Global Change Biology Bioenergy最新文献

Magnetite nanoparticles can boost methane production via direct interspecies electron transfer. However, the combined effect of inoculum and particle characteristics on magnetite's methanogenesis stimulation is poorly understood. Here, the influence of inoculum type, particle size, and particle concentration on the ability of magnetite to accelerate methanogenesis was studied in batch anaerobic digestion experiments. Fresh and degassed mesophilic digester sludge was used as inoculum, representing methanogenic communities in the exponential or stationary growth and endogenous decay phases, respectively. Three magnetite particle size ranges, small (50–150 nm), medium (168–490 nm), and large (800 nm–4.5 μm), at two different concentrations (2 and 7 mM) were used. With degassed sludge, the effect of magnetite on the methane production rate was weak and depended on the particle size and concentration. Only magnetite of medium size at both 2 and 7 mM significantly increased the methane production rate by 12% compared to the control with no magnetite. The lag phase was reduced by 17% compared to the control, only with 2 mM of both small and medium size magnetite. Conversely, adding magnetite into fresh sludge significantly increased the methane production rate by an average of 32% while simultaneously decreasing the lag phase by 15%–40%, as compared to the control, independently of the magnetite's size and concentration. The stimulation of methane production depends on magnetite and inoculum characteristics.

Biofuels are essential to ensure the energy transition and mitigating of climate change. However, understanding the impact of land use change (LUC) and management practices on soil organic carbon (SOC) stocks is fundamental to ensuring well-founded policymaking and assessing the sector's carbon footprint. Here, we conducted a meta-analysis (511 pairwise observations) to obtain Brazil's SOC stock change factors (SOC_scf) for LUC and management practices in sugarcane fields. Our results showed that converting native vegetation to sugarcane reduced the SOC stock in all assessed periods. The conversion from annual crops to sugarcane showed a reduction in SOC stock in the first 10 years but with a recovery over time. The conversion of pasture to sugarcane reduced the SOC stock only in the 10–20-year period and had a neutral effect in other periods evaluated. However, our dataset showed high variability in SOC_scf, with many observations indicating an increase in SOC stock, which is related to degraded pastures. We observed that the SOC accumulation rate for each ton of sugarcane straw was affected by the interaction between soil texture and precipitation. Regarding straw management, a low removal rate (< 34%) did not affect the SOC stock, while moderate (34%–66%) and high (> 66%) removal resulted in losses of 5.0% (SOC_scf 0.950) and 9.9% (SOC_scf 0.901), respectively. Our results also showed that reduced tillage and vinasse application increased SOC stocks by 24.0% (SOC_scf 1.24) and 10.0% (SOC_scf 1.10) respectively, proving to be good strategies to support C sequestration in sugarcane fields. Finally, we highlight that our results can contribute to the improvement of public policies and also be used in future life cycle assessment (LCA) and modeling studies, as they provide robust data to establishing regional SOC_scf induced by LUC and management practices, enhancing the reliability of the C footprint assessment of biofuel production.

Biomass feedstocks are growing in importance due to their ability to serve as a renewable alternative to fossil fuels for large scale energy generation, with bioenergy projected to be a growing part of the UK's energy mix. Combined with technologies such as carbon capture and storage, sustainable bioenergy has the potential to produce negative emissions with including counterbalancing residual emissions. This paper presents a systematic review of the sustainability impacts of wood biomass (forestry/SRC) and Miscanthus, which are grown as energy fuels, comparing the three key indicators of sustainability: soil organic carbon sequestration rates, biodiversity, and water use efficiency (WUE). Analysis has shown significant influence from primary soil composition (p < 0.001) and previous land use (p < 0.001) on soil organic carbon sequestration rates following conversion to biomass feedstock production. Conversion from arable to forestry can have positive rates of sequestration of 1.4 ± 0.3 Mg C ha⁻¹ year⁻¹ on mineral soils, while similar conversions on a highly organic soils can lead to losses of −25 Mg C ha⁻¹ year⁻¹. This indicates a strong need for careful site selection for future forestry plantations. Miscanthus showed no preference under mineral or organic soils for carbon sequestration rate. Biodiversity at different trophic scales is impacted differently by biomass feedstock production. No significant impact on invertebrates was demonstrated between feedstocks but there is a significant difference between crops (p < 0.001) for vertebrates at higher trophic levels. A limited dataset was collected for WUE from the review, but analysis showed comparable WUE rates for Miscanthus and short rotation coppice, while forestry had significantly lower (p < 0.001) WUE. With global temperatures increasing and changes to climate, water stress is likely to increase. WUE will play an important role in the considerations dfor long term biomass feedstock planning and sourcing.

Countries are looking to reduce their agricultural sector's carbon footprint while encouraging economic and environmental sustainability. One proposed method of making agriculture more sustainable while maintaining farm incomes is through the production of bioenergy feedstocks. We examine the spatial aspect of the production of renewable energy feedstocks in Ireland. Two feedstocks are looked at—grass silage and short-rotation coppice (SRC) willow. Spatial microsimulation analysis is utilised to assess the spatial suitability for alternative land uses, simulating land-use change to compare economic returns with the current agricultural use. A farm-based carbon subsidy is modelled based on avoided agricultural emissions and carbon sequestered. We find that midlands counties, especially those in the north midlands, have the highest proportion of land where feedstocks would be more profitable than the current agricultural use. Counties on the western seaboard have the lowest proportion of land where feedstocks would give greater returns. The amount of land where feedstocks are more profitable increases as greater carbon subsidies are provided. Of the two feedstocks assessed, SRC willow cultivation is more profitable than grass silage production. The overwhelming majority of land where producing feedstocks would be more profitable has cattle farming as its current use.

This study investigates the relationship between corn prices in Brazil and the international market, considering a rise in corn ethanol production in Brazil's Midwest region since 2017. Did the entry of the corn ethanol industry in Brazil affect the relationship between domestic and international corn prices? A cointegration analysis was made with a monthly time series from May 2005 to August 2023 controlling for different exogenous events or shocks that may have affected global agricultural markets. The study's findings indicate a stable long-term relationship between the international and Brazilian corn prices, with changes in international prices being predictors of variations in Brazilian domestic prices, while the opposite was not statistically supported. The study also found no evidence to support the claim that the entry of the corn ethanol industry into Mato Grosso state in 2017 impacted the prices paid to local producers. Therefore, the increase in Brazilian corn prices cannot be attributed to additional demand for corn by local mills, an important result that contributes to discussions such as food versus fuel and indirect land use change.

Miscanthus is a perennial grass that can yield substantial amounts of biomass in land areas considered marginal. In the Coastal Plain region of North Carolina, marginal lands are typically located in coarse-textured soils with low nutrient retention and water-holding capacity, and high erosivity potential. Little is known about miscanthus water use under these conditions. We conducted a study to better understand the efficiency with which miscanthus uses natural resources such as water and radiant energy to produce harvestable dry biomass in comparison to corn, a typical commodity crop grown in the region. We hypothesized that under non-limiting soil water conditions, miscanthus would have greater available energy and water use rates owing to its greater leaf area, thus leading to greater agronomic yields. Conversely, these effects would be negated under drought conditions. Our measurements showed that miscanthus intercepted more radiant energy than corn, which led to greater albedo (by 0.05), lower net radiation (by 4% or 0.4 MJ m⁻² day⁻¹), and lower soil heat flux (by 69% or 1.0 MJ m⁻² day⁻¹) than corn on average. Consequently, miscanthus had greater available energy (by 7% or 0.6 MJ m⁻² day⁻¹) and water use rates (by 14% or 0.5 mm day⁻¹) than corn throughout the growing season on average, which partially confirmed our hypothesis. Greater water use rates and radiation interception by miscanthus did not translate to greater water-use (1.5 g kg⁻¹ vs. 1.6 g kg⁻¹) and radiation-use (0.9 g MJ⁻¹ vs. 1.1 g MJ⁻¹) efficiencies than corn. Compared to literature values, our data indicated that water and radiation availability were not limiting at our study site. Thus, it is likely that marginal land features present at the Coastal Plain region such as low soil fertility and high air temperatures throughout the growing season may constrain agronomic yields even if soil water and radiant energy are non-limiting.

This study investigates uncertainties in greenhouse gas (GHG) emission factors related to switchgrass-based biofuel production in Michigan. Using three life cycle assessment (LCA) databases—US lifecycle inventory (USLCI) database, GREET, and Ecoinvent—each with multiple versions, we recalculated the global warming intensity (GWI) and GHG mitigation potential in a static calculation. Employing Monte Carlo simulations along with local and global sensitivity analyses, we assess uncertainties and pinpoint key parameters influencing GWI. The convergence of results across our previous study, static calculations, and Monte Carlo simulations enhances the credibility of estimated GWI values. Static calculations, validated by Monte Carlo simulations, offer reasonable central tendencies, providing a robust foundation for policy considerations. However, the wider range observed in Monte Carlo simulations underscores the importance of potential variations and uncertainties in real-world applications. Sensitivity analyses identify biofuel yield, GHG emissions of electricity, and soil organic carbon (SOC) change as pivotal parameters influencing GWI. Decreasing uncertainties in GWI may be achieved by making greater efforts to acquire more precise data on these parameters. Our study emphasizes the significance of considering diverse GHG factors and databases in GWI assessments and stresses the need for accurate electricity fuel mixes, crucial information for refining GWI assessments and informing strategies for sustainable biofuel production.

The UK sixth carbon budget has recommended domestic biomass supply should increase to meet growing demand, planting a minimum of 30,000 hectares of perennial energy crops a year by 2035, with a view to establishing 700,000 hectares by 2050 to meet the requirements of the balanced net zero pathway. Miscanthus is a key biomass crop to scale up domestic biomass production in the United Kingdom. A cohesive land management strategy, based on robust evidence, will be required to ensure upscaling of miscanthus cultivation maximizes the environmental and economic benefits and minimizes undesirable consequences. This review examines research into available land areas, environmental impacts, barriers to uptake, and the challenges, benefits, and trade-offs required to upscale miscanthus production on arable land and grassland in the United Kingdom. Expansion of perennial biomass crops has been considered best restricted to marginal land, less suited to food production. The review identifies a trade-off between avoiding competition with food production and a risk of encroaching on areas containing high-biodiversity or high-carbon stocks, such as semi-natural grasslands. If areas of land suitable for food production are needed to produce the biomass required for emission reduction, the review indicates there are multiple strategies for miscanthus to complement long-term food security rather than compete with it. On arable land, a miscanthus rotation with a cycle length of 10–20 years can be employed as fallow period for fields experiencing yield decline, soil fatigue, or persistent weed problems. On improved grassland areas, miscanthus presents an option for diversification, flood mitigation, and water quality improvement. Strategies need to be developed to integrate miscanthus into farming systems in a way that is profitable, sensitive to local demand, climate, and geography, and complements rather than competes with food production by increasing overall farm profitability and resilience.

Biochar possesses unique characteristics, including a substantial surface area, a high carbon content, sufficient capacity for cation exchange, and a robust structure. However, biochar contains hazardous pollutants like volatile organic compounds that harm soil properties and functionality. Although several studies on biochar production from various feedstocks have been undertaken in recent years, several issues about feedstock preparation, economic feasibility, influencing factors, and the proper utilization of biochar production processes need to be addressed. This paper thus addresses these issues by providing potential solutions identified through a comprehensive review. Slow pyrolysis of lignocellulosic biomass and Acacia nilotica yields biochar from 20 to 52 wt% at various temperatures and residence times. Biochar yield varies from 29 to 48.3 wt% when waste tires and corn stalks are rapidly pyrolyzed at higher temperatures and for shorter periods. Torrefaction of algal biomass at moderate temperatures with different residence times can result in a substantial yield of 50–60 wt%. However, the variability and heterogeneity of waste feedstocks pose potential challenges affecting biochar's quality and properties. Given its widespread use in carbon sequestration, soil remediation, wastewater purification, and organic waste composting, the mechanisms of biochar production in environmental usage need to be investigated.