Energy-Water Nexus for Mass Cultivation of Algae

Abstract

Microalgae are currently considered a potential feedstock for the production of biofuels. This work addresses the energy needed to manage the water used in the mass cultivation of saline, eukaryotic algae grown in open pond systems. Estimates of both direct and upstream energy requirements for obtaining, containing, and circulating water within algae cultivation systems are developed. Potential productivities are calculated for each of the 48 states within the continental U.S. based on theoretical photosynthetic efficiencies, growing season, and total available land area. Energy output in the form of algal biodiesel and the total energy content of algal biomass are compared to energy inputs required for water management. The analysis indicates that, for current technologies, energy required for water management alone is approximately seven times greater than energy output in the form of biodiesel and more than double that contained within the entire algal biomass. While this analysis addresses only currently identified species grown in an open-pond system, the water management requirements of any algae system will be substantial; therefore, it is critical that an energy assessment of water management requirements be performed for any cultivation technology and algal type in order to fully understand the energy balance of algae-derived biofuels.

Learning for the Future: Educating Career Fisheries and Wildlife Professionals

“…Water quality and use Pimentel et al 2004, Schilling 2009, Murphy and Allen 2011, NRC 2011 for converting sugars directly to electricity (Chaudhuri and Lovley 2003), and development of engineered yeast for increased ethanol yields (Alper et al 2006) among others. In some cases, fuel production may be coupled with water treatment plants because oil can be extracted from microbes that digest sludge.…”

Algae Biofuel in the Nigerian Energy Context

“…There is a possibility to earn about US $129 million from biofuel investment, these have the potentials to promote the production of the crop plant output, and further enhance the implementation of the biofuel strategy. In line with this prospect, a total value of US $92,000 grant have been received from Nigerian-German biofuel partnership initiative called Renewable Energy and Energy Efficiency Partnership (REEEP) [24]. The aim of this partnership is to reduce overdependence on fossil fuel and mitigate environmental pollution.…”

“…The government also launched a biofuel initiative to identify industries that could create jobs and reduce the unemployment rate in the country. On a national scale, the benefits of the biofuel programme would generate income to the government, empowerment, economic growth, agricultural enhancement, synergistic energy benefit and greenhouse gas emissions [24].…”

“…The largest is the Niger River which occupies more than 60 % of land [14], [30]. In the study of the requirements for mass cultivation of algae by, they require about 80 % water of their weight, which is utilized for growth based on its photosynthetic nature [24]. One mole of water molecule is required for the process, which means that about 10 kg of water molecules are absorbed by a kilogram of algae.…”

Comprehensive Evaluation of Algal Biofuel Production: Experimental and Target Results

“…(1) using waste and recycled nutrients (e.g., waste water and animal waste) [11,15,[25][26][27][28]65,71,72]; (2) using waste heat and flue-gas from industrial plants [44,59], carbon in wastewater [28], or developing energy-efficient means of using atmospheric CO 2 ; (3) developing ultra-productive algal strains (e.g., genetically modified organisms) [73][74][75]; (4) minimizing pumping [58,76,77]; (5) establishing energy-efficient water treatment and recycling methods [55]; (6) employing energy-efficient harvesting methods, such as chemical flocculation [66,78,79], and (7) avoiding separation via distillation.…”