venerdì, 18 Settembre, 2020





Third Generation Biofuels

Biofuels utilization is well known and well developed by now. According to one of my favorite theories which says: “the best is limitless”, there are, nevertheless, several researches in order to optimize biofuels use in the industrial and the transportation contexts (upstream the biofuels production process) and in order to increase the productive efficiency (downstream) through different technologies and different substrates. Biofuels are classified, often and easily, by first generation and second generation ones. The first ones have been obtained from well known, diffused and food cultivations (colza oil, soy, sunflowers, palm, corn, beet sugar and sugar cane). The second ones are not – significantly – diffused in the market and they are produced from substrates, which, generally, cannot be used as food (wooden materials, inedible oils, agro industrial wastes).

During past years scientists started talking about third generation biofuels, which are the ones developed from the cultivation and processing of algae and microalgae. This process come from the Second World War II in Germany but it has been studied mainly in U.S. and, then, in Japan and in Korea. The most interesting characteristics of this kind of substrates are:

  • High productivity. Algae have a high lipid contents and, as a consequence, a high surface productivity. American professor Peter McKendry has studied how – ideally – in order to reach the 50% of the US transport fuel demand it would need almost 1500 Mha of corn or 45 Mha of palm or just 2 Mha (considering the best case) of microalgae. The latter are characterized by a high conversion efficiency of solar light through the photosynthesis process: about 7% against 0,5% (1% maximum) of common biomasses. High efficiencies are possible because of the controlled cultivation of the algae in monitored environments, such as photobiorectors.
  • Uncompetitiveness in respect to the food-market. During last years, traditional harvests have been gathering because of the biofuels production (especially bioethanol). This has led to an unsustainable increase of the raw material costs and to a not negligible impact due to the reconversion of forests and pastures to energetic cultivations. The latter could spring environmental, economic and social impacts even if they absorb the same amount of CO2 of any other biomass.
  • Non-productive lands utilization. Algae cultivations could take place in locations that are not usable in other ways, such as the sea, which represents more than the 70% of the earth surface. This point is fundamental because it is functional to the sustainability – intended as general as possible – of their production.
  • Utilization of different water Algae cultivations could take place in different water environments like freshwater and saltwater, but also zootechnical and urban wastewaters, reducing their impact and using them as productive location instead of processing waste.
  • Optimal compatibility with the transportation fuel existing infrastructure. Algae and microalgae biofuels have the same chemical and physical (Low Heating Value) properties of the other traditional biofuels.
  • Combined production of energy and fertilizer. Like every organic material, also the algae, after their energetic processing, could be used as high value biofertilizers. In addition, their cultivation has more economic benefits because algae could be used as human and animal food.
  • Carbon dioxide emission reduction. Algae are characterized by the well-known CO2 emission null cycle, because they release in the atmosphere – during their combustion – the same amount of CO2 absorbed during their biochemical process life.
  • Integration with other productive and industrial processes. It is possible reach more energetic efficiency and environmentally benefits though the integration between algae cultivations and water treatments plants and/or intensive livestock.


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Lorenzo Rubino
Laureato magistrale a 24 anni in ingegneria energetica al PoliTO. Esperto in efficienza energetica industriale, commerciale, residenziale. Progettista tecnico di impianti rinnovabili e tradizionali. Responsabile di #EnergyCuE da marzo 2015. Appassionato di nuove tecnologie e policy, soprattutto se finalizzate alla sostenibilità della produzione di energia. Mi sento curioso, riflessivo ma anche spontaneo, diretto e pragmatico, da buon ingegnere!