▶ Addresses a wide range of timely environment, economic and energy topics ▶ A forum to review, analyze and stimulate the development, testing and implementation of mitigation and adaptation strategies at regional, national and global scales ▶ Contributes to real-time policy analysis and development as national and international policies and agreements are discussed and promulgated ▶ 94% of authors who answered a survey reported that they would definitely publish or probably publish in the journal again

Mitigation and Adaptation Strategies for Global Change

Production of liquid biofuels from renewable resources

Cultivation, photobioreactor design and harvesting of microalgae for biodiesel production: A critical review

Biodiesel is a renewable transportation fuel consisting of fatty acid methyl esters (FAME), generally produced by transesterification of vegetable oils and animal fats. In this review, the fatty acid (FA) profiles of 12 common biodiesel feedstocks were summarized. Considerable compositional variability exists across the range of feedstocks. For example, coconut, palm and tallow contain high amounts of saturated FA; while corn, rapeseed, safflower, soy, and sunflower are dominated by unsaturated FA. Much less information is available regarding the FA profiles of algal lipids that could serve as biodiesel feedstocks. However, some algal species contain considerably higher levels of poly-unsaturated FA than is typically found in vegetable oils. Differences in chemical and physical properties among biodiesel fuels can be explained largely by the fuels’ FA profiles. Two features that are especially influential are the size distribution and the degree of unsaturation within the FA structures. For the 12 biodiesel types reviewed here, it was shown that several fuel properties – including viscosity, specific gravity, cetane number, iodine value, and low temperature performance metrics – are highly correlated with the average unsaturation of the FAME profiles. Due to opposing effects of certain FAME structural features, it is not possible to define a single composition that is optimum with respect to all important fuel properties. However, to ensure satisfactory in-use performance with respect to low temperature operability and oxidative stability, biodiesel should contain relatively low concentrations of both long-chain saturated FAME and poly-unsaturated FAME.

Review of biodiesel composition, properties, and specifications

The potential of sustainable algal biofuel production using wastewater resources

Sustainability is a key principle in natural resource management, and it involves operational efficiency, minimisation of environmental impact and socio-economic considerations; all of which are interdependent. It has become increasingly obvious that continued reliance on fossil fuel energy resources is unsustainable, owing to both depleting world reserves and the green house gas emissions associated with their use. Therefore, there are vigorous research initiatives aimed at developing alternative renewable and potentially carbon neutral solid, liquid and gaseous biofuels as alternative energy resources. However, alternate energy resources akin to first generation biofuels derived from terrestrial crops such as sugarcane, sugar beet, maize and rapeseed place an enormous strain on world food markets, contribute to water shortages and precipitate the destruction of the world's forests. Second generation biofuels derived from lignocellulosic agriculture and forest residues and from non-food crop feedstocks address some of the above problems; however there is concern over competing land use or required land use changes. Therefore, based on current knowledge and technology projections, third generation biofuels specifically derived from microalgae are considered to be a technically viable alternative energy resource that is devoid of the major drawbacks associated with first and second generation biofuels. Microalgae are photosynthetic microorganisms with simple growing requirements (light, sugars, CO 2 , N, P, and K) that can produce lipids, proteins and carbohydrates in large amounts over short periods of time. These products can be processed into both biofuels and valuable co-products. This study reviewed the technologies underpinning microalgae-to-biofuels systems, focusing on the biomass production, harvesting, conversion technologies, and the extraction of useful co-products. It also reviewed the synergistic coupling of microalgae propagation with carbon sequestration and wastewater treatment potential for mitigation of environmental impacts associated with energy conversion and utilisation. It was found that, whereas there are outstanding issues related to photosynthetic efficiencies and biomass output, microalgae-derived biofuels could progressively substitute a significant proportion of the fossil fuels required to meet the growing energy demand.

/pdf/biofuels-from-microalgae-a-review-of-technologies-for-1t1wwr5e69.pdf

Biofuels from microalgae—A review of technologies for production, processing, and extractions of biofuels and co-products

Enhancement of BODIPY505/515 lipid fluorescence method for applications in biofuel-directed microalgae production.

Rapid methods to characterise biomass for energy are needed due to the increasing use of biomass in the energy system and the expanding varieties of biomasses available. Chemical information on biomasses can be utilised in integrated management systems, allowing for the appropriate selection and optimum use of biomass to energy conversion techniques. Composition of biomass has important implications for optimisation of conversion processes such as pelletising/briquetting, combustion, gasification, pyrolysis and anaerobic digestion. There are opportunities to develop rapid spectroscopic techniques for both biomass to biofuel and biofuel to bioenergy process control. Rapid spectroscopic techniques and chemometrics may also be used to predict the key biomass and biofuel parameter calorific value and could be used to improve energy crop growing programmes. This review brings together the reported uses of infrared spectroscopic analysis coupled with chemometric techniques which have been applied to optimising biomass to biofuel and bioenergy conversion processes.

Evaluation of infrared techniques for the assessment of biomass and biofuel quality parameters and conversion technology processes: A review

Continued reliance on fossil fuel reserves as the primary energy resource is increasingly becoming unsustainable, owing to the need for: minimal exposure to the associate price volatility, reduction of greenhouse gas emissions by energy conservation, and deployment of cleaner and locally produced energy feedstock (including recovery from waste). Based on current knowledge and technology projections, third-generation biofuels (low input-high yielding feedstock) specifically derived from microalgae are considered to be viable alternative energy resource. They are devoid of the major drawbacks associated with first-generation biofuels (mainly terrestrial crops, e.g. sugarcane, sugar beet, maize and rapeseed) and second-generation biofuels (derived from lignocellulosic energy crops and agricultural and forest biomass residues). This chapter focuses on technologies underpinning microalgae-to-biofuels production systems, and evaluates the scale-up and commercial potential of biofuel production, including benchmarking of fuel standards. It articulates the importance of integrating biofuels production with the production of high-value biomass fractions in a biorefinery concept. It also addresses sustainability of resource deployment through the synergistic coupling of microalgae propagation techniques with CO2 sequestration and bioremediation of wastewater treatment potential for mitigation of environmental impacts associated with energy conversion and utilisation.

Biofuels from Microalgae: Towards Meeting Advanced Fuel Standards

Bio-fixation of carbon dioxide (CO2) by microalgae has been recognised as an attractive approach to offset anthropogenic emissions. Biological carbon mitigation is the process whereby autotrophic organisms, such as microalgae, convert CO2 into organic carbon and O2 through photosynthesis; this process through respiration produces biomass. In this study Dunaliella tertiolecta was cultivated in a semicontinuous culture to investigate the carbon mitigation rate of the system. The algae were produced in 1.2-L Roux bottles with a working volume of 1 L while semicontinuous production commenced on day 4 of cultivation when the carbon mitigation rate was found to be at a maximum for D. tertiolecta. The reduction in CO2 between input and output gases was monitored to predict carbon fixation rates while biomass production and microalgal carbon content are used to calculate the actual carbon mitigation potential of D. tertiolecta. A renewal rate of 45 % of flask volume was utilised to maintain the culture in exponential growth with an average daily productivity of 0.07 g L−1 day−1. The results showed that 0.74 g L−1 of biomass could be achieved after 7 days of semicontinuous production while a total carbon mitigation of 0.37 g L−1 was achieved. This represented an increase of 0.18 g L−1 in carbon mitigation rate compared to batch production of D. tertiolecta over the same cultivation period.

Liam Brennan

Papers

Biofuels from microalgae—A review of technologies for production, processing, and extractions of biofuels and co-products

Enhancement of BODIPY505/515 lipid fluorescence method for applications in biofuel-directed microalgae production.

Evaluation of infrared techniques for the assessment of biomass and biofuel quality parameters and conversion technology processes: A review

Biofuels from Microalgae: Towards Meeting Advanced Fuel Standards

Carbon dioxide utilisation of Dunaliella tertiolecta for carbon bio-mitigation in a semicontinuous photobioreactor.