”The Stone Age did not end for lack of stone, and the Oil Age will end long before the world runs out of oil” (Sheikh Zaki Yamani, the former Saudi Arabia Oil Minister).
The fundamental challenge that we face in this new century is the conversion of a society based on consumption controlled only by demand and market forces into a sustainable society based on more realistic needs and natural resources; from a wasteful and destructive attitude towards the environment to one which respects the Earth as a limited and sensitive resource. We need to develop eco-biotechnologies able to provide the necessary amount of energy and polymers needed by our society in the spirit of conservation of natural resources.

Several green technologies are already developed and applied world-wide to produce renewable energy. Most of them use the sun energy directly or through energy carriers as the main energy source. In any green energy technology, there are several key aspects, among them the most important are: high efficiency in energy conversion; energy storage until consumption; carbon foot print; wastes generated; environmental impact etc. If we analyze these important factors, the living cells, or the biomass seems to entirely fulfill the requirements of ”the greenest renewable energy carrier”, as the living organisms are the most efficient energy convertors; for energy storage there is no need to manufacture chemical accumulators made of rare and difficult to recycle minerals – the accumulator is the organism itself; the carbon foot print of photosynthesis is negative, and of other technologies involved in the processing of biomass, as fermentation technologies is very low; plant wastes are entirely biodegradable; the environmental impact of a sustainable agriculture is much lower than the changes brought by installing for example wind turbines into a natural landscape. All these arguments indicate the agricultural biomass as an important energy carrier of the future.
In this project, we will consider the agricultural biomass as the most ecological battery that accumulates and carries the energy from the sun. After the energy is consumed through hydrolysis and fermentation processes, the empty battery (the sorghum bagasse) can be converted into more energy (methane) and into a valuable fertilizer. The central objective of a future sustainable global economy should constitute the strategically integrated application of various biotechnologies based on two concepts: the biorefinery – as the industry of the future, and the sustainable agriculture by conservation of the existing bioresources. Probably the most important difficulty rises when different biotechnologies needs to be connected together in order to develop a sustainable and efficient eco-bio-technology.


Sweet sorghum, an annual C4 crop, is the fourth major cereal crop of the world in production has following characteristics: high yields up to 3500 litres of ethanol per hectare per season; water efficient crop – requires only one‐half of the water required to grow corn; ability to grow in marginal soil; not harmful to the environment – requires less fertilizer in comparison to maize; rapid growth – only 4 months to reach maturity (ideal for catch crop); energy efficient and easy to harvest. Due to its demand of higher temperatures at seeding compared to maize it can be grown as a catch crop after winter cereals. Harvesting is done at a dry matter content of 35 %, where yields between 10 and 33 tons dry matter per hectare are reported.

Sugar contents in the whole crop between 8 and 9 % in the fresh material and 18 to 20 % in dry matter can be reached. Therefore under European conditions 3.5 to 4 tons of sugar could be achieved per hectare. The sugar contains of 63 % of sucrose, 21 % glucose and 16 % of fructose. Due to high sugar content as well as starch contained in the seeds, Sorghum bicolor varieties are of great interest as raw material source for the ethanol industry.


Elements of originality and innovation generated and transfered to the field

 

 

The ecological and economic feasibility is caused by the combined utilization of the side-products (bagasse, distillation residues) for cellulosic ethanol and biogas production, and by the utilization of the digestate which returns as high value fertilizer on the crops land. Sweet sorghum produced in Romania as the main feed stock in an integrated process can serve as a model for a sustainable biorefinery concept.

Research in this project will provide scientific results concerning the potential of renewable energy production from agricultural biomass and will find ways to develop sustainable processes of biomass conversion into biorefineries. From our point of view, the most original approach in this project is closing the loop in the processing path of agricultural biomass and returning organic matter into soil through biogas technology (see scheme above).

Biotechnological research in this project will demonstrate that biogas production must constitute the final link in the concept of biorefinery, because by this technology, products and residues from the production of other biofuels can be further processed, obtaining a larger amount of energy through methane fermentation and nutrients will be returned in the soil by applying the digestate as fertilizer. This approach will avoid nutrient depletion in the soil, an aspect which is the important for the notion of "renewable" – because if the soil quality is affected by intensive use and in time will become unsuitable for agriculture, the technology applied is unsustainable and biomass production technology will become a non-renewable activity.