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Alternative fuels and green aviation
Published in Emily S. Nelson, Dhanireddy R. Reddy, Green Aviation: Reduction of Environmental Impact Through Aircraft Technology and Alternative Fuels, 2018
From 1978 to 1996, the U.S. Department of Energy funded the Aquatic Species Program (ASP) to quantitatively explore the concept of producing biodiesel from algae. The program analyzed over 3,000 strains of microalgae and diatoms (algae with a cell wall of silica), which were narrowed down to the 300 most promising microbes. The intent was not only to understand which species were the best at oil production, but also their hardiness with respect to seasonal temperature variation, pH, and salinity, and the ability to outgrow wild competitors, all of which affect the stability of the culture. Algal growth in industrial-scale open ponds with 1,000 m2 surface area was examined for feasibility of mass production in California, Hawaii, and New Mexico (Sheehan et al., 1998). As is typical of open-pond aquaculture, the depth of the ponds was shallow to aid in light penetration; here 10 to 20 cm. The ASP determined that microalgae use far less water and land than oil-producing seed crops, estimating that 200,000 ha could produce significantly more energy than seed crops: about one quadrillion Btu energy (~1*1018 J, or roughly 1% of global energy consumption). Nevertheless, the ASP concluded that biofuel from algae would not be cost-competitive with petroleum fuel. In their 1995 evaluation, they projected the cost of algae-based biofuel to be 59 to 186 U.S.$/bbl compared with petroleum at $20/bbl. Since then, the gap has likely narrowed because of adjustments on both types of fuel.
Crop Protection in Open Ponds
Published in Stephen P. Slocombe, John R. Benemann, Microalgal Production, 2017
Robert C. McBride, Val H. Smith, Laura T. Carney, Todd W. Lane
Contaminating nontarget strains of algae are another significant challenge in open pond algal cultivation systems. Algae are widely distributed in the landscape, and many species are capable of rapid growth in a broad range of environmental conditions (Wang et al. 2013). The DOE Aquatic Species Program screened hundreds of strains of algae and could not maintain dominant single strains for extended periods of time in open culture due to contaminating invasions of green algae (Sheehan et al. 1998). Contamination of Dunaliella strains by non-carotenoid producing Dunaliellastrains has also been reported (Day and Stanley 2012). Outdoor cultures of the cyanobacterium Arthrospira have been known to become contaminated with eukaryotic microalgae such as Chlorella and Oocystis, as well as by other species of cyanobacteria (Vonshak et al. 1983; Vonshak and Richmond 1988; Belay 1997; Vonshak 1997).
Biomass
Published in Roy L. Nersesian, Energy Economics, 2016
Groundwork for producing biodiesel from algae was laid in a nearly 20-year program (1978–1996) conducted by the US Department of Energy’s Office of Fuels Development. The peak funding year for the Aquatic Species Program (ASP) was only $2.75 million, yet from this program came the entire framework of identifying the right type of algae and right conditions for maximum productivity. The conclusion of the program was that the process was not economic. But that was 1996. With current prices of crude oil and with the possibility of selling carbon credits, the economic equation has changed considerably. Moreover, technological progress has been made since the cessation of ASP to further reduce capital and operating costs and enhance productivity.
Microalgae biodiesel production: a solution to increasing energy demands in Turkey
Published in Biofuels, 2022
Closed systems allow the operator to have efficient control of the process parameters; therefore, enhanced heat and mass transfer result in higher biomass yields, averaging 8 g/L [22]. The best way to cultivate microalgae is using photobioreactors because they allow for the continuity of a single culture [4,149]. These reactors should be tightly controlled to provide the necessary conditions under which microorganisms can develop. The variables to be controlled are nutrient level, pH, temperature, aeration rate, CO2 concentration, distribution of illumination, injection period, and magnitude [151]. Although there are many studies on and applications for raising microalgae, only a few microalgae species can be commercially grown. By changing the nutrients and physical conditions, the algae biomass and component yield can be increased. Nutrients with different types and concentrations of carbon, nitrogen (N), and phosphorus (P) sources have effects on microalgae yield. Process parameters related to the physical conditions, such as high light density, salinity, and electromagnetic field, also affect the yield [152]. According to the Aquatic Species Program [153] and other studies, a proper microalgae species should have high and/or constant lipid content, continuous or constant growth and yield in a variable environment, and minimum pollution, and its harvest should be easy, flexible, and extractable.