Comparative economic analysis of perennial, annual, and intercrops for biomass production

Herbaceous crops may be an important source of renewable energy. Production costs can be more competitive by increasing yields so that overhead costs are applied to more biomass. Most previous economic studies of energy crops have concentrated on the production of switchgrass (Panicum virgatum L.). This study analyzes the biomass yield and economic potential of several high-yielding annual and perennial crops on prime and marginal, sloping land. Crops evaluated were reed canarygrass (Phalaris arundinacea L.) harvested twice per year; switchgrass and big bluestem (Andropogon gerardii Vitman var. gerardii); alfalfa (Medicago sativa L.); and sweet sorghum, forage sorghum [both Sorghum bicolor (L.) Moench], and maize (Zea mays L.). The intercropping of the two sorghum species into reed canarygrass and alfalfa was also analyzed. All crops but alfalfa were fertilized with 0, 70, 140, or 280 kgNha⁻¹, with economic analysis performed assuming 140 kgNha⁻¹. Sorghums were most productive, with more than 16 t of dry matter ha⁻¹. Switchgrass was the highest-yielding perennial crop. Costs per ton of biomass produced were lowest for sorghum, somewhat higher for switchgrass, higher still for big bluestem, and highest for alfalfa and reed canarygrass. Yields per ton for intercropped species were higher than for perennial species but lower than for monocrop sorghum. Costs per ton for intercropped species were less than for either alfalfa or reed canarygrass, but were higher than costs per ton of monocrop sorghum. Although the sorghums had the highest yields, high potential for erosion on sloping soils may preclude their use on these soils.     

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.     

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.     

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.     

Effects of nutrient supply and soil cadmium concentration on cadmium removal by willow

This investigation studied the effect of an increased biomass production as a result of fertilization and an elevated Cd concentration in the topsoil on concentration and amount of Cd in two clones of Salix (81090 and 78183). The experiment was conducted over a three year period using 200-dm³ lysimeters filled with clay soil. A liquid fertilizer containing all essential macro- and micronutrients in balanced proportions by weight was applied at two rates according to growth. The lower rate corresponded to 0, 20 and 20 kg N ha⁻¹ during years 1, 2 and 3, respectively, while the higher rate was 30, 60 and 60 kg N ha⁻¹ for the same period. The Cd levels in the topsoil were an initial content of 0.3 mg Cd (kg dw soil)⁻¹ and 0.6 mg Cd (kg dw soil)⁻¹ after addition of CdSO₄.

Biomass production increased significantly due to fertilization. In general, this increase in biomass resulted in a higher Cd amount in the stem. However, the magnitude was small and only statistically significant in some cases, mainly because increased biomass also resulted in a lowered Cd concentration due to an effect of biological dilution. Addition of Cd to the topsoil resulted in higher Cd concentrations and total Cd amounts (concentration×biomass) in the Salix plants. In most cases the increase in total stem Cd amount was 40–80% of the increase in soil Cd concentration, although a directly proportional increase was observed occasionally. Clone 81090 had higher concentrations and total amounts of Cd in the stems than clone 78183, while clone 78183 produced more stem biomass. The leaves had the highest Cd concentrations, but the total amounts of Cd were largest in the stems.     

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.     

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.     

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.     

Effect of fertilization on the biomass production of coppiced mixed birch and willow stands on a cut-away peatland

This investigation deals with the biomass production of coppiced mixed birch and willow stands growing on a peat cut-away area at Aitoneva, Kihniö (62°12′N, 23°18′E), Finland. The 16-year-old stands were harvested and left to coppice for 14 years, fertilization experiment (control, PK and wood ash fertilization) with three replications was established after the clear cutting. The mother stands before clear cutting (11,000 stems per hectare on average) were dominated by silver birch (69% of the stem number). After clear cutting the number of stems rose 7-fold to 75 500 stems ha⁻¹. Now the stands were dominated by Betula pubescens with 46% out of the total stem number, the share of B. pendula being only 25% and with Salix spp 29%. At the age of 14 years self-thinning had decreased the stem number to 12,800 stems ha⁻¹. The leafless biomass production of the coppiced stands on the control plots was lower than that of the seed originated mother stands had been during the previous rotation. However, with fertilization the 14-year-old coppiced stands reached the same total production as the 16-year-old mother stands had reached. The foliar phosphorus concentrations showed a severe phosphorus deficiency on the controls. Fertilization increased biomass of the stands considerably. After 14 growing seasons the above-ground leafless dry-mass of the fertilized stands was 61.8 (PK-fertilization) and 61.4 t ha⁻¹ (Ash) and that of the control stands 37.6 t ha⁻¹. A single PK fertilizer application had increased the standing biomass by 24 t ha⁻¹ (64%). Even though fertilization increased biomass production it did not increase nutrient concentrations of wood and bark, but rather decreased them. Fertilization decreased the nitrogen concentrations of leafless above-ground biomass.     

Biomass equations for determining fractions of European aspen growing on abandoned farmland and some practical implications

A study was conducted in order to construct functions for aboveground biomass of fractions of young European aspens (Populus tremula L.). The constructed functions were designed to be used for predicting the amount of biofuel produced from small areas. Biomass production was estimated in 11 stands of European aspen growing on abandoned farmland. The stands were located in Sweden at latitudes ranging from 65° to 60° N, and their total age varied from 5 to 24 years. A modified “mean tree technique” was used to estimate biomass production; i.e. depending on the plot area size, the number of sampled trees was chosen. The mean total dry weight above stump level for aspen stands was 78 tonnes ha⁻¹ with a range of 14–162 d.w. ha⁻¹. Mean annual increment for the stands was 5.56 tonnes ha⁻¹ year⁻¹ (2.86–9.15). Aspens growing on silt soils produced more than on fine sand soils. In addition to estimating conventional dry weights of trees and tree components, specific leaf area, total surface area and LAI, among other measures, were estimated. The mean LAI was 2.58 and the specific leaf area was 9.4 m² kg⁻¹. Some practical implications are given.     

Bio-oils from arid land plants: Flash pyrolysis of Euphorbia characias bagasse

The devolatilization of the bagasse obtained by solvent extraction of dried Euphorbia characias, a bushy plant growing in arid land of the Mediterranean area, was investigated under rapid heating conditions at atmospheric pressure using a bench-scale fluidized bed pyrolyser. Particle heating rates exceeded 10⁴°C s⁻¹. Bagasse was fed continuously at the rate of 6 g h⁻¹ directly into a sand bed fluidized by nitrogen operating in the temperature range of 400°–750°C. The yields of oils, gases and chars are reported. A maximum oil yield of 44% (wt/wt) (moisture free bagasse) was obtained at 500°C. Yields of gases, CO, CO₂, C₁–C₄ hydrocarbons increased with the rise in temperature, reaching a maximum at 750°C. Elemental analyses showed that the composition of oils and chars was dependent on pyrolysis temperature. The nitrogen content is fairly high; an upgrading process could be necessary for its remotion before the use of the bio-oil as combustible. The other characteristics of oils fall in the range of oils derived from other biomass feedstocks. Chars have a high HHV (15.36 MJ kg⁻¹ at 500°C), representing a valuable fuel.     

Growth patterns and biomass productivity of two Salix species grown under short-rotation intensive culture in southern Quebec

Samples of two species of Salix, Salix discolor, which grows naturally in the northern half of North America and S. viminalis, which originated from central Europe, were studied to compare their productivity and their growth patterns under the short-rotation, intensive-culture system (SRIC). The study was conducted in the nursery of the Montreal Botanical Garden on former agricultural land. The plantation was established at a density of 27,000 trees per hectare from unrooted cuttings without any fertilizer or irrigation. Growth parameters were measured at regular intervals during summer of the two first years following planting. At the end of each growing season, after leaf drop, a part of each plot was cut down and the stems and branches were harvested and weighed to evaluate their annual growth rates and their biomass yields. For the first growing season, height growth in both species was greater than 2 m. Although S. viminalis grew more rapidly early in summer, S. discolor grew about three weeks longer and its total height at the end of the growing season was greater than the former. Meanwhile the stem-branch dry weight of S. discolor was similar to the one produced by S. viminalis. Two growing seasons after establishment, the total tree height was about 3.5 m for both species, while the biomass of stems and branches of S. viminalis was weakly superior in comparison to S. discolor and reached very high values-about 27 Mg ha⁻¹ for S. viminalis. The growth patterns and yields of the one-year-old coppice (one-year-cycle) were similar to those recorded at the end of the first year for trees developed directly from cuttings. Both species produced a comparable quantity of sprout biomass. The yield of the trees harvested two years after planting was about twice the total biomass harvested two times, at the end of each growing season, suggesting that a two-year cycle is more productive than a one-year cycle.     

Biomass power cost and optimum plant size in western Canada

The power cost and optimum plant size for power plants using three biomass fuels in western Canada were determined. The three fuels are biomass from agricultural residues (grain straw), whole boreal forest, and forest harvest residues from existing lumber and pulp operations (limbs and tops). Forest harvest residues have the smallest economic size, 137 MW, and the highest power cost, $63.00 MWh⁻¹ (Year 2000 US$). The optimum size for agricultural residues is 450 MW (the largest single biomass unit judged feasible in this study), and the power cost is $50.30 MWh⁻¹. If a larger biomass boiler could be built, the optimum project size for straw would be 628 MW. Whole forest harvesting has an optimum size of 900 MW (two maximum sized units), and a power cost of $47.16 MWh⁻¹ without nutrient replacement. However, power cost versus size from whole forest is essentially flat from 450 MW ($47.76 MWh⁻¹) to 3150 MW ($48.86 MWh⁻¹), so the optimum size is better thought of as a wide range.

None of these projects are economic today, but could become so with a greenhouse gas credit. All biomass cases show some flatness in the profile of power cost vs. plant capacity. This occurs because the reduction in capital cost per unit capacity with increasing capacity is offset by increasing biomass transportation cost as the area from which biomass is drawn increases. This in turn means that smaller than optimum plants can be built with only a minor cost penalty. Both the yield of biomass per unit area and the location of the biomass have an impact on power cost and optimum size. Agricultural and forest harvest residues are transported over existing road networks, whereas the whole forest harvest requires new roads and has a location remote from existing transmission lines. Nutrient replacement in the whole forest case would make power from the forest comparable in cost to power from straw.     

Nitrogen mineralization of sewage sludge and composted poultry manure applied to willow in a greenhouse experiment

Nitrogen requirements for production of intensively cultured willow for use as a bioenergy crop coupled with the need for safe disposal of nutrient rich organic wastes provide an opportunity to reduce costs associated with bioenergy plantations. In order to minimize N leaching from sites treated with organic wastes, knowledge of the rate of N mineralization is needed. The objective of this study was to assess N mineralization rates of four organic residuals in a controlled greenhouse environment: composted poultry manure, composted sewage sludge, and anaerobically digested sewage sludge from two different municipalities. Thirty-six weeks after application, disappearance of the mass initially applied ranged from 20% to 50%. Gross nitrogen mineralization rate (N mass released expressed as a percentage of initially applied N) ranged from 12% to 57%. Non-composted treatments released greater amounts of nitrogen than composted treatments. Within composted treatments, net N release was estimated as 325 kgNha⁻¹ for poultry manure and 86 kgNha⁻¹ for sewage sludge. Syracuse and New York City sewage sludges, with 57% and 30% gross N release rates respectively, provided approximately 360 and 240 kg plant available Nha⁻¹, respectively. These estimates of N release suggest that the application rates could be halved and that sufficient N would be provided to meet crop needs and reduce leaching losses.     

Productivity and water use efficiency of sweet sorghum (Sorghum bicolor (L.) Moench) cv. “Keller” in relation to water regime

Sweet sorghum (Sorghum bicolor (L.) Moench) has been recognized as an alternative crop for energy purposes. In the central area of the Iberian Peninsula, its main growth period coincides with the dry season and irrigation is needed for reasonable sorghum productivity. Knowledge of irrigation-yield relationships is fundamental, since water is a scarce resource there. Our objectives in this work were to study the effect of water regime on the productivity and water use efficiency (WUE) in a sweet sorghum cultivar “Keller” grown in lysimeters in Madrid. Experiments were carried out during three crop cycles. Three irrigation regimes: H₁, H₂ and H₃, corresponding to a water supply of 5.7, 11.4 and 17.1 dm³ m⁻² day⁻¹ were experimented with during the main growth period. Maximum aerial biomass production was 4.0 10³g DM m⁻² in the H₃ regime. WUE was quite similar for every irrigation regime but varied between sorghum seasons. 4.6 g aerial biomass DM dm⁻³ was obtained as the average for a crop cycle length of approximately 130 days. The water regime did not clearly affect the sugar content in stalk sections. The mean value of sugar content in whole stalks was 41.4% w/w on a dry-weight basis. The ratio of ethanol production to evapotranspired crop water was estimated at 0.63 g dm⁻³ (mean value).     

Evaluation of usher wood and karkadeh stem for charcoal in Sudan

Two unusual biomass materials Hibiscus sabdarifja var. sabdariffa (karkadeh) stem and Calotropis procera (usher) wood were investigated in the laboratory as potential raw materials for charcoal making in Sudan. The materials were characterized physically and chemically and despite the low density and high bark-to-wood ratio by volume, good yields and quality of charcoal were predicted. The carbonization trials with a laboratory retort at conditions close to those of field metal kiln gave very good charcoal yields (35% for karkadeh and 38% for usher) with high energy transformation (58% and 62%, respectively). The karkadeh charcoal, except for a somewhat high ash content, was good for domestic uses (79% fixed carbon and 30.3 MJ kg⁻¹ heat value). The usher charcoal was better with respect to fixed carbon (86.5%) and gross heat value (32.4 MJ kg⁻¹ ). Both charcoals were of low density (140–160 kg m⁻³) and further assessment of their economic suitability should be carried out under field conditions. The carbonization by-products were also collected and characterized by means of gas chromatography.     

Quantity and quality of harvestable biomass from Populus short rotation coppice for solid fuel use—a review of the physiological basis and management influences

Woody biomass from poplar and aspen (Populus sp.) short rotation coppice (SRC) has good combustion properties compared to non wood solid bio fuels and fossil solid fuels. This review compiles and discusses relevant literature on fuel quality and yield for Central European conditions. The most problematic quality parameter of woody biomass from Populus SRC is its high water content at harvest time (55–60%). Storing unchipped material on the field during summer is an efficient tool to lower it. In order to control other quality parameters—mainly nitrogen (N), potassium (K) and heavy metal contents but also yield—one has to take into account the physiological background of SRC. Important features are species/clone, age of sprouts, growth pattern, site and nutrient cycling. Maximum mean annual increment (MAI) occurs later than in willows. Therefore rotations should be longer than in willow: at least 6–7 years for poplars and,—due to differences in growth pattern,—10 to 12 years for aspen. Both results in MAIs of 10–12 o.d.t.ha⁻¹ yr⁻¹ and reduced nutrient concentrations due to a lower share of branches and twigs in the harvested biomass. However, with elongated rotations costs rise because yet no automated (and thus cheap) harvest methods for large stem diameters were developed. Although sometimes ignored poplars are demanding concerning site characteristics. Basic requirements are good water (minimum 350 mm rainfall during growing season) and nutrient supplies, deep soils and favourable climatic conditions (average air temperature between June and September at least 14°C). Only aspen are partly suited for poorer conditions. For Populus-SRC in general weed control during establishing phase is essential.     

Biomass and energy production in Casuarina equisetifolia plantation stands in the degraded dry tropics of the Vindhyan plateau, India

Two age groups of Casuarina equisetifolia (Forst.) plantation stands in the Renukoot forest division of the Vindhyan plateau were investigated over the span of three years for total and component biomass, annual net primary production, energy storage and annual net energy fixation. A high range of biomass (44–81 t ha⁻¹) was recorded in a densely populated stand at ages 5–7 years in comparison to a sparsely populated stand at ages 8–10 years. The contribution of the hole component gradually increased with increasing diameter class while foliage and branch components had a large proportion of biomass in the lower diameter classes. Maximum litterfall occurred in May and foliage litter contributed 87–95% of total litterfall. The energy content and storage in component parts were higher than some other promising tree species for energy plantation in the dry tropics. Production estimates of 19–29 t ha⁻¹ yr⁻¹ showed that the performance of Casuarina is good for dry tropical conditions. The biomass accumulation ratio and production efficiency showed a significant positive and negative (logarithmic) relationship, respectively with plantation age. The energy conserving efficiency of the 5-year old stand was more than twice that of the 8-year old stand.     

Development of a BB-2590/U rechargeable lithium-ion battery

PolyStor has teamed with Hawker Eternacell (US) to develop a BB-2590/U rechargeable lithium-ion battery under contract with the US Army CECOM (Ft. Monmouth, NJ, USA). The concept involves using commercially available ICR-18650 cylindrical lithium-ion cells. The individual cells have a high specific energy of 135 Wh kg⁻¹ and an energy density of 335 Wh dm⁻³. Electronic circuitry was developed to provide pack protection, charge equalization and battery management (fuel gauging). PolyStor's rechargeable BB-2590/U battery provides 4.5 Ah at 28 V nominal or 9.0 Ah at 14 V nominal, translating into 108 Wh kg⁻¹ and 150 Wh dm⁻³. The key developments are discussed in this paper.     

Commercial-scale rapid thermal processing of biomass

Rapid Thermal Processing (RTP) utilizes proprietary reactor systems to convert both biomass and petroleum-based materials to high yields of chemical and liquid fuel products. The essential feature is the ability to transfer heat rapidly with precise control of short contact times. The process involves thermal or thermocatalytic refining of biomass, and is somewhat analogous to the refining of petroleum materials. Nevertheless, the chemical and fuel products from biomass are unique, and not similar to petroleum-derived products. Furthermore, RTP is not to be confused with conventional pyrolysis, from which it differs fundamentally with respect to product yield and quality, and process conditions and chemistry. Short-term applications include the production of specialty chemicals, fuel oil substitutes and engine fuels for both diesel and turbine applications. Research in support of these applications is in progress and is briefly reviewed. The paper focuses primarily on the status of RTP hardware, including the operation of a 2.5 tonne day⁻¹ plant and a 25 tonne day⁻¹ commercial plant.