A model for solar radiation conversion to algae in a shallow pond

In recent years there has been considerable interest in solar energy utilization through bioconversion, and a promising application involves the mass culture of unicellular algae. The purpose of this study has been to develop systematic procedures for predicting the yield of such cultures as a function of geographic location and diurnal and seasonal conditions. The procedures allow for the use of available insolation data and account for both the spectral and directional characteristics of the incident radiation. Calculations for the maximum hourly production of algae and oxygen have been performed for the Indianapolis, Indiana region, and the results are in reasonable agreement with field data obtained at similar latitudes.     

海藻生物燃料产业化开发的进展

海藻种类多样、光合作用效率高、生长周期短、生物产量高、自身合成油脂能力强,同时还能大量吸收CO2,是制备生物柴油最佳的生物质原料之一。国内外对海藻生物燃料技术的研发均取得一定成果。海藻生物柴油的生产过程主要包括海藻大规模培养、海藻油萃取、酯交换反应、生物柴油后处理4个步骤,而最重要的是海藻的大规模培养。光生物反应器已成为高效、快速、大量培养藻类的关键没备,其一般分为开放式和封闭式两种。AlgaeLink NV公司的海藻光生物反应器是目前世界上唯一已商业化的小型装置。我国企业采用自主研发的反应器装置,通过对环境条件因素进行控制,在技术上已达到海藻含油率40％,日产量1～1．4kg／m^3。当海藻含油率达到60％,日产量平均达到3kg／m^3以上时,海藻生物柴油的生产成本将接近石油柴油的批发价,海藻生物柴油产业将成为一个新兴的替代能源产业。     

Sustainable production of bioethanol from renewable brown algae biomass

Brown algae have been considered as renewable biomass for bioethanol production because of high growth rate and sugar level. Saccharification of brown algae biomass is relatively easy due to the absence of lignin. Among the major sugar components of brown algae, alginate cannot be directly used because industrial microorganisms are not able to metabolize alginate. This problem has been overcome by the development of metabolically engineered microbes to efficiently utilize alginate. This review analyzes and evaluates recent research activities related to bioethanol production from brown algae. This review mainly deals with the recent development and potential of a metabolically engineered microbial cell factory and bioethanol production from brown algae biomass including alginate as the main carbohydrate. Future researches for cost-effective bioethanol production from brown algae are discussed.     

Quality control of solar radiation data within the RMIB solar measurements network

Assessment of the solar resource is based upon measured data, where available. However, with any measurement there exist errors. Consequently, solar radiation data do not exhibit necessarily the same reliability and it often happens that users face time series of measurements containing questionable values though preliminary technical control has been done before the data release. To overcome such a situation, a major effort has been undertaken at the Royal Meteorological Institute of Belgium (RMIB) to develop procedures and software for performing post-measurement quality control of solar data from the radiometric stations of our in situ solar monitoring network. Moreover, because solar energy applications usually need continuous time series of solar radiation data, additional procedures have also been established to fill missing values (data initially lacking or removed via quality checks).     

A review on pretreatment methods,photobioreactor design and metabolic engineering approaches of algal biomass for enhanced biohydrogen production

The development of alternative fuels has been promoted by the extreme fossil fuel consumption brought on by urbanisation and deteriorating pollution. Due to its high energy and combustible qualities, biohydrogen has been perceived as a potential fuel substitute in dealing with issues related to the rising emission of greenhouse gases and global warming. As a source of carbon sequestration and sustainable renewable energy, biohydrogen synthesis by algae species has been prevalent in research scale. This review focuses on the novel and recent metabolic approaches for enhanced algal based biohydrogen production. Pretreatment methods available and scaling techniques used for enhancing the biohydrogen productivity using algal species have been elaborated in the review. Algal characteristics that make them suitable alternative for biohydrogen production are discussed briefly. Various pretreatment methods such as physical, chemical, biological and thermal are elaborated. In addition, the factors involved in influencing the biohydrogen productivity and the metabolic engineering approaches for modifying the pathway in algae are highlighted. Scaling up of process using different types of photobioreactors such as tubular, flat panel, airlift and stirred tank are reported that briefs about merits and demerits of each photobioreactor.     

Cultivation of algae with indigenous species – Potentials for regional biofuel production

The massive need for sustainable energy has led to an increased interest in new energy resources, such as production of algae, for use as biofuel. There are advantages to using algae, for example, land use is much less than in terrestrial biofuel production, and several algae species can double their mass in 1 day under optimized conditions. Most algae are phototrophs and some are nitrogen-fixing. Algae production therefore requires only small amounts of amendments such as carbon sources and nutrients. In the present paper an experiment was performed using water sampled from Lake Mälaren in Sweden. The lake water is considered nutrient rich, has relatively neutral pH and is rich in organic compounds and suspended solids. The idea behind this research was to enhance indigenous algae production rather than inoculate new species into the system. A simple experimental setup was designed where algae biomass growth was measured regularly over a 13 day period. FT-IR absorption spectra were evaluated in order to determine protein, lipid, carbohydrate and silicate contents of the algae. The algae community structure was characterized throughout the production cycle. Furthermore, the potential for energy supply for the transportation sector in the Mälardalen region from algae cultivated as tested in the experiment was evaluated.     

Global assessment of research and development for algae biofuel production and its potential role for sustainable development in developing countries

The possibility of economically deriving fuel from cultivating algae biomass is an attractive addition to the range of measures to relieve the current reliance on fossil fuels. Algae biofuels avoid some of the previous drawbacks associated with crop-based biofuels as the algae do not compete with food crops. The favourable growing conditions found in many developing countries has led to a great deal of speculation about their potentials for reducing oil imports, stimulating rural economies, and even tackling hunger and poverty. By reviewing the status of this technology we suggest that the large uncertainties make it currently unsuitable as a priority for many developing countries. Using bibliometric and patent data analysis, we indicate that many developing countries lack the human capital to develop their own algae industry or adequately prepare policies to support imported technology. Also, we discuss the potential of modern biotechnology, especially genetic modification (GM) to produce new algal strains that are easier to harvest and yield more oil. Controversy surrounding the use of GM and weak biosafety regulatory system represents a significant challenge to adoption of GM technology in developing countries. A range of policy measures are also suggested to ensure that future progress in algae biofuels can contribute to sustainable development.     

Combustion of algae oil methyl ester in an indirect injection diesel engine

An experimental study has been carried to use raw Algae oil and its methyl esters in an indirect injection diesel engine. Effects of engine speed, engine load output, injection timing of the algae biofuel and engine compression ratio on the engine output torque, combustion noise (maximum pressure rise rate), maximum pressure and maximum heat release rate have been studied. Raw oil extracted from microalgae and two versions of its methyl ester (0.1 and 0.2 methyl ester versions) have been evaluated in a Ricardo E6 engine. It has been shown that the algae oil methyl ester’s properties are similar to diesel fuel and its use has been successful in running the diesel engine smoothly. However, its use reduced the engine output torque slightly and increased the combustion noise. The engine output can be increased and the combustion noise can be reduced by controlling the engine design parameters e.g. injection timing and compression ratio.     

Algae as a sustainable energy source for biofuel production in Iran: A case study

Algae can be converted directly into energy, such as biodiesel, bioethanol and biomethanol and therefore can be a source of renewable energy. There is a growing interest for biodiesel production from algae because of its higher yield non-edible oil production and its fast growth that does not compete for land with food production. About 50% of algae weight is oil that this lipid oil can be used to make biodiesel. Algae is capable of yielding 30 times more oil per acre than the crops currently used in biodiesel production. Processes for biodiesel production from algae-oil are similar to food and non-food crops derived biodiesel processes. Because of disadvantages of fossil fuels, renewable energy sources are getting importance for sustainable energy development and environmental protection. Among the renewable sources, Iran has high biofuel energy potential. The Iranian government is considerable attention to the utilization of renewable energy, especially biofuels. Iran has enough land in order to algae cultivation that does not compete with food production. A salt lake (Lake Orumieh) in Iran's West Azarbaijan province, Maharlu salt lake in Iran's Fars province, Qom salt lake in Iran's Qom province have given rise to a new species of algae for biofuel. Algae are frequent in the shallow-marine lime stones in Zagros Mountains in north of Fars province. Greenish blooms of algae can be seen in the Persian Gulf and Caspian Sea, south and north of Iran respectively. This study presents a brief introduction to the resource, status and prospect of algae as a sustainable energy source for biodiesel production in Iran. The main advantages of using algae for biodiesel production in Iran are described.     

Fracture mechanics assessment of industrial pressure vessel failures

Fracture mechanics assessment procedures, such as BSI PD6493; 1991, R6 and ASME XI, have become well established in industry. These published procedures provide methods for assessing the acceptability of flaws in fusion welded structures. For such procedures to be used with confidence, it is essential that their application be validated by comparison with large scale fracture mechanics tests, and actual structural failures. This paper describes eight industrial pressure vessel failures, for which PD6493 fracture assessments have been performed. It has been demonstrated that the assessment procedures are safe to use, provided that input data are reliable.     

Brine clarity maintenance in salinity-gradient solar ponds

Brine transparency is an important part of the maintenance of a salinity-gradient solar pond as it affects the amount of solar radiation reaching the storage zone and hence has an influence on the thermal performance. There is a wide range of factors that can hinder the transmission of light in a solar pond. Algal and microbial growths are the most common problems encountered in working solar ponds and control of their densities is essential to maintain transparency. Two different chemical treatment methods for algae growth prevention are described in this paper: chlorine and a novel chemical product – copper ethylamine complex. The latter method has never been implemented previously in a working pond. This paper discusses the theory of the algae control methods used and presents the experimental results of the chemical treatments. The results showed that Cupricide is more effective than chlorine and is therefore the recommended chemical for algae control in solar ponds; it improves the water transparency especially in the upper convective zone and lower convective zone with all measurement values less than 1 NTU. Chlorine was found to be more corrosive than Cupricide due to the acidic effect it has on the pH. The preliminary cost analysis showed that granular chlorine is the cheapest chemical. A more detailed financial analysis is nevertheless required to refine these costs.     

Pyrolysis kinetics and reactivity of algae–coal blends

This paper presents results from a thermogravimetric analysis and modelling based study using a fresh water alga, Chlorococcum humicola, and a Victorian Brown Coal and their blends at different proportions. Pyrolysis was studied using the pure coal and pure algae as well as their blends to a final temperature of 1000 °C at different heating rates to understand the kinetics. The kinetic data of pure algae and pure coal were used to predict the pyrolysis characteristics of coal–algae blends at various heating rates using a modified distributed activation energy model which closely matched the experimental data. The experimental results also indicate that there is no chemical interaction between the algae and coal during pyrolysis.     

Catalytic pyrolysis of microalgae to high-quality liquid bio-fuels

The pyrolytic conversion of chlorella algae to liquid fuel precursor in presence of a catalyst (Na₂CO₃) has been studied. Thermal decomposition studies of the algae samples were performed using TGA coupled with MS. Liquid oil samples were collected from pyrolysis experiments in a fixed-bed reactor and characterized for water content and heating value. The oil composition was analyzed by GC-MS. Pretreatment of chlorella with Na₂CO₃ influences the primary conversion of chlorella by shifting the decomposition temperature to a lower value. In the presence of Na₂CO₃, gas yield increased and liquid yield decreased when compared with non-catalytic pyrolysis at the same temperatures. However, pyrolysis oil from catalytic runs carries higher heating value and lower acidity. Lower content of acids in the bio-oil, higher aromatics, combined with higher heating value show promise for production of high-quality bio-oil from algae via catalytic pyrolysis, resulting in energy recovery in bio-oil of 40%.     

Resource demand implications for US algae biofuels production scale-up

Photosynthetic microalgae with the potential for high biomass and oil productivities have long been viewed as a promising class of feedstock for biofuels to displace petroleum-based transportation fuels. Algae offer the additional benefits of potentially being produced without using high-value arable land and fresh water, thereby reducing the competition for those resources between expanding biofuels production and conventional agriculture. Algae growth can also be enhanced by the use of supplemental CO₂ that could be supplied by redirecting concentrated CO₂ emissions from stationary industrial sources such as fossil-fired power plants, cement plants, fermentation industries, and others. In this way, algae may offer an effective means to capture carbon emissions for reuse in renewable fuels and co-products, while at the same time displacing fossil carbon fuels to help bring about a net reduction in overall carbon emissions. Significant displacement of petroleum fuels will require that algae feedstock production reach large volumes that will put demands on key resources. This scenario-based analysis provides a high-level assessment of land, water, CO₂ and nutrient (nitrogen, phosphorus) demands resulting from algae biofuel feedstock production reaching target levels of 10 billion gallons per year (BGY), 20 BGY, 50 BGY, and 100 BGY for four different geographical regions of the United States. Different algae productivities are assumed for each scenario region, where relative productivities are nominally based on annual average solar insolation. The projected resource demands are compared with data that provide an indication of the resource level potentially available in each of the scenario regions. The results suggest that significant resource supply challenges can be expected to emerge as regional algae biofuel production capacity approaches levels of about 10 BGY. The details depend on the geographic region, the target feedstock production volume, and the level of algae productivity that can be achieved. The implications are that the supply of CO₂, nutrients, and water, in particular, can be expected to severely limit the extent to which US production of algae biofuel can be sustainably expanded unless approaches are developed to mitigate these resource constraints in parallel to emergence of a viable algae technology. Land requirements appear to be the least restrictive, particularly in the Western half of the country where larger quantities of potentially suitable classes of land exist. Within the limited scope and assumptions of this analysis, sustainable photosynthetic microalgae biofuel feedstock production in the US in excess of about 10 BGY will likely be a challenge due to other water, CO₂ and nutrient resource limitations. Developing algae production approaches that can effectively use non-fresh water resources and minimize both water and nutrient requirements will help reduce resource constraints. Providing adequate CO₂ resources for enhanced algae production appears the biggest challenge, and could emerge as a constraint at oil production levels below 10 BGY.     

新型水质藻类传感器及遥测预警系统研究

为满足我国主要湖泊及河流藻类污染实时监测预警需求,研发了一套新型水质藻类遥测预警系统,采用基于暗激光束的单个粒子监测方法（IPSA）对藻类进行监测,借助新型水质藻类遥测预警系统的传感器、遥测设备、应用软件、系统集成等核心技术对藻类信息进行分析。试验结果表明,该系统实时性强、精度高,为预防水华现象的发生提供了及时的预报和监控。     

大型海藻发酵生产甲烷技术研究

大型海藻发酵生产甲烷属生物质能,是一种碳中性的清洁能源,是重要的海洋生物碳汇。不同种类的藻类发酵产甲烷的潜力是不一样的,其中巨藻含有丰富的甲烷成分,但其自然资源量有限,而人工养殖依然是一个难题,如何持续不断地提供原材料是巨藻生物质能源开发中亟待解决的问题。海藻发酵产甲烷是多种微生物联合作用的结果,从整体上可划分为产甲烷菌群和不产甲烷菌群,它们相互依赖又相互制约,产甲烷菌利用不产甲烷菌的代谢产物H2、CO2等最终合成甲烷。海藻发酵过程的微生物要求具有一定的耐盐性,大体可以利用沼气发酵微生物经过定向培养和筛选而获得。多数人支持将沼气发酵过程分为水解液化、酸化和甲烷化三个阶段的理论,而甲烷形成途径包括菌种间H2的转移和由乙酸产生甲烷。甲烷发酵的影响因素包括原料的预处理、原料的成分和颗粒大小以及接种物、发酵温度、发酵料液pH值、接种率及接种物中对发酵菌活性有影响的物质等,甲烷产率最大化的最主要前提是反应条件要达到最优化。我国在海藻大规模养殖方面具有先天的自然条件及技术和人力优势,为海藻生物质能源开发提供了巨大的潜力,但在技术上还有待突破,特别是在接种物培养、甲烷产率控制等一些特定环节上还需加强研究。     

Integrated biological hydrogen production

Biological systems offer a variety of ways by which to generate renewable energy. Among them, unicellular green algae have the ability to capture the visible portion of sunlight and store the energy as hydrogen (H₂). They hold promise in generating a renewable fuel from nature's most plentiful resources, sunlight and water. Anoxygenic photosynthetic bacteria have the ability of capturing the near infrared emission of sunlight to produce hydrogen while consuming small organic acids. Dark anaerobic fermentative bacteria consume carbohydrates, thus generating H₂ and small organic acids. Whereas efforts are under way to develop each of these individual systems, little effort has been undertaken to combine and integrate these various processes for increased efficiency and greater yields. This work addresses the development of an integrated biological hydrogen production process based on unicellular green algae, which are driven by the visible portion of the solar spectrum, coupled with purple photosynthetic bacteria, which are driven by the near infrared portion of the spectrum. Specific methods have been tested for the cocultivation and production of H₂ by the two different biological systems. Thus, a two-dimensional integration of photobiological H₂ production has been achieved, resulting in better solar irradiance utilization (visible and infrared) and integration of nutrient utilization for the cost-effective production of substantial amounts of hydrogen gas. Approaches are discussed for the cocultivation and coproduction of hydrogen in green algae and purple photosynthetic bacteria entailing broad utilization of the solar spectrum. The possibility to improve efficiency even further is discussed, with dark anaerobic fermentations of the photosynthetic biomass, enhancing the H₂ production process and providing a recursive link in the system to regenerate some of the original nutrients.     

Calculation of monthly average insolation on tilted surfaces

Several simplified design procedures for solar energy systems require monthly average meteorological data. Monthly average daily totals of the solar radiation incident on a horizontal surface are available. However, radiation data on tilted surfaces, required by the design procedures, are generally not available. A simple method of estimating the average daily radiation for each calendar month on surfaces facing directly towards the equator has been presented by Liu and Jordan [1]. This method is verified with experimental measurements and extended to allow calculation of monthly average radiation on surfaces of a wide range of orientations.     

Study of the flow mixing in a novel ARID raceway for algae production

A novel flow field for algae raceways has been proposed, which is fundamentally different from traditional paddlewheel-driven raceways. To reduce freezing and heat loss in the raceway during cold time, the water is drained to a deep storage canal. The ground bed of the new raceway has a low slope so that water, lifted by propeller pump, can flow down in laterally-laid serpentine channels, relying on gravitational force. The flow rate of water is controlled so that it can overflow the lateral channel walls and mix with the main flow in the next lower channel, which thus creates a better mixing. In order to optimize the design parameters of the new flow field, methods including flow visualization, local point velocity measurement, and CFD analysis were employed to investigate the flow mixing features. Different combinations of channel geometries and water velocities were evaluated. An optimized flow field design and details of flow mixing are presented. The study offers an innovative design for large scale algae growth raceways which is of significance to the algae and biofuel industry.     

Development of High-Speed and Large-Scale Culture Technology of Marine Algae Using Seawater With High Concentrations of Dissolved Carbon Dioxide

The effective use of marine biomass has recently been identified as a feasible method of renewable energy production. Therefore, to facilitate the effective use of algae biomass, it is essential to develop techniques for the mass production of algal cultures. It is also important to develop artificial culture techniques that are not affected by natural phenomena such as weather. This study utilized a newly developed culture technology that uses seawater with high concentrations of dissolved CO₂ (CO₂ seawater). The experiments in this study were conducted to test the effects of CO₂ seawater on algal growth. In addition to experimental conditions that were previously investigated in industrial algae farming scenarios, it is also necessary to consider the effects of new parameters associated with increased CO₂ concentrations. The following four conditions were experimentally investigated: (1) the tolerance of algae to changes in pH, (2) the effect of CO₂ seawater on long-term culture growth, (3) the effect of continuous culture experiments, and (4) the effect of water flow rate on cultured algae. The results in terms of having excelled especially indicate that a 1-month long-term algae culture period in seawater with CO₂ concentration of 1.0% led to growth that was approximately 4.5 times faster than growth in seawater without the CO₂ additive. Furthermore, the results also provided useful information regarding the proper flow rate needed to enhance algal growth.