**12. Economic importance**

Compared to biofuels from agricultural crops, the amount of land required would be minimal. Trials in ideal conditions show that fast-growing micro-algae can yield 1800–2000 gallons/(acre - year) of oil—compare this with 50 gallons for soyabeans, 130 gallons for rapeseed and \_650 gallons for palm oil. It can grow on fresh or brackish water on marginal land so that it does not compete with areas for agricultural cultivation. As Sean Milmo points out in his article in Oils and Fats International [Milmo, 2008]; oil from algae on 20–40 M acres of marginal land would replace the entire US supply of imported oil, leaving 450 M acres of fertile soil in the country entirely for food production. Biomass can also be harvested from marine algae blooms and algae can even be cultivated in sewage and water treatment plants. However, most estimates of algal fuel productivity estimate that with current production technologies algal diesel can be manufactured for, at best, \$4.54 per gallon using high density photobioreactors. In order to compete economically with petroleum diesel costs – and not accounting for any potential subsidy scheme, which is a likely possibility – requires the reduction of these costs to near \$1.81 per gallon relative to

*Nostoc muscorum* T3 12.50±2.65 7.40±0.74 5.10±0.74

T3 7.40±0.95 5.00±0.61 2.40±0.61 *Anabaena flous* 

*Chlorella vulgaris* T3 13.20±1.87 8.50±1.74 4.70±1.74

*Oscillatoria sp* T2 6.80±0.65 3.80±0.32 3.00±0.32

*Spirulina platensis* T3 7.30±0.44 5.00±0.51 2.30±0.51

*Anabaena oryzae* T4 8.00±0.16 4.70±0.12 3.30±0.12

*Nostoc humifusum* T1 15.50±1.65 11.80±1.52 3.70±1.52

*Phormedium sp* T2 11.60±0.88 8.40±0.65 3.20±0.65

Each value is presented as mean of triplet treatments, LSD: Least different significantly at P ≤ 0.05

T1: waste water without treatment; T2: waste water after sterilization; T3: waste water+ nutrients with

Table 10. Total lipids, biodiesel, glycerine+pigments percentage and color, pH of biodiesel

Compared to biofuels from agricultural crops, the amount of land required would be minimal. Trials in ideal conditions show that fast-growing micro-algae can yield 1800–2000 gallons/(acre - year) of oil—compare this with 50 gallons for soyabeans, 130 gallons for rapeseed and \_650 gallons for palm oil. It can grow on fresh or brackish water on marginal land so that it does not compete with areas for agricultural cultivation. As Sean Milmo points out in his article in Oils and Fats International [Milmo, 2008]; oil from algae on 20–40 M acres of marginal land would replace the entire US supply of imported oil, leaving 450 M acres of fertile soil in the country entirely for food production. Biomass can also be harvested from marine algae blooms and algae can even be cultivated in sewage and water treatment plants. However, most estimates of algal fuel productivity estimate that with current production technologies algal diesel can be manufactured for, at best, \$4.54 per gallon using high density photobioreactors. In order to compete economically with petroleum diesel costs – and not accounting for any potential subsidy scheme, which is a likely possibility – requires the reduction of these costs to near \$1.81 per gallon relative to

LSD 0.159 0.159 0.152

*Wollea sp* T3 7.20±1.32 4.00±0.22 3.23±0.22

**water treatment Algal species**

according to Duncan's multiple range tests.

**12. Economic importance** 

sterilization T4: waste water+ nutrients without sterilization

from different microalgae species cultivated in different waste water

*aquae*

**pigments Total lipids Biodiesel Optimal waste** 

**Glycerin +** 

2006 fuel prices. These cost reduction figures take into account the fact that materials input and refining of fuels (in this case the algae vegetable oil) account for roughly 71% of total at pump fuel cost [Chisti, 2007]. Algal biodiesel becomes even more plausible given the potential for GHG regulation in the near future. Since for every ton of algal biomass produced, approximately 1.83 tons of carbon dioxide is fixed while petroleum diesel carries a massive negat balance, the competitiveness of algae diesel increases as GHG externalities are taken into account. Given certain research objectives these cost reductions are achievable in the near future. The National Renewable Energy Laboratory (NREL) outlines many such research objects including: increasing photosynthetic efficiency of algae species for high lipid production, control of mechanisms of algae biofocculation, understanding the effects of non-steady-state operating conditions, and methods of species selection and control [Sheehan *et al*., 1998].
