Reducing life cycle greenhouse gas emissions of corn ethanol by integrating biomass to produce heat and power at ethanol plants

A life-cycle assessment (LCA) of corn ethanol was conducted to determine the reduction in the life-cycle greenhouse gas (GHG) emissions for corn ethanol compared to gasoline by integrating biomass fuels to replace fossil fuels (natural gas and grid electricity) in a U.S. Midwest dry-grind corn ethanol plant producing 0.19 hm³ y⁻¹ of denatured ethanol. The biomass fuels studied are corn stover and ethanol co-products [dried distillers grains with solubles (DDGS), and syrup (solubles portion of DDGS)]. The biomass conversion technologies/systems considered are process heat (PH) only systems, combined heat and power (CHP) systems, and biomass integrated gasification combined cycle (BIGCC) systems. The life-cycle GHG emission reduction for corn ethanol compared to gasoline is 38.9% for PH with natural gas, 57.7% for PH with corn stover, 79.1% for CHP with corn stover, 78.2% for IGCC with natural gas, 119.0% for BIGCC with corn stover, and 111.4% for BIGCC with syrup and stover. These GHG emission estimates do not include indirect land use change effects. GHG emission reductions for CHP, IGCC, and BIGCC include power sent to the grid which replaces electricity from coal. BIGCC results in greater reductions in GHG emissions than IGCC with natural gas because biomass is substituted for fossil fuels. In addition, underground sequestration of CO₂ gas from the ethanol plant’s fermentation tank could further reduce the life-cycle GHG emission for corn ethanol by 32% compared to gasoline.     

Life cycle assessment of electricity generation using fast pyrolysis bio-oil

Biomass is expected to become an important energy source in U.S. electricity generation under state-lead renewable portfolio standards. This paper investigated the greenhouse gas (GHG) emissions for energy generated from forest resources through pyrolysis-based processing. The GHG emissions of producing pyrolysis bio-oil (pyrolysis oil) from different forest resources were first investigated; logging residues collected from natural regeneration mixed hardwood stands, hybrid poplar cultivated and harvested from abandoned agricultural lands, short rotation forestry (SRF) willow plantations and waste wood available at the site of the pyrolysis plant. Effects of biomass transportation were investigated through a range of distances to a central pyrolysis facility through road transport by semi-truck. Pyrolysis oil is assumed to be converted to electrical power through co-combustion in conventional fossil fuels power plants, gas turbine combined cycle (GTCC) and diesel generators. Life cycle GHG emissions were compared with power generated using fossil fuels and power generated using biomass direct combustion in a conventional Rankine power plant. Life cycle GHG savings of 77%–99% were estimated for power generation from pyrolysis oil combustion relative to fossil fuels combustion, depending on the biomass feedstock and combustion technologies used. Several scenario analyses were conducted to determine effects of pyrolysis oil transportation distance, N-fertilizer inputs to energy crop plantations, and assumed electricity mixes for pyrolysis oil production.     

The economical and environmental performance of miscanthus and switchgrass production and supply chains in a European setting

The purpose of this study is to analyse the economical and environmental performance of switchgrass and miscanthus production and supply chains in the European Union (EU25), for the years 2004 and 2030. The environmental performance refers to the greenhouse gas (GHG) emissions, the primary fossil energy use and to the impact on fresh water reserves, soil erosion and biodiversity. Analyses are carried out for regions in five countries. The lowest costs of producing (including storing and transporting across 100 km) in the year 2004 are calculated for Poland, Hungary and Lithuania at 43–64 € per oven dry tonne (odt) or 2.4–3.6 € GJ^?1 higher heating value. This cost level is roughly equivalent to the price of natural gas (3.1 € GJ^?1) and lower than the price of crude oil (4.6 € GJ^?1) in 2004, but higher than the price of coal (1.7 € GJ^?1) in 2004. The costs of biomass in Italy and the United Kingdom are somewhat higher (65–105 € odt^?1 or 3.6–5.8 € GJ^?1). The doubling of the price of crude oil and natural gas that is projected for the period 2004–2030, combined with nearly stable biomass production costs, makes the production of perennial grasses competitive with natural gas and fossil oil. The results also show that the substitution of fossil fuels by biomass from perennial grasses is a robust strategy to reduce fossil energy use and curb GHG emissions, provided that perennial grasses are grown on agricultural land (cropland or pastures). However, in such case deep percolation and runoff of water are reduced, which can lead to overexploitation of fresh water reservoirs. This can be avoided by selecting suitable locations (away from direct accessible fresh water reservoirs) and by limiting the size of the plantations. The impacts on biodiversity are generally favourable compared to conventional crops, but the location of the plantation compared to other vegetation types and the size and harvesting regime of the plantation are important variables.     

Biofuels and their potential to aid the UK towards achieving emissions reduction policy targets

The potential of biofuels contributing to the UK emission reduction targets in the formulated UK Low Carbon Transition Plan (LCTP) and the UK’s obligation in the wider EU emissions reduction targets are assessed using four scenarios. The scenarios were evaluated using hybrid lifecycle assessment developed in a multi-regional input–output (MRIO) framework. In the hybrid MRIO LCA framework, technology-specific processes in the biofuels and fossil fuels LCA systems are integrated into a generalised 2-region (UK and Rest of the World) environmental-economic input–output framework in order to account for economy-wide indirect GHG emissions in the biofuels and fossil fuels LCA systems in addition to other indirect impacts such as indirect land use change. The lifecycle greenhouse gas emissions of biodiesel (soybean, palm, rape, waste cooking oil) and bio-ethanol (sugarcane, sugarbeet, corn) were assessed and compared to fossil fuel (diesel and petrol) baseline. From one of the scenarios, biodiesel production from waste cooking oil and bioethanol from sugarbeet offer the biggest potential for emissions savings relative to fossil fuel equivalent and offering a maximum emission savings of 4.1% observed with a biofuel market share of 10% reached in 2020. It was also established that under current biofuel feedstock mix, to achieve the 6% emissions saving primarily from biofuels as proposed in the LCTP, 23.8% of the transport fuels market would be required to be held by biofuels by 2020.     

Addressing uncertainty in life-cycle carbon intensity in a national low-carbon fuel standard

Policies formulated to reduce greenhouse gas (GHG) emissions, such as a low-carbon fuel standard, frequently rely on life-cycle assessment (LCA) to estimate emissions, but LCA results are often highly uncertain. This study develops life-cycle models that quantitatively and qualitatively describe the uncertainty and variability in GHG emissions for both fossil fuels and ethanol and examines mechanisms to reduce those uncertainties in the policy process. Uncertainty regarding emissions from gasoline is non-negligible, with an estimated 90% confidence interval ranging from 84 to 100 g CO₂e/MJ. Emissions from biofuels have greater uncertainty. The widths of the 90% confidence intervals for corn and switchgrass ethanol are estimated to be on the order of 100 g CO₂e/MJ, and removing emissions from indirect land use change still leaves significant remaining uncertainty. Though an opt-in policy mechanism can reduce some uncertainty by incentivizing producers to self-report fuel production parameters, some important parameters, such as land use change emissions and nitrogen volatilization, cannot be accurately measured and self-reported. Low-carbon fuel policies should explicitly acknowledge, quantify, and incorporate uncertainty in life cycle emissions in order to more effectively achieve emissions reductions. Two complementary ways to incorporate this uncertainty in low carbon fuel policy design are presented.     

Evaluation of ecological impacts of synthetic natural gas from wood used in current heating and car systems

A promising option to substitute fossil energy carriers by renewables is the production of synthetic natural gas (SNG) from wood, as this results in a flexible energy carrier usable via existing infrastructure in gas boilers or passenger cars. The comprehensive life cycle-based ecological impact of SNG is investigated and compared with standard fuels delivering the same service (natural gas, fuel oil, petrol/diesel, and wood chips). Life cycle impact assessment methodologies and external costs from airborne emissions provide measures of overall damage. The results indicate that the SNG system has the best ecological performance if the consumption of fossil resources is strongly weighted. Otherwise natural gas performs best, as its supply chain is energy-efficient and its use produces relatively low emissions. Wood systems are by far the best in terms of greenhouse gas emissions (GHG), where SNG emits about twice as much as the wood chips system. The main negative aspects of the SNG system are NO_x and particulate emissions and the relatively low total energy conversion efficiency resulting from the additional processing to transform wood to gas. Direct wood combustion has a better ecological score when highly efficient particulate filters are installed. SNG performs better than oil derivatives with all the evaluation methods used. External costs for SNG are the lowest as long as GHG are valued high. SNG should preferably be used in cars, as the reduction of overall ecological impacts and external costs when substituting oil-based fuels is larger for current cars than for heating systems.     

EUBIONET III—Solutions to biomass trade and market barriers

The EUBIONET III project has boosted (i) sustainable, transparent international biomass fuel trade, (ii) investments in best practice technologies and (iii) new services on biomass heat sector. Furthermore, it identified cost-efficient and value-adding use of biomass for energy and industry. The aims of this article are to provide a synthesis of the key results of this project. Estimated annual solid biomass potential in the EU-27 is almost 6600 PJ (157 Mtoe), of which 48% is currently utilised. The greatest potential for increased use lies in forest residues and herbaceous biomass. Trade barriers have been evaluated and some solutions suggested such as CN codes for wood pellets and price indexes for industrial wood pellets and wood chips. The analysis of wood pellet and wood chip prices revealed large difference amongst EU countries, but also that on the short term prices of woody and fossil fuels are barely correlated. Sustainable production and use of solid biomass are also deemed important by most European stakeholders, and many support the introduction of harmonised sustainability criteria, albeit under a number of preconditions. The study identified also that a number of woody and agro-industrial residue streams remain un- or underutilised. The estimated European total potential of agro-industrial sources is more than 250 PJ (7.2 Mtoe), the amount of unutilised woody biomass (the annual increment of growing stock) even amounts to 3150 PJ (75 Mtoe). Finally 35 case studies of biomass heating substituting fossil fuels were carried out, showing that the potential to reduce GHG emissions ranges between 90 and 98%, while costs are very similar to fossil fuel heating systems. Overall, we conclude that solid biomass is growing strongly, and is likely to heavily contribute to the EU renewable energy targets in the coming decade.     

How certain are greenhouse gas reductions from bioenergy? Life cycle assessment and uncertainty analysis of wood pellet-to-electricity supply chains from forest residues

Climate change and energy policies often encourage bioenergy as a sustainable greenhouse gas (GHG) reduction option. Recent research has raised concerns about the climate change impacts of bioenergy as heterogeneous pathways of producing and converting biomass, indirect impacts, uncertainties within the bioenergy supply chains and evaluation methods generate large variation in emission profiles. This research examines the combustion of wood pellets from forest residues to generate electricity and considers uncertainties related to GHG emissions arising at different points within the supply chain. Different supply chain pathways were investigated by using life cycle assessment (LCA) to analyse the emissions and sensitivity analysis was used to identify the most significant factors influencing the overall GHG balance. The calculations showed in the best case results in GHG reductions of 83% compared to coal-fired electricity generation. When parameters such as different drying fuels, storage emission, dry matter losses and feedstock market changes were included the bioenergy emission profiles showed strong variation with up to 73% higher GHG emissions compared to coal. The impact of methane emissions during storage has shown to be particularly significant regarding uncertainty and increases in emissions. Investigation and management of losses and emissions during storage is therefore key to ensuring significant GHG reductions from biomass.     

Competition for the biomass resource: Greenhouse impacts and implications for renewable energy incentive schemes

In Australia, the Mandatory Renewable Energy Target (MRET) scheme, which targets a 9.5 TWh per annum increase in renewable electricity generation by 2010, is stimulating interest in bioenergy. Development of bioenergy projects may cause competition for biomass resources. For example, sawmill residues are an attractive feedstock for bioenergy, but are also utilised for particleboard manufacture. This study compares the greenhouse gas (GHG) mitigation impacts of alternative scenarios where sawmill residues are used either for generation of electricity or for manufacture of particleboard. The study considers a theoretical particleboard plant processing 100 kt feedstock of dry sawmill residues per annum. If the sawmill residues are used instead for bioenergy, and the particleboard plant utilises fresh plantation biomass, 205 kt CO₂eq emissions are displaced. However, GHG emissions for particleboard manufacture increase by about 38 kt CO₂eq, equivalent to 19% of the fossil fuel emissions displaced, due to the higher fossil fuel requirements to harvest, transport, chip and dry the green biomass. Also, plantation carbon stock declines by 147 kt CO₂eq per year until a new equilibrium is reached after 30 years. This result is influenced particularly by the fossil fuel displaced, the relative efficiency of the fossil fuel and bioenergy plants, the moisture content of the sawmill residues, and the efficiency of the dryer in the particleboard plant.Under MRET, calculation of Renewable Energy Certificates is based solely on the quantity of power generated. This study illustrates that indirect consequences can reduce the GHG mitigation benefits of a bioenergy project. Increased emissions off-site, and loss of forest carbon stock, should be considered in calculating the net GHG mitigation benefit, and this should determine the credit earned by a bioenergy project.     

Environmental aspects of ethanol derived from no-tilled corn grain: nonrenewable energy consumption and greenhouse gas emissions

Nonrenewable energy consumption and greenhouse gas (GHG) emissions associated with ethanol (a liquid fuel) derived from corn grain produced in selected counties in Illinois, Indiana, Iowa, Michigan, Minnesota, Ohio, and Wisconsin are presented. Corn is cultivated under no-tillage practice (without plowing). The system boundaries include corn production, ethanol production, and the end use of ethanol as a fuel in a midsize passenger car. The environmental burdens in multi-output biorefinery processes (e.g., corn dry milling and wet milling) are allocated to the ethanol product and its various coproducts by the system expansion allocation approach.The nonrenewable energy requirement for producing 1 kg of ethanol is approximately 13.4–21.5 MJ (based on lower heating value), depending on corn milling technologies employed. Thus, the net energy value of ethanol is positive; the energy consumed in ethanol production is less than the energy content of the ethanol (26.8 MJ kg⁻¹).In the GHG emissions analysis, nitrous oxide (N₂O) emissions from soil and soil organic carbon levels under corn cultivation in each county are estimated by the DAYCENT model. Carbon sequestration rates range from 377 to 681 kg C ha⁻¹ year⁻¹ and N₂O emissions from soil are 0.5–2.8 kg N ha⁻¹ year⁻¹ under no-till conditions. The GHG emissions assigned to 1 kg of ethanol are 260–922 g CO₂ eq. under no-tillage. Using ethanol (E85) fuel in a midsize passenger vehicle can reduce GHG emissions by 41–61% km⁻¹ driven, compared to gasoline-fueled vehicles. Using ethanol as a vehicle fuel, therefore, has the potential to reduce nonrenewable energy consumption and GHG emissions.     

Life cycle assessment (LCA) of an integrated biomass gasification combined cycle (IBGCC) with CO2 removal

Based on the results of previous studies, the efficiency of a Brayton/Hirn combined cycle fuelled with a clean syngas produced by means of biomass gasification and equipped with CO₂ removal by chemical absorption reached 33.94%, considering also the separate CO₂ compression process. The specific CO₂ emission of the power plant was 178 kg/MW h. In comparison with values previously found for an integrated coal gasification combined cycle (ICGCC) with upstream CO₂ chemical absorption (38–39% efficiency, 130 kg/MW h specific CO₂ emissions), this configuration seems to be attractive because of the possibility of operating with a simplified scheme and because of the possibility of using biomass in a more efficient way with respect to conventional systems. In this paper, a life cycle assessment (LCA) was conducted with presenting the results on the basis of the Eco-Indicator 95 impact assessment methodology. Further, a comparison with the results previously obtained for the LCA of the ICGCC was performed in order to highlight the environmental impact of biomass production with fossil fuels utilisation. The LCA shows the important environmental advantages of biomass utilisation in terms of reduction of both greenhouse gas emissions and natural resource depletion, although an improved impact assessment methodology may better highlight the advantages due to the biomass utilisation.     

An optimized process design for oxymethylene ether production from woody-biomass-derived syngas

The conversion of biomass for the production of liquid fuels can help reduce the greenhouse gas (GHG) emissions that are predominantly generated by the combustion of fossil fuels. Oxymethylene ethers (OMEs) are a series of liquid fuel additives that can be obtained from syngas, which is produced from the gasification of biomass. The blending of OMEs in conventional diesel fuel can reduce soot formation during combustion in a diesel engine. In this research, a process for the production of OMEs from woody biomass has been simulated. The process consists of several unit operations including biomass gasification, syngas cleanup, methanol production, and conversion of methanol to OMEs. The methodology involved the development of process models, the identification of the key process parameters affecting OME production based on the process model, and the development of an optimal process design for high OME yields. It was found that up to 9.02 tonnes day⁻¹ of OME₃, OME₄, and OME₅ (which are suitable as diesel additives) can be produced from 277.3 tonnes day⁻¹ of wet woody biomass. Furthermore, an optimal combination of the parameters, which was generated from the developed model, can greatly enhance OME production and thermodynamic efficiency. This model can further be used in a techno-economic assessment of the whole biomass conversion chain to produce OMEs. The results of this study can be helpful for petroleum-based fuel producers and policy makers in determining the most attractive pathways of converting bio-resources into liquid fuels.     

Planning for increased bioenergy use—Evaluating the impact on local air quality

The Swedish energy system is undergoing a transformation due to threats about climate change and political decisions to reduce green house gases and to phase out the nuclear power. The goal is to convert the energy system from a system based on fossil fuels and nuclear power to one based on renewable energy sources. Bioenergy is an available domestic, renewable, carbon dioxide neutral energy source and therefore an increase of the use is forecasted in the future. Studies have shown that bioenergy may cause negative impacts on human health and on the environment due to emissions to air. The aim of this study was to investigate how a future conversion to bioenergy-based heating affect the air quality in residential areas. The contribution of particulate matter (PM₁₀) and benzene from existing heating systems as well as from conversion from electrical heating and firewood boilers to pellets and small-scale district heating systems was investigated. The investigations included monitoring of energy need for heating, identifying suitable energy systems for conversion, identifying emission factors, dispersion calculations and application of the results in a geographical information system (GIS). The results show that conversion from electrical heating to pellets in the investigated areas does not affect the air quality. The GIS maps showed the expected concentrations caused by small-scale combustion of bioenergy-based fuels clearly. The dispersion pattern of the emitted gases and particulates was visualized and the maps can be used for planning purposes when dealing with new residential areas.     

A comparison of avoided greenhouse gas emissions when using different kinds of wood energy

In this study, micro-level data from wood energy producers in Hedmark County were gathered and analysed. The aim was to find how much greenhouse gas (GHG) emissions various kinds of wood energy cause (not only CO₂, but also CH₄ and N₂O), which energy they substitute, their potential to reduce GHG emissions, and the major sources of uncertainty. The method was life cycle assessment. Six types of wood energy were studied: fuel wood, sawdust, pellets, briquettes, demolition wood, and bark.GHG emissions over the life cycle of the wood energy types in this study are 2–19% of the emissions from a comparable source of energy. The lowest figure is for demolition wood substituting oil in large combustion facilities, the highest for fuel wood used in dwellings to substitute electricity produced by coal-based power plants.Avoided GHG emissions per m³ wood used for energy were from 0.210 to 0.640 tonne CO₂-equivalents. Related to GWh energy produced, avoided GHG emissions were from 250 to 360 tonne CO₂-equivalents. Avoided GHG emissions per tonne CO₂ in the wood are 0.28–0.70 tonne CO₂-equivalents. The most important factors were technology used for combustion, which energy that is substituted, densities, and heating values. Inputs concerning harvest, transport, and production of the wood energy are not important.Overall, taking the uncertainties into account there is not much difference in avoided GHG emissions for the different kinds of wood energy.     

A life cycle assessment of pennycress (Thlaspi arvense L.) -derived jet fuel and diesel

Field Pennycress (Thlaspi arvense L.) is a member of the mustard family and may be grown as a winter crop between traditional summer crops to produce renewable biomass for renewable diesel and jet fuel. This paper estimated total annual biofuel production potential of 15 million cubic metres from rotation between corn and soybeans on 16.2 million hectares in the Midwest without impact on food production. This study also investigated the life cycle greenhouse gas (GHG) emissions and energy balance of pennycress-derived Hydroprocessed Renewable Jet (HRJ) fuel and Renewable Diesel (RD). Both system expansion and allocation approaches were applied to distribute environmental impacts among products and co-products along the life cycle of each biofuel. The life cycle GHG emissions (excluding land use change) for RD and HRJ range from 13 to 41 g MJ⁻¹ (CO₂ eq.) and −18 to 45 g MJ⁻¹ (CO₂ eq.), respectively, depending on how the co-products are credited. The majority of the energy required for each biofuel product is derived from renewable biomass as opposed to non renewable fossil. The fossil energy consumptions are considerably lower than the petroleum fuels. Scenario analyses were also conducted to determine response to model assumptions, including nitrogen fertilizer application rate, nitrogen content in crop residues, and sources of H₂. The results show that pennycress derived biofuels could qualify as advanced biofuels and as biomass-based diesel as defined by the Renewable Fuels Standard (RFS2).     

Fossil fuels substitution by the solar energy utilization for the hot water production in the heating plant “Cerak” in Belgrade

The main objective of this paper is to evaluate energy and environmental benefits of the large-scale solar heating system connection with district heating system. The assessment of fossil fuels substitution by the solar energy for the hot water production for domestic use, during the summer period, is done. Hot water for district heating and domestic use is produced in heating plant “Cerak” placed in the suburb of Belgrade. The existing production and distribution system are based on fossil fuel energy, mainly on the natural gas. In the first phase of the project plan was to install about 10,000 m² of solar collectors to substitute nearly 25% of natural gas consumption. During the summer period, the saving of natural gas calculated for presented system is approximately 430,000 m³ and in this way 900 t of the CO₂ emissions would be reduced.     

Incorporating uncertainty analysis into life cycle estimates of greenhouse gas emissions from biomass production

Before further investments are made in utilizing biomass as a source of renewable energy, both policy makers and the energy industry need estimates of the net greenhouse gas (GHG) reductions expected from substituting biobased fuels for fossil fuels. Such GHG reductions depend greatly on how the biomass is cultivated, transported, processed, and converted into fuel or electricity. Any policy aiming to reduce GHGs with biomass-based energy must account for uncertainties in emissions at each stage of production, or else it risks yielding marginal reductions, if any, while potentially imposing great costs.This paper provides a framework for incorporating uncertainty analysis specifically into estimates of the life cycle GHG emissions from the production of biomass. We outline the sources of uncertainty, discuss the implications of uncertainty and variability on the limits of life cycle assessment (LCA) models, and provide a guide for practitioners to best practices in modeling these uncertainties. The suite of techniques described herein can be used to improve the understanding and the representation of the uncertainties associated with emissions estimates, thus enabling improved decision making with respect to the use of biomass for energy and fuel production.     

Life cycle assessment of hydrogen production from biomass gasification systems

In this study, a Life Cycle Assessment (LCA) of biomass-based hydrogen production is performed for a period from biomass production to the use of the produced hydrogen in Proton Exchange Membrane (PEM) fuel cell vehicles. The system considered is divided into three subsections as pre-treatment of biomass, hydrogen production plant and usage of hydrogen produced. Two different gasification systems, a Downdraft Gasifier (DG) and a Circulating Fluidized Bed Gasifier (CFBG), are considered and analyzed for hydrogen production using actual data taken from the literature. Fossil energy consumption rate and Green House Gas Emissions (GHG) are defined and indicated first. Next, the LCA results of DG and CFBG systems are compared for 1 MJ/s hydrogen production to compare with each other as well as with other hydrogen production systems. While the fossil energy consumption rate and emissions are calculated as 0.088 MJ/s and 6.27 CO₂ eqv. g/s in the DG system, they are 0.175 MJ/s and 17.13 CO₂ eqv. g/s in the CFBG system, respectively. The Coefficient of Hydrogen Production Performance (CHPP) (newly defined as a ratio of energy content of hydrogen produced from the system to the total energy content of fossil fuels used) of the CFBG and DG systems are then determined to be 5.71 and 11.36, respectively. Thus, the effects of some parameters, such as energy efficiency, ratio of cost of hydrogen, on natural gas and capital investments efficiency are investigated. Finally, the costs of GHG emissions reduction are calculated to be 0.0172 and 0.24 $/g for the DG and CFBG systems, respectively.     

Land use changes, greenhouse gas emissions and fossil fuel substitution of biofuels compared to bioelectricity production for electric cars in Austria

Bioenergy is one way of achieving the indicative target of 10% renewable energy in the transportation sector outlined in the EU Directive 2009/28/EC. This article assesses the consequences of increasing the use of bioenergy for road transportation on land use, greenhouse gas (GHG) emissions, and fossil fuel substitution. Different technologies, including first and second generation fuels and electric cars fuelled by bioelectricity are assessed in relation to existing bioenergy uses for heat and power production. The article applies a spatially explicit energy system model that is coupled with a land use optimization model to allow assessing impacts of increased biomass utilization for energy production on land use in agriculture and forest wood harvests. Uncertainty is explicitly assessed with Monte-Carlo simulations of model parameters. Results indicate that electric mobility could save GHG emissions without causing a significant increase in domestic land use for energy crop production. Costs of electric cars are still prohibitive. Second generation biofuels are more effective in producing fuels than first generation ethanol. However, competition with power and heat production from ligno-cellulosic feedstock causes an increase in GHG emissions when introducing second generation fuels in comparison to a baseline scenario.     

Keep that fire burning: Fuel supply risk management strategies of Swedish district heating plants and implications for energy security

Recent decades have seen a strong increase in bioenergy utilization in Sweden, from 52 TWh in 1983 to 128 TWh in 2013. Much of this increase has been achieved by replacing fossil fuels with different forms of bioenergy in district heating. Increased use of bioenergy is generally seen as key to reducing fossil fuel consumption and greenhouse gas emissions and improving energy security.However, replacing fossil fuels with solid biomass fuels in stationary heat and power generation entails significantly more complicated fuel supply logistics, with geographically scattered material associated with storage difficulties and low energy density. Given these risks and challenges and the key role of biomass-based district heating in the Swedish energy system, disturbances in fuel supply to district heating could potentially be an energy security issue.Through literature studies and interviews with employees at 18 district heating plants, we mapped present and future risks and risk management strategies in district heating supply in the Mälardalen region, south-east Sweden. We found that although small disturbances to fuel supply are not uncommon, the likelihood of heat supply failures due to fuel supply problems is low. Risk awareness is generally high among fuel supply managers, with widespread use of multilevel redundancies and diversification as key risk management strategies. However, fuel supply to plants is highly dependent on functioning truck transport and, consequently, availability of diesel fuel for trucks. Risk management can be strengthened further by implementation of forward-looking risk assessments that are less reliant on past experiences.