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Bioenergy with carbon capture and storage (BECCS) plays a central role in scenario pathways that limit global warming in line with the objectives of the Paris Agreement. Yet deliberate policy efforts to incentivise BECCS—whether through amending existing climate policies or introducing entirely new ones—remain rare. In this paper, we contend that BECCS must be incentivised responsibly, through policy-making processes which account for diverse and geographically varying societal values and interests. More specifically, we make the case for responsible incentivisation by undertaking a comparative analysis of stakeholder attitudes to four idealised policy scenarios for BECCS, including representatives of government, business, nongovernmental and academic communities, in the UK and Sweden. The scenarios were: business as usual; international policy reform; national BECCS policy; and national policy for negative emissions technologies. Based on our findings, we recommend that policymakers 1) recognise the need to develop new incentives and make enabling reforms to existing policy instruments; 2) consider the risk of mitigation deterrence in their real world (and not abstracted) contexts; 3) employ multi-instrument approaches to incentivisation that do not overly rely on carbon pricing or 4) force a choice between technology specific or technology neutral policies; and 5) attend to the diversity of stakeholder and wider public perspectives that will ultimately determine the success—or failure—of their policy designs.

In this paper we present a distributed second-order augmented Lagrangian method for distributed model predictive control. We distribute the computations for search direction, step size, and termination criteria over what is known as the clique tree of the problem and calculate each of them using message passing. The algorithm converges to its centralized counterpart and it requires fewer communications between sub-systems as compared to algorithms such as the alternating direction method of multipliers. Results from a simulation study confirm the efficiency of the framework.

One of the main aspects of switched affine systems that makes their stabilizability study intricate is the existence of (generally) infinitely many attainable equilibrium points in the state space. Thus, prior to designing the switched control, the user must specify one of these equilibrium points to be the goal or reference. This can be a cumbersome task, especially if this goal is partially given or only defined as a set of constraints. To tackle this issue, in this paper we describe algorithms that can determine whether a given goal is an equilibrium point of the system and also jointly search for equilibrium points and design stabilizing switching functions.

Food waste is a significant problem within public catering establishments, caused mainly by serving waste arising from overcatering. Overcatering means that public catering establishments rarely run out of food but surplus ends up as food waste. The challenge is to find a solution that minimizes food waste while ensuring that sufficient food can be provided. A key element in this balancing act is to forecast accurately the number of meals needed and cook that amount. This study examined conventional forecasting methods (last-value forecasting, moving-average models) and more complex models (prophet model, neural network model) and calculated associated margins for all models. The best-performing model for each catering establishment was then used to evaluate the optimal number of portions based on stochastic inventory theory. Data used in the forecasting models are number of portions registered at 21 schools in the period 2010–2019. The past year was used for testing the models against real observations. The current business as usual scenario results in a mean average percentage error of 20–40%, whereas the best forecasting case around 2–3%. Irrespective of forecasting method, meal planning needed some safety margin in place for days when demand exceeded the forecast level. Conventional forecasting methods were simple to use and provided the best results in seven cases, but the neural network model performed best for 11 out of 21 kitchens studied. Forecasting can be one option on the road to achieve a more sustainable public catering sector.

The operation of power-to-X systems requires measures to control the cost and sustainability of electricity purchased from spot markets. This study investigated different bidding strategies for the day-ahead market with a special focus on Sweden. A price independent order (PIO) strategy was developed assisted by forecasting electricity prices with an artificial neural network. For comparison, a price dependent order (PDO) with fixed bid price was used. The bidding strategies were used to simulate H2 production with both alkaline and proton exchange membrane electrolysers in different years and technological scenarios. Results showed that using PIO to control H2 production helped to avoid the purchase of expensive and carbon intense electricity during peak loads, but it also reduced the total number of operating hours compared to PDO. For this reason, under optimal conditions for both bidding strategies, PDO resulted in an average of 10.9% lower levelised cost of H2, and more attractive cash flows and net present values than PIO. Nevertheless, PIO showed to be a useful strategy to control costs in years with unexpected hourly price behaviour such as 2018. Furthermore, PIO could be successfully demonstrated in a practical case study to fulfil the on-demand requirement of an industrial captive customer.

Land use affects the global climate through greenhouse gas and aerosol emissions, as well as through changes in biophysical properties of the surface. Anthropogenic land use change over time has caused substantial climate forcing related to albedo, i.e. the share of solar radiation reflected back off the ground. There is growing concern that albedo change may offset climate benefits provided by afforestation, bioenergy or other emission reduction measures that affect land cover. Conversely, land could be managed actively to increase albedo as a strategy to combat global warming. Albedo change can be directly linked to radiative forcing, which allows its climate impact to be compared with that of greenhouse gases in Life Cycle Assessment (LCA). However, the most common LCA methods are static and linear and thus fail to account for the spatial and temporal dependence of albedo change and its strength as a climate forcer. This study sought to develop analytical methods that better estimate radiative forcing from albedo change by accounting for spatial and temporal variations in albedo, solar irradiance and transmission through the atmosphere. Simplifications concerning the temporal resolution and aggregation procedures of input data were evaluated. The results highlight the importance of spatial and temporal variations in determining the climate impact of albedo change in LCA. Irradiance and atmospheric transmittance depend on season, latitude and climate zone, and they co-vary with instantaneous albedo. Ignoring these dependencies led to case-specific errors in radiative forcing. Extreme errors doubled the climate cooling of albedo change or resulted in warming rather than cooling in two Swedish cases considered. Further research is needed to understand how different land use strategies affect the climate due to albedo, and how this compares to the effect of greenhouse gases. Given that albedo change and greenhouse gases act on different time scales, LCAs can provide better information in relation to climate targets if the timing of flows is considered in life cycle inventory analysis and impact assessment.

Agricultural land use and management practices affect the global climate due to greenhouse gas (GHG) fluxes and changes in land surface properties. Increased albedo has the potential to counteract the radiative forcing and warming effect of emitted GHGs. Thus considering albedo could be important to evaluate and improve agricultural systems in light of climate change, but the albedo of individual practices is usually not known. This study quantified the albedo of individual crops under regional conditions, and evaluated the importance of albedo change for the climate impact of current crop production using life cycle assessment (LCA). Seven major crops in southern Sweden were assessed relative to a land reference without cultivation, represented by semi-natural grassland. Crop-specific albedo data were obtained from a MODIS product (MCD43A1 v6), by combining its spatial response pattern with geodata on agricultural land use 2011-2020. Fluxes of GHGs were estimated using regional data and models, including production of inputs, field operations, and soil nitrogen and carbon balances. Ten-year mean albedo was 6-11% higher under the different crops than under the reference. Crop-specific albedo varied between years due to weather fluctuations, but differences between crops were largely consistent. Increased albedo countered the GHG impact from production of inputs and field operations by 17-47% measured in GWP

The climate impact of bioenergy is debated, especially due to potential land use change effects and biogenic carbon fluxes. This study assessed the climate impact and energy efficiency of conventio ...

This paper studies the time-optimal path tracking problem for a cooperative robotic system. The considered system is composed of two two-link planar manipulators with non-actuated end-effectors rigidly grasping a bar. Given a predefined geometric path, the objective is to cooperatively move the bar along the path in minimum time subject to inequality constraints on the joint torques. We show that this problem can be cast as a convex optimization problem by using the existing results for a single manipulator, and also the fact that the desired motion of the bar can be achieved by incorporating its dynamics into the manipulators’ dynamics. We illustrate our results in simulation.

The time-dependent climate impact of beef production, including changes in soil organic carbon, was examined in this study. A hypothetical suckler cow system located in south-east Sweden was analysed using a time-dependent life cycle assessment method in which yearly fluxes of greenhouse gases were considered and the climate impact in terms of temperature response over time was calculated. The climate impact expressed as carbon dioxide equivalents, i.e. global warming potential in a 100-year time perspective, was also calculated. The Introductory Carbon Balance Model was used for modelling yearly soil organic carbon changes from land use. The results showed an average carbon sequestration rate of 0.2 Mg C ha−1 and yr−1, so carbon sequestration could potentially counteract 15–22% of emissions arising from beef production (enteric fermentation, feed production and manure management), depending on system boundaries and production intensity. The temperature response, which showed a high initial increase due to methane emissions from enteric fermentation, started to level off after around 50 years due to the short atmospheric lifetime of methane. However, sustained production and associated methane emissions would maintain the temperature response and contribute to climate damage. A forage-grain beef system resulted in a lower climate impact than a forage-only beef system (due to higher slaughter age), even though more carbon was sequestered in the forage-only system.

In system identification, input selection is a challenging problem. Since less complex models are desireable, non-relevant inputs should be methodically and correctly discarded before or under the estimation process. In this paper we investigate an input selection extension in least-squares ARX estimation and show that better model estimates are achieved compared to the least-square ssolution, in particular, for short batches of estimation data.

Short rotation coppice willow (SRCW) is a high-yielding energy crop that can be used to produce solid, liquid or gaseous biofuels. The crop is harvested during the winter, when the leaves have dropped. For economic reasons, however, most fuel processing plants require continuous year-round delivery of raw material. Thus, SRCW should be harvested as stems or in larger pieces in order to be storable, and not chipped directly at harvest for immediate use in large-scale heating plants, which is common practice at present. The aim of the project within which this study was conducted is to find cost-effective whole-stem harvesting and handling systems for year-round deliveries of natural-dried SRCW. A discrete event simulation model for such systems was developed in this study, taking weather, soil trafficability, geographical conditions, natural drying of the material and storage losses into account. The model was applied to a fictitious processing plant in Uppsala, Sweden. Machine performance and costs for a system with one stem harvester and up to three in-field shuttles, together with one chipper truck for chipping and transport, were investigated. The simulations showed that field trafficability had a crucial impact on total quantity harvested. The total cost was € 40 t −1 dry matter. Yield of SRCW and harvest productivity were important factors regarding costs. The model can be used to design cost-effective harvesting and handling systems for year-round deliveries of SRCW.

Two-dimensional (2D) heterosheets built from silicon and boron may exhibit an intrinsic metallic behavior. From density-functional-theory computer simulations, we have demonstrated that a 2D honeycomb binary compound (h-SiB), which exhibits robust structural and thermal stabilities, maintains its metallicity by increasing hydrogen coverages at 25%, 50%, and 75% on boron or silicon sublattices. However, under a total hydrogenation condition (100%) on B or Si sites, h-SiB opens a well-defined bandgap, meaning that it is possible to obtain a metal-insulator transition at zero temperature in 2D. Additional calculations show that the hydrogenation on B sublattices is energetically more favorable than on silicon.

Earlier studies have highlighted the importance of quality and quantity in forest fuel supply chains, since these parameters affect product value and handling properties, but both are constantly changing over time. Great monetary losses can be incurred if forest fuel material has to be delivered to end-users in non-optimal condition, e.g. to meet seasonal fuel demand with its large short-term variations. Thus earlier studies have also highlighted the importance of more information on the forest fuel supply chain. This paper describes development of a model for Weather-driven Analysis of Forest Fuel Systems (WAFFS) that can be used when analysing forest fuel supply chains and that accounts for both active machine activities and passive activities such as quality changes during storage. The aim was to develop a methodology that can be used to evaluate forest fuel supply chain scenarios and analyse various delivery strategies under different conditions. Application of WAFFS to evaluate delivery strategies for forest fuels showed that system improvements were possible when the right biomass was delivered at the right time. The WAFFS model gives an overview of biomass actually stored at different geographical locations and places (heaps or windrows) in terms of both quality and quantity. Delivery strategies actively prioritising biomass storage proved capable of delivering more energy when most needed, thereby improving yearly machine utilisation for contractors in the supply chain.

Many small farmland ponds are built for nutrient retention, the conservation of biodiversity or both, yet they are relatively neglected habitats. For example, little is known about the potential for ponds to influence populations of beneficial terrestrial insects, deliver ecosystem services across the aquatic–terrestrial boundary and affect crop yield in insect-pollinated cash crops. We assessed whether the presence of a pond affects the abundance of pollinators and the quality and quantity of strawberry yield. We compared the abundance of pollinators and the quality and quantity of strawberries between habitats adjacent to the pond, semi-natural terrestrial habitat and field border without semi-natural vegetation (control habitat). We found significantly higher abundances of syrphids and bees next to ponds compared to control habitats. Also, syrphids were significantly more abundant at pond habitats compared to vegetation habitats and a similar tendency, although not significant, was found for the abundance of bees. The quantity and quality of strawberries was significantly higher near the vegetation and pond habitats compared to the control habitats. Our result supports the theory that the presence of semi-natural habitats, in the agricultural landscape benefits both public interest in biodiversity conservation and farmers’ interest in crop pollination. These benefits may also come from ponds as semi natural habitats. However, further studies are required to disentangle the effect of the pond per se and the effect of the associated terrestrial vegetation.

This study analysed the environmental impacts of taxation on Swedish food consumption and sought to identify potential synergies and goal conflicts between environmental aspects. This was done by analysing various taxation scenarios to reduce environmental impacts of food, including taxation based on: climate impact; a score based on weighting of several environmental impacts; and adjusted rates of value-added tax (VAT). A net decrease in food consumption was seen for most taxation scenarios, resulting in reduced burdens for climate change and most other environmental categories. An exception was found for a scenario simulating reduced VAT rates for plant-based products, where a net increase of food consumption was seen, resulting in an increased burden for all environmental categories. Many of the scenarios resulted in a decrease in beef consumption, and hence a decline in pasture use. This is positive from a global perspective by limiting expansion of agricultural land, but on regional level in Sweden it could cause a goal conflict with maintaining biodiversity-rich semi-natural pastures. To avoid this, beef production on semi-natural pastures could be further incentivised by production-side measures. With regard to biodiversity loss, the overall burden could increase if taxation leads to an increase in products from biodiverse regions.

Tree stump harvesting could significantly increase the amount of bioenergy feedstock that forestry can supply to substitute for fossil alternatives. However, the climate mitigation potential of using stumps for bioenergy has been debated due to their often long residence time in the forest caused by slow decomposition. This study evaluated the climate effect over time of utilising stumps for bioenergy using ecosystem forest carbon modelling and time-dependent LCA methodology, including uncertainties in soil carbon changes. Different climate impact metrics were used (global mean temperature change, global warming potential and cumulative radiative forcing) and evaluations were made for single harvest as well as continuous supply over a landscape. Stump harvesting scenarios for spruce forests across Sweden were simulated and the forest net carbon balance was estimated as the difference compared with a reference scenario where the stumps were left to decompose in the forest. The results showed that using stump residues from commercial forestry in Sweden gives a climate benefit when they substitute for fossil fuel, even in a shorter perspective of around two decades. The temperature impact from using stumps for bioenergy at the stand level peaked after 10–15 years and then declined steadily to ∼15% of the maximum level during the following 4–5 decades. The remaining long-term climate impact was small compared to using fossil fuel. An immediate climate benefit was achieved when replacing fossil coal, whereas the parity time, i.e. the time to reach climate benefit was 12–16 years (±2 years) when replacing natural gas, depending on geographical location. For continuous supply of stump bioenergy over a landscape, the corresponding parity time was 22–28 years. There was a higher impact on global climate for northern Sweden, although the absolute difference was small. Sensitivity analysis indicated a moderate additional climate warming effect from the soil disturbance caused by stump harvesting.

Food waste is a major problem and therefore measures are needed to reduce it. Since expired best-before date is a frequently cited cause of food waste in supermarkets, prolonging shelf life could reduce food waste. Longer shelf life could be achieved in different ways, e.g. reduced storage temperature. However, there is limited knowledge regarding the extent to which longer shelf life actually leads to reduced food waste, and whether the benefits of reduced waste exceed the increased energy costs of maintaining reduced storage temperature. Therefore this study calculated the net effect of reducing food waste in supermarkets by reducing the storage temperature through simulating the relationships between food waste reduction, longer shelf life, reduced storage temperature and increased energy costs. A case study was performed using three years of data on cheese, dairy, deli and meat product waste in six Swedish supermarkets, together with published data on microbiological growth at different temperatures and on the energy requirement for cold storage at different temperatures. Food waste was found to be reduced with lower storage temperature for all food products tested. This measure gave increasing net savings in terms of money and greenhouse gas emissions for meat products with decreasing storage temperature. Deli products had net savings close to zero, while for dairy and cheese products there were net losses, since the costs of reducing storage temperature exceeded the potential savings. Therefore, reducing storage temperature has the potential to reduce waste, but at a total net cost. However, a net benefit can be achieved if the measure is only introduced for products with high relative waste, low turnover and high value per unit mass.

Sweden and Finland have national goals to reach net negative greenhouse gas emissions before mid-century. Achieving these ambitious goals could employ negative emission technologies, such as bioenergy with carbon capture and storage, but it is unclear how this technology could be realized in an energy transition. Sweden and Finland stand out for having a large share of substantial point source emissions of biogenic carbon dioxide, in the production of pulp, heat and power. In the European Pollutant Release and Transfer Register, Sweden and Finland reported 64% and 51% biogenic emissions, respectively, in facilities emitting over 100 kt of carbon dioxide in 2017, while the corresponding collective figure for all European states in the database is 6%. This qualitative study highlights company actors’ perspectives on bioenergy with carbon capture and storage within a Nordic regional context and explores their perspective on emerging tensions in the energy transition. Semi-structured interviews were conducted with 20 of the 24 companies with the largest point sources of biogenic emissions. The results are framed around four emerging tensions regarding bioenergy with carbon capture and storage from companies’ perspectives in this study: (1) absence of reliable long-term policies; (2) limits to companies’ climate change responsibility; (3) technical trade-offs of carbon capture; and (4) lack of customer demands for negative emissions. According to most of the companies, it is technically feasible to capture carbon dioxide, but it could be a challenge to determine who is responsible to create a financially viable business case, to enact supporting policies, and to build transport and storage infrastructure. Company representatives argue that they already contribute to a sustainable society, therefore bioenergy with carbon capture and storage is not their priority without government collaboration. However, they are willing to contribute more and could have an increasing role towards an energy transition in an international context. Funding agencies: The work has been carried out within the scope of the Graduate School in Energy Systems and MESAM, financed by the Swedish Energy Agency under the project, 'An integrative systems approach to a carbon neutral industry'. This research was supported by the Swedish Energy Agency [grants 46222-1 and 46036-1]; Formas - The Swedish Research Council for Environment, Agricultural Sciences and Spatial Planning [grant 2016-00958]; and the Swedish Research Council [grant 2016-06359]. We would also like to thank the company representatives who participated in this study, extend appreciation to colleagues who contributed feedback on the text, and thank the Linkoping University Library for covering the costs to make this article open access.

Legumes have been proposed as biorefinery feedstock primarily due to their low nitrogen fertilizer demand, low fossil energy-related greenhouse gas emissions and high protein content, enabling efficient protein feed, food or amino acid production. Grain legumes (pulses) occupy approx. 1.2% of the arable land in Sweden, with faba bean, which is used as a protein feed, being one of the most common. Utilization of the whole crop, including the beans and the remaining aboveground biomass, can enable co-production of feed, food and/or fuel in high quantities, as faba bean has potentially high total biomass yield. In this study, Consequential Life Cycle Assessment (CLCA) was used to analyze a change from the current use of faba bean as protein feed for dairy cows (Reference scenario) to two alternative uses where the whole crop is harvested: whole crop processing in a green biorefinery producing ethanol, protein concentrate feed and fuel briquettes (Biorefinery scenario), or with the whole crop used as roughage feed (Roughage scenario). Impacts on climate change, arable land use and primary fossil energy use were considered. The changed use of faba bean resulted in changes in the feedstuff requirements for dairy cows, which were highly influential for the results. Whole crop harvesting as opposed to bean harvesting with return of crop residues resulted in increased climate impact and energy use during the agricultural and processing stages. On including substitution effects of the products, the Biorefinery scenario resulted in + 25, − 20% and − 100% change for climate impact, arable land use and energy use, respectively, in relation to the Reference situation. The increase in climate impact was primarily due to soil carbon changes and increased demand for marginal grain. When the whole faba bean crop was used as roughage (Roughage scenario), the corresponding changes were + 164%, − 130% and + 167% for climate change, arable land use and energy use, respectively. The increased impact was due to increased use of feed grain as a result of using the protein-rich roughage.

There is a growing awareness of the climate impact of agricultural production, not least from cattle farms. Major sources of GHG emissions from milk production are enteric fermentation followed by fossil fuel use and manure/soil management systems. This study analyzes the potential to eliminate fossil fuel use from milk production farms in Sweden, by using residual farm resources of biomass to obtain self-sufficiency in fuel, heat and electricity. The change from a fossil-based energy system to a renewable system based on A) Biogas based on manure and straw and B) Biogas based on manure + RME were analyzed with consequential life cycle assessment (CLCA) methodology. Focus was energy use and GHG emissions and the functional unit was 1 kg of energy-corrected milk (ECM). The results show that organic milk producers can become self-sufficient in energy and reduce total GHG emissions from milk production by 46% in the Biogas system, or 32% in the Biogas + RME system compared to the Fossil system.

Food waste is a problem with economic, environmental and social implications, making it both important and complex. Previous studies have addressed food waste management options at the less prioritised end of the waste hierarchy, but information on more prioritised levels is also needed when selecting the best available waste management options. Investigating the global warming potential of different waste management options offers a limited perspective, but is still important for validating generations from the waste hierarchy in a local context. This study compared the effect on greenhouse gas emissions of different food waste management scenarios representing different levels in the waste hierarchy in the city of Uppsala, Sweden. A life cycle assessment was performed for six waste management scenarios (landfill, incineration, composting, anaerobic digestion, animal feed and donations), using five food products (bananas, grilled chicken, lettuce, beef and bread) as examples when treated as individual waste streams. For all five waste streams, the established waste hierarchy was a useful, but approximate, tool for prioritising the various options, since landfill proved to be the worst option and donation, anaerobic digestion and incineration with energy recovery the best options, for easily handle products, wet products and dry products, respectively, taking into account the GHG emissions. The greatest potential for reducing greenhouse gas emissions was in the bread waste stream, since bread is an energy-rich product with a relatively low carbon footprint, increasing the possibilities for replacing fossil energy carriers. Lettuce, with its high water content, had the least potential to reduce greenhouse gas emissions when the waste management method was changed. Waste valorisation measures should therefore focus on food products with the potential to replace production of goods and services, rather than on food products that are wasted in large quantities or have a high carbon footprint.

Farmers can use their own agricultural biomass residues for heat production in small-scale systems, enabling synergies between the district heating (DH) sector and agriculture. The barriers to entry into the Swedish heat market were extremely high as long as heat distribution were considered natural monopoly, but were recently lowered due to the introduction of a regulated third party access (TPA) system in the DH sector. This study assesses the potential impact on greenhouse gas emissions and cost-based heat price in the DH sector when farmers vertically integrate into the heat supply chain and introduce more local and agricultural crops and residues into the fuel mix. Four scenarios with various degree of farmer integration, were assessed using life cycle assessment (LCA) methodology, and by analysis of the heat production costs. The results show that full integration of local farm and forest owners in the value chain can reduce greenhouse gas emissions and lower production costs/heat price, if there is an incentive to utilise local and agricultural fuels. The results imply that farmer participation in the DH sector should be encouraged by e.g. EU rural development programmes.

This study assessed the environmental impacts of recycling the plant nutrients in anaerobically digested food waste as fertilizer in agriculture. This was compared with the impacts of using chemical fertilizer, where the food waste was incinerated, producing heat. The study site was a biogas plant in central Sweden and life cycle assessment methodology was used. The impacts studied were primary energy use, global warming potential (GWP), potential acidification, potential eutrophication, cadmium flow to farmland and use of phosphate rock. Use of digested food waste as fertilizer proved to have larger negative results than use of chemical fertilizer in all categories assessed except use of non-renewable phosphate rock. Sensitivity analyses showed that the scenarios were comparable in terms of primary energy use and better for GWP if some improvements in the anaerobic digestion system were made. However, acidification and eutrophication caused by digestate handling and the cadmium content of digestate should still be considered.

Submerged macrophytes play a key role in the functioning of stream ecosystems since they strongly affect the biological and physical environment of the habitat. On the other hand, flow velocity may affect growth and establishment of submerged macrophytes in streams and rivers. However, little attention has been paid to the morphological responses of submerged macrophytes to different stream flows and in the present study we investigate the intraspecific difference in flow adaptation of a common submerged macrophyte, Myriophyllum spicatum L We found no difference in length of main shoot or total length of lateral shoots of M. spicatum plants grown at high and low stream flow. However, shoot and root dry weight biomass, number of lateral shoots, degree of branching and stem diameter of the main shoot increased significantly with increasing water velocity. In contrast, the opposite trend was observed for leaf whorl area and distances between the internodes of the main shoot. The amount of periphytic algae also decreased with increased water velocity, whereas the macroinvertebrate abundances were nine fold higher at high than at low stream flow, suggesting that grazing may, besides higher stream flow, have been a process behind the lower periphyton growth at high flow. Hence, stream flow not only acts as a stress factor leading to morphological changes in submerged macrophytes, but also induces cascading trophic interactions among periphytic algae and invertebrate assemblages, thereby being a major force in shaping the organism communities of streams and rivers. (C) 2014 Elsevier B.V. All rights reserved. (Less)

Short rotation coppice willow is an energy crop used in Sweden to produce electricity and heat in combined heat and power plants. Recent laboratory-scale experiments have shown that SRC willow can also be used for biogas production in anaerobic digestion processes. Here, life cycle assessment is used to compare the climate impact and energy efficiency of electricity and heat generated by these measures. All energy inputs and greenhouse gas emissions, including soil organic carbon fluxes were included in the life cycle assessment. The climate impact was determined using time-dependent life cycle assessment methodology. Both systems showed a positive net energy balance, but the direct combustion system delivered ninefold more energy than the biogas system. Both systems had a cooling effect on the global mean surface temperature change. The cooling impact per hectare from the biogas system was ninefold higher due to the carbon returned to soil with the digestate. Compensating the lower energy production of the biogas system with external energy sources had a large impact on the result, effectively determining whether the biogas scenario had a net warming or cooling contribution to the global mean temperature change per kWh of electricity. In all cases, the contribution to global warming was lowered by the inclusion of willow in the energy system. The use of time-dependent climate impact methodology shows that extended use of short rotation coppice willow can contribute to counteract global warming.

Sweden has the potential to increase fuel pellet production from alternative raw materials, such as willow and poplar, and also to use former agricultural land for energy crop production. This study used a life cycle perspective to investigate district heat production from pellets produced from willow or poplar cultivated on fallow land in Sweden. The energy efficiency and global warming potential of the systems was evaluated, additionally was the climate impact, expressed in global mean surface temperature change, evaluated from annual greenhouse gas data, including the most relevant fossil and biogenic sources and sinks. The systems were also compared with a fossil fuel alternative in which coal was assumed to be used for heat production. The results showed that the systems investigated had a cooling effect on both global mean surface temperature and global warming potential within the 100-year study period owing mainly to an increase in live biomass and a more long-term increase in soil organic carbon (C), which shows the importance of land use. At the same time, the systems produced renewable energy. The poplar system contributed to a larger cooling effect than the willow system due to more C being sequestered in live biomass and soil in the longer growth periods between harvests and to higher yield. The energy efficiency of the willow and poplar systems used for pellet fuel production was about 11 times the energy input.

Co-production of high-value biobased products in biorefineries is a promising option for optimized utilization of biomass. Lignocellulosic materials such as agricultural and forest residues have been identified as attractive alternative feedstocks because of their high availability and low resource demand. This study assessed the greenhouse gas (GHG) performance and energy balance of ethanol co-production with biogas and electricity in biorefineries using straw and forest residues. Two calculation methods were used: Method I (ISO), which applied the international standard for life cycle assessment, and Method II, which applied the EU Renewable Energy Directive (RED) methodology. These methods differed in allocation procedure, functional unit and system boundaries. Analysis of the importance of significant methodological choices and critical parameters showed that the results varied depending on calculation method, with co-product handling and the inclusion of upstream impacts from residue harvesting explaining most of the differences. Important life cycle steps were process inputs in terms of enzymes and changes in soil organic carbon content due to removal of residues. Ethanol produced from forest residues generally gave lower GHG emissions than straw-based ethanol. The GHG savings for both feedstocks were 51–84% relative to fossil fuel. Omission of upstream impacts from residue recovery in agriculture and forestry in the RED method means that it risks overlooking important environmental effects of residue reuse. Furthermore, the default allocation procedure used in the RED method (energy allocation) may need revision for biorefineries where multiple products with different characteristics are co-produced.

Geoengineering could counteract climate change by either altering the earth's global energy balance by reflecting sunlight or removing CO2 from the atmosphere. Geoengineering evokes various ethical and political challenges that are increasingly reflected in public debate and deliberation. Via a qualitative textual analysis of 1500 articles, we investigate discursive claims critical of geoengineering, considering what subjects are the most controversial, and what worldviews, values, and problematizations are shared by the actors subscribing to this discourse. We argue that the controversy about geoengineering differs, discursively, from other techno-political conflicts. Geoengineering proponents are described as reluctantly favouring research and deployment and displaying an unusual self-reflexivity, as they are well aware of and seriously consider all the technology's risks. Our analysis demonstrates that the discourse critical of geoengineering differs from and questions the dominant pro-geoengineering discourse in several profound ways with lasting implications for energy scholarship and analysis. LUCE

The carbon footprint (CF), the amount of greenhouse gases (GHG) emitted during a product's lifecycle, was evaluated as an indicator of the wider environmental impacts of meat production using existing life cycle assessments of different types of meat (pork, chicken and beef). The CF generally acts as an indicator of acidification and eutrophication potential, since more efficient use of nitrogen leads to less eutrophying and acidifying substances being released to the environment and to lower GHG emissions in nitrous oxide form. GHG mitigation strategies based on more efficient use of feed can therefore also lead to decreased acidification and eutrophication potential. Decreased GHG emissions due to increased productivity mean less land is required for feed production, so CF can act as a proxy for land use. For the impact category primary energy use, apparent conflicts with CF were identified. Pasture-based beef production can be either very energy-efficient or energy-demanding, but both forms produce high CH4 emissions from enteric fermentation. For monogastric animal production, CF can function as an indicator of primary energy use, as both energy use and GHG emissions originate mainly from feed production. It is unclear how the biodiversity impact category correlates to CF. More intensive production can allow more land to be left in its natural state, but can involve increased use of pesticides and fertilisers and monocropping locally, threatening biodiversity. Using CF as an indicator of the environmental impact of meat can generate conflicts with other environmental categories in some cases. However, the risk of damaging other environmental areas when acting on CF must be weighed against the risk of further neglecting to act on global warming by failing to exploit the current market momentum of carbon footprinting.

Fishing activity has been suggested to affect food web structure and functioning of aquatic ecosystems. Based on changes of the mean trophic level index of fishery catch, the present study demonstrates long-term ecosystem impacts of fisheries in Lake Chaohu, a freshwater lake in Anhui Province, China. The decline of mean trophic level (MTL) in the last five decades, coupled with a dramatic increasing of the fishery catches from the lake, can be interpreted as a result of a decrease in the abundance of high trophic level, large piscivorous benthic fishes relative to low-trophic level, small planktivorous pelagic fishes. The mean trophic level of the total fishery catches declined as fishing effort (number of fishing boats and fishermen) increased, which suggests that an expansion of fishing capacity can lead to changes in the food web structures of a lake. Various direct and indirect relationships between MTL, nutrient concentrations and air temperatures were observed, suggesting that environmental changes, jointly with fishing, may have caused cascading effects which make the system less resistant to disturbance. In such context, our results, which complement traditional fisheries assessment, add to the understanding of the interactions among different trophic level of the ecosystem and their alterations due to fisheries and environmental changes. (c) 2012 Elsevier B.V. All rights reserved. (Less)

To prevent retail food wastage, better understanding of waste patterns is necessary. Flows of fruit and vegetables at six Swedish retail stores were analysed in this study, both by analysing recorded data and by performing physical measurements. Total wasted fresh fruits and vegetables were 4.3% of delivered quantity. The largest category was pre-store waste (goods rejected at delivery; 3.01%), followed by recorded in-store waste (0.99%) and unrecorded in-store waste (0.3%). A positive correlation between unrecorded in-store waste and total waste was found, indicating that a thorough recording of waste could be an effective way to reduce retail waste of fresh fruits and vegetables. The praxis allowing large amounts of reclamations of delivered goods was recognised as the main reason for waste, since pre-store waste contributed with the majority of the waste flow. Initiatives to reduce fresh fruit and vegetable waste in the studied retail chain thus need to focus on the pre-store waste to be efficient.

In this paper we derive the maximum likelihood problem for missing data from a Gaussian model. We present in total eight different equivalent formulations of the resulting optimization problem, four out of which are nonlinear least squares formulations. Among these formulations are also formulations based on the expectation-maximization algorithm. Expressions for the derivatives needed in order to solve the optimization problems are presented. We also present numerical comparisons for two of the formulations for an ARMAX model.

The diagnostic beam line at the MAX III synchrotron light source utilizes the synchrotron radiation (SR) in the visible to ultraviolet range to form images of the transverse electron beam profile. The emission and subsequent propagation and focusing of the SR is modeled, taking into account effects such as diffraction and the longitudinally distributed SR generation. A detailed description of the setup of the beam line and method used to determine the transverse beam profile is given in the paper. In order to investigate the imaging method, a series of measurements were performed where the beam line configuration was varied to utilize different wavelengths and polarizations of the SR and different horizontal opening angles of the measurement system. A suggestion is made how to measure future small horizontal beam sizes. (C) 2011 Elsevier B.V. All rights reserved. (Less)

Animal by-products (ABP) are rich in nutrients and energy. This LCA study assessed and compared the environmental impact of using meat meal as fertilizer with that of using chemical fertilizer. In one system the nutrient content of ABP Category 2 was recovered and used as a meat meal fertilizer on arable land, replacing chemical fertilizers. In the other system a chemical fertilizer was used and the energy content of the ABP material recovered. The functional unit consisted of one kg of harvested spring wheat and treatment of 0.59 kg of ABP Category 2. The system for nutrient recovery and chemical fertilizer replacement had lower emissions of greenhouse gases and acidification than the energy recovery system, but had higher total use of energy and eutrophying emissions. Overall, the results of the study greatly depended on the fuels replaced.

Emissions from vehicle diesel engines constitute a considerable share of anthropogenic emissions of pollutants, including many non-regulated compounds such as aromatic hydrocarbons and alkenes. One way to reduce these emissions might be to use fuels with low concentrations of aromatic hydrocarbons, such as Fischer–Tropsch (F–T) diesels. Therefore this study compared Swedish Environmental Class 1 diesel (EC1) with the F–T diesel fuel Ecopar™ in terms of emissions under varied conditions (steady state, controlled transients and realistic work operations) in order to identify factors influencing emissions in actual operation. Using F–T diesel reduced emissions of aromatic hydrocarbons, but not alkenes. Emissions were equally dependent on work operation character (load, engine speed, occurrence of transients) for both fuels. There were indications that the emissions originated from unburnt fuel, rather than from combustion products.

The development and deployment of carbon capture and storage (CCS) are sensitive to public debates that socially frame the technology. This study examines the evolving CCS debates, focusing on the media's framing of firms. Corporations are central CCS actors, and we analyze them in light of the nation-state, which has been emphasized in previous research as the primary context of CCS politics. Empirically, we compare framings of Statoil and Vattenfall in the Norwegian and Swedish media, drawing on a qualitative dataset of news media articles published between 2005 and 2009. We conclude that firms make regular media statements either to foster legitimacy or to respond to criticism of CCS. We also conclude that framing is not necessarily linked to technological success or failure and that interpretations of the technology have different forms depending on whether the related activity occurs in domestic or foreign markets. Finally, we explain the media framings based on the domestic energy situation and politics.

Carbon capture and storage (CCS) is a controversial climate change mitigation technology that has been receiving increased public and private investment over the past decade in several countries. During this time, a diverse international network of professionals focused on the advancement of CCS technology has emerged. Within this international CCS community, a shared perception of the value of advancing CCS technology is generally assumed, and this community has been influential in lobbying for increased support for the development of CCS in many countries and at the international level. The phenomenon of an apparently shared perspective within a specific community relates to Haas’ (1992a) description of the evolution of an epistemic community, or a knowledge-based network of recognized experts who “not only hold in common a set of principled and causal beliefs but also have shared notions of validity and a shared policy enterprise”. Understanding the extent to which a given community can be characterized as an epistemic community can provide insights about the effectiveness of its policy intervention, its association with the broader public, and the success of communicating the messages that it wants to convey. The goal of this research is to begin to explore the nature of the CCS community; to provide a preliminary characterization of the community, and to consider whether and in what ways the community might be considered to be an epistemic community or a compilation of multiple different epistemic communities. This characterization suggests that although the CCS community may be influencing decision-makers and successfully garnering political support for advancing CCS technology, a potential disconnect with the concerns of a broader public is deserving of more attention and social science research.

Emissions from agricultural tractors have a detrimental impact on health and the environment. Stricter emission standards have resulted in great reductions in emissions from new vehicles. However, the long life time of tractors means that emissions from older vehicles remain substantial. One way to reduce these emissions is to retrofit catalytic converters, but the manufacture and use of catalytic converters consumes resources and slightly reduces engine efficiency. Life cycle assessment (LCA) can be used to determine their full environmental impact. This study considered three after-treatment options: no retrofit; a diesel oxidation catalyst (DOC)/diesel particulate filter (DPF) system; and a selective catalytic reduction (SCR) catalytic converter. Two vehicle usage patterns were considered, one following the legal test cycle (used for all off-road vehicles) and one corresponding to average agricultural tractor usage. With most of the assessment methods used in LCA, the impact change was small and totally dominated by changes in tractor emissions. All assessment methods gave the SCR catalytic converter a better value than the DOC/DPF system. The DOC/DPF system decreased the impact on human health, while the SCR catalytic converter decreased the acidification and eutrophication impact. Both catalytic converter increased abiotic resource consumption substantially. The legal test cycle produced similar results to the agricultural tractor usage cycle.

Biomass produced on farm land is a renewable fuel that can prove suitable for small-scale combined heat and power (CHP) plants in rural areas. However, it can still be questioned if biomass-based energy generation is a good environmental choice with regards to the impact on greenhouse gas emissions, and if there are negative consequences of using of agricultural land for other purposes than food production. In this study, a simplified life cycle assessment (LCA) was conducted over four scenarios for supply of the entire demand of power and heat of a rural village. Three of the scenarios are based on utilization of biomass in 100 kW (e) combined heat and power (CHP) systems and the fourth is based on fossil fuel in a large-scale plant. The biomass systems analyzed were based on 1) biogas production with ley as substrate and the biogas combusted in a microturbine, 2) gasification of willow chips and the product gas combusted in an IC-engine and 3) combustion of willow chips for a Stirling engine. The two first scenarios also require a straw boiler. The results show that the biomass-based scenarios reduce greenhouse gas emissions considerably compared to the scenario based on fossil fuel, but have higher acidifying emissions. Scenario 1 has by far the best performance with respect to global warming potential and the advantage of utilizing a byproduct and thus not occupying extra land. Scenario 2 and 3 require less primary energy and less fossil energy input than 1, but set-aside land for willow production must be available. The low electric efficiency of scenario 3 makes it an unsuitable option.

The robust H2 norm plays an important role in analysis and design in many fields. However, for many practical applications, design and analysis is based on finite frequency range. In this paper we review the concept of the robust finite frequency H2 norm, and we provide an algorithmic method for calculating an upper bound for the mentioned quantity.

The agricultural industry today consumes large amounts of fossil fuels. This study used consequential life cycle assessment (LCA) to analyse two potential energy self-sufficient systems for organic arable farms, based on agricultural residues. The analysis focused on energy balance, resource use and greenhouse gas (GHG) emissions. A scenario based on straw was found to require straw harvest from 25% of the farm area; 45% of the total energy produced from the straw was required for energy carrier production and GHG emissions were reduced by 9% compared with a fossil fuel-based reference scenario. In a scenario based on anaerobic digestion of ley, the corresponding figures were 13%, 24% and 35%. The final result was sensitive to assumptions regarding, e.g., soil carbon content and handling of by-products.

The task of generating time optimal trajectories for a six degrees of freedom industrial robot is discussed and an existing convex optimization formulation of the problem is extended to include new types of constraints. The new constraints are speed dependent and can be motivated from physical modeling of the motors and the drive system. It is shown how the speed dependent constraints should be added in order to keep the convexity of the overall problem. A method to, conservatively, approximate the linear speed dependent constraints by a convex constraint is also proposed. A numerical example proves versatility of the extension proposed in this paper. Vinnova's Industry Excellence Center LINK-SIC at Linköoping University

The demand for biofuel pellets has increased considerably in recent years, causing shortage of the traditional raw materials sawdust and wood shavings. In this study, the costs and energy requirements for the production of pellets from agricultural raw materials were analysed. The materials studied were Salix, reed canary grass, hemp, straw, screenings, rape-seed meal, rape cake and distiller’s waste. Four production scales were analysed, having an annual output of 80,000, 8000, 800 and 80 tonnes of pellets per year. It was concluded that the raw materials of greatest interest were Salix and reed canary grass. They had competitive raw material costs and acceptable fuel properties and could be mixed with sawdust in existing large-scale pelleting factories. Straw had low production costs but can cause serious ash-related problems and should, as also is the case for screenings, be avoided in small-scale burners. Hemp had high raw material costs and is of less commercial interest, while distiller’s waste, rape-seed meal and rape cake had higher alternative values when used as protein feed. The scale of production had a crucial influence on production costs. The machinery was used much more efficiently in large-scale plants, resulting in clear cost savings. Small-scale pelleting, both static and mobile, required cheap raw materials, low labour costs and long utilisation times to be profitable. In most cases, briquetting would be more commercially viable. The energy use in manufacturing pellets from air-dried crops was generally no higher than when moist sawdust was used as the raw material.

Swedish Environmental Class One (MK1) diesel fuel and three diesel substitutes were compared during steady state conditions, during transients and during work operations commonly performed by tractors and construction equipment. This was carried out in order to determine how fuel, typical engine load/speed and transient effects influence emissions and engine efficiency during common work operations. The results showed that the differences between the fuels were small, except for particulates. Differences in typical engine load/speed and transients effects could; however, cause emissions to vary between 0.5 and 3 times those expected from the current (steady state) ISO 8178C1 cycle, whilst the fuel consumption was only moderately affected. Transient effects appeared to be able to double the emissions.

Semi-autonomous operation with shared control between the human operator and control computer has been developed and examinedfor a large-scalemanipulator for gripping and lifting heavy objects in u ...