Using an inventory control model to establish biomass harvesting policies

The financial performance of a biomass-dependent production system was evaluated using an inventory control model. Dynamic programming was employed to examine the constraints and capabilities of producing ethanol from various biomass crops. In particular, the model evaluated the plantation, harvest, and manufacturing components of a woody biomass supply system. Using inventory control to establish biomass harvesting policies is one way of achieving a cost efficient operation. The optimum wood to ethanol production scheme could produce 38 million 1 of ethanol in any given harvest year, a 13.6 million 1 increase over the least optimal policy. Delivered cost was $0.38 l⁻¹ consistent with the unit costs from other studies. Nearly 60% of the cost was from the manufacturing component of the system. The remaining costs were attributed to growing biomass (14%), harvest and shipment of the crop (18%), storage of the raw material and finished product (7%), and “lost sales” (2%). Inventory control, in all phases of production, could influence total delivered costs of ethanol by as much as 62%. A comparison between the least costly wood system and alternative systems further illustrated the benefits of inventory control.     

Modelling the costs of energy crops: A case study of US corn and Brazilian sugar cane

High crude oil prices, uncertainties about the consequences of climate change and the eventual decline of conventional oil production raise the prospects of alternative fuels, such as biofuels. This paper describes a simple probabilistic model of the costs of energy crops, drawing on the user's degree of belief about a series of parameters as an input. This forward-looking analysis quantifies the effects of production constraints and experience on the costs of corn and sugar cane, which can then be converted to bioethanol. Land is a limited and heterogeneous resource: the crop cost model builds on the marginal land suitability, which is assumed to decrease as more land is taken into production, driving down the marginal crop yield. Also, the maximum achievable yield is increased over time by technological change, while the yield gap between the actual yield and the maximum yield decreases through improved management practices. The results show large uncertainties in the future costs of producing corn and sugar cane, with a 90% confidence interval of 2.9–7.2$/GJ in 2030 for marginal corn costs, and 1.5–2.5$/GJ in 2030 for marginal sugar cane costs. The influence of each parameter on these supply costs is examined.     

Techno-economic assessment of pellets produced from steam pretreated biomass feedstock

Minimum production cost and optimum plant size are determined for pellet plants for three types of biomass feedstock – forest residue, agricultural residue, and energy crops. The life cycle cost from harvesting to the delivery of the pellets to the co-firing facility is evaluated. The cost varies from 95 to 105 $ t⁻¹ for regular pellets and 146–156 $ t⁻¹ for steam pretreated pellets. The difference in the cost of producing regular and steam pretreated pellets per unit energy is in the range of 2–3 $ GJ⁻¹. The economic optimum plant size (i.e., the size at which pellet production cost is minimum) is found to be 190 kt for regular pellet production and 250 kt for steam pretreated pellet. Sensitivity and uncertainty analyses were carried out to identify sensitivity parameters and effects of model error.     

Energy crop production costs in the EU

The objective of this study was to calculate indicative ranges of production costs and assess the main sources of cost for a number of energy crops, both annual and perennial, on a regional level in Europe. The production costs were calculated in terms of the economic compensation required by the farmer in order to grow the crop, and therefore include not only the cost of cultivation, but also the costs of land and risk, which are often omitted in production cost calculations. The cost of land was calculated as the opportunity cost based on the production of cereals. Thus, higher food prices lead to higher land costs, which in turn lead to higher energy crop production costs. The analysis was performed for three cases with different assumptions concerning yields and production cost reductions resulting from scale (total cultivation area in the region), and learning effects. The calculated energy crop production costs were found to be consistently lowest for short-rotation coppice (SRC) crops and highest for annual straw crops. The production costs of SRC crops were calculated to be about 4–5 € GJ⁻¹ under present conditions and 3–4 € GJ⁻¹ under improved future conditions. The production costs for perennial grasses were calculated to be about 6–7 € GJ⁻¹ and 5–6 € GJ⁻¹ under present and improved future conditions, respectively. The production costs for annual straw crops were estimated to be 6–8 € GJ⁻¹ under present conditions with small potential for cost reductions in the future.     

Sugar-ethanol-electricity co-generation in Hawai’i: An application of linear programming (LP) for optimizing strategies

This research develops a linear programming (LP) model to assess various options for sugar and biofuel production from sugarcane and other feedstock in Hawaii. More specifically, the study focuses on finding optimal sugar and biomass feedstock that would maximize producer profits in the production of sugar, ethanol and electricity. Feedstock included in the model were sugarcane, banagrass, energy cane and sweet sorghum. Given available land resources for growing energy crops on the island of Maui, four land resource scenarios were considered. If available land resources were used in the production of sugarcane and energy crops with added utilization of non-prime lands, Hawaii's ethanol goal for year 2020 could be achieved while maintaining two-thirds of Hawaii's current sugar production. Crop yields and unit production costs are key factors in determining optimal quantities of feedstock in the optimization model tested in this study.     

A review of agricultural crop residue supply in Canada for cellulosic ethanol production

This paper estimates the availability of agricultural crop residue feedstocks in Canada for cellulosic ethanol production. Canada's major field crops generate 100.6 million dry mega grams (Mg) of crops per year while non-forage crops produce 67 million dry Mg, leaving abundant agricultural residues for use as second generation feedstock for cellulosic ethanol production. This study used crop production and livestock data from Statistics Canada for a 10-year period (2001–2010), as well as tillage data from Statistics Canada census years 2001 and 2006, to estimate crop residue availability by province and soil zone. Total residue yield from crops is calculated by incorporating straw to grain ratios. Total agricultural residues available for ethanol production are computed by deducting soil conservation and livestock uses. An average of 48 million dry Mg of agricultural residues is available per year, with a minimum of 24.5 million dry Mg in drought year 2002. This implies an average yearly potential ethanol production of 13 billion litres from crop residues over the 2001–2010 period, with a minimum of 6.6 billion litres in 2002. Ontario, Manitoba, Saskatchewan, and Quebec have enough agricultural residue supply to set up ethanol plants using agricultural crop residues as primary lignocellulosic feedstocks. There is great variability in agricultural residue production between the provinces and by soil zone. Understanding variability in feedstock supply is important for the economics and operational planning of a cellulosic ethanol biorefinery. Factors such as residue yield per hectare and soil zone will influence cellulosic ethanol plant establishment in order to exploit the abundance of lignocellulosic biomass for an ethanol plant.     

Wood pellet production costs under Austrian and in comparison to Swedish framework conditions

Owing to the rapidly increasing importance of pellets as high-quality biomass fuel in Austria and Europe within the last years, many companies, mainly from the wood industry, are thinking of entering this market. The calculation of the production costs before starting a pellet plant is essential for an economic operation. Based on comprehensive investigations within the EU-ALTENER project “An Integrated European Market for Densified Biomass Fuels” calculations of the pellet production costs loco factory for different framework conditions with basic data based on already realised plants as well as a questionnaire survey of pellet producers in Austria, South Tyrol and Sweden have been performed.

The production costs for wood pellets are mainly influenced by the raw material costs and, in the case of using wet raw materials, by the drying costs. Depending on the framework conditions these two parameters can contribute up to one-third of the total pellet production costs. Other important parameters influencing the pellet production costs are the plant utilisation (number of shifts per week) as well as the availability of the plant. For an economic production of wood pellets at least three shifts per day at 5 days per week are necessary. An optimum would be an operation at 7 days per week. A low plant availability also leads to greatly increased pellet production costs. A plant availability of 85–90% should therefore be achieved.

The calculations show that a wood pellet production is possible both in small-scale (production rates of some hundred tonnes per year) as well as in large-scale plants (some ten thousand tonnes per year). However, especially for small-scale units it is very important to take care of the specific framework conditions of the producer, because the risk of a non-economic pellet production is considerably higher than for large-scale systems.

The direct comparison of typical pellet production costs in Austria and Sweden showed the Swedish pellet production costs to be considerably lower due to larger plant capacities, the combination of pellet production and biomass CHP or biomass district heating plants and the implementation of technologies which allow an efficient heat recovery from the dryers. Moreover, another difference between the Austrian and the Swedish framework conditions is the price of electricity, which is much lower in Sweden.     

Modeling biomass procurement tradeoffs within a cellulosic biofuel cost model

We develop a long-run cellulosic biofuel cost model that minimizes feedstock procurement and processing costs per gallon. The distinguishing feature of the model is that it accounts for the procurement tradeoff between the intensive margin (biomass producers' participation rate) and extensive margin (biomass capture region). To investigate the extent to which this procurement tradeoff affects processors' cost-minimizing decisions, we apply the model to switchgrass ethanol production in U.S. crop reporting districts. Results suggest that location characteristics will determine the extent to which processors can reduce their total procurement costs by offering a higher biomass price to increase participation near the plant and reduce transportation costs.     

Thermochemical energy transport costs for a distributed solar power plant

Thermochemical energy transport costs are calculated for a solar thermal power plant based on a distributed network of para-boloidal collectors. The optimum pipe size distribution within the fluid transport network has been generated subject to requirements of minimum cost and pressure drop equality across parallel conduction paths. The optimization procedure includes the installed capital cost of pipework together with the effective cost of pumping power. An analytical expression for the overall thermochemical energy transport cost has been derived, based on a Black and Veatch pipe cost survey in which conventional pipelaying technology is assumed. Thermochemical energy transport costs are calculated for systems based on ammonia, methanol, water-methane and sulphur trioxide. The derived costs are dominated by the pipe installation component whereas other parameters such as choice of system, operating pressure, reaction enthalpy and degree of reaction are of secondary importance. Larger collectors favour a lower installed cost per unit energy while increases in network area and hence in plant output capacity lead to slow increases in unit cost. Typical thermochemical energy transport costs for a solar thermal power plant operating only during sunlight hours and based on large collectors are estimated at $20 kWt^?1 (1974 U.S. dollars). It is suggested that there is a need for reduction of this estimate by developments in pipelaying technology tailored to the requirements of solar thermal power plants. Such developments would seem to be feasible for thermochemical energy transfer systems based on small diameter pipes and hence on high system pressures.     

Potential for rice straw ethanol production in the Mekong Delta,Vietnam

This study is to evaluate the potential for development of a cellulosic ethanol facility in Vietnam. Rice straw is abundant in Vietnam and highly concentrated in the Mekong Delta, where about 26 Mt year⁻¹ of rice straw has been yearly produced. To minimize the overall production cost (PC) of ethanol from rice straw, it is crucial to choose the optimal facility size. The delivered cost of rice straw varied from 20.5 to 65.4 $ dry t⁻¹ depending on transportation distance. The Mekong Delta has much lower rice straw prices compared with other regions in Vietnam because of high density and quantity of rice straw supply. Thus, this region has been considered as the most suitable location for deploying ethanol production in Vietnam. The optimal plant size of ethanol production in the region was estimated up to 200 ML year⁻¹. The improvement in solid concentration of material in the hydrothermal pre-treatment step and using residues for power generation could substantially reduce the PC in Vietnam, where energy costs account for the second largest contribution to the PC, following only enzyme costs. The potential for building larger ethanol plants with low rice straw costs can reduce ethanol production costs in Vietnam. The current estimated production cost for an optimal plant size of 200 ML year⁻¹ was 1.19 $ L⁻¹. For the future scenario, considering improvements in pre-treatment, enzyme hydrolysis steps, specific enzyme activity, and applying residues for energy generation, the ethanol production cost could reduce to 0.45 $ L⁻¹ for a plant size of 200 ML year⁻¹ in Vietnam. These data indicated that the cost-competitiveness of ethanol production could be realized in Vietnam with future improvements in production technologies.     

Understanding the reductions in US corn ethanol production costs: An experience curve approach

The US is currently the world's largest ethanol producer. An increasing percentage is used as transportation fuel, but debates continue on its costs competitiveness and energy balance. In this study, technological development of ethanol production and resulting cost reductions are investigated by using the experience curve approach, scrutinizing costs of dry grind ethanol production over the timeframe 1980–2005. Cost reductions are differentiated between feedstock (corn) production and industrial (ethanol) processing. Corn production costs in the US have declined by 62% over 30 years, down to 100$₂₀₀₅/tonne in 2005, while corn production volumes almost doubled since 1975. A progress ratio (PR) of 0.55 is calculated indicating a 45% cost decline over each doubling in cumulative production. Higher corn yields and increasing farm sizes are the most important drivers behind this cost decline. Industrial processing costs of ethanol have declined by 45% since 1983, to below 130$₂₀₀₅/m³ in 2005 (excluding costs for corn and capital), equivalent to a PR of 0.87. Total ethanol production costs (including capital and net corn costs) have declined approximately 60% from 800$₂₀₀₅/m³ in the early 1980s, to 300$₂₀₀₅/m³ in 2005. Higher ethanol yields, lower energy use and the replacement of beverage alcohol-based production technologies have mostly contributed to this substantial cost decline. In addition, the average size of dry grind ethanol plants increased by 235% since 1990. For the future it is estimated that solely due to technological learning, production costs of ethanol may decline 28–44%, though this excludes effects of the current rising corn and fossil fuel costs. It is also concluded that experience curves are a valuable tool to describe both past and potential future cost reductions in US corn-based ethanol production.     

Ethanol Production from Sugar Cane: Assessing the Possibilities of Improving Energy Efficiency through Exergetic Cost Analysis

The sugar and ethanol production is one of the most important economical activities in Brazil, mainly due its high efficiency and competitiveness. Ethanol production is done by a series of steps: juice extraction, treatment, fermentation, and distillation. The juice extraction and treatment is a common operation of both the sugar and ethanol industries. The process begins with the sugar cane juice extraction, usually done by mills, where the cane is compressed between large cylinders for the separation of the juice from the bagasse. Recently, a juice extraction system, called a diffuser, was introduced in some sugar and ethanol plants. In diffusers, after the sugar cane preparation stage was completed with knives and shredders, the cane passes through a bed where the juice is separated from bagasse by the addition of imbibition water and steam, resulting in a leaching process. The present study evaluates different possibilities of decreasing the thermal energy consumption through exergetic cost analysis. The base case is a traditional ethanol production plant, for which the unitary exergetic cost of ethanol and electrical energy are determined. In the following cases, two proposals were assessed: the use of the diffuser as an extraction system and the use of pinch technology to perform an energetic integration between distillation and extraction (diffuser) systems. The results of exergetic efficiency, irreversibility generation, and unitary exergetic cost of products of the three cases are analyzed and compared. The results show the feasibility of using diffusers and heat recovery to decrease thermal energy consumption in ethanol production plants.     

籽实作物、茎秆作物和块根(茎)作物作车用乙醇原料的优势探讨

对我国主要车用乙醇原料作物的经济性状和优势进行了分析,结果表明:能源甘蔗、水果甘蔗、糖料甘蔗等茎秆作物的经济产量最高,达75～300t/hm2,可产车用乙醇约5.4～27.5 t/hm2;生产1 t车用乙醇需要的耕地面积最少,约0.1～0.14 hm2;原料成本最低,约1 600～4 430元/t;经济效益最高,约2 130～2 480元/t和9 100～89 700元/hm2.因此,甘蔗是车用乙醇产业首选的原料作物.甘薯、木薯、马铃薯及甜菜等块根(茎)作物各项性状居中,生产成本较低,经济效益较高,是车用乙醇产业第二选择的原料作物.玉米、水稻、小麦等籽实作物单位质量的车用乙醇产量最高,但吨车用乙醇原料需要的耕地最多,约达0.28～0.69hm2/t;原料成本最高,约为3 520～4 770元/t;经济效益最低,约为230～1 740元/t和-221～7 980元/hm2.因此,籽实作物用作车用乙醇原料不具有优势.     

Technical and economic analysis of biogas production in Ireland utilising three different crop rotations

The Biofuels Directive sets reference values for the quantity of biofuels and other renewable fuels to be placed on the transport market. Biogas from agricultural crops can be used to meet this directive. This paper investigates biogas production for three crop rotations: wheat, barley and sugar beet; wheat, wheat and sugar beet; wheat only. A technical and economic analysis for each crop rotation was carried out. It was found that wheat produces significantly more biogas than either barley or sugar beet, when examined on a weight basis. However sugar beet produces more biogas and subsequently more energy when examined on an area basis. When producing biofuels, land is the limiting factor to the quantity of energy that may be produced. Thus if optimising land then a crop rotation of wheat, wheat and sugar beet should be utilised, as this scenario produced the greatest quantity of energy. This scenario has a production cost of €0.90/m_N³, therefore, this scenario is competitive with petrol when the price of petrol is at least €1.09/l (VAT is charged at 21%). If optimising the production costs then a crop rotation of wheat only should be utilised when the cost of grain is less than €132/ton. This scenario has the least production cost at €0.83/m_N³, therefore, this scenario is competitive with petrol when the price of petrol is at least €1.00/l. But as this scenario produces the least quantity of biogas, it also produces the least quantity of energy. In comparing with other works by the authors it is shown that a biomethane system produces more energy from the same crops at a cheaper cost than an ethanol system.     

Sweet sorghum as a bioenergy crop: Literature review

Sweet sorghum (Sorghum bicolor L. Moench) is a widely adapted sugar crop with high potential for bioenergy and ethanol production. Sweet sorghum can yield more ethanol per unit area of land than many other crops especially under minimum input production. Sweet sorghum is well-adapted to marginal growing conditions such as water deficits, water logging, salinity, alkalinity, and other constraints. Sweet sorghum potential exists for ethanol yield of 6000 L ha⁻¹ with more than three units of energy attained per unit invested. Traditionally, sweet sorghum has served as a syrup crop and its culture and production are well understood. Sweet sorghum is genetically diverse and variations exits for characteristics such as Brix % (13–24), juice sucrose concentration (7.2–15.5%), total stalk sugar yield (as high as 12 Mg ha⁻¹), fresh stalk yield (24–120 Mg ha⁻¹), biomass yield (36–140 t ha⁻¹) and others indicating potential for improvement. Transitioning sweet sorghum to a bioenergy crop is hampered by inadequate technology for large-scale harvest, transport and storage of the large quantities of biomass and juice produced, especially where the harvest window is short. Conversion of sweet sorghum to ethanol can be achieved by fermenting juice expressed from stems or directly fermenting chopped stalks. Integration of the fermentation and distillation of sweet sorghum juice in corn ethanol plants has not yet been achieved.     

Plant size: Capital cost relationships in the dry mill ethanol industry

Estimates suggest that capital costs typically increase less than proportionately with plant capacity in the dry mill ethanol industry because the estimated power factor is 0.836. However, capital costs increase more rapidly for ethanol than for a typical processing enterprise, judging by the average 0.6 factor rule. Some estimates also suggest a phase of decreasing unit costs followed by a phase of increasing costs. Nonetheless dry mills could be somewhat larger than the current industry standard, unless other scarce factors limit capacity expansion. Despite the statistical significance of an average cost-size relationship, average capital cost for plant of a given size at a particular location is still highly variable due to costs associated with unique circumstances, possibly water availability, utility access and environmental compliance.     

US military expenditures to protect the use of Persian Gulf oil for motor vehicles

Analyses of the full social cost of motor vehicle use in the US often estimate an “oil import premium” that includes the military cost of defending oil supplies from the Persian Gulf. Estimates of this cost have ranged from essentially zero to upwards of a $1 per gallon (about Analyses of the full social cost of motor vehicle use in the US often estimate an “oil import premium” that includes the military cost of defending oil supplies from the Persian Gulf. Estimates of this cost have ranged from essentially zero to upwards of a $1 per gallon (about $0.25 per liter). In this paper, we attempt to narrow this range, by carefully answering the question: “If the US highway transportation sector did not use oil, how much would the US federal government reduce its military commitment in the Persian Gulf?” We work towards our answer in five steps, accounting for interests not related to oil, the interests of other oil-consuming countries, the interests of producers apart from the interests of consumers, and the interests of non-highway users of oil. We estimate that were there no oil in the Persian Gulf, then US combined peacetime and wartime defense expenditures might be reduced in the long run by roughly $27–$73 billion per year (in 2004 dollars), of which roughly $6–$25 billion annually ($0.03–$0.15 per gallon or $0.01–$0.04 per liter) is attributable to motor-vehicle use.     

Optimal locations for second generation Fischer Tropsch biodiesel production in Finland

A country level spatially explicit mixed integer linear programming model has been applied to identify the optimal Fischer Tropsch biodiesel production plants locations in Finland. The optimal plant locations with least cost options are identified by minimizing the complete costs of the supply chain with respect to feedstock supply (energywood, pulpwood, sawmill residuals, wood imports), industrial competition (pulp mill, sawmill, combined heat and power plants, pellet industries) and energy demand (biodiesel, heat, biofuel import). Model results show that five biodiesel production plants of 390 MWfeedstock are needed to be built to meet the 2020 renewable energy target in transport (25.2 PJ). Given current market conditions, the Fischer Tropsch biodiesel can be produced at a cost around 18 €/GJ including by-products income. Furthermore, the parameter sensitivity analysis shows that the production plant parameters such as investment costs and conversion efficiency are found to have profound influence on the biodiesel cost, and then followed by feedstock cost and plant size. In addition, the variations in feedstock costs and industrial competition determine the proportion of feedstock resource allocation to the production plants. The results of this study could help decision makers to strategically locate the FT-biodiesel production plants in Finland.     

Biomass supply from alternative cellulosic crops and crop residues: A spatially explicit bioeconomic modeling approach

This paper introduces a spatially-explicit bioeconomic model for the study of potential cellulosic biomass supply. For biomass crops to begin to replace current crops, farmers must earn more from them than from current crops. Using weather, topographic and soil data, the terrestrial ecosystem model, EPIC, dynamically simulates multiple cropping systems that vary by crop rotation, tillage, fertilization and residue removal rate. EPIC generates predicted crop yield and environmental outcomes over multiple watersheds. These EPIC results are used to parameterize a regional profit-maximization mathematical programming model that identifies profitable cropping system choices. The bioeconomic model is calibrated to 2007-09 crop production in a 9-county region of southwest Michigan. A simulation of biomass supply in response to rising biomass prices shows that cellulosic residues from corn stover and wheat straw begin to be supplied at minimum delivered biomass:corn grain price ratios of 0.15 and 0.18, respectively. At the mean corn price of $162.6/Mg ($4.13 per bushel) at commercial moisture content during 2007-2009, these ratios correspond to stover and straw prices of $24 and $29 per dry Mg. Perennial bioenergy crops begin to be supplied at price levels 2-3 times higher. Average biomass transport costs to the biorefinery plant range from $6 to $20/Mg compared to conventional crop production practices in the area, biomass supply from annual crop residues increased greenhouse gas emissions and reduced water quality through increased nutrient loss. By contrast, perennial cellulosic biomass crop production reduced greenhouse gas emissions and improved water quality.     

Estimating global production and supply costs for green hydrogen and hydrogen-based green energy commodities

Green energy commodities are expected to be central in decarbonising the global energy system. Such green energy commodities could be hydrogen or other hydrogen-based energy commodities produced from renewable energy sources (RES) such as solar or wind energy. We quantify the production cost and potentials of hydrogen and hydrogen-based energy commodities ammonia, methane, methanol, gasoline, diesel and kerosene in 113 countries. Moreover, we evaluate total supply costs to Germany, considering both pipeline-based and maritime transport. We determine production costs by optimising the investment and operation of commodity production from dedicated RES based on country-level RES potentials and country-specific weighted average costs of capital. Analysing the geographic distribution of production and supply costs, we find that production costs dominate the supply cost composition for liquid or easily liquefiable commodities, while transport costs dominate for gaseous commodities. In the case of Germany, importing green ammonia could be more cost-efficient than domestic production from locally produced or imported hydrogen. Green ammonia could be supplied to Germany from many regions worldwide at below the cost of domestic production, with costs ranging from 624 to 874 $/t NH₃ and Norway being the cheapest supplier. Ammonia production using imported hydrogen from Spain could be cost-effective if a pan-European hydrogen pipeline grid based on repurposed natural gas pipelines exists.