Woody biomass supply potential for thermal power plants in Japan

Biomass energy is one of mitigation method of CO₂ reduction. In Japan, it aimed to reduce fossil fuels supply 670,000 kL of crude oil equivalent in thermal power plants and 340,000 kL of crude oil equivalent in the utilization of heat by biomass. It was decided to use 25% or more of the forestry products such as logging residues. Japanese government aim to supply 634 PJ of woody biomass for power generation in 2010. This amount of energy accounts for 2.8% of total primary energy. More than 68% of Japan is covered by forests, and more than 40% of these forests are plantations. But the use of woody biomass is limited because it is still not seen as economically viable. In this article, we developed a large scale forestry economic model which can estimate the wood chips supply for coal thermal power plants across all around Japan. By using this model, wood chips supply potential is currently 32,000 m³/year and supply will increase drastically when wood chips price increase or carbon credit is installed and we found that biomass production of 15 PJ that is the numeric target of Japanese government is possible. Especially, the lengthening of rotation period of forestry and the decrease of wood chips transportation cost is important for wood chips use in coal thermal plant.     

Possibility of efficient utilization of wood waste as a renewable energy resource in Serbia

Wood biomass in Serbia is traditionally used for energy. However, the manner of its use is outdated, and efficiency is very low. Annually over 3.5 million m³ of wood is cut down for energy needs in Serbia. In order to better exploit all forms of woody biomass, especially the one that is now treated as waste, and in order to fulfil the obligations from the outlined Convention on Climate Change it is necessary to switch to a modern way of production and utilization of woody biomass. Serbia is now at the very beginning of this process. This paper gives an overview and an analysis of the possibilities of utilization of wood waste as a renewable source of energy and the problems that producers in Serbia are facing due to undeveloped markets and excessive funds that are needed to start the production of briquettes and pellets. The ecological and economical advantages of using woody biomass, as well the possible support measures for the use of woody biomass in Serbia are also the topic of this paper. The present situation in this area, the manner of waste management in sawmills and the reasons for the necessity of future development of this industrial production are also briefly described.     

A comparative investigation of various greenhouse heating options using exergy analysis method

This study deals with modeling and analyzing the performance of greenhouses from the power plant through the heating system to the greenhouse envelope using exergy analysis method, the so-called low exergy or LowEx approach, which has been and still being successfully used in sustainable buildings design, for the first time to the best of the author’s knowledge. For the heating applications, three options are studied with (i) a solar assisted vertical ground-source heat pump greenhouse heating system, (ii) a wood biomass boiler, and (iii) a natural gas boiler, which are driven by renewable and non-renewable energy sources. In this regard, two various greenhouses, the so-called small greenhouse and large greenhouse, considered have heat load rates of 4.15 kW and 7.5 MW with net floor areas of 11.5 m² and 7.5 ha, respectively. The overall exergy efficiency values for Cases 1–3 (solar assisted vertical ground-source heat pump, natural gas boiler and wood biomass boiler) of the small greenhouse system decrease from 3.33% to 0.83%, 11.5% to 2.90% and 3.15% to 0.79% at varying reference state temperatures of 0 to 15 °C while those for Cases 1 and 2 (wood biomass and natural gas boilers) of the large greenhouse system decrease from 2.74% to 0.11% and 4.75% to 0.18% at varying reference state temperatures of −10% to 15 °C. The energetic renewability ratio values for Cases 1 and 3 of the small greenhouse as well as Case 1 of the large greenhouse are obtained to be 0.28, 0.69 and 0.39, while the corresponding exergetic renewability ratio values are found to be 0.02, 0.64 and 0.29, respectively.     

EUBIONET III—Solutions to biomass trade and market barriers

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

The economic potential of wood pellet production from alternative,low-value wood sources in the southeast of the U.S.

The global demand for wood pellets used for energy purposes is growing. Therefore, increased amounts of wood pellets are produced from primary forestry products, such as pulp wood. The present analysis demonstrates that substantial amounts of alternative, low-value wood resources are available that could be processed into wood pellets. For three resources, test batches have been produced and tested to qualify for industrial pellet standards. These include: primary forestry residues from premerchantable thinning operations, secondary forestry residues from pole mills and post-consumer wood wastes from discarded wooden transport pallets. The total wood potential of these resources in the southeast of the U.S. (Florida, Georgia, North Carolina, South Carolina), was estimated to be 1.9 Tg y⁻¹ (dry) available at roadside (excluding transport cost) for 22 $ Mg⁻¹ (dry) increasing to over 5.1 Tg y⁻¹ at 33 $ Mg⁻¹ (dry). In theory, 4.1 Tg y⁻¹ pellets could be produced from the estimated potential. However, due to the geographically dispersed supply of these resources, the cost of feedstock supply at a pellet plant increases rapidly at larger plants. It is therefore not expected that the total potential can be processed into wood pellets at costs competitive with those of conventional wood pellets. The optimal size of a pellet plant was estimated at between 55 Gg y⁻¹ and 315 Gg y⁻¹ pellets depending on the location and feedstock supply assumptions. At these locations and plant sizes, pellets could be produced at competitive costs of between 82 $ Mg⁻¹ and 100 $ Mg⁻¹ pellets.     

Southeastern United States wood pellets as a global energy resource: a cradle-to-gate life cycle assessment derived from empirical data

Given increased policies driving renewable electricity generation and insufficient local production of woody biomass, many countries are reliant upon the importation of wood pellets. Of current wood pellet exports, the vast majority originates from the Southeastern United States (US). In this paper we present results from a cradle-to-gate, attributional process life cycle assessment in which two production scenarios of wood pellets were modelled for the Southeastern US: one utilising roundwood from a silviculture operation and the other utilising sawmill residues. The system boundary includes all steps from harvesting of the wood biomass, through delivery of the finished wood pellets to a US port facility. For each of the impact categories assessed, wood pellets from sawmill residues resulted in higher values, ranging from 5% to 31%. In relation to Global Warming Potential, roundwood pellets resulted in a 13–21% lower value than pellets produced from sawmill residues, depending upon the allocation method.     

An environmental impact assessment of exported wood pellets from Canada to Europe

There have been increased interests on exporting wood pellets from Canada to Europe to meet the increased demand on biofuels in European countries. The wood pellet industry in Canada, especially in the west coastal region, has grown at an annual rate of more than 20% averaged over last 5 years due to the steady supply of wood residues. This paper attempted to analyze the fuel consumption and air emissions associated with the wood pellet production in British Columbia and export to Sweden based on a streamlined life cycle analysis, starting from tree harvesting for wood residue production to the shipping of wood pellets from Vancouver to Stockholm in Sweden. The results showed that about 7.2 GJ of energy is consumed for each tonne of wood pellets produced and shipped to Europe, representing about 39% of the total energy content of the wood pellets. Among those energies consumed over the life cycle, about 2.6 GJ is associated with long-distance ocean transportation. The ocean transportation is also the major contributor to environmental and health impacts, followed by the pellet production processes. The fossil fuel content, which quantifies the amount of fossil fuel consumed over the life cycle, for exported wood pellets ranged from 19% to 35%, depending on whether natural gas or wood residue is used in the drying operation during the wood pellet production stage. To reduce the fossil fuel content and the environmental impacts, wood residues should be used in the drying operation and, if possible, local market should be explored to reduce the energy consumption associated with wood pellet transportation over long distances.     

Productivity and cost of mechanized energy wood harvesting in Northern Scotland

At present, the utilization of timber in the Northern part of the Scottish Highlands is low due to a lack of a wood utilizing industry. As a consequence, the majority of forest owners do not receive any income from timber and in some cases stumpage prices can even be negative. At the same time, increasing prices of oil, gas and electricity pose a great challenge for local industries and homeowners. The establishment of wood fueled heating systems is therefore expected to improve the situation and at the same time create a market for the local timber resources. Consequently, a local energy source to produce heat and electricity at a competitive price would have positive benefits for both local industries and forest owners. Due to the current lack of competition, roundwood could be chipped for fuel, which has many associated benefits compared to the harvesting and chipping of logging residues. It is the aim of this research to apply existing Finnish know-how in regards to wood fuel harvesting in order to develop and investigate the price level of sustainable and local wood fuel supply chains.To determine the most suitable supply chain for forest fuels, various research methods were applied. An estimation of the forest resources in the Wick area was the first step of the research. The different cost components of the supply chain such as cutting, forwarding and chipping were then calculated based on Finnish experiences and adapted to conditions in Northern Scotland. Detailed transportation distance calculations and cost of transportation were calculated using GIS tools.Of the various supply chain designs considered, chipping at the landing seems to be the most suitable option. Chipping the roundwood at a central terminal would also be feasible; however, a suitable site would have to be identified since chipping of the material at the heating plant is not an option. Calculations indicate that forest chips can be delivered starting from approximately 20 € MWh⁻¹ within a 50 km transportation distance when chipping is at roadside. If the transportation distance is 100 km wood chips could be delivered at approximately 23 € MWh⁻¹. Results from the GIS analysis indicate that a sufficient supply of raw material will be available in the future. According to these calculations forest fuels can be a competitive energy source for heat and electricity production in Northern Scotland.     

Sickle bush (Dichrostachys cinerea L.) field performance and physical–chemical property assessment for energy purposes

The sickle bush (Dichrostachys cinerea (L.) Wight & Arn.) comprises a woody legume shrub which is widely distributed throughout of the tropical areas of Africa, Asia and Oceania, being found as well in Cuba where it represents a difficult to control invasive plant. It holds great silvopasture and energy crop potentials. In southwestern Spain a two year field trial was conducted contemplating also another six hardwood taxa commonly used as energy crops. The sickle bush above ground dry biomass fraction was 60.4%; sickle bush displayed a high transpiration rate during hot days (3.02 kg m⁻² d⁻¹ to 6.82 kg m⁻² d⁻¹); cold winter temperatures (<−2 °C) together with hot and dry summer air (<20% relative humidity) committed survival and growth. The physical-chemical wood properties and the pellets thereof derived were analyzed and compared to those of the other energy crop taxa. The within other woody species normal chemical composition range coupled to a high wood density and energetic use properties (19.2 MJ kg⁻¹ higher heating value, 29 g kg⁻¹ ash content) all allow for an industrial use. Pellets evidenced also good physical and mechanical properties (690 kg m⁻³ bulk density, 42 g kg⁻¹ moisture content). However, the mechanical durability (93.9%) was slightly less than that required by the non-industrial use standards, therefore further improvements should be studied. All of the above could encourage scrubland cuts in Cuba as a mechanical control method, in addition to the expansion of plantations within of their tropical climate based natural habitats.     

A GIS-based analysis on the relationship between the annual available amount and the procurement cost of forest biomass in a mountainous region in Japan

The feasibility of utilization of forest biomass for energy in a mountainous region in Japan is discussed based on analyses with a geographic information system (GIS). In this study, ‘forest biomass’ denotes logging residues, thinned trees, and trees from broad-leaved forests. First, using the GIS, the distribution map of biomass resources was completed, and the topographical information of each sub-compartment was prepared. Second, harvesting and transportation systems were classified into six types by fraction of tree for energy (two types) and by topographical conditions (three types). Equations for cost calculation were developed and included the variables slope, skidding/yarding distance, and transportation distance. Finally, the relationship between the mass and the procurement cost of forest biomass in the region was analyzed. The results show that logging residues (the available amount was 4.035 Gg y⁻¹ on a dry-mass basis) were the least costly followed by broad-leaved forests (20.317 Gg y⁻¹) while thinned trees (27.854 Gg y⁻¹) were the most costly. The analysis may support operational planning, especially the decision of selecting sub-compartments to be felled. For instance, the amount of biomass needed to supply a power-plant covering 24.8% of the regional household need was calculated to 30.106 Gg y⁻¹. This amount of forest biomass could optimally be harvested from sub-compartments whose procurement costs were lower than 108.6 US$ Mg⁻¹.     

Pd-Ag dense membrane application to improve the energetic efficiency of a hydrogen production industrial plant

This paper investigates the possibility of increasing the energetic efficiency of a hydrogen production industrial plant through the introduction of dense membranes in the steam reforming process. A simulation tool, developed in the Aspen Plus^® framework has been used to model a 1500 N m³/h hydrogen production plant. Besides the original plant layout with a PSA purification unit, three different membrane installation configurations have been considered: before the shift reactor, at the exit of the shift reactor and before the PSA unit. For all the three configurations the plant capacity was set at 75%, changing the permeated hydrogen flow. The membrane surface and cost were also estimated for each solution. Membranes installation just after the shift reactor gives the best solution in terms of both plant energetic efficiency and cost reduction.     

Worldwide commercial development of bioenergy with a focus on energy crop-based projects

Bioenergy consumption is greatest in countries with heavy subsidies or tax incentives, such as China, Brazil, and Sweden. Conversion of forest residues and agricultural residues to charcoal, district heat and home heating are the most common forms of bioenergy. Biomass electric generation feedstocks are predominantly forest residues (including black liquor), bagasse, and other agricultural residues. Biofuel feedstocks include sugar from sugarcane (in Brazil), starch from maize grain (in the US), and oil seeds (soy or rapeseed) for biodiesel (in the US, EU, and Brazil). Of the six large land areas of the world reviewed (China, EU, US, Brazil, Canada, Australia), total biomass energy consumptions amounts to 17.1 EJ. Short-rotation woody crops (SRWC) established in Brazil, New Zealand, and Australia over the past 25 years equal about 50,000 km². SRWC plantings in China may be in the range of 70,000–100,000 km². SRWC and other energy crops established in the US and EU amount to less than 1000 km². With some exceptions (most notably in Sweden and Brazil), the SRWC have been established for purposes other than as dedicated bioenergy feedstocks, however, portions of the crops are (or are planned to be) used for bioenergy production. New renewable energy incentives, greenhouse gas emission targets, synergism with industrial waste management projects, and oil prices exceeding 60 $ Bbl⁻¹ (in 2005) are major drivers for SRWC or energy crop based bioenergy projects.     

A study of energy production from cork residues: Sawdust,sandpaper dust and triturated wood

In the present work the gasification process of cork residues sourced in an industrial procedure in the regions of Extremadura (Spain) and Alentejo (Portugal) was studied. These by-products were classified as black agglomerates (low and high granulate), sandpaper dust (white agglomerate) and triturated wood. Samples of several residues obtained through different phases of the cork manufacturing process were collected and next quantified. In order to test their ability to produce energy, all the referred residues were gasified. The air flow was varied, ranging from 50 up to 400 cm³ min⁻¹. The thermal treatment temperature was also varied from 650 °C up to 800 °C. The experimental results indicate that the optimal conditions in terms of energy production were an air flow equal to 200 cm³ min⁻¹ and a treatment temperature of 800 °C.     

Optimizing the mixture of wood biomass for greenhouse heating

This paper presents the development of a linear programming model to determine the optimum fuel mix for greenhouse heating. The model is applied to two cases (a 7.5 hectare (ha) vegetable greenhouse and a 2 ha flower greenhouse) in British Columbia, which use a combination of wood pellets and wood residue to provide heat. The objective of the model is to minimize the annual total cost of combusting wood pellets and wood residue, while the heat demand is satisfied and all resources and emission limitations are not exceeded. The boiler system was enhanced with an electrostatic precipitator to limit the particulate matter emissions to acceptable levels. The results show that the optimal fuel mix for a 2 ha flower greenhouse is 641 tonne (t) of wood pellets and 381 t of wood residues, and it is 10 106 t of wood pellets and 3007 t of wood residues for a 7.5 ha vegetable greenhouse. The minimized annual total cost, including amortized capital cost, is estimated to be C$216 030 y^?1 and C$1 611 866 y^?1 for a 2 ha flower greenhouse and a 7.5 ha vegetable greenhouse, respectively. A sensitivity analysis indicated that these optimal solutions would not change even when the variable costs (material cost and emission fee) of wood pellets decreased by 58% or the variable costs of wood residue increased by 150%. Copyright © 2008 John Wiley & Sons, Ltd.     

Evolution of the Wairakei geothermal reservoir during 50 years of production

The Wairakei geothermal field has been under production for more than 50 years. Exploration wells show that the high-temperature and very permeable, productive resource extends over about 12 km² within a greater area of about 25 km² that shows various effects of thermal activity. Up to 2006, 3 km³ of fluid and 2750 PJ of energy had been extracted at an average rate of 5250 t/h and enthalpy of 1130 kJ/kg. Significant production started in 1955 and up to 1978 there was no injection of cooled geothermal fluids. During the first decade of operation a pressure drawdown of up to 20 bars (2 MPa) developed and spread evenly across the reservoir, even though fluid extraction was focused within an area of 1 km² close to the northeastern field boundary. This pressure reduction resulted in widespread boiling and formation of segregated steam zones at the top of the reservoir together with inflow of cooler fluids into its northeastern part via the original natural outflow channels. From 1975 to 1997 pressures in the deep liquid reservoir stabilized at 23–25 bars (2.3–2.5 MPa) below the original pressure, with little change up to the time injection commenced in 1998. This natural pressure support indicates that prior to injection there was substantial recharge, 80% of which is assessed as high-temperature deep inflow. Since 1998 about 30% of the extracted fluids have been injected and reservoir pressures have increased by 3–4 bars (0.3–0.4 MPa). To date, significant returns of injected fluids have not been detected in the production areas. Over the 50 years of operation, temperatures in the main production areas have declined from 250 to 220 °C while deeper production zones toward the western boundary of the reservoir have remained at about 250 °C. A series of deeper makeup wells to maintain future production have been drilled in the high-temperature recharge area. An increasing fraction of injection, both in-field and out-field is planned over the next few years.     

Synthesis gas production by biomass pyrolysis: Effect of reactor temperature on product distribution

This paper describes mass, C, H, and O balances for wood chips pyrolysis experiments performed in a tubular reactor under conditions of rich H₂ gas production (700–1000 °C) and for determined solid heating rates (20–40 °C s⁻¹). Permanent gases (H₂, CO, CH₄, CO₂, C₂H₄, C₂H₆), water, aromatic tar (10 compounds from benzene to phenanthrene and phenols), and char were considered in the balance calculations. Hydrogen (H) from dry wood is mainly converted into CH₄ (more than 30% mol. of H at 900 °C), H₂ (from 9% to 36% mol. from 700 to 1000 °C), H₂O, and C₂H₄. The molar balances showed that the important yield increase of H₂ from 800 to 1000 °C (0.10 Nm³ kg⁻¹ to 0.24 Nm³ kg⁻¹ d.a.f. wood) cannot be solely explained by the analyzed hydrocarbon compounds conversion (CH₄, C₂, aromatic tar). Possible mechanisms of H₂ production from wood pyrolysis are discussed.     

Assessing plantation biomass for co-firing with coal in northern Indiana: A linear programming approach

Tightening environmental regulations and the signing of the Kyoto Protocol have prompted electric utilities to consider co-firing biomass with coal to reduce the levels of CO₂, SO₂, and NO_x in stack emissions. This analysis examines the cost competitiveness of plantation produced woody biomass and waste wood with coal in electricity production. A case study of woody biomass production and co-firing in northern Indiana is presented. A Salix (willow) production budget was created to assess the feasibility of plantation tree production to supply biomass to the utility for fuel blending. Co-firing with waste wood from primary and secondary wood processing activities and local municipalities also is considered. A linear programming model was developed to examine the optimal co-firing blend of coal and biomass while minimizing variable cost, including the cost of ash disposal and material procurement costs. This model was used to examine situations where coal is the primary fuel and waste wood, willow trees, or both are available for fuel blending. The results indicate that co-firing woody biomass is cost-effective for the power plant. Sensitivity analysis explored the effect of waste wood prices on co-firing cost.     

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

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

Hydrogen production from biopolymers by Caldicellulosiruptor saccharolyticus and stabilization of the system by immobilization

The biopolymers agarose and alginic acid, and hemicellulose-rich pine tree wood shavings, frequently discarded as waste, proved to be utilized as energy sources for hydrogen production by the extreme thermophilic bacterium Caldicellulosiruptor saccharolyticus. The addition of 0.5% (w/v) pine wood shavings to the growth medium yielded a 14-fold increase in hydrogen production over a period of 55 days relative to cultures grown in the same medium without wood shavings (average rate was about 0.45 ml H₂ ml culture⁻¹ day⁻¹). The shavings were also shown to be degraded by C. saccharolyticus in the absence of any other carbohydrate source.     

Techno-economic comparison of series hybrid, plug-in hybrid, fuel cell and regular cars

We examine the competitiveness of series hybrid compared to fuel cell, parallel hybrid, and regular cars. We use public domain data to determine efficiency, fuel consumption, total costs of ownership and greenhouse gas emissions resulting from drivetrain choices. The series hybrid drivetrain can be seen both as an alternative to petrol, diesel and parallel hybrid cars, as well as an intermediate stage towards fully electric or fuel cell cars.We calculate the fuel consumption and costs of four diesel-fuelled series hybrid, four plug-in hybrid and four fuel cell car configurations, and compared these to three reference cars. We find that series hybrid cars may reduce fuel consumption by 34-47%, but cost €5000-12,000 more. Well-to-wheel greenhouse gas emissions may be reduced to 89-103 g CO₂ km⁻¹ compared to reference petrol (163 g km⁻¹) and diesel cars (156 g km⁻¹). Series hybrid cars with wheel motors have lower weight and 7-21% lower fuel consumption than those with central electric motors.The fuel cell car remains uncompetitive even if production costs of fuel cells come down by 90%. Plug-in hybrid cars are competitive when driving large distances on electricity, and/or if cost of batteries come down substantially. Well-to-wheel greenhouse gas emissions may be reduced to 60-69 g CO₂ km⁻¹.