There was a laboratory study of the microalgae Chlorella sp. to examine the potential as a feedstock for biodiesel production and the feasibility to use non-lipid cells for byproducts. Chlorella sp. was grown at photobioreactors of 25L under optimal growth conditions. [37]
The highest development activity observed during the period June to September of 2014, when lipids were extracted and many other valuable compounds. The maximum dry cell weight was 4 g/L, and the growth rate was 2/day at pH: 8.5, salinity: 45g/L, nitrate: 0,4 g/L and 30% solubility. The results showed that the ash content was 4mg/L, chlorophyll was 10.47 mg/L and carotenoids 6.12 mg/L. Furthermore, the content of the lipid was 20% of dry weight. Characterization of the oil was studied by acid value 0.449, soap formation value 50.5 and molecular weight 336.26. However in delipidated cells of microalgae, the quantities of proteins and carbohydrates were 100.50 mg/L and 15.5mg/L respectively. [36]
The amino acid analysis showed the presence of the necessary fragments in the appropriate amounts (Table 4) Also detailed fatty acid composition analysis of the biodiesel was made (Table 5) .The sequences of acids are ranging from C6-C20, in the presence of monounsaturated, polyunsaturated and saturated fatty acids. The largest percentage reaches 61%, represented by the C16: 0 and C18: 0 leading to the production of good quality biodiesel. There are also very important fractions C16: 1, C18: 1 and C18: 2. [4] [37]
The Nannochloropsis sp. was isolated and cultured at photobioreactors 25L in optimal light conditions promoting growth, salinity 30 g/L, nitrate 6 mg/L, pH 9 and 10% dilution. The highest development activity observed during autumn of 2014. Results showed that the maximum dry cell weight was 3.3 g / L, and the growth rate was 1.5/day. Biochemical results expressed by % of dry weight were: carbohydrates content 22, protein content 32, lipid content 40%. Ash content was 1.1 mg/L, chlorophyle a 0,58 mg/L, total carotenoids 2,56 mg/L, amino acid analysis showed the presence of 15 fractions.
More than 43% of total acids are constituted by C20 fatty acids and can adversely affect the biodiesel. Also the C16: 1 and C18: 1 are the most suitable and C16: 0 and C18: 0 give good cetane number. [38] The study showed that the Nannochloropsis sp. are promising microalgae for biofuels production predecessors and are a source of valuable ingredients it contains carbohydrates, proteins, and ash. [37]
The following scenarios A, B and C were analyzed for the sustainability of biodiesel production through this project. [39]
The assumptions adopted for the calculation fundamentals for scenario A were:
The unit will be installed near the power plant Vassilikos in Cyprus
The unit will process six tons of biomass/year and produces 0.7 tonnes of biodiesel with a closed type cultivation of microalgae (PBRs).
Average electricity cost of 20 cents / kWh (industrial area).
The plant will operate 24 hours a day for 330 days a year.
For the cultivation of microalgae used seawater and available source of CO2 coming from the power station.
The labor employment of staff: 1 person
The maintenance costs amount to 2% of the total installation cost.
Lending rate 7.75% Borrowings 60%
Own financing 40%. [39]
Annual growth rate 5%
Annual growth rate of operating expenses 3%. It was estimated that the first year’s income was 3.106 €, from which it seems biodiesel production is not viable only by the sale of the produced biodiesel. By selling but of carotenoids are found to be 40kg / t / year with an available dry biomass 6t, and at a price set at the lowest hypothetical market at 150 € / kg, biodiesel production becomes viable.
The assumptions adopted for the calculation fundamentals for scenario B were almost the same as the previous one except that the persons employed is 2 and that due to greater scale produced 7.2 tons of biodiesel by processing 61.4 tons of biomass. Using the products as carotenoids, proteins and carbohydrates, after the third year the biodiesl production will become viable. [39]
For scenario C there is no contribution of CO2, the initial biomass to be processed is
lower than in scenario B. After the process of growing and harvesting, via in situ- transesterification, biomass converted into biodiesel without prior extraction of lipids.
The quality of biodiesel does not meet the standard :
The content of esters reaches 98.7% while that in EN 14214 reaches 96.5%, which shows that the process was carried out properly,
The density is 834,1kg / m3 slightly lower than the range 860-900 kg / m3 the standard is likely due to moisture,
The viscosity is much lower in price 2.36 mm2 mm2/s of the standard,
The content of sulfur (S) is out of limits of 10mg / kg with a value 35 mg / kg and this is because Nannochloropsis sp. are marine organisms,
The cetane number of 54 is close enough to the standard 51[40] / s relative to the range 3.5-5
[4] Xiaochen Ma “Biodiesel Production from Algae through In Situ Transesterification Technology”, 2012
[36] http://www.med-algae.com/index.php/downloads/summary/48- leaflet/138- leaflet-greek
[37] Nagwa G-E Mohammady, Heba S. El-Sayed, Hala M. Taha, Eman M. Fakhry, Nairouz H. Mahmoud, Jihan H. Mohamed, and Liena M. Mekawy “Chlorella sp. as a Source of Biodiesel and By-Products: An Integral Study of Med-Algae Project” Botany and Microbiology Department, Faculty of Science, Alexandria University, Alexandria, Egypt.National Institute of Oceanography and Fisheries, Alexandria, Egypt, 2015
[38] http://www.med-algae.com/index.php/downloads/viewdownload/44-presentation/377-presentation-of-bloom , 2015
[39] Mr. Haris Kordatos “Show map areas of possible development and utilization of microalgae in selected Mediterranean countries, assessment results report greenhouse gas emissions and for preliminary techno-economic analysis of the unit installation of large-scale microalgae in Cyprus ” Cyprus Energy Agency, Published on 27 May https://www.youtube.com/watch?v=jORuwabh7cQ, 2015
[40] Dr. Michalis Omirou “Isolation and evaluation of native microalgae bloom in biofuel production, Agricultural Research Institute” Med Algae presentation, Published on 27 May https://www.youtube.com/watch?v=bf1nl2xF, 2015