• Energy Research

Surface-atmosphere energy exchange is strongly ecosystem-specific. At the same time, as the energy balance constitutes responses of an ecosystem to environmental stressors including precipitation, humidity and solar radiation, it results in feedbacks of potential importance for the regional climate. Northern peatlands represent a diverse class of ecosystems that cover nearly 6 x 10(6) km(2) in the Boreal region, which makes the inter-comparison of their energy balances an important objective. With this in mind we studied energy exchange across a broad spectrum of peatlands from pristine fens and bogs to forested and agriculturally managed peatlands, which represent a large fraction of the landscape in Finland and Sweden. The effects of management activities on the energy balance were extensively examined from the micrometeorological point of view, using eddy covariance data from eight sites in these two countries (56 degrees 12'-62 degrees 11' N, 13 degrees 03'-30 degrees 05' E). It appears that the surface energy balance varies widely amongst the different peatland types. Generally, energy exchange features including the Bowen ratio, surface conductance, coupling to the atmosphere, responses to water table fluctuations and vapour pressure deficit could be associated directly with the peatland type. The relative constancy of the Bowen ratio in natural open mires contrasted with its variation in tree-covered and agricultural peatlands. We conclude that the impacts of management and the consequences of land-use change in peatlands for the local and regional climate might be substantial. Peer reviewed

Abstract The transition from a fossil-based economy to a circular bioeconomy is a critical challenge and opportunity in the face of global climate change. Sweden and Finland, with their abundant forest resources and strong commitment to sustainability, are well positioned to lead this transition. The WoodPro project exemplifies this effort by exploring innovative ways to valorize forest residues into high-value products such as 2,3-butanediol (2,3-BDO), biopolymers and hydrochar. This perspective outlines the project’s multidisciplinary approach, which integrates advanced bioprocessing technologies with dynamic system analysis to optimize the sustainability and economic feasibility of these biorefining pathways. We highlight the potential of these interconnected processes to reduce greenhouse gas emissions, close nutrient loops and stimulate rural development, while positioning the Nordic countries as global leaders in the circular bioeconomy. The insights gained from this project highlight the importance of holistic, systems-based approaches in achieving carbon neutrality and offer a model for similar transitions worldwide.

Achieving a balance between greenhouse gas mitigation and biomass production in grasslands necessitates optimizing irrigation frequency and nitrogen addition, which significantly influence grassland productivity and soil nitrous oxide emissions, and consequently impact the ecosystem carbon dioxide exchange. This study aimed to elucidate these influences using a controlled mesocosm experiment where bermudagrass (Cynodon dactylon L.) was cultivated under varied irrigation frequencies (daily and every 6 days) with (100 kg ha-1) or without nitrogen addition; measurements of net ecosystem carbon dioxide exchange, ecosystem respiration, soil respiration, and nitrous oxide emissions across two cutting events were performed as well. The findings revealed a critical interaction between water-filled pore space, regulated by irrigation, and nitrogen availability, with the latter exerting a more substantial influence on aboveground biomass growth and ecosystem carbon dioxide exchange than water availability. Moreover, the total dry matter was significantly higher with nitrogen addition compared to without nitrogen addition, irrespective of the irrigation frequency. In contrast, soil nitrous oxide emissions were observed to be significantly higher with increased irrigation frequency and nitrogen addition. The effects of nitrogen addition on soil respiration components appeared to depend on water availability, with autotrophic respiration seeing a significant rise with nitrogen addition under limited irrigation (5.4 ± 0.6 μmol m-2 s-1). Interestingly, the lower irrigation frequency did not result in water stress, suggesting resilience in bermudagrass. These findings highlight the importance of considering interactions between irrigation and nitrogen addition to optimize water and nitrogen input in grasslands for a synergistic balance between grassland biomass production and greenhouse gas emission mitigation.

Abstract Increase in concerns over greenhouse gas emissions and depletion of fossil fuels has led to the search for alternative strategies of energy. Rice straw mainly composed of cellulose, hemicelluloses, and lignin, is one of the surpluses available lignocellulosic biomass that can serve as a potential feedstock for the production of bio-butanol. One of the main challenges in the conversion of rice straw to bio-butanol is the development of an economically viable and eco-friendly pretreatment strategy for better hemicellulose and lignin removal as well as the development of hyper-productive and solvent-tolerant microbial strains for effective fermentation. This review focuses on the recent trends, challenges, and possibilities in the production of butanol utilizing rice straw.

AbstractThe valorization of agricultural and industrial wastes for fuel and chemical production benefits environmental sustainability. 2, 3-Butanediol (2,3-BDO) is a value-added platform chemical covering many industrial applications. Since the global market is increasing drastically, production rates have to increase. In order to replace the current petroleum-based 2,3-BDO production, renewable feedstock's ability has been studied for the past few decades. This study aims to find an improved bioprocess for producing 2,3-BDO from agricultural and industrial residues, consequently resulting in a low CO2 emission bioprocess. For this, screening of 13 different biomass samples for hydrolyzable sugars has been done. Alkali pretreatment has been performed with the processed biomass and enzyme hydrolysis performed using commercial cellulase. Among all biomass hydrolysate oat hull and spruce bark biomass could produce the maximum amount of total reducing sugars. Later oat hull and spruce bark biomass with maximum hydrolyzable sugars have been selected for submerged fermentation studies using Enterobacter cloacae SG1. After fermentation, 37.59 and 26.74 g/L of 2,3-BDO was obtained with oat hull and spruce bark biomass, respectively. The compositional analysis of each step of biomass processing has been performed and changes in each component have been evaluated. The compositional analysis has revealed that biomass composition has changed significantly after pretreatment and hydrolysis leading to a remarkable release of sugars which can be utilized by bacteria for 2,3-BDO production. The results have been found to be promising, showing the potential of waste biomass residues as a low-cost raw material for 2,3-BDO production and thus a new lead in an efficient waste management approach for less CO2 emission. Graphical Abstract

Abstract. One of the strategies to reduce carbon dioxide (CO2) emissions from the energy sector is to increase the use of renewable energy sources such as bioenergy crops. Bioenergy is not necessarily carbon neutral because of greenhouse gas (GHG) emissions during biomass production, field management and transportation. The present study focuses on the cultivation of reed canary grass (RCG, Phalaris arundinaceae L.), a perennial bioenergy crop, on a mineral soil. To quantify the CO2 exchange of this RCG cultivation system, and to understand the key factors controlling its CO2 exchange, the net ecosystem CO2 exchange (NEE) was measured during three years using the eddy covariance (EC) method. The RCG cultivation thrived well producing yields of 6200 and 6700 kg DW ha−1 in 2010 and 2011, respectively. Gross photosynthesis (GPP) was controlled mainly by radiation from June to September. Vapour pressure deficit (VPD), air temperature or soil moisture did not limit photosynthesis during the growing season. Total ecosystem respiration (TER) increased with soil temperature, green area index and GPP. Annual NEE was −262 and −256 g C m−2 in 2010 and 2011, respectively. Throughout the studied period, cumulative NEE was −575 g C m−2. When compared to the published data for RCG on an organic soil, the cultivation of this crop on a mineral soil had higher capacity to take up CO2 from the atmosphere.

AbstractThe majority of northern peatlands were initiated during the Holocene. Owing to their mass imbalance, they have sequestered huge amounts of carbon in terrestrial ecosystems. Although recent syntheses have filled some knowledge gaps, the extent and remoteness of many peatlands pose challenges to developing reliable regional carbon accumulation estimates from observations. In this work, we employed an individual‐ and patch‐based dynamic global vegetation model (LPJ‐GUESS) with peatland and permafrost functionality to quantify long‐term carbon accumulation rates in northern peatlands and to assess the effects of historical and projected future climate change on peatland carbon balance. We combined published datasets of peat basal age to form an up‐to‐date peat inception surface for the pan‐Arctic region which we then used to constrain the model. We divided our analysis into two parts, with a focus both on the carbon accumulation changes detected within the observed peatland boundary and at pan‐Arctic scale under two contrasting warming scenarios (representative concentration pathway—RCP8.5 and RCP2.6). We found that peatlands continue to act as carbon sinks under both warming scenarios, but their sink capacity will be substantially reduced under the high‐warming (RCP8.5) scenario after 2050. Areas where peat production was initially hampered by permafrost and low productivity were found to accumulate more carbon because of the initial warming and moisture‐rich environment due to permafrost thaw, higher precipitation and elevated CO2 levels. On the other hand, we project that areas which will experience reduced precipitation rates and those without permafrost will lose more carbon in the near future, particularly peatlands located in the European region and between 45 and 55°N latitude. Overall, we found that rapid global warming could reduce the carbon sink capacity of the northern peatlands in the coming decades.