Logistics cost analysis of rice straw for biomass power generation in Thailand

The logistics of the fuel supply have a large impact on the economy of a biomass power generation facility, especially for low density biomass fuels like straw. A detailed cost analysis of a typical rice straw logistics process for two baling options in three regions of Thailand shows that the costs for all logistics operations vary from a minimum of 18.75 USD/t for small rectangular bales in the Northern region of Thailand to maximum 19.89 USD/t for large rectangular bales in the North-eastern region. The difference in costs is not very significant due to the higher ownership and operating costs of the equipment for using large rectangular bales; however, the specific fuel consumption cost is substantially lower by around 17.5% and a total transport cost reduction is about 31.5%. Analysis of the logistics economies of scale for projected power plant capacities of 2-35 MW_e showed that each doubling the capacity of the energy facility increases the specific costs of the logistics operations only by around 4% in all regions.     

Evaluation of two round baling systems for harvesting understory biomass

The objective of this study was to evaluate the performance and to estimate costs of two round baling systems for harvesting understory biomass. One system was a cutter-shredder-baler prototype (Bio-baler). The other system required two successive operations. The first operation was cutting and shredding with a Supertrak tractor equipped with a Fecon mulcher head. The second operation was baling with a Claas baler. The machines were evaluated in three different pine stands on the Osceola National Forest in Florida, United States. Data collection included time study, fuel consumption and bale measurements. Material was collected from a sample of bales for heat and moisture content determination. On the most representative site (Site 2), the Bio-baler recovered 8.05 green t ha⁻¹ while the mulcher and the Claas baler recovered 9.75 green t ha⁻¹ (43 and 52 percent of original understory biomass, respectively). Productivity was 0.30 ha h⁻¹ for the Bio-baler and 0.51 ha h⁻¹ for the Claas baler. Density of the bales was 321 green kg m⁻³ for the Bio-baler and 373 green kg m⁻³ for the Claas baler. Average net heat content was 6263 MJ bale⁻¹ for the Bio-baler and 6695 MJ bale⁻¹ for the Claas baler with biomass containing 38 percent of moisture content on a wet basis. Cost per unit area was less with the Bio-baler (US$320.91 ha⁻¹) than with the mulcher-baler system (US$336.62-US$596.77 ha⁻¹).     

Marginal cost of delivering switchgrass feedstock and producing cellulosic ethanol at multiple biorefineries

Limited information is available regarding the change in cost to deliver dedicated energy crop feedstock as the quantity of required feedstock increases. The objective is to determine the marginal cost to produce and deliver switchgrass feedstock to biorefineries. A mathematical programming model that includes 77 production regions (Oklahoma counties), monthly feedstock requirements, integer activities for harvest machines and integer activities for each of 16 potential biorefinery locations was constructed. The model was initially solved for a single biorefinery. The number of plants was incremented by one and the model resolved until nearly 10% of the cropland and improved pasture land was converted to switchgrass. The estimated cost to deliver 1.0 Mg of feedstock to a single 189 dam³ y⁻¹ capacity biorefinery is 55 $. The cost to deliver feedstock increases as additional biorefineries are constructed and the cost for the ninth biorefinery of 87 $ Mg⁻¹ is 58% greater than the cost to deliver to the first biorefinery. The cost difference is primarily due to differences in transportation cost. Initial cellulosic biorefineries will have an opportunity for establishing a feedstock cost advantage by carefully selecting land for conversion to switchgrass and by negotiating long term leases.     

Carbon dioxide emissions from switchgrass and cottonwood grown as bioenergy crops in the Lower Mississippi River Alluvial Valley

Marginal land of the Lower Mississippi Alluvial Valley (LMAV) has the potential to be utilized for substantial production of bioenergy feedstocks. However, resulting ecosystem services associated with dedicated bioenergy crop production, such as soil respiration and carbon dioxide (CO₂) emissions, which play an important role in global carbon (C) cycling, are not well understood. The objective of this study was to evaluate the effects of land use [i.e., switchgrass (Panicum virgatum) and eastern cottonwood (Populus deltoides) grown as dedicated bioenergy crops and a soybean (Glycine max)-grain sorghum (Sorghum bicolor) agroecosystem rotation] on monthly respiration and estimated annual CO₂ emissions for 2012 and 2013 from a silt -loam soil in east-central Arkansas. Peak monthly fluxes achieved each year differed (p < 0.05) somewhat among ecosystems. Annual CO₂ emissions differed among ecosystems (p < 0.001), but not between years (p = 0.45). Cottonwood emitted less CO₂ in both years (7.3 and 7.4 Mg ha⁻¹ for 2012 and 2013, respectively) compared to the other two ecosystems, while emissions from the switchgrass did not differ from those from the soybean in 2012 (10.3 and 9.5 Mg ha⁻¹, respectively) or grain sorghum in 2013 (9.7 and 9.2 Mg ha⁻¹, respectively). Results showed established bioenergy feedstock cropping systems do not have greater soil CO₂ emissions compared with a traditional soybean-grain sorghum crop rotation. Results also indicated that different bioenergy feedstocks can produce different quantities of CO₂ emissions, which may be important to consider when converting marginal lands to bioenergy feedstock cropping systems.     

Integrated energy,environmental and financial analysis of ethanol production from cellulosic switchgrass

Ethanol production from cellulosic sources such as switchgrass (Panicum virgatum L.) requires the use of natural resources, fossil fuels, electricity, and human-derived goods and services. We used emergy accounting to integrate the ultimate amount of environmental, fossil fuel, and human-derived energy required to produce ethanol from switchgrass. Emergy is the total amount of energy of one form required directly and indirectly to make another form of energy. Forty-four percent of required emergy came from the environment either directly or embodied in purchased goods, 30% came from fossil fuels either directly or embodied in purchased goods, and 25% came from human-derived services indirectly. Ethanol production per petroleum use (emergy/emergy) was 4.0-to-1 under our Baseline Scenario, but dropped to 0.5-to-1 under a scenario that assumed higher input prices, lower conversion efficiencies and less waste recycling. At least 75% of total emergy was from non-renewable sources. Energy ‘hidden’ in indirect paths such as goods and services was 65% of the total. Cellulosic-ethanol is not a primary fuel source that substitutes for petroleum because its production relies heavily on non-renewable energy and purchased inputs. It is a means for converting natural resources to liquid fuel.     

Switchgrass cofiring: pilot scale and field evaluation

A study is under way to evaluate the feasibility, costs, and benefits of co-milling and direct injection cofiring of switchgrass with coal as a potential renewable energy source. Switchgrass is an American native prairie grass, ideally adapted to the eastern United States. The grass is highly productive, requires little fertilization and herbicide, and can be grown on marginal land. There are four phases in the study, which look at (1) farm production issues, (2) pilot co-milling, (3) pilot combustion tests, and (4) full-scale demonstration. To date, good data have been obtained on farm production costs and field processing and handling issues. Pilot-scale milling tests and combustion tests of blends of switchgrass with coal have been successfully completed, and a full-scale demonstration of direct pneumatic injection of switchgrass for co-firing in a pulverized coal boiler is planned for the spring of 2001.     

Catalytic effects observed during the co-gasification of coal and switchgrass

We are investigating catalytic gasification of coal char using biomass-derived potassium salts. Alkali metal salts, especially those containing potassium, are excellent promoters of gasification reactions but are generally considered too expensive for commercial use. Fast-growing biomass, which contains large quantities of potassium, may prove to be an excellent source of inexpensive gasification catalyst. A series of CO₂-char gasification tests were performed in a thermogravimetric analyzer (TGA) to evaluate the catalytic activity of alkali-rich biomass-derived materials. Both switchgrass char and switchgrass ash displayed catalytic activity in mixtures with coal char produced from Illinois No. 6 coal. The results obtained with switchgrass ash were especially impressive, with an almost eight-fold increase in coal char gasification rate at 895°C in a 10:90 mixture of coal char and switchgrass ash. These results give encouragement that biomass could be the source of inexpensive, coal gasification catalysts.     

Technical cost modelling for a generic 45-m wind turbine blade producedby vacuum infusion (VI)

A detailed technical cost analysis has been conducted on a generic 45-m wind turbine blade manufactured using the vacuum infusion (VI) process, in order to isolate areas of significant cost savings. The analysis has focused on a high labour cost environment such as the UK and investigates the influence of varying labour costs, programme life, component area, deposition time, cure time and reinforcement price with respect to production volume. A split of the cost centres showed the dominance of material and labour costs at approximately 51% and 41%, respectively. Due to the dominance of materials, it was shown that fluctuations in reinforcement costs can easily increase or decrease the cost of a turbine blade by up to 14%. Similarly, improving material deposition time by 2 h can save approximately 5% on the total blade cost. However, saving 4 h on the cure cycle only has the potential to provide a 2% cost saving.     

Characterization of a Trichoderma atroviride strain isolated from switchgrass bales and its use to saccharify ammonia-pretreated switchgrass for biobutanol production

The feedstock-specific enzyme systems for saccharification of biofuel feedstocks like switchgrass may potentially provide better enzymatic systems for production of second-generation biofuels. One strategy to develop these enzyme systems could be to harness the microorganisms growing naturally on specific feedstocks. This study presents the isolation and screening of fungal cultures from switchgrass bales for saccharification of ammonia-pretreated switchgrass for subsequent biobutanol production. The best performing fungal isolate during screening was identified through Sanger sequencing of its ITS region to be a unique strain of Trichoderma atroviride and further characterized for production of an enzyme system for saccharification of ammonia pretreated switchgrass. The maximum FPase, CMCase and xylanase activity produced by T. atroviride CUA1 were 0.25 fpu/mL, 0.18 IU/mL and 5.8 IU/mL, respectively. T. atroviride CUA1 also produced considerable amount of β-glucosidase activity. This isolate was used to produce an enzyme system to convert switchgrass to soluble sugars that were then fermented to butanol, ethanol, acetate and butyrate. Glucose was the major product of hydrolysis of ammonia-pretreated switchgrass performed using the enzyme system produced by the isolate. This fungus may be useful for the hydrolysis for the bioenergy crop of switchgrass to overcome this rate-limiting step in the overall conversion of biomass to biofuels.     

Switchgrass production and establishment in the Southern Italy climatic conditions

Standard productivity trials on switchgrass (Panicum virgatum L.) have been performed at the ENEA Research Centre Trisaia in the framework of the FAIR Project (IV FWP). The main objective of the research work was to develop knowledge about the adaptability of this new crop in the South Italy climatic conditions. To achieve this goal, two sets of experiments with various genotypes were conducted to determine the switchgrass yields at the field level. In the nursery trial, 15 varieties were tested, while in the production experiment, only five varieties at different nitrogen fertiliser levels (0, 75, 150 kg N ha⁻¹) were tested for their yield. The experimental results obtained relating to biomass yield and genotype response to nitrogen fertilisation are discussed in the present communication. Though it seems that the N fertilisation did not directly influence the switchgrass productivity, most of the switchgrass varieties showed quite a good response for biomass production.     

Economic analysis of the renovation of small-scale district heating systems—4 Lithuanian case studies

This paper describes the renovation and replacement problems of small district heating systems (DHS), which are characteristic to small towns in Lithuania and other Central and East European (CEE) countries. These problems have been scarcely investigated till present and are still the subject of acute energy policy discussions.     

Cost analysis of different solar still configurations

The enhancement of the productivity of the solar desalination system, in a certain location, could be attained by a proper modification in the system design. Therefore, different design configurations could be found in literatures. However, the increase in the system productivity with high system cost may increase also the average annual cost of the distillate. Cost analysis of different design configurations of solar desalination units is essential to evaluate the benefit of modification from the economical point of view. The main objective of this work is to estimate the water production cost for different types of solar stills. In this paper 17 design configurations are considered. Systems with higher and lower values of productivity are considered in this investigation. A simplified model for cost analysis is applied in this study. The results show that, the best average and maximum daily productivity are obtained from solar stills of single-slope and pyramid-shaped. The higher average annual productivity for a solar still is about 1533 l/m² using pyramid-shaped while the lower average annual productivity is about of 250 l/m² using modified solar stills with sun tracking. The lowest cost of distilled water obtained from the pyramid-shaped solar still is estimated as 0.0135 $/l while highest cost from the modified solar stills with sun tracking is estimated as 0.23 $/l.     

The exogenous factors affecting the cost efficiency of power generation

This paper employs a stochastic frontier analysis (SFA) to examine cost efficiency and scale economies in Taiwan Power Company (TPC) by using the panel data covering the period of 1995–2006. In most previous studies, the efficiency estimated by the Panel Data without testing the endogeneity may bring about a biased estimator resulting from the correlation between input and individual effect. A Hausman test is conducted in this paper to examine the endogeneity of input variables and thus an appropriate model is selected based on the test result. This study finds that the power generation executes an increasing return to scale across all the power plants based on the pooled data. We also use installed capacity, service years of the power plant, and type of fuel as explanatory variable for accounting for the estimated cost efficiency of each plant by a logistic regression model to examine the factor affecting the individual efficiency estimates. The results demonstrate that the variable of installed capacity keeps a positive relationship with cost efficiency while the factor of working years has a negative relationship.