ENERGY FROM ALGAE 

1. WHAT IS ALGAE?

Algae are photosynthetic organisms which live in most habitats. They vary from small, single cell forms to complex multicellular forms, such as the giant that grow to 65 meters in length.[1]Algae commonly live in bodies of water, nevertheless could be found in terrestrial environments. [6]  

Categorization: [2] 

Algae are classified on the basis of:

-       Colour (photosynthetic pigments)                 

 - Storage material

-       Flagella                                                         

- Cell wall

Main division is focus in these groups:

-       Chlorophytes (green algae)

 -       Phaeophytes (brown algae)

-       Rhodophytes (red algae)

-       Cyanobacteria (blue-green algae)

How algae live? [3]

Algae use the sun´s energy to create food such as sugar, through photosynthesis process; they produce more oxygen than all the plants in the world.

At the photosynthesis process light energy (radiation) in transformed into chemical energy. Plants absorb carbon dioxide, radiation and water and the process produce oxygen and carbohydrates (sucrose, glucose, starch). [4]  

Like plants; algae main food source are phosphate and nitrate, for example; fish waste, uneaten food, decaying plants and animals, contain phosphates and nitrates which are used by algae. [5]  

 

Algae use:

[6]   Algae are used in several applications, the most important are:

-       Fertilizer: due to the algae nutrients content (phosphate and nitrogen), algae have be used for centuries as fertilizer.

-       Soil conditioner-       Livestock feed

-       Pollution control: effluents treatment, wastewater treatments,

-       Algaculture

-       Source of food: they are excellent source of vitamins, therefore algae is commercially cultivated as nutritional supplement and used as human food.

-       Pharmaceuticals

-       Cosmetics, etc. [7] 

2. ENERGY AND ALGAE:

[8] There exist more than 100.000 strains of algae, with different types of molecules: oils carbohydrates and protein. Algae with high concentration of carbohydrates, cam produce starches, which can be separated and fermented into ethanol. Algae with high concentration of oil can be processed to produce biodiesel. Oil content in some algae could be 40%. The remaining proteins can be used in animal grains.  Besides algae can be used as substrates in biogas plants.

Investigations have published the yield comparison for different feedstock:

-       Soy: 50 gal oil/acre

-       Canola : 150 gal of oil/acre

-       Palm: 650 gal of oil/acre

-       Algae: 10.000 of gal oil/acre

An important advantage from algae, is that they could be cultivates in underutilized desert or semi-desert lands.

 3. CURRENT PROJECTS:

Alga production is growing fast, currently there are some companies producing algae at high scale, for energy proposes:

§  Colorado Silox Biofuels

§  Valcent products and the Canadian energy company, Global Green Solutions, have invested about $5 million, in El Paso, Texas facility.  [9] 

§  Solar Energy Research Institute (SERI) in Golden, Colorado has an intensive program where isolated 320 strains of microalgae, of which five were recognized containing more than 40% of lipids. [10]

§  BioFields, Sonora, México is investing $850 million, in a bioethanol plant based in algae. This plant will use carbon dioxide from The Electricity Federal Commission and hot water from a Hydroelectric plant. The project is planning to use blue-green algae in ponds, and will start to operate at the end of 2009. BioFields will use Algenol´s technology, which process is very different from usual methods, due to does not have to be cultivates. Instead, algae produce ethanol in gas form and is condensed into liquid. The system can produce 6.000 gallons of ethanol per acre per year, so much more than sugar cane´s 890 gallons per acre per year. The process absorbs 90% of the CO₂ that is fed into the algae bioreactors.[11-12]          

 

4. ADVANTAGES AND DISADVANTAGES:

Advantages:

-       High energy yields from algae and high production per acre.

-       Clean energy source

-       Fast growing

-       Algae absorbs CO₂, therefore biofuels from algae are CO₂ free.

-       Nitrogen consumption

-       High nutrient content (nitrates and phosphate)

-       Algae can be cultivated in underutilized desert or semi-desert lands.

 -       Biofuels from algae does not compete with food.

Disadvantages:

-       Algae cultivation is expensive and biofuels technology process are very expensive

-       Open ponds of algae cultivation can be invaded by other species.

-       Need of constant temperature

REFERENCES: