions reduction are obtained. The computed NER (1.92) guarantees an energy harvest almost twice the energetic cost needed to produce the microalgal fuel. The total CO2 emissions are reduced of approximately 0.48%, identifying microalgae cofiring as a solution able to reduce the environmental impact of electricity generation. A simplified economic analysis has allowed an estimate of the algal system investment cost (about 235 k€ ha−1) and of the levelized cost of electricity (LCOE) (554.4 € MWh−1). A set of sensitivity analyses is finally performed to investigate the influence of the initial hypotheses on the results.

Keywords

  • Renewable energy;
  • Biomass;
  • Bioenergy;
  • Microalgae;
  • Raceway pond;
  • Cofiring

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