Global Change Biology Bioenergy最新文献

Bioenergy with carbon capture and storage (BECCS) holds promise for achieving negative greenhouse gas (GHG) emissions while generating electricity. When using forestry or agricultural residues as feedstock, BECCS may also avoid or reduce land-use based impacts compared to dedicated energy crops. It is, however, unclear how negative emissions from residue-based BECCS compare to alternative uses (bioenergy with no CCS, 2G ethanol, paper and boards, animal feed and decomposition) and how quickly BECCS can achieve climate benefits compared to these other uses. In this study, we used life-cycle assessment (LCA) to quantify supply chain emissions of BECCS for two power plants in the Netherlands, using residue-based wood pellets from Louisiana, USA, and sugarcane bagasse pellets from Louisiana and São Paulo, Brazil, as feedstock. Using an attributional LCA approach, we showed that the two BECCS plants combined use 7.5 Mt of biomass_dry per year. This system generates between 10.3 and 11.1 TWh of electricity and provides 11.0 and 11.3 Mt CO₂-eq. of negative emissions annually, for wood or bagasse, respectively. This results in a footprint of −0.63 (wood) and −0.65 (bagasse) t CO₂-eq./t_{wet biomass}. Following a consequential approach, we contrasted the GHG emissions per tonne of biomass residue used for BECCS with those associated with alternative uses, accounting for the (avoided) emissions from any substituted products and electricity. Here, BECCS negative emissions of approximately −0.6 t CO₂-eq./t_{wet biomass} compare favourably to emissions of alternative uses, which range from −0.3 to +0.12 t CO₂-eq./t_{wet biomass}. This study showed BECCS' potential for achieving negative emissions and climate benefits compared to other biomass uses.

Perennial grasses like switchgrass (Panicum virgatum) and miscanthus (Miscanthus × giganteus) are expected to supply a substantial amount of the United States bioeconomy's feedstock demand. However, uncertainties around their long-term yields challenge the viability of their potential and limit their wider adoption. To resolve their long-term yield patterns, we analyzed over 200 plantings of switchgrass and miscanthus across Michigan and Wisconsin, USA, measured over 5–15 years. We found a consistent two-phase long-term yield dynamic; during a yield-building phase, peak yields occurred within 4–5 years after planting, followed by a yield-decline phase in which switchgrass and miscanthus lost 30%–47% and 14%–40% of peak yields, respectively. Among the potential drivers of this dynamic and the yield decline, we found that weather conditions had little impact, as the variation across years was not large enough to drive the observed yield differences. Added nitrogen increased peak yields by 10%–20% and attenuated the yield decline by 20%–50%. However, since fertilized stands still showed a yield decline, other factors became limiting as stands aged. This conserved long-term yield dynamic has direct implications on management. A farm-to-gate economic analysis suggests replanting switchgrass and miscanthus 5 and 9 years following their peak yields maximizes profit over a 30-year time horizon. Results call for further management and breeding strategies to mitigate the yield-decline phase, and for reparameterization of global bioenergy models with carbon capture and storage, which may overestimate yields and the economic and environmental benefits of crops grown for bioenergy feedstocks.

This paper investigates the relationship between sugarcane ethanol production and food security in Brazil. It presents an original investigation of the multidimensionality of food security through two econometric approaches, using municipal-level panel data and household-level microdata. The results do not support the “food versus fuel” hypothesis. Our findings suggest that efficient large-scale biofuel production can be combined with the population’s food security, aligning with sustainability goals.

Carbon dioxide removal (CDR) practices are essential to mitigating the adverse impacts of climate change. Some CDR practices depend on the availability and accessibility of feedstocks. The climate change mitigation potential of these practices relies on the difference between their location-specific efficiency and the greenhouse gas (GHG) emissions associated with establishing them. Focusing on biochar from forestry harvest residues in British Columbia (Canada), this manuscript demonstrates that optimizing the selection of biochar application areas and transportation routes can double the climate change mitigation potential of the practice across the province, as compared to random selection. We argue that spatially explicit ex-ante modeling of CDR potential and transportation optimization should become the norm for any new relevant CDR project to ensure the maximization of its climate change mitigation potential.

Miscanthus spp. are increasingly cultivated in agricultural fields worldwide due to their potential for bioenergy production and the various ecological benefits they offer. However, the long-term impacts of cropland conversion to harvested Miscanthus without sulfur fertilizer on soil microorganisms and the sulfur cycle remain poorly understood. This study aimed to investigate the effects of Miscanthus transformation on soil microorganisms and the sulfur cycle over a 15-year period. We evaluated the influence of long-term Miscanthus planting on the diversity, relative abundance, functions, and correlations of soil sulfur-cycling microbial communities, as well as how changes in soil properties affect the sulfur conversion process. The results indicated that Miscanthus planting significantly increased the concentrations of soil sulfate (SO₄²⁻, 47.39%, p < 0.05), total sulfur (TS, 13.26%, p < 0.05), and available sulfur (AS, 156.37%, p < 0.05), while decreasing soil pH (8.83%). Sulfur exhibited a positive correlation with the abundance of Acidobacteria, Proteobacteria, unclassified_d_unclassified, and Actinobacteria, while total nitrogen (TN) content was positively correlated with sulfur metabolism. The activity of oxidoreductase in Miscanthus was significantly higher (p < 0.05) than in other land use types, facilitating the conversion of organic sulfur into plant-available inorganic sulfur (SO₄²⁻). Analysis of the microbial community based on 16S rRNA gene sequences revealed that the diversity and richness of the microbial community in Miscanthus planting areas were greater, and the microbial community structure was significantly different from that of bare soil and cultivated land. Actinobacteria and Proteobacteria were identified as the dominant microbial taxa. Redundancy analysis indicated that TN was the primary factor influencing the microbial community. These findings provide theoretical support and practical guidance for farmers to promote large-scale cultivation of Miscanthus on marginal croplands in Northern China.

Six years after replacing a maize/soybean cropping system, perennial grasses miscanthus (Miscanthus × giganteus) and switchgrass (Panicum virgatum), and a 28-species restored prairie increased particulate organic carbon in surface soils without increasing soil organic carbon (SOC). To resolve potential changes in the quantity and distribution of SOC, soils were resampled after seven to thirteen years to measure bulk density, carbon (C) content, and stable C isotopes to a depth of 1 m. SOC stocks increased between 1.75 and 2.5 Mg ha⁻¹ year⁻¹ in all perennial crops between 2008 and 2016 (nine growing seasons). Despite relatively low litter inputs and belowground biomass, the highest rate of SOC accrual was in restored prairie (2.5 Mg ha⁻¹ year⁻¹), followed by miscanthus (2.0 Mg ha⁻¹ year⁻¹) and switchgrass (1.75 Mg ha⁻¹ year⁻¹). The change in SOC in maize/soybean was not significant. After 2016, total SOC decreased in maize/soybean and miscanthus, resulting in slower overall rates of SOC accumulation over the full sampling period for miscanthus (0.8 Mg ha⁻¹ year⁻¹). The rate of SOC accumulation was greatest below 50 cm depth for restored prairie and switchgrass but in the top 10 cm for miscanthus. Stable isotope analysis showed ¹³C enrichment in all depths of switchgrass soils, an indication of new organic C accumulation, but mixed results in all other crops. Planting perennial crops on land formerly in an annual maize/soybean cropping system can slow or reverse soil carbon losses, with the greatest increases in SOC from species-rich prairie.

Global warming is projected to accelerate soil carbon (C) loss to the atmosphere. However, soil CO₂ emissions under warming and the underlying microbial processes are not adequately studied in bioenergy croplands. To address this issue, a soil warming experiment was established in a switchgrass cropland at Tennessee State University in May 2021. Four paired plots with infrared and dummy heaters (i.e., warming vs. control plots) were randomly installed in four blocks. Collections of hourly soil heterotrophic respiration (R_s), temperature, and moisture at surface soil (0–10 cm), as well as biweekly soil organic carbon (SOC), total nitrogen (TN), microbial biomass carbon, and nitrogen (MBC and MBN), and extracellular enzyme activities (EEAs) were conducted consecutively for 2 years. Warming elevated soil temperature by 2.2°C, reduced volumetric water content by 17.5%, and significantly increased hourly R_s but had no significant effects on the contents of SOC, TN, MBC, MBN, and soil EEAs. Despite the insensitive responses of soil microbial, enzymatic, and bulk features, the elevated R_s was closely associated with warming-caused changes in soil temperature and moisture. Overall, the elevated R_s in response to 2-year experimental warming informed a likely positive response of switchgrass soil CO₂ emission to a warmer future and a shift toward increased autotrophic respiration. The current study implied the importance of long-term experimental observations to accurately predict soil respiratory responses in switchgrass croplands.

The growing interest in high-biomass sorghum (Sorghum bicolor L. Moench), hereafter referred to as sorghum, as a bioenergy feedstock in the United States requires an understanding of geographical adaptation to identify the most suitable hybrids for the Midwest. In this study, 13 sorghum hybrids (H1–H13) were evaluated for biomass yield potential in central and southern IL over two growing seasons (2022 and 2023). In addition to biomass yield, the effects of nitrogen (N) fertilization on yield, nutrient removal (N, P, and K), and feedstock composition (cellulose, hemicellulose, lignin, and soluble fractions) were determined to identify the best-performing sorghum hybrid across environmental gradients. The experimental design was a split-plot arrangement within a randomized complete block design with four replications at each of two locations: N rates (0 and 112 kg-N ha⁻¹) as a whole plot factor and 13 sorghum hybrids as a subplot factor. As a result, complex genotypes (13 hybrids) by environment (2 sites and 2 years) and management (2 N rates) interactions were observed in biomass yield. The best hybrids at both sites were H1 (ATx2932/F10702_PSL) and H13 (TX08001), which were very photoperiod sensitive (PS). These hybrids produced superior biomass yield, and they also exhibited less nutrient removal and high energy-rich feedstock compositions (cellulose, hemicellulose, and lignin). Biomass yield potential was associated with morphological and phenological traits according to environmental conditions. Low-yielding hybrids were short-stature (H5 and H6) with pollinators (F10801_PSL-3dw and F10805_PSL-3dw) that are recessive at the Dw3 locus. Moderate PS hybrids (H7, H8, H11, and H12) that produced grain panicles at harvest showed high biomass yield plasticity and excessive nutrient removal as they accumulated high K concentrations in biomass tissues and high N and P in grain panicles.

Bioenergy is a critical element in many national and international climate change mitigation efforts, including as a carbon dioxide removal strategy combined with the capture and durable geological storage of flue gas emissions (BECCS). However, divergent results on the effectiveness of bioenergy as a climate change mitigation measure are reported in the scientific literature. Climate impacts of bioenergy depend on case-specific factors, primarily biophysical features of the biomass production system, and the design and efficiency of conversion and capture processes. Estimates of climate impacts are also strongly affected by methodological choices and assumptions, and much of the divergence between studies derives from differences in the assumed alternate use of the land or feedstock, the alternate energy source and the system boundaries applied. We present a methodology to support robust estimates of the climate change effects of bioenergy systems, updating the standard methodology developed by the International Energy Agency's Technology Collaboration Program on Bioenergy. We provide guidance on the key choices including the reference land use and energy system that bioenergy is assumed to displace, spatial and temporal system boundaries, co-product handling, climate forcers considered, metrics applied and time horizon of impact assessment. Researchers should consider the whole bioenergy system including all life cycle stages, and choose system boundaries, reference systems and treatment of co-products that are consistent with the intended application of the results. The assessment should be normalised to a functional unit that can be compared with other systems delivering an equivalent quantity of the same function. All significant climate forcers should be included, and climate effects should be quantified using appropriate impact assessment methods that distinguish the impact of time. Consistency in methodology and interpretation will facilitate comparison between studies of different bioenergy systems.