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Vaasa, Finland

Zhu L.,University of Vaasa | Naaranoja M.,University of Vaasa | Hiltunen E.,Vaasa Energy Institute
Advanced Materials Research | Year: 2012

The issues of energy shortage, global warming and climate change have led to an increased interest in new energy sector, such as microalgae-based biofuels. There are many advantages to produce microalgae as a biofuel feedstock, for instance, high photosynthesis efficiency and uncompetition with traditional agriculture on farmlands. Benefiting from current culturing technologies, such as open ponds and photobioreactors, commercial microalgae farming (e.g., Earthrise) is booming. In this regard, identifying the main environmental benefits associated with microalgae production is pretty important to support this promising industry. Although there are many researches on microalgae production, published information available on the sustainably environmental benefits is fragmented. The aims of this paper are to investigate and analyze environmental benefits related with microalgae biomass production for biofuel usage from sustainability perspective, systematically and explicitly, including water resource, land, nutrient, greenhouse gases and genetic modification dimensions.

Zhu L.,Vaasa Energy Institute | Zhu L.,Cranfield University | Huo S.,Jiangsu University | Qin L.,CAS Guangzhou Institute of Energy Conversion
International Journal of Green Energy | Year: 2015

The interest in using microalgae to produce biodiesel is rapidly increasing in an effort to search for renewable and alternative energy. In an attempt to support algal biodiesel industry, the exploration of sustainability concerns involved in biodiesel refinery is becoming more and more necessary and important. From a sustainability perspective, this paper addresses the environmental, economic, social, and cultural implications of microalgae-based biodiesel refinery. From an environmental standpoint, there are four main related concerns: first, less water is required and water used can be recycled greatly, but it might cause water and even groundwater pollution; second, although low-value lands can be used for construction, it might cause land use changes and soil erosion; third, infrastructure construction and eutrophication by water pollution will threaten on local biodiversity; finally, there are some disputes of energy input and greenhouse gases emissions. From an economic point of view, the main benefit lies in an increase of employment and incomes, while the main drawback is the overwhelming investments required due to high costs. Socially, it can improve energy security and create jobs, while, on the other hand, it might affect the health of local animals and people. From a cultural viewpoint, algal biodiesel concept is a new element, and it requires time for people to adapt. With effective use of measures in technologies and policies, the microalgae-derived biodiesel industry will commercialize at levels of sustainability. Copyright © 2015 Taylor & Francis Group, LLC.

Zhu L.D.,CAS Guangzhou Institute of Energy Conversion | Zhu L.D.,University of Vaasa | Zhu L.D.,Vaasa Energy Institute | Hiltunen E.,University of Vaasa | And 6 more authors.
Renewable and Sustainable Energy Reviews | Year: 2014

To confront energy shortage, global warming and climate changes, biofuels derived from biomass have received increasing attention from the industry, academia and governments. Of the potential sources of biofuels a most promising one is the simple photosynthetic microalgae, which can be grown in open ponds, photobioreactors and fermenters. The advantages to produce biofuels from microalgae include easy adaption to environmental conditions, high photosynthesis efficiency, high lipid content and noncompetition for farmlands. Nonetheless, the real hallmark of microalgae is the fact that these microscopic organisms can provide the biomass feedstock for the flexible production of several different types of renewable and sustainable biofuels such as biodiesel, bioethanol, biogas, biohydrogen among others via thermochemical and biochemical conversion processes. Amazingly, from a sustainability perspective the integrated algal biofuels production, where biodiesel, bioethanol and biogas are continuously produced from one biomass source, can evidently lead to an increase in the energetic productivity of the microalgal biomass, thus improving the economics of this algal biorefinery approach. Developments in several areas, such as genetic and metabolic engineering, are expected to further improve the costeffectiveness of the biofuels from microalgae in an environmentally sustainable manner. © 2013 Elsevier Ltd.

Zhu L.,University of Vaasa | Zhu L.,Vaasa Energy Institute | Hiltunen E.,University of Vaasa | Hiltunen E.,Vaasa Energy Institute | And 4 more authors.
Applied Energy | Year: 2014

Algae have been considered as a promising biodiesel feedstock. One of the major factors affecting large-scale algae technology application is poor wintering cultivation performance. In this study, an integrated approach is investigated combining freshwater microalgae Chlorella zofingiensis wintering cultivation in pilot-scale photobioreactors with artificial wastewater treatment. Mixotrophic culture with the addition of acetic acid (pH-regulation group) and autotrophic culture (control group) were designed, and the characteristics of algal growth, lipid and biodiesel production, and nitrogen and phosphate removal were examined. The results showed that, by using acetic acid three times per day to regulate pH at between 6.8 and 7.2, the total nitrogen (TN) and total phosphate (TP) removal could be increased from 45.2% to 73.5% and from 92.2% to 100%, respectively. Higher biomass productivity of 66.94mgL-1day-1 with specific growth rate of 0.260day-1 was achieved in the pH-regulation group. The lipid content was much higher when using acetic acid to regulate pH, and the relative lipid productivity reached 37.48mgL-1day-1. The biodiesel yield in the pH-regulated group was 19.44% of dry weight, with 16-18 carbons as the most abundant composition for fatty acid methyl esters. The findings of the study prove that pH adjustment using acetic acid is efficient in cultivating C. zofingiensis in wastewater in winter for biodiesel production and nutrient reduction. © 2014 Elsevier Ltd.

Zhu L.-D.,Hubei University | Zhu L.-D.,University of Vaasa | Zhu L.-D.,Vaasa Energy Institute | Hiltunen E.,University of Vaasa | Hiltunen E.,Vaasa Energy Institute
Renewable and Sustainable Energy Reviews | Year: 2016

Microalgae as a renewable and alternative energy feedstock have come under increased research interest, in response to the energy crisis, global warming and climate changes. Microalgal growth needs large amounts of chemical or organic fertilizers, causing substantial costs and risking the environment due to nutrient release. Using nutrient-rich wastewaters to cultivate microalgae appears a promising choice for the removal of nutrients and production of biofuels. Meanwhile, livestock production is rapidly increasing, especially in developing countries, because of increased consumption demands for meat. As a result, large quantities of animal wastes are left over, threatening environmental hygiene and becoming a barrier for development if not disposed of appropriately. Hence, the efforts to seek for an effective way to manage livestock wastes are also extremely important. This paper evaluates the feasibility of microalgal cultivation with livestock waste compost for continuous production of multiple bioproducts such as high values, biodiesel and biogas. A feasibility framework is proposed to fulfill this target. System integration and engineering is highlighted and main challenges are also discussed. Through careful microalgal biorefinery, the improvement of the economics of microalgal biofuels can be potentially achieved. Applying livestock waste compost to cultivate microalgae appears as a sustainable solution to realize both livestock waste management and bioproducts recovery, thus driving the industry towards sustainable growth. © 2015 Elsevier Ltd. All rights reserved.

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