Milledge, John J. ORCID: 0000-0003-0252-6711 and Heaven, Sonia (2017) Energy balance of biogas production from microalgae: Effect of harvesting method, multiple raceways, scale of plant and combined heat and power generation. Journal of Marine Science and Engineering, 5 (1). p. 9. ISSN 2077-1312 (Print), 2077-1312 (Online) (doi:https://doi.org/10.3390/jmse5010009)

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Abstract

A previously-developed mechanistic energy balance model for production of biogas from the anaerobic digestion of microalgal biomass grown in open raceway systems was used to consider the energetic viability of a number of scenarios, and to explore some of the most critical parameters affecting net energy production. The output demonstrated that no single harvesting method of those considered (centrifugation, settlement or flocculation) produced an energy output sufficiently greater than operational energy inputs to make microalgal biogas production energetically viable. Combinations of harvesting methods could produce energy outputs 2.3–3.4 times greater than the operational energy inputs. Electrical energy to power pumps, mixers and harvesting systems was 5–8 times greater than the heating energy requirement. If the energy to power the plant is generated locally in a combined heat and power unit, a considerable amount of ‘low grade’ heat will be available that is not required by the process, and for the system to show a net operational energy return this must be exploited. It is concluded that the production of microalgal biogas may be energetically viable, but it is dependent on the effective use of the heat generated by the combustion of biogas in combined heat and power units to show an operational energy return

Item Type:	Article
Additional Information:	© 2017 by the authors; licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/).
Uncontrolled Keywords:	Microalgae; Algae; Bioenergy; biogas; Anaerobic digestion; Energy balance
Faculty / School / Research Centre / Research Group:	Faculty of Engineering & Science Faculty of Education, Health & Human Sciences > School of Human Sciences (HUM)
Last Modified:	09 Oct 2021 04:45
URI:	http://gala.gre.ac.uk/id/eprint/16244

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