Expanding perennial grass bioenergy crops and influence on allergenic burden: A short review

In recent years, the world's population has been dealing with the increasing challenges of global warming. For this reason, second-generation perennial grass energy crops are increasingly becoming the focus of research. It is expected that the utilisation of these plants can make a significant contribution to achieving the goals of reducing greenhouse gas emissions, promoting sustainable development and improving energy efficiency. In our review, we look at the potential of the most interesting second-generation perennial energy grasses in the south-eastern (Phalaris arundinacea L.; Phragmites australis (Cav.) Trin. ex Steude; Miscanthus × giganteus Greef et Deu.; Arundo donax L.; Panicum virgatum L.). These plants are notable for high biomass production (average 6-25 t ha-1), low costs, and versatile utilization. In addition to combustion (average 14-18 MJ kg-1), biomass is also used for the production of bioenergy, biofuels, chemicals, biopolymers, biocomposites or as a building material. Perennial energy crops provide sustainable energy production with lower emissions of greenhouse gases than fossil fuels, as part of the CO2 released is returned to the atmosphere from which it was originally absorbed through photosynthesis. These plants are a promising option for biofuel production due to their simple agrotechnology and efficient use of water and nitrogen. Growth possibility on poor quality and degraded soils is also a positive aspect of these plants.

The development and current status of perennial rhizomatous grasses as energy crops in the US and Europe

Perennial tall-statured grasses are regarded as a sustainable source of renewable energy for their high yields of lignocellulosic biomass, low resource input, wide ecological tolerance and capacity for storing large amounts of atmospheric CO2 in their perennial underground rhizome systems. These same traits, that make such crops agronomically attractive and sustainable, make these species highly competitive and potentially invasive. Several perennial energy crop grasses are outbreeding species that belong to cosmopolitan polyploid species complexes, i.e. groups of interbreeding species with ploidy variation. The cultivation of such highly productive and genetically diverse crops can have unwanted consequences through the evolution of invasive species. The goal of this review is to provide the scientific community, including agronomists, breeders, users and nature managers, with an introduction to the genetic dynamics occurring within the polyploid species complexes of the emerging energy species Arundo donax, Miscanthus × giganteus, Panicum virgatum, Phalaris arundinacea and Phragmites australis, and the broad biogeographical extent of their gene flow impact. Such aspects are difficult to predict, and are not captured by invasion risk assessments and by the sustainability certifications of the bioenergy supply chain. The review integrates literature from the phylogenetic, cytology, population ecology and agronomic research and focuses on the evolutionary processes that shape invasiveness that can be activated post-introduction by the dispersal of pollen, seeds and plant fragments from the energy crops to the environment. Due to the high genetic diversity of the crops, the adverse effects that genetic drift and founder effect can have on the establishment of small populations are very unlikely. On the contrary the data collected suggests that the risk of fostering panmictic continental invasive populations is high. Agronomic measures, regulations and genetic improvements that can contain dispersal from crops are discussed, as well as urgent research needs.

OOS 38: Ecological Dimensions of Biofuel Production

Ranking yields of energy crops: A meta-analysis using direct and indirect comparisons

Miscanthus, switchgrass, giant reed, and bulbous canary grass as potential bioenergy crops in a semi-arid Mediterranean environment

Biogas production plays an important role in the clean energy economy and is reducing the problems of the energy crisis. The main objective of the current study is to analyze environmental performance by using perennial energy crops in the agricultural sector. Perennial energy crops are neutral for carbon and can be used for electricity and heating, which may mitigate climate change as well. The purpose of this work was to investigate and compare the energy–economy effectiveness and environmental performance of the suitability of four perennial crops for biogas production. Environmental performance was analyzed using the method of the life cycle assessment. To identify the most environmentally sustainable perennial crops for biogas production, a comparative analysis was conducted on four different crops: Lucerne, Miscanthus, Switchgrass, and Reed canary grass. The results of the analysis showed that Lucerne and Miscanthus, during the first–sixth years period, have lower indirect energy input (from 15.2 to 3.2 GJ/ha and 15.6 to 3.2 GJ/ha) than Switchgrass (from 20.9 to 3.2 GJ/ha) and Reed canary grass (from 16.7 to 3.2 GJ/ha). However, the highest direct energy input was determined by Lucerne (from 15.7 to 1.6 GJ/ha), and Miscanthus (from 11.9 to 0.9 GJ/ha) compared to Switchgrass (from 7.4 to 1.8 GJ/ha) and Reed canary grass (from 8.1 to 1.6 GJ/ha). Additionally, the lowest result of the direct economy and indirect economy costs was determined by Lucerne (from 3.9 to 3.7 kEUR/ha (direct) and 9.9 to 2.1 kEUR/ha (indirect)) and by Miscanthus (from 2.4 to 4.9 kEUR/ha (direct) and 11.8 to 1.9 kEUR/ha (indirect)) compared to Switchgrass (5.9 to 5.7 kEUR/ha (direct) and 17.5 to 2.1 kEUR/ha (indirect)), and reed canary grass (from 5.3 to 4.9 kEUR/ha (direct) and 13.7 to 1.9 kEUR/ha (indirect), respectively. The assessment of environmental performance revealed that Reed canary grass and Miscanthus had a more pronounced impact on Acidification. In contrast, Lucerne and Switchgrass had a more significant impact on Eutrophication indicators. The crop cultivation of four perennial crops impacted the environment in various significant ways. Despite the varying environmental impacts of the four perennial crops, the analysis revealed that all of them have the potential to increase biogas production.

A concise and up‐to‐date review has been undertaken to summarize consistent or diverging agronomic points of view on dedicated energy crops for advanced biofuels in the USA and the EU‐27. The main purpose of this review is to discuss those crops where many agronomic constraints have been resolved, bringing them closer to large‐scale production and commercialization. Where possible, examples of crop management practices that would enhance sustainability and energy yields are provided. The most promising crops and agronomic strategies for their production in the EU‐27 and the USA are discussed. We also provide discussion of what the theoretically ideal characteristics of advanced biofuel crops might be. On both continents, understanding of management practices for switchgrass (Panicum virgatum L.) and miscanthus (Miscanthus x giganteus) as energy crops appears to be at an advanced stage. Two other widely considered energy crop candidates – sorghum (Sorghum bicolor (L.) Moench) and reed canary grass (Phalaris arundinacea L.) – have production and management guidelines that were developed for forage uses, but can be easily applied to biomass feedstock production. Giant reed (Arundo donax L.) has been developed as a bioenergy crop mainly in Europe. In the USA, giant reed is considered a noxious weed in many states, and its planting is prohibited. Establishing crop management practices that will be successful at a large scale and for the long term will help attract growers and investors to produce advanced biofuels, i.e. second‐generation biofuels, which can help reduce our dependence on fossil energy sources. © 2013 Society of Chemical Industry and John Wiley & Sons, Ltd

Impact of feedstock, land use change, and soil organic carbon on energy and greenhouse gas performance of biomass cogeneration technologies

Arundo donax L. has been recognized as a promising energy crop for biomass production. Nitrogen is the primary macronutrient with the highest effect on plant production. Different studies have shown that N granular fertilizers slightly increase the biomass yield of giant reed. The aim of this work is to evaluate the effect of N fertilization applied in fertigation on the yield of Arundo donax grown in Central Spain. The experiment was carried out in field. The fertigation treatment was applied in June and July 2015. Three levels of N were established N0 (0 kgN.ha-1), N1 (60 kgN.ha-1); and N2 (120 kgN.ha-1) applied 50% June, 50% July. The effect of fertigation on plant traits and biomass production was evaluated. The plant height was determined in both June and October as well as the chlorophyll content. In October the basal diameter was also measured. Biomass production was evaluated at harvest time. Results showed higher values in plant height and weight in N1 and N2 in relation to control plants. Higher chlorophyll content and higher basal diameter were found in plants treated with N2. In the assay conditions, nitrogen applied in fertigation had a positive effect on Arundo growth. Keywords: arundo donax, production, fertilization, perennial energy crops.

Comparison of Arundo donax L. and Miscanthus x giganteus in a long-term field experiment in Central Italy: Analysis of productive characteristics and energy balance

Method and apparatus for gas manufacture from carbonaceous materials

Core Ideas Annual crops produced a third more biomass and three times as much ethanol as perennials. Perennial crops used half as much nitrogen fertilizer as annual crops. Grain from most annual crops enhanced ethanol production per unit of biomass. Sweet sorghum produced substantially more ethanol than all other crops. Sorghum yielded more biomass and potential ethanol than corn in hot, dry years. Although energy crops could eventually supply a growing portion of cellulosic biofuel feedstocks, long‐term comparisons of annual and perennial crops are rare. An experiment was established in 2007 near Manhattan, KS, to compare biomass productivity and ethanol yield of perennial and annual crops. Perennial crops included three C4 grasses: switchgrass (Panicum virgatum L.), big bluestem (Andropogon gerardii Vitman), and miscanthus (Miscanthus sacchariflorus). Annual C4 crops were corn (Zea mays L.) in two rotations: continuous and rotated with soybean [Glycine max (L.) Merr.]; and five types of sorghum [Sorghum bicolor (L.) Moench]: photoperiod sensitive, sweet, dual purpose (grain and biomass), brown mid‐rib, and grain; all rotated with soybean. Annual crops produced 7 Mg ha−1 yr−1 more biomass than perennial crops throughout 11 yr, with sweet sorghum exceeding 22 Mg ha−1 yr−1, and 12 m3 ha−1 yr−1 of ethanol. Biomass yield of miscanthus approached 14 Mg ha−1 yr−1, essentially the same as for several annual crops but with half as much fertilizer nitrogen. Annual ethanol production from miscanthus and switchgrass was 3.6 m3 ha−1 yr−1, half as much as that of several annual crops that produced similar biomass yields. Big bluestem consistently produced the least biomass and ethanol, less than 7 Mg ha−1 yr−1 and 1.7 m3 ha−1 yr−1, respectively. Rotated corn averaged 7.1 m3 ha−1 yr−1 of ethanol. Eleven years of results indicate that annual corn and sorghum crops as well as perennial grasses such as miscanthus and switchgrass could play a role as potential bioenergy feedstocks in diversified production systems.

Besides its bioenergy potential, perennial grasses can also have positive impacts on soil quality. However, responses of soil organic carbon (SOC) and total nitrogen (TN) depend on multiple factors, including grass species selection and N and P addition. We investigated the effect of four N and P fertility treatments (control = 0 kg N + 0 kg P ha–1 [N0P0]; 100 kg N + 0 kg P ha–1 [N1P0]; 0 kg N + 100 kg P ha–1 [N0P1]; 100 kg N + 100 kg P ha–1 [N1P1] applied annually] across 9 yr in Uruguay on soil nutrient balances, C and N pools, and biomass yields of elephantgrass (EG) (Pennisetum purpureum Schum.), giant reed (GR) (Arundo donax L.), and switchgrass (SW) (Panicum virgatum L.). Across years, EG had the highest biomass yield, followed by GR and SW (18.9, 16.3, and 14.1 Mg ha–1 yr–1, respectively). Across species, aboveground biomass increased by 46% with N addition. Yield response to P fertilization was lower (+11%). Elephantgrass had the highest N and P negative balance. Soil organic C and TN concentration were affected by species but not by fertilizer treatments. Giant reed had the highest SOC content gain in the first 0–40 cm (540 kg C ha– yr–1), and was the only species maintaining TN content from the beginning of the study. Giant reed could be an excellent option as a bioenergy crop due to its high aboveground biomass production, and its positive impacts on SOC and TN pools.

Cradle-to-farm gate life cycle assessment in perennial energy crops