Long-term biomass production and nutrient uptake of birch, alder and willow plantations on cut-away peatland

The leafless above-ground biomass production of planted silver birch (Betula pendula), downy birch (Betula pubescens), grey alder (Alnus incana), indigenous willows (Salix triandra and Salix phylicifolia) and an alder-willow mixture growing on a cut-away peatland area in Central Finland was investigated during a period of 18 (willows) or 19 (birches and alders) years. Biannual fertilization of the birches (0, NPK) and alders (0, PK) and annual fertilization of the willows (NPK1, NPK2) were continued for 10 years. S. phylicifolia had the highest yield (123 t ha⁻¹). The yield of the fertilized downy and silver birch was 112 t ha⁻¹ and 108 t ha⁻¹ respectively, and that of fertilized grey alder 85 t ha⁻¹, and alder S. triandra mixture 93 t ha⁻¹. The mean annual increment of willow was highest at the age of 10 years (S. phylicifolia 7.9 t ha⁻¹ a⁻¹; S. triandra 5.6 t ha⁻¹ a⁻¹). NPK-fertilization increased the 19-year biomass production of downy and silver birch by 14 and 29 t ha⁻¹ respectively and PK fertilization that of alders by 25 t ha⁻¹. The alder plantations bound more N, P, K, Ca and Mg per unit leafless biomass produced after 10–11 growing seasons than the silver birch and downy birch plantations. The silver birch used more N, K and Ca, but similar amounts of P and Mg per unit leafless biomass produced than the downy birch. S. triandra used more N, P, K and Mg per unit biomass produced than S. phylicifolia and both birch species.     

Assessment of the adequacy of different Mediterranean waste biomass types for fermentative hydrogen production and the particular advantage of carob (Ceratonia siliqua L.) pulp

The conversion of agro-industrial byproducts, residues and microalgae, which are representative or adapted to the Mediterranean climate, to hydrogen (H₂) by C. butyricum was compared. Five biomass types were selected: brewery’s spent grain (BSG), corn cobs (CC), carob pulp (CP), Spirogyra sp. (SP) and wheat straw (WS). The biomasses were delignified and/or saccharified, except for CP which was simply submitted to aqueous extraction, to obtain fermentable solutions with 56.2–168.4 g total sugars L^?1. In small-scale comparative assays, the H₂ production from SP, WS, CC, BSG and CP reached 37.3, 82.6, 126.5, 175.7 and 215.8 mL (g biomass)^?1, respectively. The best fermentable substrate (CP) was tested in a pH-controlled batch fermentation. The H₂ production rate was 204 mL (L h)^?1 and a cumulative value of 3.9 L H₂ L^?1 was achieved, corresponding to a H₂ production yield of 70.0 mL (g biomass)^?1 or 1.6 mol (mol of glucose equivalents)^?1_. The experimental data were used to foresight a potential energy generation of 2.4 GWh per year in Portugal, from the use of CP as substrate for H₂ production.     

Supply chain network design and operation: Systematic decision-making for centralized,distributed, and mobile biofuel production using mixed integer linear programming (MILP) under uncertainty

Biomass resources are dispersed and subject to seasonal and geographical uncertainties. Therefore, supply chain network design and management can significantly influence the economic viability of a biofuel technology. Fast pyrolysis offers several advantages for biofuel production. It is a relatively cheap process and can be conducted in centralized, decentralizes, or even mobile configurations. Furthermore, it does not overlap with the human food supply chain, using wastes or lignocellulosic feedstocks. In this article, a mixed integer (piece-wise) linear program (MILP) was developed to determine the optimal supply chain design and operation, under uncertainty. Rigorous process modelling and detailed economic analysis were coupled with exhaustive search of potential production locations and biomass resources in order to enhance the fidelity of the solution. The optimisation results suggest that a combination of geographically centralized pyrolysis and upgrading centres would suffice for supply chain management under deterministic conditions. However, under uncertain scenarios, it is advantageous to deploy mobile pyrolyzers to add extra flexibility to the process operation. Further analysis suggested that as the mobile pyrolyzers are commercialized and their unit price is reduced, this technology has the potential to become a key member of the biofuel supply chain.