Small-scale biochar production on Swedish farms

Several small-scale pyrolysis plants have been installed on Swedish farms and the trend is also expanding in the Nordic countries. These projects are driven by ambitions of achieving carbon dioxide removal, reducing environmental impacts and improving farmers’ economy and resilience. The pyrolysis plants are fuelled with either commercial pellets or agricultural residues. The pyrolysis plants co-produce heat for the farm’s buildings, biochar for non-oxidative applications, mostly agricultural ones, and electricity in some cases. In the Nordic context, on-farm biochar production potential is thus linked to energy consumption. The main research question investigated is whether farms producing biochar can meet their own biochar needs in an energy-efficient way. The research also provides insights on how biochar production at various scales, centralized and decentralized, can be integrated in a given landscape. Please click Additional Files below to see the full abstract

Tackling complexity and problem formulation in rural electrification through conceptual modelling in system dynamics

Mini-grids are considered important in order to improve access to electricity in developing countries. Their technical and organizational independence from the large national grids and their interactions with local social, economic, and environmental factors suggests that system dynamics is a useful method of analysis. However, the successful implementation of mini-grids in rural electrification has partly been prevented due to complexity issues, making problem formulation difficult. Most problem-solving methods, such as system dynamics, require well-defined problems. Previous work on the problem formulation process in system dynamics is limited. This work presents a conceptual framework for tackling complexity and uncertainties in rural electrification. The conceptual framework is general and draws on research in conceptual modelling and system dynamics. The focus is on the learning that can be achieved from a system description and how it can be used to tackle complexity by reducing uncertainties and improving knowledge

Serotonin Depletion-Induced Maladaptive Aggression Requires the Presence of Androgens

The sex hormone testosterone and the neurotransmitter serotonin exert opposite effects on several aspects of behavior including territorial aggression. It is however not settled if testosterone exerts its pro-aggressive effects by reducing serotonin transmission and/or if the anti-aggressive effect of serotonin requires the presence of the androgen. Using the resident intruder test, we now show that administration of the serotonin synthesis inhibitor parachlorophenylalanine (300 mg/kg x 3 days) increases the total time of attack as well as the percentage amount of social behavior spent on attack but not that spent on threat - i.e. that it induces a pattern of unrestricted, maladaptive aggression - in gonadectomized C57Bl/6 male mice receiving testosterone replacement; in contrast, it failed to reinstate aggression in those not given testosterone. Whereas these results suggest the pro-aggressive effect of testosterone to be independent of serotonin, and not caused by an inhibition of serotonergic activity, the pCPA-induced induction of maladaptive aggression appears to require the presence of the hormone. In line with these findings, pCPA enhanced the total time of attack as well the relative time spent on attacks but not threats also in wild-type gonadally intact male C57Bl/6 mice, but failed to reinstate aggression in mice rendered hypo-aggressive by early knock-out of androgen receptors in the brain (AR(NesDel) mice). We conclude that androgenic deficiency does not dampen aggression by unleashing an anti-aggressive serotonergic influence; instead serotonin seems to modulate aggressive behavior by exerting a parallel-coupled inhibitory role on androgen-driven aggression, which is irrelevant in the absence of the hormone, and the arresting of which leads to enhanced maladaptive aggression

Life cycle assessment of urban uses of biochar and case study in Uppsala, Sweden

Biochar is a material derived from biomass pyrolysis that is used in urban applications. The environmental impacts of new biochar products have however not been assessed. Here, the life cycle assessments of 5 biochar products (tree planting, green roofs, landscaping soil, charcrete, and biofilm carrier) were performed for 7 biochar supply-chains in 2 energy contexts. The biochar products were benchmarked against reference products and oxidative use of biochar for steel production. Biochar demand was then estimated, using dynamic material flow analysis, for a new city district in Uppsala, Sweden. In a decarbonised energy system and with high biochar stability, all biochar products showed better climate performance than the reference products, and most applications outperformed biomass use for decarbonising steel production. The climate benefits of using biochar ranged from - 1.4 to - 0.11 tonne CO2-eq tonne(-1) biochar in a decarbonised energy system. In other environmental impact categories, biochar products had either higher or lower impacts than the reference products, depending on biochar supply chain and material substituted, with trade-offs between sectors and impact categories. However, several use-phase effects of biochar were not included in the assessment due to knowledge limitations. In Uppsala's new district, estimated biochar demand was around 1700 m(3) year(-1) during the 25 years of construction. By 2100, 23% of this biochar accumulated in landfill, raising questions about end-of-life management of biochar-containing products. Overall, in a post-fossil economy, biochar can be a carbon dioxide removal technology with benefits, but biochar applications must be designed to maximise co-benefits

Assessing the diverse environmental effects of biochar systems: An evaluation framework

Biochar has been recognised as a carbon dioxide removal (CDR) technology. Unlike other CDR technologies, biochar is expected to deliver various valuable effects in e.g. agriculture, animal husbandry, industrial processes, remediation activities and waste management. The diversity of biochar side effects to CDR makes the systematic environmental assessment of biochar projects challenging, and to date, there is no common framework for evaluating them. Our aim is to bridge the methodology gap for evaluating biochar systems from a life-cycle perspective. Using life cycle theory, actual biochar projects, and reviews of biochar research, we propose a general description of biochar systems, an overview of biochar effects, and an evaluation framework for biochar effects. The evaluation framework was applied to a case study, the Stockholm Biochar Project. In the framework, biochar effects are classified according to life cycle stage and life cycle effect type; and the biochar?s end-of-life and the reference situations are made explicit. Three types of effects are easily included in life cycle theory: changes in biosphere exchanges, technosphere inputs, and technosphere outputs. For other effects, analysing the cause-effect chain may be helpful. Several biochar effects in agroecosystems can be modelled as future productivity increases against a reference situation. In practice, the complexity of agroecosystems can be bypassed by using empirical models. Existing biochar life cycle studies are often limited to carbon footprint calculations and quantify a limited amount of biochar effects, mainly carbon sequestration, energy displacements and fertiliser-related emissions. The methodological development in this study can be of benefit to the biochar and CDR research communities, as well as decision-makers in biochar practice and policy

Linking household and productive use of electricity with mini-grid dimensioning and operation

Off-grid systems, and mini-grids in particular, are expected to play a significant role in improving electricity access to one billion people until 2040. One of the major challenges for mini-grids is associated with their high costs, low financial viability and local development impact. Productive use of electricity can be an important driver of local development and impacts the total load in a mini-grid. By using a mixture of high-resolution (minutes) measurements and long-term data (years) on electricity expenditures and purchased electricity from a mini-grid in the Tanzanian highlands, we analyse the technical and economic impact from household and productive use of electricity, respectively. The high-resolution data is analysed using performance indicators and the long-term data using regression tools. We find that a mixture of household use and productive use of electricity provides both technical and economic benefits for the operator. In addition, we find that while productive use customers only represent 25% of the customers, they generate 44% of the operator\u27s income. Furthermore, productive use of electricity customers are also likely responsible for the peak demand in the mini-grid, which occurs during day time. Lastly, we find empirical evidence suggesting that expenditures and demand are unit elastic, which has implications on economic policies for supporting rural electrification