Evaluation of microalgae-based biorefinery alternatives

Daniel Fozer, Nora Valentinyi, Laszlo Racz, P. Mizsey

Research output: Contribution to journalArticle

10 Citations (Scopus)

Abstract

Microalgae-based biorefineries for the production of renewable biofuels like biodiesel, upgraded bio-oil, biochar, biogas and other high-value chemicals have received great attention in recent decades as potential major sources of energy for the future. Microalgae are a suitable species to produce biodiesel and other high energy density by-products; however, it is questionable whether a net energy gain can be realized or not considering the whole processing chain. In the present study, the energy balances of different algae-based biofuel and bioenergy production technologies are investigated in detail and compared to each other corresponding to a cradle-to-grave overall energetic analysis. The study includes cultivation, harvesting, cell pretreatments (cell disruption, drying, grinding), lipid extraction, transesterification, gasification and hydrothermal liquefaction with bio-oil stabilization and hydroprocessing. The energy consumption and energy gain are estimated for each operational step to determine the net energy ratio (NER, energy output over energy input) for the overall technologies studied. Our detailed investigation enables to detect the most energy consuming unit operation, that is, the bottleneck point(s) of the microalgae-based technologies which should be still improved in the future for the sake of more efficient algae-based biorefineries. The investigation makes also possible to evaluate and compare the different large scale alternatives for biomass transformation. Positive energy balances with a NER value of 1.109 and 1.137 are found in two already existing processes: open raceway ponds and closed photobioreactors, respectively. Our work gives also a detailed algorithm that can be followed at the evaluation of other microalgae-based biorefineries.

Original languageEnglish
Pages (from-to)1-15
Number of pages15
JournalClean Technologies and Environmental Policy
DOIs
Publication statusAccepted/In press - Jun 25 2016

Fingerprint

Biofuels
Algae
Biodiesel
Energy balance
Photobioreactors
energy
Transesterification
Biogas
Ponds
Liquefaction
Oils
Gasification
Lipids
Byproducts
Drying
Biomass
Energy utilization
Stabilization
biofuel
energy balance

Keywords

  • Biodiesel
  • Biorefinery
  • Hydrothermal liquefaction
  • Microalgae
  • Net energy ratio

ASJC Scopus subject areas

  • Environmental Chemistry
  • Environmental Engineering
  • Management, Monitoring, Policy and Law

Cite this

Evaluation of microalgae-based biorefinery alternatives. / Fozer, Daniel; Valentinyi, Nora; Racz, Laszlo; Mizsey, P.

In: Clean Technologies and Environmental Policy, 25.06.2016, p. 1-15.

Research output: Contribution to journalArticle

Fozer, Daniel ; Valentinyi, Nora ; Racz, Laszlo ; Mizsey, P. / Evaluation of microalgae-based biorefinery alternatives. In: Clean Technologies and Environmental Policy. 2016 ; pp. 1-15.
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