Engineering,nutrient removal,and feedstock conversion evaluations of four corn stover harvest scenarios

Crop residue has been identified as a near-term source of biomass for renewable fuel, heat, power, chemicals and other bio-materials. A prototype one-pass harvest system was used to collect residue samples from a corn (Zea mays L.) field near Ames, IA. Four harvest scenarios (low cut, high-cut top, high-cut bottom, and normal cut) were evaluated and are expressed as collected stover harvest indices (CSHI). High-cut top and high-cut bottom samples were obtained from the same plot in separate operations. Chemical composition, dilute acid pretreatment response, ethanol conversion yield and efficiency, and thermochemical conversion for each scenario were determined. Mean grain yield in this study (10.1 Mg ha⁻¹ dry weight) was representative of the average yield (10.0 Mg ha⁻¹) for the area (Story County, IA) and year (2005). The four harvest scenarios removed 6.7, 4.9, 1.7, and 5.1 Mg ha⁻¹ of dry matter, respectively, or 0.60 for low cut, 0.66 for normal cut, and 0.61 for the total high-cut (top+bottom) scenarios when expressed as CSHI values. The macro-nutrient replacement value for the normal harvest scenario was $57.36 ha⁻¹ or $11.27 Mg⁻¹. Harvesting stalk bottoms increased stover water content, risk of combine damage, estimated transportation costs, and left insufficient soil cover, while also producing a problematic feedstock. These preliminary results indicate harvesting stover (including the cobs) at a height of approximately 40 cm would be best for farmers and ethanol producers because of faster harvest speed and higher quality ethanol feedstock.     

Exploration of regional and global cost–supply curves of biomass energy from short-rotation crops at abandoned cropland and rest land under four IPCC SRES land-use scenarios

We explored the production cost of energy crops at abandoned agricultural land and at rest land at a regional and a global level to the year 2050 using four different land-use scenarios. The estimations were based on grid cell data on the productivity of short-rotation crops on the available land over time and assumptions regarding the capital and the labour input required to reach these productivity levels. It was concluded that large amounts of grown biomass at abandoned agricultural land and rest land, 130–270 EJ yr^?1 (about 40–70% of the present energy consumption) may be produced at costs below $2 GJ^?1 by 2050 (present lower limit of cost of coal). Interesting regions because of their low production cost and significant potentials are the Former USSR, Oceania, Eastern and Western Africa and East Asia. Such low costs presume significant land productivity improvements over time and cost reductions due to learning and capital-labour substitution. An assessment of biomass fuel cost, using the primary biomass energy costs, showed that the future costs of biomass liquid fuels may be in the same order of the present diesel production costs, although this may change in the long term. Biomass-derived electricity costs are at present slightly higher than electricity baseload costs and may directly compete with estimated future production costs of fossil fuel electricity with CO₂ sequestration. The present world electricity consumption of around 20 PWh yr^?1 may be generated in 2050 at costs below $45 MWh^?1 in A1 and B1 and below $55 MWh^?1 in A2 and B2. At costs of $60 MWh^?1, about 18 (A2) to 53 (A1) PWh yr^?1 can be produced.     

The potential biomass for energy production in the Czech Republic

Biomass production is a promising alternative for the Czech Republic's (CZ) agricultural sector. Biomass could cover the domestic bio-energy demand of 250 PJ a⁻¹ (predicted for 2030), and could be exported as bio-fuels to other EU countries. This study assesses the CZ's biomass production potential on a regional level and provides cost–supply curves for biomass from energy crops and agricultural and forestry residues. Agricultural productivity and the amount of land available for energy crop production are key variables in determining biomass potentials. Six scenarios for 2030 with different crop-yield levels, feed conversion efficiencies and land allocation procedures were built. The demand for food and fodder production was derived from FAO predictions for 2030. Biomass potential in the CZ is mainly determined by the development of food and fodder crop yields because the amount of land available for energy crop production increases with increasing productivity of food and fodder crops. In most scenarios the NUTS-3 regions CZ020, 31 and 32 provided the most land for energy-crop production and the highest biomass potentials. About 110 PJ a⁻¹, mostly from agricultural and forestry residues, can be provided from biomass when the present Czech agricultural productivity is maintained. About 195 PJ a⁻¹ (105 PJ from energy crops) can be provided when production systems are optimised with regard to fertilizer regimes and 365 PJ a⁻¹ (290 PJ from energy crops) when the yield level of Dutch agriculture is reached. Costs for woody biomass decrease with increasing plantation yield and range between 2.58 and 4.76 € GJ⁻¹. It was concluded that Czech agriculture could provide enough biomass for domestic demand and for export if agricultural productivity is increased.     

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.     

Bioenergy technologies for carbon abatement

In this paper, bioenergy technologies (BETs) are presented as potential carbon abatement opportunities substituting fossil fuel or traditional (less efficient) biomass energy systems. Cost of energy (produced or saved) of BETs is compared with fossil fuel and traditional biomass energy systems to estimate the incremental cost (IC). The IC of carbon abatement for each of the selected BETs (in $ kWh⁻¹ or $ GJ⁻¹) is estimated using the carbon emission (tC kWh⁻¹ or tC GJ⁻¹) reduction obtained by substituting fossil fuel and traditional biomass alternatives. The abatement costs are estimated and compared for ten combinations of BETs (with seven technology alternatives) substituting conventional technologies. The analysis indicates that out of the ten project cases six have negative ICs in the range of −37 to −688 $ tC⁻¹ and four have positive ICs in the range of 52–162 $ tC⁻¹ mitigation. The negative ICs indicate that the suggested alternatives are cheaper than the original technologies. Thus, results indicate that the chosen BETs are cost-effective mitigation opportunities and are currently aggressive candidates under Clean Development Mechanism.     

Contribution of renewable energy sources to electricity production in the La Rioja Autonomous Community,Spain. A review

The implementation of the emissions market should imbue renewable energies with a greater degree of competitiveness regarding conventional generation. In order to comply with the Kyoto protocol, utilities are going to begin to factor in the cost of CO₂ (environmental costs) in their overall generating costs, whereby there will be an increase in the marginal prices of the electricity pool.This article reviews the progress made in the La Rioja Autonomous Community (LRAC) in terms of the introduction of renewable energy technologies since 1996, where renewable energy represents approximately only 10% of the final energy consumption of the LRAC. Nonetheless, the expected exploitation of renewable energies and the recent implementation of a combined cycle facility mean that the electricity scenario in La Rioja will undergo spectacular change over the coming years: we examine the possibility of meeting a target of practical electrical self-sufficiency by 2010.In 2004, power consumption amounted to 1494 GWh, with an installed power of 1029.0 MW of electricity. By 2010, the Arrúbal combined cycle facility will produce around 9600 GWh/year, thereby providing a power generation output in La Rioja of close to 2044.7 MW, which will involve almost doubling the present output, and multiplying by 8.9 that recorded in this Autonomous Community in 2001.     

Farm-scale bio-power-to-methane: Comparative analyses of economic and environmental feasibility

Power-to-gas technologies are considered to be part of the future energy system, but their viability and applicability need to be assessed. Therefore, models for the viability of farm-scale bio-power-to-methane supply chains to produce green gas were analysed in terms of levelised cost of energy, energy efficiency and saving of greenhouse gas emission. In bio-power-to-methane, hydrogen from electrolysis driven by surplus renewable electricity and carbon dioxide from biogas are converted to methane by microbes in an ex situ trickle-bed reactor. Such bio-methanation could replace the current upgrading of biogas to green gas with membrane technology. Four scenarios were compared: a reference scenario without bio-methanation (A), bio-methanation (B), bio-methanation combined with membrane upgrading (C) and the latter with use of renewable energy only (all-green; D). The reference scenario (A) has the lowest costs for green gas production, but the bio-methanation scenarios (B-D) have higher energy efficiencies and environmental benefits. The higher costs of the bio-methanation scenarios are largely due to electrolysis, whereas the environmental benefits are due to the use of renewable electricity. Only the all-green scenario (D) meets the 2026 EU goal of 80% reduction of greenhouse gas emissions, but it would require a CO₂ price of 200 € t⁻¹ to achieve the levelised cost of energy of 65 €ct Nm⁻³ of the reference scenario. Inclusion of the intermittency of renewable energy in the scenarios substantially increases the costs. Further greening of the bio-methanation supply chain and how intermittency is best taken into account need further investigation.     

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.     

An analysis of long-term scenarios for the transition to renewable energy in the Korean electricity sector

This paper analyzes the energy, environmental and economic influences of three electricity scenarios in Korea by 2050 using the “Long-range Energy Alternatives Planning system” (LEAP) model. The reference year was 2008. Scenarios include the baseline (BL), new governmental policy (GP) and sustainable society (SS) scenarios. The growth rate of electricity demand in the GP scenario was higher than that of the BL scenario while the growth rate in the SS scenario was lower than that of the BL scenario.Greenhouse gas emissions from electricity generation in 2050 in the BL and GP scenarios were similar with current emissions. However, emissions in 2050 in the SS scenario were about 80% lower than emissions in 2008, because of the expansion of renewable electricity in spite of the phase-out of nuclear energy.While nuclear and coal-fired power plants accounted for most of the electricity generated in the BL and GP scenarios in 2050, the SS scenario projected that renewable energy would generate the most electricity in 2050. It was found that the discounted cumulative costs from 2009 to 2050 in the SS scenario would be 20 and 10% higher than that of the BL and GP scenarios, respectively.     

Management alternatives of energy wood thinning stands

Energy wood thinning has become a feasible treatment alternative of young stands in Finland. Energy wood thinnings have been carried out mainly in stands where precommercial thinning has been neglected and the harvesting conditions for industrial wood thinning are difficult. Despite of its positive effects on harvesting costs and on renewable energy potential, whole-tree harvesting has been constantly criticized for causing growth loss. In this paper, the profitability of energy wood thinning was studied in 20 Scots pine-dominated stands where energy wood thinning was carried out. The growth of the stands after thinning was predicted with the help of Motti-stand simulator. Entire rotation time of the stands was simulated with different management alternatives. The intensity of first thinning and recovery level of logging residues varied between alternatives. In order to attain acceptable harvesting conditions, industrial wood thinning had to be delayed. The effect of energy wood thinning on subsequent stem wood growth was almost the same as in conventional thinning. Whole-tree harvesting for energy proved to be profitable alternative if the stumpage price is around 3€ m⁻³, the interest rate is 3% or 5% and the removal of pulpwood is less than 20 m³ ha⁻¹. If the harvestable pulpwood yield is over 20 m³ ha⁻¹, integrated harvesting of industrial and energy wood or delayed industrial wood harvesting becomes more profitable.     

Strategic Eurasian natural gas market model for energy security and policy analysis: Formulation and application to South Stream

The mathematical formulation of a strategic Eurasian natural gas market model is presented. The model represents horizontal oligopolistic relationships among producers, bilateral market power between producer (Russia) and transit (Ukraine) countries, detailed transport constraints, and operation decisions over a 20 year time horizon. To demonstrate the model's capabilities, a financial and market analysis of the proposed South Stream gas pipeline from Russia via the Black Sea to South Europe is summarized. Insights obtained include the following. First, expectations of high demand growth in Europe and/or transit risks do not justify the construction of the South Stream pipeline because under all demand and Ukraine transit interruption scenarios, the net benefits to the South Stream participants are negative (the NPV ranges from − $1.9 billion (bn) to − $7.4 bn). Second, Ukraine's perception of high transit market power vis-à-vis Russia may trigger the construction of the otherwise unprofitable South Stream project. Thus, under Ukraine's high transit market power scenario, the NPV of South Stream ranges between $2.4 bn and $24.5 bn. Third, we find that the South Stream investment increases the efficiency of the European gas market under the following conditions: (i) when gas demand in Europe grows 2% per year up to 2030, (ii) when Ukraine poses high transit market power, or (iii) under a combination of severe transit risks through Ukraine and low demand scenarios in Europe. It should be noted that the value of South Stream to both its project sponsors and the market as a whole is much higher when Ukraine exercises transit market power than under the high demand scenario. Therefore, whether Ukraine is likely to wield market power is crucial to the success of the South Stream project because that is the only scenario in which the project yields both a positive expected NPV to its sponsors and the highest value to the market as a whole.     

Evaluating the impact of three incentive programs on the economics of cofiring willow biomass with coal in New York State

Plantations of fast-growing willow shrubs are being promoted as a source quality biomass feedstock for bioenergy and bioproducts in New York State (NY). In the near-term, cofiring of the feedstock—in combination with other woody biomass—with coal in existing utility power boilers is considered to be the most promising conversion method for energy generation. Despite the clear technological viability and associated environmental benefits, cofiring of willow has not been widely adopted. The relatively high production cost of the willow feedstock, which is over twice that of coal, is the primary reason for this lack of interest. Taxes that account for some of the social costs of using coal and/or incentives that appropriate value for some of the social benefits of using willow are essential for eliminating most or the entire current price differential. This paper presents an integrated analysis of the economics of power generation from cofiring willow biomass feedstock with coal, from the perspective of the grower, aggregator and the power plant. Emphasis is placed on analyzing the relative impact of a green premium price, a closed-loop biomass tax credit, and payments to growers under the proposed Conservation Reserve Program (CRP) harvesting exemption policy. The CRP payments reduced the delivered cost of willow by 36–35%, to $1.90 GJ⁻¹ and $1.70 GJ⁻¹, under current and increased yield conditions, respectively. These prices are still high, relative to coal. Other incentives are required to ensure commercial viability. The required levels of green premium price (0.4–1.0 cents kWh⁻¹) and biomass tax credit (0.75–2.4 cents kWh⁻¹) vary depending on whether the incentives were being applied by themselves or in combination, and whether current yield or potential increased yields were being considered. In the near term, cofiring willow biomass and coal can be an economically viable option for power generation in NY if the expected overall beneficial effects associated with the production and use of the biomass is accounted for.     

Forest treatment residues for thermal energy compared with disposal by onsite burning: Emissions and energy return

Mill residues from forest industries are the source for most of the current wood-based energy in the US, approximately 2.1% of the nation's energy use in 2007. Forest residues from silvicultural treatments, which include limbs, tops, and small non-commercial trees removed for various forest management objectives, represent an additional source of woody biomass for energy. We spatially analyzed collecting, grinding, and hauling forest residue biomass on a 515,900 ha area in western Montana, US, to compare the total emissions of burning forest residues in a boiler for thermal energy with the alternatives of onsite disposal by pile-burning and using either natural gas or #2 distillate oil to produce the equivalent amount of useable energy. When compared to the pile-burn/fossil fuel alternatives, carbon dioxide emissions from the bioenergy alternative were approximately 60%, methane emissions were approximately 3%, and particulate emissions less than 10 μm were 11% and 41%, respectively, for emission control and no-control boilers. Emissions from diesel consumption for collecting, grinding, and hauling biomass represented less than 5% of the total bioenergy emissions at an average haul distance of 136 km. Across the study area, an average 21 units of bioenergy were produced for each unit of diesel energy used to collect, grind, and haul biomass. Fossil fuel energy saved by the bioenergy alternative relative to the pile-burn/fossil fuel alternatives averaged 14.7–15.2 GJ t^?1 of biomass.     

The impact of sustainability criteria on the costs and potentials of bioenergy production – Applied for case studies in Brazil and Ukraine

The goal of this paper is to analyse the impact of the implementation of a certification system on the management system (costs) of and the availability of land (quantity) for bioenergy production. Twelve socio-economic areas of concern (food supply, child labour, (minimum) wages, employment, health care and education) and environmental areas of concern (soil erosion, depletion of fresh water resources, nutrient losses and soil nutrient depletion, pollution from chemicals and biodiversity) are included. Since there is no generally accepted definition of sustainability, a loose and strict set of criteria are defined. Short rotation coppice (SRC) production systems in Ukraine and South East Brazil in 2015 are taken as case studies. The results indicate that it seems feasible to produce biomass for energy purposes at reasonable cost levels and meeting strict sustainability criteria at the same time. The loose set of criteria has no impact on the costs of energy crop production, which are calculated to be 1.7 € GJ^?1 in Brazil and 2.1 € GJ^?1 in Ukraine. The strict set of criteria results in an increase of the costs of energy crop production by 42 % in Brazil and 14 % in Ukraine. In general, compliance with strict socio-economic criteria has a limited impact on the costs, because SRC is relatively labour extensive. Strict environmental criteria likely have a larger impact.     

Net carbon dioxide emissions from alternative firewood-production systems in Australia

The use of firewood for domestic heating has the potential to reduce fossil-fuel use and associated CO₂ emissions. The level of possible reductions depends upon the extent to which firewood off-sets the use of fossil fuels, the efficiency with which wood is burnt, and use of fossil fuels for collection and transport of firewood. Plantations grown for firewood also have a cost of emissions associated with their establishment. Applying the FullCAM model and additional calculations, these factors were examined for various management scenarios under three contrasting firewood production systems (native woodland, sustainably managed native forest, and newly established plantations) in low-medium rainfall (600–800 mm) regions of south-eastern Australia. Estimates of carbon dioxide emissions per unit of heat energy produced for all scenarios were lower than for non-renewable energy sources (which generally emit about 0.3–1.0 kg CO₂ kWh⁻¹). Amongst the scenarios, emissions were greatest when wood was periodically collected from dead wood in woodlands (0.11 kg CO₂ kWh⁻¹), and was much lower when obtained from harvest residues and dead wood in native forests (<0.03 kg CO₂ kWh⁻¹). When wood was obtained from plantations established on previously cleared agricultural land, use of firewood led to carbon sequestration equivalent to −0.06 kg CO₂ kWh⁻¹ for firewood obtained from a coppiced plantation, and −0.17 kg CO₂ kWh⁻¹ for firewood collected from thinnings, slash and other residue in a plantation grown for sawlog production. An uncertainty analysis, where inputs and assumptions were varied in relation to a plausible range of management practices, identified the most important influencing factors and an expected range in predicted net amount of CO₂ emitted per unit of heat energy produced from burning firewood.     

European biomass resource potential and costs

The objective of this study is to assess the European (EU27⁺ and Ukraine) cost and supply potential for biomass resources. Three methodological steps can be distinguished (partly based on studies explained elsewhere in this volume) (i) an evaluation of the available ‘surplus’ land, (ii) a modeled productivity and (iii) an economic assessment for 13 typical bioenergy crops. Results indicate that the total available land for bioenergy crop production – following a ‘food first’ paradigm – could amount to 900 000 km² by 2030. Three scenarios were constructed that take into account different development directions and rates of change, mainly for the agricultural productivity of food production. Feedstock supply of dedicated bioenergy crop estimates varies between 1.7 and 12.8 EJ y^?1. In addition, agricultural residues and forestry residues can potentially add to this 3.1–3.9 EJ y^?1 and 1.4–5.4 EJ y^?1 respectively. First generation feedstock supply is available at production costs of 5–15 € GJ^?1 compared to 1.5–4.5 € GJ^?1 for second generation feedstocks. Costs for agricultural residues are 1–7 € GJ^?1 and forestry residues 2–4 € GJ^?1. Large variation exists in biomass production potential and costs between European regions, 280 (NUTS2) regions specified. Regions that stand out with respect to high potential and low costs are large parts of Poland, the Baltic States, Romania, Bulgaria and Ukraine. In Western Europe, France, Spain and Italy are moderately attractive following the low cost high potential criterion.     

Techno-economic analysis of fuel cell auxiliary power units as alternative to idling

This paper presents a techno-economic analysis of fuel-cell-based auxiliary power units (APUs), with emphasis on applications in the trucking industry and the military. The APU system is intended to reduce the need for discretionary idling of diesel engines or gas turbines. The analysis considers the options for on-board fuel processing of diesel and compares the two leading fuel cell contenders for automotive APU applications: proton exchange membrane fuel cell and solid oxide fuel cell. As options for on-board diesel reforming, partial oxidation and auto-thermal reforming are considered. Finally, using estimated and projected efficiency data, fuel consumption patterns, capital investment, and operating costs of fuel-cell APUs, an economic evaluation of diesel-based APUs is presented, with emphasis on break-even periods as a function of fuel cost, investment cost, idling time, and idling efficiency. The analysis shows that within the range of parameters studied, there are many conditions where deployment of an SOFC-based APU is economically viable. Our analysis indicates that at an APU system cost of $ 100 kW⁻¹, the economic break-even period is within 1 year for almost the entire range of conditions. At $ 500 kW⁻¹ investment cost, a 2-year break-even period is possible except for the lowest end of the fuel consumption range considered. However, if the APU investment cost is $ 3000 kW⁻¹, break-even would only be possible at the highest fuel consumption scenarios. For Abram tanks, even at typical land delivered fuel costs, a 2-year break-even period is possible for APU investment costs as high as $ 1100 kW⁻¹.     

Climate policy scenarios in Brazil: A multi-model comparison for energy

This paper assesses the effects of market-based mechanisms and carbon emission restrictions on the Brazilian energy system by comparing the results of six different energy-economic or integrated assessment models under different scenarios for carbon taxes and abatement targets up to 2050. Results show an increase over time in emissions in the baseline scenarios due, largely, to higher penetration of natural gas and coal. Climate policy scenarios, however, indicate that such a pathway can be avoided. While taxes up to 32 US$/tCO₂e do not significantly reduce emissions, higher taxes (from 50 US$/tCO₂e in 2020 to 16 2US$/tCO₂e in 2050) induce average emission reductions around 60% when compared to the baseline. Emission constraint scenarios yield even lower reductions in most models. Emission reductions are mostly due to lower energy consumption, increased penetration of renewable energy (especially biomass and wind) and of carbon capture and storage technologies for fossil and/or biomass fuels. This paper also provides a discussion of specific issues related to mitigation alternatives in Brazil. The range of mitigation options resulting from the model runs generally falls within the limits found for specific energy sources in the country, although infrastructure investments and technology improvements are needed for the projected mitigation scenarios to achieve actual feasibility.     

High-temperature steam electrolysis: Technical and economic evaluation of alternative process designs

A high-temperature water-vapor electrolysis (HTE) unit operating at an average temperature of 1000°C was integrated into a preliminary process design using electrical and thermal energy derived from coal. Process variations with either steam or water feeds under isothermal or nonisothermal HTE operation were considered. Operating and capital costs were estimated for each process flowsheet, with the lowest costs being obtained for operation with high steam conversions in the electrolyzer. Estimated H₂ production costs were compared with estimates obtained from the literature for other H₂ production processes. The estimated HTE H₂ production costs ranged from $0.17 to $0.22 standard m⁻³ H₂ produced ($13–17 GJ⁻¹, using the higher heating value), assuming $1.90 GJ⁻¹ for thermal energy and $13.90 GJ⁻¹ for electrical energy.     

Environmental and economic assessment of landfill gas electricity generation in Korea using LEAP model

As a measure to establish a climate-friendly energy system, Korean government has proposed to expand landfill gas (LFG) electricity generation capacity. The purpose of this paper is to analyze the impacts of LFG electricity generation on the energy market, the cost of generating electricity and greenhouse gases emissions in Korea using a computer-based software tool called ‘Long-range Energy Alternative Planning system’ (LEAP) and the associated ‘Technology and Environmental Database’. In order to compare LFG electricity generation with existing other generating facilities, business as usual scenario of existing power plants was surveyed, and then alternative scenario investigations were performed using LEAP model. Different alternative scenarios were considered, namely the base case with existing electricity facilities, technological improvement of gas engine and LFG maximum utilization potential with different options of gas engine (GE), gas turbine (GT), and steam turbine (ST). In the technological improvement scenario, there will be 2.86 GWh or more increase in electricity output, decrease of 45 million won (Exchange rate (1$=1200 won)). in costs, and increase of 10.3 thousand ton of CO₂ in global warming potentials due to same period (5 year) of technological improvement. In the maximum utilization potential scenario, LFG electricity generation technology is substituted for coal steam, nuclear, and combined cycle process. Annual cost per electricity product of LFG electricity facilities (GE 58MW, GT 53.5MW, and ST 54.5MW) are 45.1, 34.3, and 24.4 won/kWh, and steam turbine process is cost-saving. LFG-utilization with other forms of energy utilization reduces global warming potential by maximum 75% with compared to spontaneous emission of CH₄. LFG electricity generation would be the good solution for CO₂ displacement over the medium term and additional energy profits.