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Abstract The use of bio-energy crops for electricity production is considered an effective means to mitigate the greenhouse effect, mainly due to its ability to substitute fossil fuels. A whole range of crops qualify for bio-energy production and a rational choice is not readily made. This paper evaluates the energy and greenhouse gas balance of a mixed indigenous hardwood coppice as an extensive, low-input bio-energy crop. The impact on fossil energy use and greenhouse gas emission is calculated and discussed by comparing its life cycle (cultivation, processing and conversion into energy) with two conventional bio-energy crops (short rotation systems of willow and Miscanthus). For each life cycle process, the flows of fossil energy and greenhouse gas that are created for the production of one functional unit are calculated. The results show that low-input bio-energy crops use comparatively less fossil fuel and avoid more greenhouse gas emission per unit of produced energy than conventional bio-energy crops during the first 100 yr . Where the mixed coppice system avoids up till 0.13 t CO 2 eq./GJ, Miscanthus does not exceed 0.07 t CO 2 eq./GJ. After 100 yr their performances become comparable, amounting to 0.05 t CO 2 eq./ha/GJ. However, if the land surface itself is chosen as a functional unit, conventional crops perform better with respect to mitigating the greenhouse effect. Miscanthus avoids a maximum of 12.9 t CO 2 eq./ha/yr, while mixed coppice attains 9.5 t CO 2 eq./ha/yr at the most.

Abstract Against the background of an increasing global demand for bio-energy, the need for sustainability standards and a certification system ensuring sustainable production and trade has grown rapidly. Nevertheless, there is currently no specific forum for discussions on how to deal with biomass trade at the multilateral level. Distortions in agricultural and energy trade regimes, the myriad of standards and the lack of a clear biomass classification in the multilateral trade regime suggest that bio-energy products may not deliver sustainable development gains for all trading partners. This paper analyses then the global impact of bio-energy policies on biomass production and trade, paying particular attention to sustainable development in the bio-energy sector. It examines how a possible reduction and elimination of trade barriers as well as a phasing out of trade distorting support measures would contribute to the development of a global sustainable bio-energy market.

Production of microbial protein (MP) from recovered resources - e.g. CO2-sourced formate and acetate - could provide protein while enabling CO2 capture. To assess the protein quality obtained from this process, pure cultures and enriched communities were selected and characterized kinetically, stoichiometrically and nutritionally. Growth on acetate resulted in up to 5.3 times higher maximum specific growth rate (μmax) than formate (i.e. 0.15-0.41 h-1 for acetate compared to 0.061-0.29 h-1 for formate at pH = 7). The protein content was a function of the growth phase, with the highest values during stationary phase, ranging between 18 and 82%CDW protein depending on the organism and substrate. The negative correlation between biomass productivity and protein content indicated a trade-off between production rate and product quality. The final product (i.e. dried MP) quality was in most cases superior to soybean and all cultures were rich in threonine, phenylalanine and tyrosine, regardless of the carbon source.

Abstract As bioenergy plantations are a relatively new phenomenon, long-term experimental data on their productivity and tolerance to environmental stress that provides a robust framework for site selection and potential productivity assessment is still lacking. To address this need, we developed a method to correlate the productivity of bioenergy plantations with local climate using tree-ring chronologies. Tree-ring width from 37 Populus nigra (age > 115 y) and 368 poplar hybrid (Populus nigra × Populus maximowiczii) (9–12 y) individuals were collected and analyzed at demonstration sites in the Czech Republic. The growth of mature, naturally grown solitary native trees and young congeneric hybrids grown in high density (∼10,000 ha−1) showed statistically significant correlations (r = 0.71, p

Abstract The energetic use of residues from agriculture can foster the transition towards a more renewable energy supply. However, sustainability issues have to be considered along the entire provision chain as they affect the resource and energy potential as well as the achievable contribution to climate mitigation. Straw is one of the most important agricultural residues in Germany. It is not yet used for energy purposes extensively and compared to other agricultural feedstock it shows low competition with food, feed or fiber. This paper analyses on the one hand the sustainable potential of cereal straw for energy application in Germany considering the actual agricultural conditions, and on the other hand the global warming potential from different energy provision chains based on straw. Different humus-balance tools that are able to assess the organic matter (OM) demand to presume soil fertility. The analysis of straw potentials was applied at NUTS 3 level for Germany, based on statistical data. The results of this analysis were used as input data for the modeling of concepts for straw provision and use. Greenhouse gas (GHG) emissions were calculated for each concept in order to compare the global warming potential of various energy applications, to investigate the relative contribution of different production steps and to compare them with fossil energy applications. In total, 29.8 Tg of straw (fresh matter) are produced annually in Germany (1999–2007). Approximately 4.8 Tg of the total straw occurrence are annually required by animal husbandry. Between 7.97 and 13.25 Tg straw can be classified as sustainable straw. Highest straw potential (3.99 Mg ha−1) can be found in parts of Schleswig-Holstein, Mecklenburg–West Pomerania, North Rhine-Westphalia and Lower Saxony. But there are also regions that show a net deficit. The cumulated GHG emissions for the resulting concepts are between 8 and 35 g CO2-eq. MJ−1. In comparison to fossil energy applications, the highest reduction potential occurs for concepts for combined heat and power (CHP) provision, i.e. 223 g CO 2 -eq . MJ el - 1 . This study highlights the possible contribution of straw as renewable energy carrier, but also demonstrates that there are regional restrictions for straw use.

Abstract Valorization strategies of wastes from agri-food processes are intertwined with clean technological approaches and eco-industrial management. By-products from Mediterranean agri-food processes such as olive oil, wine and fruit create a considerable disposal problem for the agro-industry. Their characteristics in combination with Mediterranean climate enhance microbial development and can be source of health and safety concerns. After pre-treatment and recovery of valuable precursor materials (lignin, pulp), pyrolysis can be used for fuels, chemicals and carbon bio-based materials production. Since thermal degradation kinetic studies are a key step for the efficient design of thermo-chemical processes, in this study pyrolysis experiments were performed, using TGA for the estimation of the process kinetic parameters. The independent parallel reaction model validated against experimental results, showing a good agreement with experimental data, with deviation values ranging from 1.07 to 3.54%.

Circular bio-economy is a significant approach to resolving global issues elevated by environmental pollution. The generation of bioenergy and biomaterials can withstand the energy-environment connection as well as substitute petroleum-based materials as the feed stock production, thereby contributing to a cleaner and low-carbon-safe environment. Open discarding of waste is a major cause of environmental pollution in developing and under developed countries. Agricultural bio-wastes are obtained through various biological sources and industrial processing, signifying a typical renewable source of energy with ample nutrients and readily biodegradable organic substances. These waste materials are competent to decompose under aerobic and anaerobic conditions. The projected global population, urbanization, economic development, and changing production and consumption behavior result in bounteous bio-waste production. These bio-wastes mainly contain starch, cellulose, protein, hemicellulose, and lipids, which can operate as low-cost raw materials to develop new value-added products. Thus, this review discussed specifically the agricultural waste and valorization processes used to convert this waste into value-added products (biofuel, enzymes, antibiotics, ethanol and single cell protein). These value added products are used in the supply chain and enhance the overall performance of agriculture waste management, execution of circular bio-economy has attained significant importance and it explains a closed-loop system in which the potential resources remain in the loop, allowing them to be sustained into a new value.

Worldwide there are numerous regions where conventional agriculture is affected by the presence of elevated amounts of plant-available trace elements, causing economic losses and food and feed quality and safety. The Belgian and Dutch Campine regions are a first-class example, with approximately 700 km(2) diffusely contaminated by historic atmospheric deposition of Cd, Zn and Pb. Primary land use in this region is agriculture, which is frequently confronted with crops exceeding the European standards for heavy metal contents in food and feed-stuffs. Phytoremediation as a soil remediation technology only appears feasible if the produced biomass might be valorised in some manner. In the current case, we propose the use of energy maize aiming at risk-reduction and generation of an alternative income for agriculture, yet in the long run also a gradual reduction of the pollution levels. Since the remediation aspect is demoted to a secondary objective with sustainable risk-based land use as first objective, we introduce the term 'phytoattenuation': this is in analogy with 'natural attenuation' of organic pollutants in soils where also no direct intended remediation measures but a risk-based management approach is implemented. In the current field experiment, cultivation of energy maize could result in 33,000-46,000 kW h of renewable energy (electrical and thermal) per hectare per year which by substitution of fossil energy would imply a reduction of up to 21 x 10(3)kg ha(-1) y(-1) CO(2) if used to substitute a coal fed power plant. Metal removal is very low for Cd and Pb but more significant for Zn with an annual reduction of 0.4-0.7 mgkg(-1) in the top soil layer.