Life cycle assessment of algae‐to‐biodiesel shallow pond production systems in the Mediterranean: influence of species, pond type, by(co)‐product valorisation and electricity mix

Abstract

The environmental sustainability of microalgae‐to‐biodiesel production systems was examined at open (outdoor) and closed (indoor, using artificial light and temperature control) raceway ponds in a Mediterranean climate (southern Greece). Spirulina platensis and Nannochloropsis sp. species were considered, with the latter having a slightly better environmental performance. In terms of energy efficiency, large cumulative energy demand (CED) values were observed, while the energy return‐on‐investment (EROI) ratio was well below 3 in all cases, indicating that, with current technology, algae‐to‐biodiesel systems have not reached sustainability yet. The impact on land use was minimal, as nonarable land was used. Shallow‐pond cultivation systems are energy intensive, especially the closed ones, and therefore were found to be associated with high environmental footprints. In all cases, the main environmental hotspot was, by and large, the electricity consumption from the Greek fossil‐fuel depended energy mix (90%). Pellet, a process co‐product, largely reduced the total environmental footprint by up to ~47%, which highlights the importance of co‐product valorization. Closed systems exhibited significantly higher environmental footprints compared to open ones, due to the large energy inputs for artificial solar irradiation and for indoor temperature control. In all the cases examined, the microalgae‐to‐biodiesel production system's environmental footprint was higher than that of fossil diesel (i.e. petrodiesel), indicating that ample room exists to improve their environmental performance. A sensitivity analysis revealed that the introduction of renewable energy solely to cover for electricity needs substantially improves environmental sustainability and could render microalgae‐to‐biodiesel systems an environmentally friendlier solution than petrodiesel. © 2018 Society of Chemical Industry and John Wiley & Sons, Ltd

Used-cooking-oil biodiesel: Life cycle assessment and comparison with first- and third-generation biofuel

“…For this reason, in order to reach endpoint, ReCiPe converts and aggregates midpoint impact categories into three damage categories, i.e. i) damage to human health, ii) damage to ecosystem diversity, and iii) damage to resource availability, which can be further aggregated into a single score and allow a more effective communication of the results, even to nonspecialised audiences [33]. The unit of measurement for ReCiPe single score results is the Eco-indicator Point (Pt), where 1000 Pt is the annual environmental load of an average…”

“…Greek setting [33,35]. However, even though the latter had been identified using ReCiPe (endpoint H/A), the total environmental footprint of the first-generation biodiesel had been estimated using Eco-Indicator 99 LCIA method.…”

“…Furthermore, when results are compared with those of the third-generation (microalgae) biodiesel, the environmental footprint of the second-generation biodiesel is substantially better (more than an order of magnitude lower). Specifically, Foteinis et al [33] estimated that the total environmental footprint of biodiesel produced from Nannochloropsis sp. in an open and closed cultivation system, and under Greek climate conditions, would amount to 1.94 MPt/t and 11.22 MPt/t, respectively [33].…”

“…Specifically, Foteinis et al [33] estimated that the total environmental footprint of biodiesel produced from Nannochloropsis sp. in an open and closed cultivation system, and under Greek climate conditions, would amount to 1.94 MPt/t and 11.22 MPt/t, respectively [33]. These are substantially higher than the 58.36…”

Environmental sustainability of biofuels: a review

“…EU RED requirement (50% reduction) for installations in operation before Oct 2015 EU RED requirement (60% reduction) for installations in operation after Oct 2015 A = 27 n = GWP of microalgae biodiesel. Based on data from[19,85,97,113,141,167,[190][191][192][193][194][195][196][197][198][199][200][201][202][203][204][205][206][207][208][209]. The negative values are due to the credits for co-products and avoided processes, such as wastewater treatment.…”