• Energy Research

A major constrain for sweet sorghum (Sorghum bicolor L. Moench) establishment as a reliable biofuel feedstock is the fast biomass degradation immediately after harvest due the high content of soluble sugars and their rapid fermentation that considerably decrease the actual ethanol yield. Such a drawback does not allow storing of sorghum for a reasonable period forcing the industry to process it immediately with consequent problems of handling, logistic, and plant size. Therefore, an appropriate harvesting and storage technique to prevent sweet sorghum juice degradation is urgently needed to ensure economic benefits to farmers. An efficient and cost-effective way to overcome this obstacle could be an on-farm storing system of undistilled ethanol from sweet sorghum juice, while the remaining bagasse could be ensiled and exploited for complementary energy generation. The objective of this study was to evaluate different harvest methods and storage techniques aiming to a low cost and efficient on-farm processing systems to store sweet sorghum biomass. Harvesting in the hard dough stage and defoliating the plants before juice extraction resulted in higher ethanol yield. The use of commercially available fructophilic yeasts allows maximizing undistilled ethanol yield and on-farm storing for about 1 year without spoilage. The residual bagasse was ensiled and inoculated with Lactobacillus bacteria commonly used in forage conservation which significantly improved its quality as feedstock for biogas fermenters. In conclusion, the integration of low-cost harvesting and storage techniques with the valorization of sweet sorghum by-products are worthwhile management strategies to be further developed.

The harvested biomass of switchgrass (Panicum virgatum L.) is generally much lower than its potential; this may be due to several factors including not recovering all the biomass at harvest, weed competition, pests, disease and spatial variation of soil features. The objective of this research was to quantify the yield spatial variation of switchgrass and relate it to soil parameters, in a field of about 5 ha, in 2004 and 2005. Several thematic maps of soil parameters and biomass yield were produced using GIS and geostatistical methods. Soil parameters changed consistently within very short distances and biomass yield varied from 3 to more than 20 Mg ha-1. This remarkable variation indicates that the potential for increasing switchgrass productivity is a real prospect. Furthermore, spatial variation of yield showed similar patterns in the 2 years (r = 0.38**), and therefore a major influence of site characteristics on switchgrass yield can be assumed to occur. Significant correlations were found between biomass yield and soil N, P, moisture and pH as well as between soil parameters. Some soil parameters such as sand content showed patchy spatial distribution. Conversely, a reliable spatial dependence could not be identified for other parameters such as P. Further research is needed.

Abstract Life cycle assessment (LCA) can be an objective, strategic and immediate criteria in determining, case-by-case, the most suitable crop for energy. In this study, a cradle-to-farm gate LCA study was performed in 4 perennial energy crops and then compared to the environmental impacts of a conventional wheat–maize rotation. The functional units energy and hectare were used for ranking the crops. The results showed clear and constant environmental benefits, on average 50% lower impacts, by substituting the conventional rotation with perennial crops. Among the latter, little differences were found on hectare basis, while the differences were strictly dependent on biomass yield, on energy basis. Giant reed, the most productive crop, showed at this regard the best performance, while cynara resulted in the lowest ecological benefits. A similar trend was also registered as concern the energy gain and efficiency that ranged from 75 (cynara) to 349 (giant reed) GJ ha−1, and from 7 to 30 (same order), respectively. On hectare basis, switchgrass achieved better results in six categories out of nine, and especially, it was from 27% to 32% less impacting than the other perennials on marine water ecotoxicity, which resulted in the clearly most affected category after normalisation on average European inhabitants. Weighting is not allowed for public comparison (ISO 14042), yet it can be helpful for some overall indications and conclusive comments. Comparing giant reed and switchgrass under different weighting sets, it emerged that resource depletion was the main discriminator for crop choice. Evenly weighting human health (HH), resource depletion (RD) and ecosystem quality (EQ) categories made the preference toward switchgrass or giant reed very uncertain. Taking three different weighting sets with RD, HH and EQ having 50% of relative importance (25% was set for the remaining two categories), switchgrass appeared the best choice in two cases (i.e. HH = 50% and EQ = 50%) out of three. Therefore, the preference toward a specific energy crop will strongly depend on weighting sets that may considerably change in space and time.

Soil is an important natural resource for agriculture and deserves special attention to possible problems that may arise. Heavy metal contamination of the soil can cause serious problems for the ecosystem in general, with consequent impact on water resources, soil quality, crop yield and human health due to the potential for heavy metal bioaccumulation in the different trophic levels of the food chain. Remediation of heavy metal contamination in soils can be done by using crops that have potential of growth and biomass production in marginal soils. The main objective of this work was to compare the growth and biomass production of Kenaf (cultivar H328, developed by IBFC in China) in soils contaminated by zinc (Zn), copper (Cu), chromium (Cr) and lead (Pb) in two different climate types (Tropical climate and Mediterranean climate). The study was performed in a pot essay and the plants were tested in clay soils. The soils were artificially contaminated, and the concentrations chosen were based on the limits established by the Decree Law 276 of 2009 (Portuguese regulation that establishes the regime for the use of sewage sludge in agricultural soils) - Zn: 450 mg/kg; Cr: 300 mg/kg; Pb: 450 mg/kg and Cu: 200 mg/kg. Results indicate that the growth in Mediterranean climate contaminated soils was more affected than in tropical climate. On average, the yields in Mozambique were 4900 g/m2, and in Portugal, merely 107 g/m2. Characterization of biomass indicate that kenaf can phytoextract zinc, copper, chromium, and not so much lead. Proceedings of the 28th European Biomass Conference and Exhibition, 6-9 July 2020, Virtual, pp. 205-208

The energy crop sweet sorghum (Sorghum bicolor L. Moench) is raising considerable interest as a source of either fermentable free sugars or lignocellulosic feedstock with the potential to produce fuel, food, feed and a variety of other products. Sweet sorghum is a C4 plant with many potential advantages, including high water, nitrogen and radiation use efficiency, broad agro-ecological adaptation as well as a rich genetic diversity for useful traits. For developing countries sweet sorghum provides opportunities for the simultaneous production of food and bioenergy (e.g. bio-ethanol), thereby contributing to improved food security as well as increased access to affordable and renewable energy sources. In temperate regions (e.g. in Europe) sweet sorghum is seen as promising crop for the production of raw material for 2nd generation bio-ethanol. The project SWEETFUEL (Sweet Sorghum: An alternative energy crop) is supported by the European Commission in the 7th Framework Programme to exploit the advantages of sweet sorghum as potential energy crop for bio-ethanol production. Thereby, the main objective of SWEETFUEL is to optimize yields in temperate and semi-arid regions by genetic enhancement and the improvement of cultural and harvest practices. Proceedings of the 18th European Biomass Conference and Exhibition, 3-7 May 2010, Lyon, France, pp. 200-206

AbstractBiofuel production from energy crops is land‐use intensive. Land‐use change (LUC) associated with bioenergy cropping impacts on the greenhouse gas (GHG) balance, both directly and indirectly. Land‐use conversion can also impact on biodiversity.The current state of quantifying GHG emissions relating to direct and indirect land‐use change (iLUC) from biomass produced for liquid biofuels or bioenergy is reviewed. Several options for reducing iLUC are discussed, and recommendations made for considering LUC in bioenergy and biofuel policies.Land used for energy cropping is subject to competing demands for conventional agriculture and forest production, as well as for nature protection and conservation. Biomass to be used for bioenergy and biofuels should therefore be produced primarily from excess farm and forest residues or from land not required for food and fiber production. The overall efficiency of biomass production, conversion, and use should be increased where possible in order to further reduce land competition and the related direct and iLUC risks.This review of several varying approaches to iLUC substantiates that, in principle, GHG emissions can be quantified and reductions implemented by appropriate policies. Such approaches can (and should) be refined and substantiated using better data on direct LUC trends from global monitoring, and be further improved by adding more accurate estimates of future trade patterns where appropriate.This brief discussion of current policies and options to reduce iLUC has identified a variety of approaches and options so that a quantified iLUC factor could be translated into practical regulations – both mandatory and voluntary – with few restrictions.Depending on the future development of energy cropping systems and yield improvements, sustainable bioenergy production could make a significant contribution to the future global energy demand. © 2010 Society of Chemical Industry and John Wiley & Sons, Ltd

AbstractAgriculture and forestry provide a wide number of crops that are used for a range of non‐food products, such as fuels, chemicals, fibers, construction materials, lubricants, etc. The term ‘energy crops’ is commonly used to indicate plants grown to make energy, such as biopower, bioheat and biofuels. Nonetheless, the development and commercialization of energy crops can initiate new and expand current markets for agricultural feedstocks, reduce dependence on petroleum and other imports of critical materials, diversify agriculture, and strengthen rural and sustainable development. As demand is growing steadily both from policy and from industry (which seeks environmentally friendly feedstocks) tensions have already risen among sectors about securing their future supplies. Among the key drivers that promote the development of one or other market, in the short and long term, the following can be considered as the most important: regular energy crops' feedstock supply and consistency in terms of quantity and quality, sustainable growth and environmental impacts, market demands and state of development, price competitiveness, and technological scale‐up. Taking these issues into account, this perspective is a concise review of the state of the energy markets in the EU27 in the light of policy demand, economic and environmentally sustainable options, and the optimum choices of energy crops from 2010 to 2030. © 2010 Society of Chemical Industry and John Wiley & Sons, Ltd

Relay cropping is an innovative cropping system where food/feed crops and dedicated lignocellulosic crops could be produced in the same land and growing season without competition issues. The objective of this study was to evaluate the effects of a dedicated lignocellulosic legume crop on relay planted wheat productivity. Wheat grain yield, bread making quality, and straw production were improved, while the cumulated biomass yield (sunn hemp biomass + wheat straw) arrived to comparable productivity levels of some high yielding perennial grasses (i.e. giant reed). These results suggest that relay cropping could be a sustainable cropping system to integrate food and dedicated biomass crops production. Proceedings of the 29th European Biomass Conference and Exhibition, 26-29 April 2021, Online, pp. 99-101