title: Energy performance and greenhouse gas emissions of kelp cultivation for biogas and fertilizer recovery in Sweden.
abstract: The cultivation of seaweed as a feedstock for third generation biofuels is gathering interest in Europe, however, many questions remain unanswered in practise, notably regarding scales of operation, energy returns on investment (EROI) and greenhouse gas (GHG) emissions, all of which are crucial to determine commercial viability. This study performed an energy and GHG emissions analysis, using EROI and GHG savings potential respectively, as indicators of commercial viability for two systems: the Swedish Seafarm project's seaweed cultivation (0.5ha), biogas and fertilizer biorefinery, and an estimation of the same system scaled up and adjusted to a cultivation of 10ha. Based on a conservative estimate of biogas yield, neither the 0.5ha case nor the up-scaled 10ha estimates met the (commercial viability) target EROI of 3, nor the European Union Renewable Energy Directive GHG savings target of 60% for biofuels, however the potential for commercial viability was substantially improved by scaling up operations: GHG emissions and energy demand, per unit of biogas, was almost halved by scaling operations up by a factor of twenty, thereby approaching the EROI and GHG savings targets set, under beneficial biogas production conditions. Further analysis identified processes whose optimisations would have a large impact on energy use and emissions (such as anaerobic digestion) as well as others embodying potential for further economies of scale (such as harvesting), both of which would be of interest for future developments of kelp to biogas and fertilizer biorefineries.
authors: Industrial Ecology, Department of Sustainable Development, Environmental Science and Engineering (SEED), KTH Royal Institute of Technology, Teknikringen 34, 10044 Stockholm, Sweden. Electronic address: pechsiri@kth.se.
authors: Joseph S
authors: JS
authors: Pechsiri
authors: Industrial Ecology, Department of Sustainable Development, Environmental Science and Engineering (SEED), KTH Royal Institute of Technology, Teknikringen 34, 10044 Stockholm, Sweden.
authors: Jean-Baptiste E
authors: JE
authors: Thomas
authors: Industrial Ecology, Department of Sustainable Development, Environmental Science and Engineering (SEED), KTH Royal Institute of Technology, Teknikringen 34, 10044 Stockholm, Sweden; Currently at Sweco Environment AB, Gjörwellsgatan 22, Stockholm, Sweden.
authors: Emma
authors: E
authors: Risén
authors: Industrial Ecology, Department of Sustainable Development, Environmental Science and Engineering (SEED), KTH Royal Institute of Technology, Teknikringen 34, 10044 Stockholm, Sweden.
authors: Mauricio S
authors: MS
authors: Ribeiro
authors: Industrial Ecology, Department of Sustainable Development, Environmental Science and Engineering (SEED), KTH Royal Institute of Technology, Teknikringen 34, 10044 Stockholm, Sweden.
authors: Maria E
authors: ME
authors: Malmström
authors: Department of Marine Sciences - Tjärnö, University of Gothenburg, SE-452 96 Strömstad, Sweden.
authors: Göran M
authors: GM
authors: Nylund
authors: School of Built Environment and Energy Technology, Linnæus University, SE-351 95 Växjö, Sweden.
authors: Anette
authors: A
authors: Jansson
authors: School of Built Environment and Energy Technology, Linnæus University, SE-351 95 Växjö, Sweden.
authors: Ulrika
authors: U
authors: Welander
authors: Department of Marine Sciences - Tjärnö, University of Gothenburg, SE-452 96 Strömstad, Sweden.
authors: Henrik
authors: H
authors: Pavia
authors: Industrial Ecology, Department of Sustainable Development, Environmental Science and Engineering (SEED), KTH Royal Institute of Technology, Teknikringen 34, 10044 Stockholm, Sweden.
authors: Fredrik
authors: F
authors: Gröndahl
keywords: Biorefinery; EURED GHG savings; Economy of scale; Energy return on investment (EROI); Saccharina latissima; Swedish macroalgae cultivation