Abstract
Spain, in the framework of the European Green Deal, has set ambitious climate and energy goals for 2030. Lignocellulosic biorefineries can make a strong contribution to these goals; however, advanced biofuels generally cannot be produced in a profitable way compared to fossil and first-generation fuels. To address this problem, the efficient production of a wide range of bioproducts, not only biofuels and bioenergy, may be the solution. Therefore, a systematic evaluation of the near-term economic potential bio-building blocks (xylitol, sorbitol, succinic, glutamic, glucaric, levulinic, lactic, and itaconic acids) is presented. Many possible combinations of feedstock and conversion technologies can be considered feasible pathways to manufacture advanced biofuels and bio-based building blocks. To map the optimal groups of technologies in the framework of Spain’s biorefineries, we apply a methodology based on a network optimization approach that combines minimum cost and energy criteria together with feedstock availability and demand constraints. The feedstocks analyzed are pine and eucalyptus residues and olive tree pruning wastes, being three largely available agroforesty residues in Spain. The results show that building blocks show good economic and energy performance compared to advanced transportation biofuels, and although their demand is much lower, they should be considered to improve the profitability of biorefineries. Secondly, advanced gasoline, bioethanol, hydrogen, and building blocks demands can be satisfied with pine, eucalyptus, and olive residues available in Spain. Finally, lactic acid production is profitable, but the remaining routes do not reach the break-even point, suggesting that further research is still needed.
Highlights
Shifting society’s dependence from petroleum-based to renewable biomass-based resources is generally viewed as the key to the development of a sustainable industrial society, energy independence, and effective management of greenhouse gas emissions [1]
The succinic production route is less energy demanding because 28% of the input feedstock is directed to a CHP unit that provides part of the energy needed for the process, whereas in the lactic route only the process waste is dedicated to energy
Pine residue xylitol has the worst economic-energy behavior of all products. This is due to the fact, that xylitol production is based on the catalytic conversion of xylose fraction of lignocellulosics biomass and pine residues has only 7% of xylan in its composition versus 16% in eucalyptus and olive residues
Summary
Shifting society’s dependence from petroleum-based to renewable biomass-based resources is generally viewed as the key to the development of a sustainable industrial society, energy independence, and effective management of greenhouse gas emissions [1]. Faced with the need to reduce greenhouse gas emissions, Spain, in the framework of the European Green Deal and the Paris Agreement, has set ambitious climate and energy targets for 2030, including a target for renewable energy of at least 42% of final gross energy consumption [2] and lignocellulosic biorefineries. The objective of the Paris Agreement to reduce greenhouse emissions by at least 42% by 2030 has significantly encouraged the use of biomass as a renewable source of energy, and forest residues such as bushes and aerial parts of trees, which play an important role in forest management, have been used mainly for fuel. Forest residues remaining in forests after thinning or logging could pose a high fire risk because, without a developed market, it is often disposed of and burned in the field, contributing to air pollution [6]
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