Site assessment for industrial mass cultivation of microalgae: case studies from Persian Gulf and Oman Sea coastal areas

Providing enough microalgae biomass is required for various applications in sectors such as food, medicine and energy. The biomass resources such as land, water, nutrient and carbon dioxide are essential in cultivation feasibility study for biomass production as well as cost benefits. The aims of this research is therefore, site assessment and prioritization of potential site locations, carbon dioxide and water requirement for microalgae biomass production in the Persian Gulf and Oman Sea coastal areas.
This analysis was undertaken to provide a preliminary assessment of the demands that may be expected on land, water, and CO2 resources in the Persian Gulf and Oman Sea coastal areas required for the large volume of biomass feedstock production by autotrophic microalgae. Emphasize was placed on the finding proper sites to achieve higher biomass productivity. This research did not address the details of microalgae biomass production systems, and parameters affecting biomass productivities. The areas were selected to provide examples where geographical differences in water evaporation and solar resources, land availability profiles, water demand profiles and stationary CO2 sources would be possible alternatives for large scale production. The water demand was calculated from water mass balance with terms for water input and output, local pressure, direct rainfall input, evaporation loss, leakage loss and change in stored water.
The assessment reported here is based on the analysis of land availability for microalgae biomass production scenarios. The scenarios considered for different geographic areas in the Persian Gulf and Oman Sea coastal, within which different amounts of biomass are assumed to be achieved. The focus is on production of microalgae biomass for further applications. The production is assumed to occur within each of four provinces located in the coastal areas. It was assumed for this scoping assessment that biomass productivities at commercial scale can reach a practical upper limit of 0.7 kg/m3 per each batch cultivation periods, which is at the moderate range reported by other published analysis, and is expected to be reached in selected areas with high solar resources and water availability conditions. However, this remains to be really demonstrated at local areas. The water demand assumed for the areas are simply based on reduction of cultivation pond water level in proportion to the average evaporation in those areas. This was calculated through geospatial analysis by pan evaporation devices as an average in the various meteorological stations presented in the Persian Gulf and Oman Sea coastal areas. Maps are presented showing the proper spatial locations observed from field studies.
The above analysis addresses only open systems for growing a known species, given that algae must be grown in an aqueous system, therefore it is needed to manage the water used in cultivation, including acquisition, movement and containment, must be accounted for. Geographical distribution of selected were 5 sites in the Khuzestan, 20 sites in Bushehr, 24 sites in Hormozghan and 12 sites in Sistan and Blucheestan provinces. In total, 9000 sites were selected with a 2 km2 were suitable for large scale microalgae cultivation. The total area of these sites were estimated to be 18000 km2. The highest number of proper sites were found in Hormozghan province and lowest numbers of sites were found in Khuzestan province. The availability of technical service, carbon dioxide point resources from oil and gas units are an advantages for microalgae related activities in the Bushehr and Khuzestan provinces. The higher quality of water in the Sistan and Bluchestan province is an advantages for development of microalgae biomass production in the area.
The priority of proper sites were investigated for microalgae biomass production with geographical and field data. It can affects the biomass production costs as well as Persian Gulf and Oman Sea coastal water management. Land requirements appear to be the least restrictive, particularly in the Sistan and Bluchestan province, where higher numbers of potentially suitable classes of land exist. In Khuzestan province a larger quantities of wide classes of land are exist convenient for larger scale productions. Within the limited scope and assumptions of this analysis, sustainable photosynthetic microalgae biomass feedstock production in the Persian Gulf and Oman Sea coastal in excess of about 540 million metric tons 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 and other nutrient resources for enhanced algae production appears the biggest challenge, and could emerge as a constraint at biomass production levels below the normal.