The economics of chipping logging residues at roadside: A study of three systems

Three biomass chipping operations of roadside logging residues were studied in New Brunswick and Maine. Two of the operations used a skidder-loader to form the roadside debris into larger piles closer to the road edge prior to chipping. Average chipping productivity ranged from 8.l oven dry Mg per Productive Machine Hour (OdMg PMH⁻¹) to 28.2 OdMg PMH⁻¹ depending on the site and chipping system used. The average cost of chips on board the chip vans ranged from $15.29 CAN OdMg⁻¹ to $25.86 CAN OdMg⁻¹. The chips were transported to three energy plants in Maine. One-way hauling distances varied from 29 km to 105 km.     

Feasibility of collecting naturally leached rice straw for thermal conversion

The practical application of field or natural leaching to rice straw was evaluated with the goal of improving biomass fuel value. Observations on three rice farms in the Sacramento Valley, California indicated that potassium, chlorine and total ash are leached from rice straw by rainfall regardless of rice variety, grain harvest method, straw arrangement, or stubble length. Leaching of sulfur by natural precipitation was not clearly established. In selected field plots leached straw was successfully collected in spring, even though biomass yields were variable (2.2–3.4 Mgha⁻¹) and equipment had to operate in difficult conditions. Total costs for collecting leached straw on an area basis ($77.07 ha⁻¹) are 31% higher compared to collecting crude straw in the fall ($58.67 ha⁻¹), due to reduced performance of machinery and addition of field curing operations. Analysis of historical rainfall data for the Sacramento Valley revealed that there is an 85% probability of receiving sufficient rainfall (250 mm or more) for substantial natural leaching of straw during the winter period. The available period for mechanized collection of rice straw after the winter period ranges from 0 to 45 days, depending on drying time needed to accomplish favorable field conditions, and planting date of the next crop. The feasibility of spring collection of rice straw could be improved if straw collection equipment were better equipped to operate under wet field conditions. The commercial implementation of natural leaching of rice straw as a strategy to improve fuel quality depends on a combination of factors that include grain harvest and straw collection practices, rainfall intensity and distribution, and field-specific factors.     

High temperature solar heated seasonal storage system for low temperature heating of buildings

A preliminary study of a solar-heated low-temperature space-heating system with seasonal storage in the ground has been performed. The system performance has been evaluated using the simulation models TRNSYS and MINSUN together with the ground storage module DST. The study implies an economically feasible design for a total annual heat demand of about 2500 MWh. The main objective was to perform a study on Anneberg, a planned residential area of 90 single-family houses with 1080 MWh total heat demand. The suggested heating system with a solar fraction of 60% includes 3000 m² of solar collectors but electrical heaters to produce peak heating. The floor heating system was designed for 30°C supply temperature. The temperature of the seasonal storage unit, a borehole array in crystalline rock of 60,000 m³, varies between 30 and 45°C over the year. The total annual heating costs, which include all costs (including capital, energy, maintenance etc.) associated with the heating system, were investigated for three different systems: solar heating (1000 SEK MWh⁻¹), small-scale district heating (1100 SEK MWh⁻¹) and individual ground-coupled heat pumps (920 SEK MWh⁻¹). The heat loss from the Anneberg storage system was 42% of the collected solar energy. This heat loss would be reduced in a larger storage system, so a case where the size of the proposed solar heating system was enlarged by a factor of three was also investigated. The total annual cost of the solar heating system was reduced by about 20% to about 800 SEK MWh⁻¹, which is lower than the best conventional alternative.     

The impact of feedstock cost on technology selection and optimum size

Development of biomass projects at optimum size and technology enhances the role that biomass can make in mitigating greenhouse gas. Optimum sized plants can be built when biomass resources are sufficient to meet feedstock demand; examples include wood and forest harvest residues from extensive forests, and grain straw and corn stover from large agricultural regions. The impact of feedstock cost on technology selection is evaluated by comparing the cost of power from the gasification and direct combustion of boreal forest wood chips. Optimum size is a function of plant cost and the distance variable cost (DVC, $ dry tonne⁻¹ km⁻¹) of the biomass fuel; distance fixed costs (DFC, $ dry tonne⁻¹) such as acquisition, harvesting, loading and unloading do not impact optimum size. At low values of DVC and DFC, as occur with wood chips sourced from the boreal forest, direct combustion has a lower power cost than gasification. At higher values of DVC and DFC, gasification has a lower power cost than direct combustion. This crossover in most economic technology will always arise when a more efficient technology with a higher capital cost per unit of output is compared to a less efficient technology with a lower capital cost per unit of output. In such cases technology selection cannot be separated from an analysis of feedstock cost.     

Biohydrogen production from forest and agricultural residues for upgrading of bitumen from oil sands

In this study, forest residues (limbs, tops, and branches) and straw (from wheat and barley) are considered for producing biohydrogen in Western Canada for upgrading of bitumen from oil sands. Two types of gasifiers, namely, the Battelle Columbus Laboratory (BCL) gasifier and the Gas Technology Institute (GTI) gasifier are considered for biohydrogen production. Production costs of biohydrogen from forest and agricultural residues from a BCL gasification plant with a capacity of 2000 dry tonnes/day are $1.17 and $1.29/kg of H₂, respectively. For large-scale biohydrogen plant, GTI gasification is the optimum technology. The delivered-biohydrogen costs are $2.19 and $2.31/kg of H₂ at a plant capacity of 2000 dry tonnes/day from forest and agricultural residues, respectively. Optimum capacity for biohydrogen plant is 3000 dry tonnes/day for both residues in a BCL gasifier. In a GTI gasifier, although the theoretical optimum sizes are higher than 3000 dry tonnes/day for both feedstocks, the cost of production of biohydrogen is flat above a plant size of 3000 dry tonnes/day. Hence, a plant at the size of 3000 dry tonnes/day could be built to minimize risk. Carbon credits of $119 and $124/tonne of CO₂ equivalent are required for biohydrogen from forest and agricultural residues, respectively.     

Energy potential through agricultural biomass using geographical information system—A case study of Punjab

Agricultural biomass has immense potential for power production in an Indian state like Punjab. A judicious use of biomass energy could potentially play an important role in mitigating environmental impacts of non-renewable energy sources particularly global warming and acid rain. But the availability of agricultural biomass is spatially scattered. The spatial distribution of this resource and the associate costs of collection and transportation are major bottlenecks for the success of biomass energy conversion facilities. Biomass, being scattered and loose, has huge collection and transportation costs, which can be reduced by properly planning and locating the biomass collection centers for biomass-based power plants. Before planning the collection centers, it is necessary to evaluate the biomass, energy and collection cost of biomass in the field. In this paper, an attempt has been made to evaluate the spatial potential of biomass with geographical information system (GIS) and a mathematical model for collection of biomass in the field has been developed. The total amount of unused agricultural biomass is about 13.73 Mt year⁻¹. The total power generation capacity from unused biomass is approximately 900 MW. The collection cost in the field up to the carrier unit is US$3.90 t⁻¹.     

Accumulation, transfers and dissipation of energy in chir pine forests

Energy stored and net energy fixed at four sites of natural chir pine forest were assessed. Of the total energy stored by the vegetation (3836.6 GJ ha⁻¹) 98.7% was in trees, 0.4% in shrubs and 0.9% in the herb layer. Net energy fixed by the vegetation was 318.5 GJ ha⁻¹ yr⁻¹ of which the shares of tree, shrub and herb layers were 84.7% 0.9% and 14.4%, respectively. The energy capture efficiency (photosynthetic radiation) of the vegetation was 1.07% (0.91% in trees, 0.01% in shrubs and 0.15% in herbs). Of the total transfer of energy to the forest floor through litter fall (142.7 GJ ha⁻¹ yr⁻¹ leaf litter and woody litter accounted for 68.4% and 31.6%, respectively. Energy stored in the above-ground biomass of the trees from 2877 ha or in the net annual above-ground production from 39,903 ha is sufficient to operate a 50 MW generating station for one year. Total biomass and net production from 1 ha of natural chir pine forest is sufficient to meet the energy need of an average household of western Himalaya for 61.1 and 4.4 years, respectively.     

Identifying agricultural sites for biomass energy production in Minnesota

This research examines the potential of producing hybrid poplar on location specific marginal agricultural lands in Minnesota. It is assumed that all poplar production would be used to meet biomass energy requirements for two potential 100 MW power plants located in Alexandria and Granite Falls, Minnesota. The delivered fuelwood costs for each power plant are calculated using a cost minimization model. In addition to traditional production and harvesting costs, the model also incorporates landowners opportunity cost of fuelwood production as well as the actual transportation costs associated with supply from each individual analysis area to each power plant. The inclusion of any analysis area as a potential fuelwood supplier is greatly dependent on the interaction and combination of variables such as the opportunity cost, yield rates, and the distance from the power plants. The results show that approximately 40×10³ hectares of land capable of producing about 3.2×10[6] dry Mg of wood would be required to fuel each power plant for a 10 year planning period. The average present value costs of delivered (to the plant gate) fuelwood is about $32 dry Mg⁻¹ for Alexandria and $37 dry Mg⁻¹ for Granite Falls.     

Cost estimates of post harvest forest biomass supply for Canada

This study estimates the potential physical amounts and financial costs of post-harvest forest residue biomass supply in Canada. The analyses incorporate the locations of harvest activities in Canada, the geographical variation of forest productivity patterns and the costs associated with the extraction and transportation of residue feedstock to bioenergy facilities. We estimated the availability of harvest residues within the extent of industrial forest management operations in Canadian forests. Our analyses focused on the extraction of biomass from roadside harvest residues that involve four major cost components: pre-piling and aggregation, loading, chipping and transportation. The estimates of residue extraction costs also included representation of basic ecological sustainability and technical accessibility constraints. Annual supply of harvestable residual biomass with these ecological sustainability constraints were estimated to be approximately 19.2–23.3 Tg_*year⁻¹ and 16.5–20.0 Tg_*year⁻¹ in scenarios that included both ecological and technical accessibility limitations. These estimates appear to be less than other similar studies, due to the higher level of spatial details on inventories and ecological and operational constraints in our analyses. The amount of residual biomass available in baseline scenarios at a supply cost of $60 ODT⁻¹ and $80 ODT⁻¹ were 1.08 and 1.38 Tg year⁻¹ and 7.82 and 10.14 Tg year⁻¹ respectively. Decreasing residue extraction costs by 35% increased the amount of residues available at a $60 ODT⁻¹ and $80 ODT⁻¹ supply price by ∼5.5–5.7 and ∼1.5–1.6 times respectively. The assessment methodology is generic and could be extended to examine residue supplies for specialized biomass markets such as lignocellulosic ethanol production.     

Processing and sorting forest residues: Cost,productivity and managerial impacts

Feedstocks generated from processing forest residues have traditionally been considered as a low value product. The economic potential of these materials can be enhanced by emerging biomass conversion technologies, such as torrefaction, briquetting, and gasification; however, these systems require higher quality feedstock. The objective of this study was to determine the cost of processing and sorting forest residues to produce feedstock, so that the best comminution machines (i.e. chipper vs. grinder) could be used to better control feedstock size distribution. The tree tops left from sawlog processing and small-diameter trees were delimbed and separated from the slash pile. Three harvest units were selected and each unit was divided into three sub-treatment units (no-, moderate, and intensive sorting). Results showed that the cost of operations were higher for the sorted sub-units when compared to the non-sorted. The total cost of operation (felling to loading) for sawlogs was lowest at 40.81 $ m⁻³ in the nosorting treatment unit, followed by moderate (42.25 $ m⁻³) and intensive treatment unit (44.75 $ m⁻³). For biomass harvesting, the cost of operation (felling to delimbing and sorting) ranged from 27 to 29 $ oven dry metric ton⁻¹. The most expensive operational phase was primary transportation; therefore, cost of treating the forest residues had less impact on the overall cost. The cost increase (1150 $ ha⁻¹) of sorting forest residues could offset cost savings from avoided site preparation expenses (1100 $ ha⁻¹), provided that the forest residues were utilized.     

A role for ammonia in the hydrogen economy

Ammonia (NH₃) is a non-polluting fuel which produces only water and nitrogen as products of combustion. Therefore, it could be an alternative to hydrogen for vehicle motive power in the hydrogen economy. For this role ‘electrolytic ammonia’ would be prepared by catalytic combination of electrolytic hydrogen and atmospheric nitrogen. The background and developmental status of hydrogen and ammonia as motor-vehicle fuels are reviewed. Engine tests have demonstrated that ammonia can replace gasoline or diesel fuel for motor vehicles, giving near-theoretical values of engine power and efficiency. Ammonia is superior to hydrogen as a vehicle fuel for several reasons: it can be stored and transported as a liquid at ambient temperatures in low-pressure containers; per unit volume ammonia has 1.3 times the heating value of liquid hydrogen; ammonia is distributed internationally in quantities of over 100 million tons per year, and procedures and facilities are established world-wide for its safe handling and distribution. These factors would greatly facilitate the commercial adoption of ammonia as a practical replacement for carbonaceous fuels. The projected cost of supplying ‘electrolytic ammonia’ to motor vehicle filling stations is estimated to be roughly half the cost of supplying electrolytic liquid hydrogen for the same purpose, i.e. $10.5–12.5 GJ⁻¹ for ammonia vs $25–30 GJ⁻¹ for LH₂ (1988$). A summary is presented of the physical and thermo-chemical characteristics and estimated costs of ammonia in comparison with hydrogen, as liquid, compressed gas or stored as metal hydride. Properties of gasoline, methanol, ethanol and liquified methane are also listed.     

Fermentation properties of agro-residues, leaf biomass and urban market garbage in a solid phase biogas fermenter

The decomposition and gas production pattern of eight unprocessed biomass feedstocks representing annual weeds, leaf litter, agro residues and market wastes were monitored in this laboratory study. Solid phase fermentation was effected with a weekly fed biomass bed sprinkled twice daily with recycled fermentor liquid to initiate and sustain biogas production from the decomposing biomass bed. Fermentors were fed from the top with gradually increasing feed rates to determine maximum feed rates sustainable. Feed rates of 1 g total solids (TS) l⁻¹d⁻¹ was possible which lead to pseudo steady state gas production rates between 0.26–0.98 l l⁻¹ d⁻¹ at specific gas yields of 0.18–0.44 l g⁻¹ TS at 35–75% volatile solids (VS) destruction. Feedstocks such as paper mulberry (Broussenetia), Parthenium, Synedrella and urban garbage lost >50% VS in 30 d while paddy straw, bagasse and sugarcane trash exhibited lower VS loss (≥35%) in this period. During decomposition, bulky biomass feedstocks underwent compaction and obviated the need for a pretreatment step. Bulk densities rose manifold to reach between 150–350 g l⁻¹ within 20 d. A higher decomposition rate, process optimization and use of pre-compacted feedstocks have the potential to increase the feed rates (0.96–1.93 g TS l⁻¹d⁻¹), quantity of feedstock held in the reactor as well as gas production rates. The current gas production rates and space economy in these fermentors compare well with Indian cattle dung fermentors (0.3–0.5 l l⁻¹ d⁻¹) and is attractive.     

Harvesting operations and energetics of tall grasses for biomass energy production: A case study

The U.S.A. imports about 50% of its energy needs while Florida imports about 85%. Among the renewable energy sources available, biomass appears promising especially in the southeast which includes Florida because of a favorable environment for production and the available methods to convert biomass to energy. Optimal production of biomass requires the identification and management of high yielding persistent perennial cultivars. Elephantgrass (Pennisetum purpureum Schum.) and energycane (Saccharum spontaneum L.) are two tall grasses that meet these requirements. To optimize the supply of convertible biomass, suitable methods of harvesting the crop must be available. The purpose of this research was to study the feasibility and energetics of harvesting, drying, and baling tall grasses with conventional farm machinery.

A Mathews rotary scythe and a New Holland 849 Auto Wrap large round baler were determined to provide a practical harvesting system for baled biomass averaging 15–27 Mg ha⁻¹. The rotary scythe can be used for harvesting and fluffing or turning a windrow over to expedite drying. This harvesting system requires about 3 kg diesel fuel Mg⁻¹ dry biomass (DB), 25 min of time Mg⁻¹ DB, and a cost of about $10 to 12 Mg⁻¹ DB. Energy requirements of harvesting operations would be about 300–375 MJ Mg⁻¹ DB, and primary energy requirements for production and harvesting are about 1100–1500 MJ Mg⁻¹ DB. For each unit of fossil fuel invested in the total production and harvesting system, 12–15 units would be returned in biomass.     

Containerized handling to minimize hauling cost of herbaceous biomass

Herbaceous biomass can contribute to the renewable energy supply for electricity, process steam, liquid fuel, and commodity chemicals. Efficient systems to harvest and store round bales of perennial grass in storage locations within 5 km of the production fields are available. The major limitations are loading these bales at the storage locations and hauling to meet a weekly demand schedule at a processing plant operating continuously for 50 weeks yr⁻¹. Analysis is presented for a 27 Mg h⁻¹ plant.

The concept is to pack 32, 1.5-m round bales into a container with the same dimensions as a 12.2-m (40-ft) ISO shipping container. These containers are loaded at a satellite storage location, hauled to a receiving facility at the processing plant, and unloaded. The analysis examines two options. Option 1 uses a forklift to place a loaded container onto a standard transport chassis at the satellite storage location. A similar forklift unloads the containers at the receiving facility. Option 2 uses a Swinglift trailer that loads and unloads the containers onto the trailer using on-board hydraulics.

The cost for Option 1 was calculated at $7.80 dry Mg⁻¹, as compared with $8.37 dry Mg⁻¹ calculated for Option 2. The cost for Option 1 is lower even though the forklift used at the satellite storage location in Option 1 is only operated at 27% of daily capacity, thus operating cost per dry Mg to load is higher than it would be if scheduling could be done such that more containers could be loaded each workday. The forklift spends most of the time waiting for the container to be packed with bales. The limiting factor established in this analysis is the feasibility of packing 32 bales into a container within an allowed 30 min.     

Quantification and use of forest biomass residues in Maputo province, Mozambique

This article describes a study on the quantification and use of forest biomass residues in Maputo province, in Mozambique. The study was performed based on information from the thematic cartography of soils of Maputo province, provided by the National Direction of Forest and Land of Mozambique, and data for the forest growth rates available in the literature. It was estimated that the total production of forest biomass residues in Maputo province is 1,233,412 ton/year, with a corresponding energy potential of 17,267,771 GJ/year. As a way of making the forest biomass residues profitable, the present work proposes the use of part of the residues as fuel in new power plants to be build in Maputo province. In this part of the study aiming at implanting power plants in Maputo province, it was taken into account the risk of forest fires, number of existing consumers of forest residues, residues availability, protected forests, transport infrastructures and existence of national electric network. It was found that the districts of Magude and Moamba are those that have the best conditions to receive the new biomass power plants. Factors such as the cost of the technology and the degree of pre-treatment of the forest residues have been taken into consideration in choosing the combustion technology for the proposed power plants. In this context, the grate burning technology appears to be the most advantageous from costs/benefits viewpoint. The proposed power plants can produce about 236,520 MWh, which is equivalent to 32% of the energy consumed in Maputo province in 2004.     

Quality of gas produced from wheat straw in a dual-distributor type fluidized bed gasifier

A 400 kW, dual distributor type fluidized bed gasifier was used to investigate the production rate and composition of the gas produced from wheat straw at various equivalence ratios (0.17, 0.20, 0.25, 0.35) and fluidization velocities (0.28, 0.33 and 0.37 m s⁻). The results showed that the equivalence ratio was the major parameter affecting the gas composition. The equivalence ratio of 0.25 appeared to be the optimum with respect to the quality of the gas. The mole fractions of the combustible components reached their maximum values at this equivalence ratio. A typical gas composition at the equivalence ratio of 0.25 was 7% H₂, 7% hydrocarbons (CH₄, C₂H₂, C₂/H₄ and C₂H₆), 14% C0₂, 22% CO and 50% N₂. The higher heating value of the produced gas (6.3–7.3 MJ Nm⁻³) obtained at this equivalence ratio appeared to be higher than most values reported in the literature for several types of biomass fuels.     

Miscanthus sinensis ‘giganteus’ production on several sites in Austria

In Austria it is planned to use Miscanthus sinensis ‘Giganteus’ as a renewable energy source. The influence of site, age of crop and time of harvest on yield, water content, nitrogen content and quality was investigated. In the first year the yield was 0.7 to 2 t dry matter ha⁻¹, in the second year 7.9 to 15.5 t ha⁻¹ and in the third year 17.4 to 24.5 t ha⁻¹. In February of the first year the water content was 40 to 50%, in the second year 34 to 49% and in the third year 24 to 38%. Sufficient precipitation (about 800 mm) in mild climates is required for high yields. On sites with more rain the water content of the plants was higher. Water and nitrogen content decreased significantly during the six week period from January to the end of February. In February of the first year the nitrogen content was 7.8 to 16.6 g kg⁻¹ dry matter, in the second year 3.7 to 6.2 g kg⁻¹ and in the third year 2.6 to 7.5 g kg⁻¹. The calorific value was as high as that of firewood (18 to 19 MJ kg⁻¹ ). The ash content exceeded firewood but was lower than that of straw. By the third year of cultivation 60 to 150 kg N ha⁻¹, 100 to 200 kg K20 ha⁻¹, 10 to 35 kg P₂ O₅ ha⁻¹, 10 to 25 kg MgO ha⁻¹ and 20 to 35 kg CaO ha⁻¹ had to be taken up by the harvest at the end of February.     

Conversion of straw and similar agricultural wastes

Mainly the economic aspects prevent a far more extensive use of biomass, including straw as a fuel in energy supply.

During the latest years several straw fired plants have been put in operation, especially in Denmark, and they have demonstrated that both district heating and combined heat and power (CHP) production based on straw are technically possible.

However, experience has shown that a very precise research and development effort is necessary before the straw fired plants are competitive to traditional plants fired with fossil fuels, as to operational safety and economy.

The R & D activities ought first and foremost to aim at: 1) Reduction of costs connected to all processes from harvest to energy production, 2) wider know-how of the firing and combustion technical characteristics of straw, and 3) environmental conditions, including emissions and ash depositing problems.     

Agronomic characteristics of US 72-1153 energycane for biomass

Biomass production and plant quality vary between plant species and morphological components of a plant. The purpose of this two-part experiment was (1) to study the influence of energycane [Saccharum sp. (L.) ‘US 72-1153’] harvest treatments (6) on dry biomass yield and (2) monitor changes in quantity and quality of plant components with increased plant height. Treatments for Part 1 determined the influence of plant height when harvested at 1.2, 2.5, and 3.7 m, mature stage in October (4.9 m, in flower), mature stage in December (4.9 m, in flower), and additional treatment harvested in October, which received half the total N (168 kg ha⁻¹) on dry biomass yield from 1986 to 1989. Part 2 treatments were to monitor changes in quantity and quality (crude protein and in vitro organic matter digestion) of plant components (green leaf, dead leaf, and stem) at 0.6 m plant height increments to a final height of 4.3 m during 1986 and 1987. Treatments from both parts of the study received 25 kg P ha⁻¹ and 93 kg K ha⁻¹ in one application and 336 kg N ha⁻¹ yr⁻¹ in single or split applications applied prior to growth of each harvest. Plants repeatedly harvested at the 1.2 m height (Part 1) and mature stage produced a 4-year average yield of 10 and 48 Mg ha⁻¹ yr⁻¹ dry biomass, respectively and decreased in dry biomass yield 89% (1.2 m harvest) and 53% (mature harvest) between years 1 and 4. The stem (1986 and 1987) and dead leaf (1986) plant components increased quadratically as plant height increased, and green leaf decreased from 70% (0.6 m) to 17% (4.3 m height). The crude protein concentration decreased 51% (green leaf) and 81% (stem) and in-vitro organic matter digestion decreased 54, 32, and 34% for dead leaf, green leaf, and stem, respectively as plant height increased from 0.6 to 4.3 m. These data indicate that harvest management is an important factor for energycane biomass yield, ratoon-crop success and plant quality if biomass is used as a methane source.     

Geographic distribution of economic potential of agricultural and forest biomass residual for energy use: Case study Croatia

This paper provides methodology for regional analysis of biomass energy potential and for assessing the cost of the biomass at the power plant (PP) location considering transport distance, transport costs and size of the power plants. Also, methodology for determination of an upper-level price of the biomass which energy plant can pay to the external suppliers has been proposed. The methodology was applied on the case of Croatia and energy potential of biomass in the Croatian counties was calculated, using different methodologies, for wheat straw, corn stover and forestry residues, types of biomass considered economically viable at the moment. Results indicate that the average energy potential of wheat straw is 8.5 PJ, corn stover 7.2 PJ and forestry residues 5.9 PJ.