Global Change Biology Bioenergy最新文献

Promoting the bioeconomy to aid in the achievement of sustainability goals has increased demand for biomass as feedstock. Residual biomass from agricultural production is an attractive option, as it is a by-product that does not compete with food production. However, crop residues are important for the preservation of soil quality, especially for the maintenance of soil organic carbon. Therefore, their use can conflict with environmental goals and initiatives that aim to preserve soil fertility and carbon stocks. Nevertheless, the adoption of intermediate crops could compensate for the negative effects of crop residue removal. Moreover, if crop residues are used for a bioeconomy pathway such as biogas production, the resulting digestate derived from the anaerobic digestion process could be returned to the soil, providing an input of highly recalcitrant carbon. In this study, we modeled the effects of removal of crop residues, the cultivation of intermediate crops, and the application of digestate on Swedish soil organic carbon stocks. Our results suggest that the inclusion of intermediate crops could raise the carbon stocks at equilibrium by an average of 1.93 t C ha⁻¹ (~3% increase) with a notable spatial variation. Digestate application showed a higher average increase (3.3 t C ha⁻¹, ~5%) with an even higher variation. The removal of crop residues was detrimental in some areas, resulting in a loss of carbon, which could not be compensated for entirely by the introduction of intermediate crops or digestate recycling. Combining these two practices showed overall positive effects on soil organic carbon stocks; however, the results cannot be generalized at any spatial location, and we emphasize the importance of assessments tailored to local conditions.

This study aimed to isolate, purify, and characterize a lipase from the gut symbiont Bacillus megaterium F25 (GenBank accession: MF597792) of the aquatic insect Rhantus suturalis, with a focus on its potential applications in biodiesel and food industries. Under optimized culture conditions, B. megaterium F25 could produce 583 U/L of lipase in shaking flask culture. The purified lipase (PL) exhibited a specific activity with 113.89 U/mg, and its molecular weight was determined as 34 kDa. The activity of PL was enhanced by methanol, ethanol, Tween-80, Triton X-100, Ca²⁺, and Mg²⁺, while β-mercaptoethanol, EDTA, SDS, Fe²⁺, Mn²⁺, and Cu²⁺ were inhibitory. PL showed optimal activity and stability at neutral and slightly acidic pHs, as well as in a temperature range of 20°C–30°C. PL displayed strong hydrolytic activity toward plant oils and animal fats, indicating its potency for both the food industry and the remediation of oil-contaminated environments. When tested as a catalyst, PL provided biodiesel production with a transesterification yield of 86.8% under optimized conditions (36 h reaction time, 4 mL enzyme solution, 30°C, pH 7.0, and waste cooking oil:methanol ratio of 10 mL/40 mL). This is the first report on the lipase-producing potential of gut microbial symbionts of aquatic insects. Furthermore, B. megaterium lipase was tested for the first time as a biocatalyst for biodiesel production.

Increasing lignocellulosic feedstock for advanced biofuels can tackle the decarbonization of the transport sector. Dedicated biomass produced alongside food systems with low indirect land use change (iLUC) impact can broaden the feedstock availability, thus streamlining the supply chains. The objective of this study was the design and evaluation of advanced ethanol value chains for the Emilia-Romagna region based on low iLUC feedstock. Two dedicated lignocellulosic crops (biomass sorghum and sunn hemp) were evaluated in double cropping systems alongside food crop residues (corn stover and wheat straw) as sources to simulate the value chains. A parcel-level regional analysis was carried out, then the LocaGIStics2.0 model was used for the spatial design and review of the biomass delivery chain options regarding cost and greenhouse gas (GHG) emissions of the different feedstock mixes. Literature data on bioethanol production from similar feedstocks were used to estimate yields, process costs, and GHG emissions of a biorefinery process based on these biomasses. Within the chain options, GHG emissions were overly sensitive to cultivation input, mostly N-fertilization. This considered, GHG emissions resulted similar across different feedstock with straw/stover (averaging 13 g CO₂eq MJ⁻¹ fuel), sunn hemp (14 g CO₂eq MJ⁻¹ fuel), and biomass sorghum (16 g CO₂eq MJ⁻¹ fuel). On the other hand, the bioethanol produced from biomass sorghum (608 € Mg⁻¹ of bioethanol) was cheaper compared with straw (632 € Mg⁻¹), sunn hemp (672 € Mg⁻¹), and stover (710 € Mg⁻¹). The bioethanol cost ranged from 0.0017 to 0.020 € MJ⁻¹ fuel depending on the feedstock, with operations and maintenance impacting up to 90% of the final cost. In summary, a single bioethanol plant with an annual capacity of 250,000 Mg of biomass could replace from 5% to 7% of the Emilia-Romagna's ethanol fuel consumption, depending on the applied sourcing scenario.

Substituting alternative materials and energy sources with forest biomass can cause significant environmental consequences, such as alteration in the released emissions which can be described by displacement factors (DFs). Until now, DFs of wood-based materials have included greenhouse gas (GHG) emissions and have been associated with lower fossil and process-based emissions than non-wood counterparts. In addition to GHGs, aerosols released in combustion processes, for example, alter radiative forcing in the atmosphere and consequently have an influence on climate. In this study, the objective was to quantify the changes in the most important aerosol emission components for cases when wood-based materials and energy were used to replace the production of high-density polyethylene (HDPE) plastic, common fossil-based construction materials (concrete, steel and brick), non-wood textile materials and energy produced by fossil fuels and peat. For this reason, we expanded the DF calculations to include aerosol emissions of total suspended particles (TSP), respirable particulate matter (PM10), fine particles (PM2.5), black carbon (BC), nitrogen oxides (NO_x), sulphur dioxide (SO₂) and non-methane volatile organic compounds (NMVOCs) based on the embodied energies of materials and energy sources. The DFs for cardboard implied a decrease in BC, SO₂ and NMVOC emissions but an increase in the other emission components. DFs for sawn wood mainly indicated higher emissions of both particles and gaseous emissions compared to non-wood counterparts. DFs for wood-based textiles demonstrated increased particle emissions and reduced gaseous emissions. DFs for energy biomass mainly implied an increase in emissions, especially if biomass was combusted in small-scale appliances. Our main conclusion highlights the critical need to thoroughly assess how using forest biomass affects aerosol emissions. This improved understanding of the aerosol emissions of the forestry sector is crucial for a comprehensive evaluation of the climate and health implications associated with forest biomass use.

Silage maize (Zea mays L.) intensification to maximise biomass production increases greenhouse gas emissions, accelerates climate change and intensifies the search for alternative bioenergy crops with high carbon (C) sequestration capacity. The perennial cup-plant (Silphium perfoliatum L.) not only serves as a viable bioenergy source but may also be a promising soil C conservator. However, the dynamics of soil organic C (SOC) under the C3 cup-plant, exposed to moderate drought conditions, that reduces growth rate without causing crop failure, compared with the drought-tolerant C4 maize, remains unexplored. Here, we investigated in a lysimeter experiment the effects of moderate drought stress on crop growth and soil CO₂ efflux under cup-plant and silage maize compared with well-watered conditions. Soil CO₂ efflux along with root and shoot biomass, soil moisture and temperature as well as SOC and nitrogen (N) were measured over three consecutive years. Irrespective of the watering regime, cup-plant induced a greater soil CO₂ efflux (16% and 23% for 2020 and 2021, respectively), which was associated with higher root and shoot biomass compared with silage maize suggesting a substantial contribution of the roots to total soil CO₂ efflux. In addition, soil CO₂ efflux correlated negatively with soil dissolved N and positively with microbial C:N imbalance suggesting that low soil N availability influences soil CO₂ efflux through processes related to N-limitation such as N-mining. Strikingly, moderate drought had no effect on soil CO₂ efflux and C content and microbial biomass C, but increased dissolved organic C and microbial biomass N in both crops suggesting a complex interplay between C availability, N-limitation and microbial adaptation under these conditions. Although cup-plant increased soil CO₂ efflux, the observed higher root and shoot biomass even under moderate drought conditions suggests a similar soil C management as silage maize; however, this still requires longer-term investigation.

Oilcane—an oil-accumulating crop engineered from sugarcane—and microbial oil have the potential to improve renewable oil production and help meet the expected demand for bioderived oleochemicals and fuels. To assess the potential synergies of processing both plant and microbial oils, the economic and environmental implications of integrating microbial oil production at oilcane and sugarcane biorefineries were characterized. Due to decreased crop yields that lead to higher simulated feedstock prices and lower biorefinery capacities, current oilcane prototypes result in higher costs and carbon intensities than microbial oil from sugarcane. To inform oilcane feedstock development, we calculated the required biomass yields (as a function of oil content) for oilcane to achieve financial parity with sugarcane. At 10 dw% oil, oilcane can sustain up to 30% less yield than sugarcane and still be more profitable in all simulated scenarios. Assuming continued improvements in microbial oil production from cane juice, achieving this target results in a minimum biodiesel selling price of 1.34 [0.90, 1.85] USD∙L⁻¹ (presented as median [5th, 95th] percentiles), a carbon intensity of 0.51 [0.47, 0.55] kg CO₂e L⁻¹, and a total biodiesel yield of 2140 [1870, 2410] L ha⁻¹ year⁻¹. Compared to biofuel production from soybean, this outcome is equivalent to 3.0–3.9 as much biofuel per hectare of land and a 57%–63% reduction in carbon intensity. While only 20% of simulated scenarios fell within the market price range of biodiesel (0.45–1.11 USD∙L⁻¹), if the oilcane biomass yield would improve to 25.6 DMT∙ha⁻¹∙y⁻¹ (an equivalent yield to sugarcane) 87% of evaluated scenarios would have a minimum biodiesel selling price within or below the market price range.

Anaerobic digestion and composting of biowastes are vital pathways to recycle carbon and nutrients for agriculture. However, plastic contamination of soil amendments and fertilizers made from biowastes is a relevant source of (micro-) plastics in (agricultural) ecosystems. To avoid this contamination, plastic containing biowastes could be pyrolyzed to eliminate the plastic, recycle most of the nutrients, and create carbon sinks when the resulting biochar is applied to soil. Literature suggests plastic elimination mainly by devolatilization at co-pyrolysis temperatures of > 520°C. However, it is uncertain if the presence of plastic during biomass pyrolysis induces the formation of organic contaminants or has any other adverse effects on biochar properties. Here, we produced biochar from wood residues (WR) obtained from sieving of biowaste derived digestate. The plastic content was artificially enriched to 10%, and this mixture was pyrolyzed at 450°C and 600°C. Beech wood (BW) chips and the purified, that is, (macro-) plastic-free WR served as controls. All biochars produced were below limit values of the European Biochar Certificate (EBC) regarding trace element content and organic contaminants. Under study conditions, pyrolysis of biowaste, even when contaminated with plastic, can produce a biochar suitable for agricultural use. However, thermogravimetric and nuclear magnetic resonance spectroscopic analysis of the WR + 10% plastics biochar suggested the presence of plastic residues at pyrolysis temperatures of 450°C. More research is needed to define minimum requirements for the pyrolysis of plastic containing biowaste and to cope with the automated identification and determination of plastic types in biowaste at large scales.

The interaction of biochar with mineral fertilization has attracted attention as a strategy to reduce N losses and enhance nitrogen use efficiency. In this study, we investigated the coapplication of biochar with two optimized fertilization strategies based on split urea and a microbial inoculant (Azospirillum brasilense) in a commercial pointed white cabbage crop. Additionally, we evaluated a third optimized N fertilization alternative, a biochar-based fertilizer (BBF) enriched in plant-available N, which was developed from the same biochar. We assessed environmental impacts such as greenhouse gasses (GHG) and NH₃ emissions, yield-scaled N₂O emissions, and global warming potential (GWP). Additionally, we evaluated agronomical outcomes such as crop yield, plant N, and chlorophyll concentration. Moreover, we examined the N-fixing gene's total and relative abundance (nifH and nifH/16S). Biochar and BBF exhibited similar crop yield, GHG, and NH₃ emissions compared to split applications of the synthetic fertilizer. The main difference was associated with the higher soil C sequestration in biochar and BBF treatments that reduced the associated GWP of these fertilization strategies. Finally, biochar favored the activity of the N-fixing bacteria spread, compared to the sole application of bacteria and BBF demonstrated a promoting effect in the soil's total abundance of natural N-fixing bacteria.

The expansion of sugarcane, a tropical high-yielding feedstock, will likely reshape the Southeastern United States (SE US) bioenergy landscape. However, the sustainability of sugarcane, particularly as it displaces grazed pastures, is highly uncertain. Here, we investigated how pasture conversion to sugarcane in subtropical Florida impacts net ecosystem CO₂ exchange (NEE) and net ecosystem carbon (C) balance (NECB). Measurements were made over three full growth cycles (> 3 years) in sugarcane—plant cane, PC; first ratoon cane, FRC; second ratoon cane, SRC—and in improved (IM) and semi-native (SN) pastures, which make up ca. 37% of agricultural land in the region. Immediately following conversion, PC was a stronger net source of CO₂ than pastures, indicating the importance of CO₂ losses related to land disturbance. Sugarcane, however, shifted to a strong net sink of CO₂ after first regrowth, and overall sugarcane was a stronger net CO₂ sink than pastures. Both stand age and low water availability during cane emergence and tillering substantially decreased its potential gross CO₂ uptake. Accounting for all C gains and removals (i.e., NECB), greater frequency of burn events and repeated harvest increased removals and overall made sugarcane a stronger C source relative to pastures despite substantial C inputs from the previous land use and a stronger CO₂ sink strength. Time since conversion substantially reduced C losses from sugarcane, and the NECB of SRC was similar to that of IM pasture but lower than that of SN pasture, indicating a rapid shift in the NECB of cane. We conclude that the C-balance implications following conversion will depend on the proportion of IM versus SN pastures converted to sugarcane. Furthermore, our findings suggest that no-burn harvest management strategies will be critical to the development of a sustainable bioenergy landscape in SE US.