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Sustainability Aspects of Bioenergy and Nutrient Recovery from Marine Biomass: Baltic Sea case studies
KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering, Industrial Ecology.ORCID iD: 0000-0003-1949-4891
2014 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Coastal areas around the world are experiencing environmental problems such as climate change and eutrophication. These, in turn, lead to emerging challenges with excessive amounts of biomass that impact coastal communities. Developing utilisation strategies for marine biomass is therefore highly relevant and forms part of the blue growth research field. In response to environmental concerns, as a waste management strategy and as part of blue growth research initiatives, several Baltic Sea coastal projects have been initiated in recent years to study utilisation of maritime biomass. However, the sustainability of these utilisation strategies has not been critically appraised. Therefore, the work presented in this thesis explored some key sustainability aspects of two Baltic Sea case studies utilising common reed (Kalmar, Sweden) and mass-occurring filamentous macroalgae (Trelleborg, Sweden) for biogas and biofertiliser recovery. Energy analyses suggested that both case studies could provide a positive energy balance and have the potential to achieve nutrient recovery. Moreover, a contingent valuation study in Trelleborg demonstrated considerable welfare benefits of biomass utilisation. These findings indicate that marine biomass utilisation strategies highlight potential to contribute to environmental and welfare benefits of these coastal communities.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2014. , p. xii, 57
Series
TRITA-IM, ISSN 1402-7615 ; 2014:03
National Category
Environmental Sciences
Research subject
Industrial Ecology
Identifiers
URN: urn:nbn:se:kth:diva-156377ISBN: 978-91-7595-365-6 (print)OAI: oai:DiVA.org:kth-156377DiVA, id: diva2:766220
Public defence
2014-12-18, F3, Lindstedtsvägen 26, KTH, Stockholm, 09:00 (English)
Opponent
Supervisors
Funder
Formas, Grant number 229-2009-468
Note

QC 20141126

Available from: 2014-11-26 Created: 2014-11-26 Last updated: 2022-06-23Bibliographically approved
List of papers
1. Assessment of biomethane production from maritime common reed
Open this publication in new window or tab >>Assessment of biomethane production from maritime common reed
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2013 (English)In: Journal of Cleaner Production, ISSN 0959-6526, E-ISSN 1879-1786, Vol. 53, p. 186-194Article in journal (Refereed) Published
Abstract [en]

Several ongoing projects are harvesting maritime biomass from the Baltic Sea for eutrophication mitigation and utilisation of the recovered biomass. Some of this biomass comprises common reed (Phragmites australis), one of the most widespread vascular plants on Earth. Reed utilisation from eutrophied coastal areas needs to be evaluated. Therefore, a system analysis was performed of reed harvesting for biofuel and biofertiliser production. The specific objectives of the analysis were to: investigate the methane yield associated with anaerobic co-digestion of reed; make a primary energy assessment of the system; quantify Greenhouse Gas (GHG) savings when a fossil reference system is replaced; and estimate the nutrient recycling potential of the system. The results from energy and GHG calculations are highly dependent on conditions such as system boundaries, system design, allocation methods and selected indicators. Therefore a pilot project taking place in Kalmar County, Sweden, was used as a case study system. Laboratory experiments using continuously stirred tank reactor digesters indicated an increased methane yield of about 220 m(3) CH4/t volatile solids from co-digestion of reed. The energy balance for the case study system was positive, with energy requirements amounting to about 40% of the energy content in the biomethane produced and with the non-renewable energy input comprising about 50% of the total energy requirements of the system. The net energy value proved to be equivalent to about 40 L of petrol/t reed wet weight. The potential to save GHG emissions compared with a fossil reference system was considerable (about 80%). Furthermore an estimated 60% of the nitrogen and almost all the phosphorus in the biomass could be re-circulated to arable land as biofertiliser. Considering the combined benefits from all factors investigated in this study, harvesting of common reed from coastal zones has the potential to be beneficial, assuming an appropriate system design, and is worthy of further investigations regarding other sustainability aspects.

Place, publisher, year, edition, pages
Elsevier, 2013
Keywords
Phragmites australis, Anaerobic digestion, Energy balance, Baltic Sea, System analysis, Nutrient recycling
National Category
Environmental Sciences
Identifiers
urn:nbn:se:kth:diva-125543 (URN)10.1016/j.jclepro.2013.03.030 (DOI)000321409100020 ()2-s2.0-84878913954 (Scopus ID)
Funder
Swedish Research Council Formas, 229-2009-468
Note

QC 20130812

Available from: 2013-08-12 Created: 2013-08-09 Last updated: 2024-03-18Bibliographically approved
2. Natural Resource Potential of Macroalgae Harvesting in the Baltic Sea-Case Study Trelleborg, Sweden
Open this publication in new window or tab >>Natural Resource Potential of Macroalgae Harvesting in the Baltic Sea-Case Study Trelleborg, Sweden
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2013 (English)In: Global Challenges in Integrated Coastal Zone Management, John Wiley & Sons, 2013, p. 69-84Chapter in book (Other academic)
Abstract [en]

The interest in harvesting biomass from the Baltic Sea has increased in recent years. However, there is a lack of available data on macroalgae biomass and of cost-effective methods for site-specific quantification of macroalgae. In this study, macroalgae biomass has been quantified in Trelleborg and thus the nutrient reduction that could be achieved by harvesting on a regional scale. The biomass was estimated on the basis of existing inventories of macroalgae, photic zone distribution and bottom substrata. An independent model for estimating the potential of macroalgae growth was applied where factors affecting the growth of macroalgae, for example nutrients, light and temperature, were considered. The estimated summer stock of macroalgae biomass along the 58 km coastal stretch in Trelleborg amounts to 19 000 tonnes dry weight (dwt) red filamentous algae. If 10-30% of this summer stock were to be harvested, a nutrient reduction of 50-150 t of nitrogen could be achieved. The model for estimating biomass proved promising and worthy of further investigation.

Place, publisher, year, edition, pages
John Wiley & Sons, 2013
Keywords
Algae biomass, Biomass quantification, Filamentous biomass, Macroalgae harvesting, Natural resource potential
National Category
Ecology
Identifiers
urn:nbn:se:kth:diva-140103 (URN)10.1002/9781118496480.ch6 (DOI)2-s2.0-84889496130 (Scopus ID)9780470657560 (ISBN)
Note

QC 20140117

Available from: 2014-01-17 Created: 2014-01-17 Last updated: 2024-03-15Bibliographically approved
3. Harvesting of drifting filamentous macroalgae in the Baltic Sea: An energy assessment
Open this publication in new window or tab >>Harvesting of drifting filamentous macroalgae in the Baltic Sea: An energy assessment
2014 (English)In: Journal of Renewable and Sustainable Energy, E-ISSN 1941-7012, Vol. 6, no 1, p. 013116-Article in journal (Refereed) Published
Abstract [en]

Eutrophication combined with climate change has caused ephemeral filamentous macroalgae to increase and drifts of seaweed cover large areas of some Baltic Sea sites during summer. In ongoing projects, these mass occurrences of drifting filamentous macroalgae are being harvested to mitigate eutrophication, with preliminary results indicating considerable nutrient reduction potential. In the present study, an energy assessment was made of biogas production from the retrieved biomass for a Baltic Sea pilot case. Use of different indicators revealed a positive energy balance. The energy requirements corresponded to about 30%-40% of the energy content in the end products. The net energy gain was 530-800 MJ primary energy per ton wet weight of algae for small-scale and large-scale scenarios, where 6 000 and 13 000 tonnes dwt were harvested, respectively. However, the exergy efficiency differed from the energy efficiency, emphasising the importance of taking energy quality into consideration when evaluating energy systems. An uncertainty analysis indicated parametric uncertainty of about 25%-40%, which we consider to be acceptable given the generally high sensitivity of the indicators to changes in input data, allocation method, and system design. Overall, our evaluation indicated that biogas production may be a viable handling strategy for retrieved biomass, while harvesting other types of macroalgae than red filamentous species considered here may render a better energy balance due to higher methane yields.

Keywords
Life-Cycle, Biogas Production, Greenhouse-Gas, Transportation Sector, Exergy Analysis, Common Reed, Net Energy, Efficiency, Biomass, Algae
National Category
Energy Engineering
Identifiers
urn:nbn:se:kth:diva-144008 (URN)10.1063/1.4862783 (DOI)000332320200032 ()2-s2.0-84901831992 (Scopus ID)
Funder
Formas, 229-2009-468
Note

QC 20140404

Available from: 2014-04-04 Created: 2014-04-04 Last updated: 2024-03-18Bibliographically approved
4. Valuing beach cast utilization and addressing preference uncertainty
Open this publication in new window or tab >>Valuing beach cast utilization and addressing preference uncertainty
(English)Manuscript (preprint) (Other academic)
Abstract [en]

Eutrophication and global warming have created major problems with decaying macroalgae on Baltic Sea beaches. A considerable amount of this biomass is retrieved, only to be returned to the sea when the tourist season ends. It is therefore essential to implement systems whereby the retrieved biomass is utilised. One potential system is anaerobic digestion for biogas and biofertiliser recovery, but knowledge about non-market benefits is lacking. This study estimated the willingness-to-pay (WTP) for algae retrieval and utilisation in a case study area and examined methods for incorporating preference uncertainty information into WTP estimates. This was done by gathering data using two different methods and comparing the results. In addition, results obtained from an open-ended interval (OEI) format were compared with those from a payment card. A substantial mean WTP was found. The two elicitation formats produced similar mean WTP estimates. However, the OEI format produced weaker results, with a significantly higher level of stated preference uncertainty and an elevated zero response rate. Comparisons of preference uncertainty information gathered with two different methods yielded unexpected results and to some extent contradicted findings on interval size in the OEI format as a good measure of preference uncertainty.

Keywords
willingness-to-pay, biogas, Baltic Sea, macroalgae, preference uncertainty, contingent valuation
National Category
Environmental Sciences
Identifiers
urn:nbn:se:kth:diva-156385 (URN)
Note

QC 20141126

Available from: 2014-11-26 Created: 2014-11-26 Last updated: 2022-06-23Bibliographically approved

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Risén, Emma

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