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- Andersson, Viktor, 1983, et al.
(author)
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Integrated Algae Cultivation for Municipal Wastewater Treatment and Biofuels Production in Industrial Clusters
- 2012
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In: World Renewable Energy Forum, WREF 2012. - 9781622760923 ; 1, s. 684-691
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Conference paper (peer-reviewed)abstract
- This paper presents a case study on biofuels production from microalgae cultivated in municipal wastewater in Gothenburg, Sweden. A) Combined biodiesel and biogas production and B) only biogas production, are compared in terms of product outputs, impact on global CO2 emissions reduction and economic performance. Land-use efficiency of biofuels from microalgae was compared with other biofuel production routes. The biofuel production process is assumed to be integrated with a wastewater treatment plant and an industrial cluster, providing the opportunity to reduce the CO2 emissions of the process compared to stand-alone operation.The results show that case A is advantageous in terms of all the studied factors. A higher area efficiency of algae biofuels production routes compared to other biofuel production routes was shown. Nutrient availability in municipal wastewater is shown to be the limiting factor regarding product output. The competitive advantage of co-location with a wastewater treatment plant is clearly shown.
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| 2. |
- Broberg, Sarah, 1983-, et al.
(author)
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Integrated Algae Cultivation for Biofuels Production in Industrial Clusters
- 2011
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Reports (other academic/artistic)abstract
- Declining fossil resources and the issue of climate change caused by anthropogenic emissions of greenhouse gases make global action towards a more sustainable society inevitable. The EU decided in 2007 that 20 % of the union´s energy use should origin from renewable resources by the year 2020. One way of achieving this goal is to increase the utilisation of biofuels. Today 2nd generation biofuels are being developed. They are seen as a more sustainable solution than 1st generation biofuels since they have a higher area efficiency (more fuel produced per area) and the biomass can be cultivated at land which is not suitable for food crops. One of these 2nd generation biofuels are fuels derived from microalgae. In this study a thorough literature survey has been conducted in order to assess the State-of-the-Art in algae biofuels production. The literature review showed the importance of a supplementary function in conjunction with algae cultivation and therefore algae cultivation for municipal wastewater treatment and capturing CO2 emissions from industry was included in the study. It was assumed that all the wastewater of the city of Gothenburg, Sweden, was treated by algae cultivation. A computer model of the whole production process has been developed, covering; algae cultivation in conjunction with wastewater treatment, algae harvesting and biofuels production. Two different cases are modelled; a first case including combined biodiesel and biogas production, and a second case investigating only biogas production. Both cases have been evaluated in terms of product outputs, CO2 emissions savings and compared to each other in an economic sense. Utilising the nutrients in the wastewater of Gothenburg it is possible to cultivate 29 ktalgae/year. In the biogas case it is possible to produce 205 GWhbiogas/year. The biogas/biodiesel case showed a production potential of 63 GWhbiodiesel/year and 182 GWhbiogas/year. There is a deficit of carbon in the wastewater, hence CO2 is injected as flue gases from industrial sources. The biodiesel/biogas case showed an industrial CO2 sequestration capacity of 24 ktCO2/year while in the biogas case 22.6 ktCO2/year, could be captured. Estimating the total CO2 emissions savings showed 46 ktCO2/year in the biodiesel/biogas case and 38 ktCO2/year for the biogas case. The importance of including wastewater treatment in the process was confirmed, as it contributes with 13.7 ktCO2/year to the total CO2 emissions savings. Economic comparison of the two cases showed that biodiesel in conjunction with biogas production is advantageous compared to only biogas production. This is mainly due to the higher overall fuel yield and the high willingness to pay for biodiesel. The total incomes from biodiesel/biogas sales were calculated to 221 million SEK/year and 193 million SEK/year for biogas. It was found that the higher incomes from biodiesel/biogas sales repay the increased investment for the biodiesel process in approximately 3 years.
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