Giorgio Nebbia nebbia@quipo.it
In the search of alternative energy sources an increasing interest is devoted at the biomass; This name --- often used properly and improperly, from the ecological and commercial point of view --- refers at any vegetal or animal organic material “built” from the Sun, the source of energy with which the vegetals use the carbon dioxide of the atmosphere, the water from the atmosphere and the soil, and few other salts of the soil to produce starch, cellulose and lignins, fats and proteins, all molecules containing carbon and hydrogen and therefore potential fuels.
The components of the biomass may “burn” in the animal (including human) body as a source of food energy: potatoes and beet or cane sugar, lettuce and so on; many components of the “solar” vegetal biomass are used to manufacture furniture or paper, or may be used to produce heat and electricity: bioethanol, biodiesel, pellets to be burned in stoves, and so on .
The energy use of biomass is contested and accused to subtract crops and fields to human food utilization in the poor countries to fuels the SUV’s of the rich; this is the case of the use as a fuel of corn or palm oil; others suggest that biomass fuels may be better obtained from residual or non-food crops.
In the word “biomass” are included many photosynthetic organisms with rapid growth that may be used as sources of commercial products and fuels: among them the algae from which is possible to extract oil substitutes, now termed oilgae (from the English oil and the latin algae); a new trend ion the utilization of solar energy.
Algae grow rapidly in ponds or tubes exposed at the solar radiation and containing water solutions of the nutritive elements phosphorus, nitrogen and potassium, the same that vegetal obtain from the soil. Algae may therefore be “cultivated” in water everywhere, without soil; when dried, algae may be burnt directly or used in any other form as fuels. At the dawn of the solar energy era, in the 40’s, there has been a great interest in the growth of algae as energy sources. Then in the low-cost oil time, the interest decreased and now, after half a century, there is a resurrection of this promising technology.
In the meantime the biologists and chemists, in the silence of their laboratories have enriched the knowledge of this chapter of biology and now many algae are known that present favourable energy and economic characteristics. As all the vegetals, the various algae contain carbohydrates, fats and proteins and many have a rather elevated (also 20-30 %) content of fats that may be converted to biodiesel. After the fat extraction the remaining panels, rich in carbohydrates and proteins, may be used as animal feed. Progress has been made also in the algae “cultivation” and in the choose of algae nutrients.
Algae grow everywhere there are nutrients like polluted superficial and waste waters; the purification with algae of polluted coastal sea waters is an help for tourism. Of increasing interest is the cultivation of “energy” algae in urban and industrial waste waters that are rich of nutrient elements; this is the case of waste waters from agroindustrial plants, beet sugar or cheese manufacture, olive oil extraction and many others. In this way it is possible to obtain less polluting waste waters and byproducts of commercial importance.
The oilgae initiatives show that it is possible to grow algae of commercial importance both in polluted waters and in special “solar” plants.
Furthermore the algae cultivation allow to obtain fuels and trade products “subtracting” carbon dioxide, the main greenhouse gas, from the atmosphere and so give a small, but not insignificant contribution to lessen the planetary warming.
The oilgae iniziatives requires better knowledge of the algae biology, of the growth processes and of the chemical composition of the algae; contributing to enlarge the commercial importance of algae already used to extract alginates, cosmetics ingredients and food fats. Nature has “organised” in the algae an unbelievable varieties of biological forms and molecules, whose knowledge is still too poor and is worth to be increased.
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