07 Alternative energy sources (bioconversion energy)

02/00980 Fuel characteristics of gasified coconut shell in a fluidized and a spouted bed reactor Hoque, M.M. and Bhattacharya, SC. Energy, 2001, 26, (l), 101-l 10. In this study, an attempt has been made to gasify coconut shell in a fluidized and a spouted bed reactor. The effects of the gasification temperature on individual gas components, their yields and heating values for both types of beds have also been studied. The fluidized bed appears slightly superior to the spouted bed both in respect to heating value and gas yield over the temperature range studied.

02/00981 Genetic selection and improvement of hard wood tree species for fuelwood production on sodic soil with particular reference-to Prosopis jufif/ora Goel, V.L. and Behl, H.M. Biomass and Bioenergy, 2001, 20, (I), 9-l 5. This study is a part of a research programme on selection and improvement of fast growing tree species suitable for wood fuel production on sodic wastelands (pH 8.6-10.5). Field trials of nine legumes (Acacia mricul(formis. A. nilotica. Alhizirr lehheck. A. procera, Dalhergirr sissoo. Leucaena leucocephalo, Pongrrmiu pinnara. Prosopis jul$lora, Pirhecellohium dtdce) and three other tree species (Azodirachla indica, Eucalyppcus rereticornis and Terminuliu arjuna) were selected for this study. Prosopis julifloru was the most promising species in terms of its biomass productivity (68.7 t ha ‘) and fuel value index (148.8) after S-year of growth. Acacia nilorica ranked second. Intra-specific variations were screened at provenance and individual tree level in order to improve fuelwood production potential of P. jtrlifloru through selection and breeding. Successful populations (gene pools) and individuals (genotypes) were cloned and conserved in clonal gardens to produce quality germplasm for plantations on sodic wastelands. Genetic testing, selection and multiplication of selected material are under progress. This will optimize gains in future afforestation programmes on sodic soils.

02/00982 Influence of thermal treatment on sequential extraction and leaching behaviour of trace metals in a contaminated,sewage sludge Obrador, A. er al. Bioresource Technology, 2001, 76, (3), 259-264. The losses of weight and organic matter of a sludge caused by thermal treatments at lWC, 300°C and 400°C were determined in order to assess how the possibilities of sludge use were influenced. The sludge heated at 180°C lost small amounts of weight and organic matter (9.8%) but the losses from the two other treatments were large enough (92.2% and 99.9% in organic matter) to preclude the use of the sludges as organic amendments. The concentration and potential lability and leachability of Cr. Cu, Fe, Mn, Ni, Pb and Zn in the native sludge and in the thermal-treated sludge samples were studied by means of a five- step chemical fractionation method and a column experiment. As a consequence of heating, the trace metals were more strongly fixed in the treated sludges, as could be seen by the decrease with temperature of the ratio between the sum of the first two sequential-extracted fractions and the residual fraction. The leaching results showed that, for the native sludge, the quantities of sudied metals leached were larger than for the sludge heated to 180°C. The order of leachability of metals was the same in both cases, and the same equation could be used to calculate the quantities of metals leached. The amounts of metals leached correlated significantly with the first extracted fraction (exchangeable metals) and an equation could be used to calculate the quantities leached, as a function of that fraction.

02/00983 Integrating composting and vermicomposting in the treatment and bioconversion of biosolids Ndegwa, P.M. and Thompson, S.A. Bioresource Technology, 2001, 76, (2) 107-l 12. Traditional thermophillic composting is commonly adopted for treat- ment of organic wastes or for production of organic/natural fertilizers. A related technique, called vermicomposting (using earthworms to breakdown the organic wastes) is also becoming popular. These two techniques have their inherent advantage and disadvantages. The integrated approach suggested in this study borrows pertinent attributes from each of these two processes and combines them to enhance the overall process and improve the products qualities. Two approaches investigated in this study are: (1) pre-composting followed by vermicomposting, and (2) prevermicomposting followed by com- posting. The substrate was biosolids (activated sewage sludge) with mixed paper-mulch as the carbon base. Eisenin,fetida (red wigglers) was the species of earthworms used in the vermicomposting processes. The results indicate that a system that combines the two processes not only shortens stabilization time, but also improves the products quality. Combining the two systems resulted in a product that was more stable and consistent (homogenous), had less potential impact on the environment and for compost-vermicomposting (CV) system, the product met the pathogen reduction requirements.

OWOO984 Peat and sapropel resources in Russia Salin, S.V. Razved. Okhr. Nedr, 2000, 10, 15-17. (In Russian)

Presently in Russia 65 000 peat deposits are known and these have resources of 186 billion tons and reserves in various categories of 154.6 billion tons. About 70% of the peat resources are in northern Siberia, and northwestern Russia has > 20 billion tons. Peat mining output reached a maximum of 135 million tons/year in the mid-1970s; the output for 1996 was 12.5 million tons. Nearly all the peat mined is used in agriculture. Russia has the largest sapropel resource in the world: nearly 225 billion tons, whioh is 90% of the total resource. The thickness of these lake deposits generally varies from 3 to 10 m but is known to reach 40 m. Reserves in category A include > 300 deposits with 720 million tons of sapropel. The largest number of deposits are in Yakutia - 1252 deposits have total reserves of 390 million tons. Systematic, detailed study is needed to establish industrial applications for the sapropel.

02/00985 Production of acetic acid and glycerol from salted and dried whey in a membrane cell recycle bioeactor Mostafa, N.A. Energy Conversion und Mcmagemem, 2001,42, (9), I l33- 1142. The use of salted whey (liquid by-product from the dairy industry containing 7.5% NaCI) as a substrate for either acetic acid or glycerol production was investigated using two yeast strains. One was Klu)?verom~ces,frugi/is. The other organism (strain L) can utilize whey lactose that was isolated from waste whey (disposal stream). 8% NaCl, 3X Na2S03 and pH 8.5 at 32°C were the optimum operating conditions for maximum acetic acid production (25.84 gl ‘) from salted whey using immobilized cells of yeast strain L. Also, strain L gave a higher yield of acetic acid (0.497 g acetic acid per gram lactose) as compared with K.,frctgili.s (0.322 g acetic acid per gram lactose). 1 u/u NasSOs at pH 7 and whey supplemented with peptone and malt extract were the optimal conditions for maximum batch glycerol production (13.2 gl ‘) from salted whey using immobilized cells of K. fragilis. The extreme values, 18.7 gl ’ for glycerol concentration and 39.78 for the percent yield of glycerol (based on sugar concentration) in a membrane cell recycle bioreactor were higher than those obtained for the immobilized cell batch reactors (13.2 gl ’ and 28, respectively).

02/00988 Relative reactivity of alkaline extracts of Taiwanese biomass residues toward formaldehyde Chen, C-M. and Liao, T.M.-Y. Biomass und Bioenergy, 2001, 20, (2), 1333139. Six Taiwanese biomass materials, namely: rice (Orycu sarivu L.) hull; rice bran; sugarcane (Sacchrrrum qfficinarrrm L.) bagasse; Taiwan acacia (Acacia cot+rsa Merr.) bark; Taiwan acacia foliage; and Taiwan acacia leaf, were extracted with a 22% solution of sodium hydroxide at 95°C for 16 h and at an elevated temperature of 135°C for 4 h. These extracts were reacted with 44% formalin for 2 h at 60 and 8O”C, respectively, to investigate their reactivity toward formaldehyde. The free formaldehyde in the reaction mixtures was quantitatively determined by hydroxylamine hydrochloride titration to an end point of pH 4. Extraction temperature, reaction temperature, and type of biomass material were found to significantly influence the reactivity of the extracts with formaldehyde. The 135°C extracts of sugarcane bagasse absorbed the highest amount of formaldehyde while the 95°C extracts of Taiwan acacia foliage absorbed the least amount of formaldehyde.

02lOO987 Role of bioenergy in a society based on sustainable resource use Kumasaki, M. Kumi Pa Gikposhi, 2000, 54, (11) 1523-1328. (In Japanese) The 20th century was that of fossil fuel while the 21st century will be that of after-fossil-fuel energy. The paper focuses on biomass as a new energy source and describes its characteristics, supply capability, possibility of a small scale power generation system from biomass and potentiality of bioenergy in Japanese forest industry.

02lOO988 Short rotation coppice tree species selection for woody biomass production in New Zealand Sims. R.E.H. ef al. Biomass and Bioenergy, 2001, 20, (5). 329-335. Nine’species of Euculyp/rrs were compared with one selected species of each of Srrli.r, Acacia and Populus for woody biomass production when grown in a temperate climate under a short rotation regime. Ten clones of the promising species E. vimincrlis were also included in the small plot, randomized block experiment. The trees, planted at a stocking density of 5000 stems/ha, were harvested as single stems at 3 years of age, then again as coppice regrowth following a further 3-year rotation. Tree survival, stump diameters (mm), heights (m), and tree dry weights were measured and used to determine the above ground biomass yields The four replicated plots, each with five trees, of E viminulis 3680, E. hotryoides, E. pseudoglohulu.s and S. mutstrdrmcr I alha i Mouiere) showed no tree mortality even after the second harvest. Most of the other species had over 80% survival rates, E. nirens being the exception at below 50%. Average heights and dry weights of the harvested coppice trees were significantly greater than when first harvested as

120 Fuel and Energy Abstracts March 2002

07 Alternative energy sources (geothermal energy)

single stems. Mean annual incremental biomass dry matter yields (tdm/ ha/year) at the single stem harvest ranged from 2.00 tdm/ha/year for E. nitens up to 39.72 tdm/ha/year for E. viminalis 3683. At the coppice harvest E. nimu was again the lowest yielding (2.94 tdm/ha/year) with other species ranging up to 50.64 tdm/ha/year for E. pscudoglohulus. On combining total biomass yields from both rotations, most Eucalyptus species produced significantly more biomass than the other genera, with E. viminalis 3678 and E. pseudoglohulus exceeding 35 tdm/ ha/year during the 6-year period.

02/00989 Study of drying characteristics of large- cardamom Govardhana Rao, V. el al. Eiomms and Bioenergy, 2001, 20, (I), 3743. India is the largest producer of large-cardamom in the world with 54% . share in world production followed by Nepal (33%) and Bhutan (13%). For long-duration storage of cardamom and in order to bring out its aroma, the fresh cardamom capsules (with SO-85% moisture) has to be dried immediately after harvesting to bring down its moisture content to less than 10% (w.b.) through a curing (drying) process. Still a primitive and inefficient (operating efficiency level of about 5-15%) smoking method (using traditional hhar!i) is being used for drying of large-cardamom resulting in huge (estimated 20 000 MT/year) wastage of fuel wood and poor (charred and blackened) quality product. This paper gives a brief description of efforts made to obtain basic drying parameters of large-cardamom (which is a pre-requisite for dryer design) under different operating conditions.

02/00990 The potential of using vegetable oil fuels as fuel for diesel engines Altin, R. er al. Energy Conversion and Munrrgemm~, 2001, 42, (5). 529- 538. Vegetable oils are produced from numerous oil seed crops. While all vegetable oils have high energy content, most require some processing to assure safe use in internal combustion engines. Some of these oils already have been evaluated as substitutes for diesel fuels. The effects of vegetable oil fuels and their methyl esters (raw sunflower oil, raw cottonseed oil, raw soybean oil and their methyl esters, refined corn oil, distilled opium poppy oil and refined rapeseed oil) on a direct injected, four stroke, single cylinder diesel engine performance and exhaust emissions was investigated in this paper. The results show that from the performance viewpoint, both vegetable oils and their esters are promising alternatives as fuel for diesel engines. Because of their high viscosity, drying with time and thickening in cold conditions, vegetable oil fuels still have problems, such as flow, atomization and heavy particulate emissions.

02/00991 Willow biomass production during ten successive annual harvests Kopp, R.F. rr al. Bionms and Eioenerg.v, 2001, 20, (I), l-7. Five willow clones and one hybrid poplar clone were planted during 1987 at 0.3 x 0.3 m spacing and harvested annually for 10 years. Half of the trees were fertilized annually with N, P and K and all trees were irrigated beginning in the third growing season. Annual biomass production fit the logistic growth curve well for four of the clones with r2 values ranging from 0.91 to 0.54, suggesting that well-adapted willow clones can be consistently productive for at least IO years with annual harvesting. Fertilizer did not increase the maximum biomass pro- duction level attained, but it reduced the time required to reach maximum production by I year. The correlation between annual biomass production and the number of growing degree days during years 4410 was high, ranging from 0.95 to 0.66.

Geothermal energy

02/00992 Analytical and experimental study of combined fruit and vegetable dryer Ivanova, D. and Andonov, K. Energ? Conversion and Munrrgemmt,

2001, 42, (S), 975-983. This article presents a structure of a dryer using solar energy and heat of geothermal water. It also presents a model of the temperature- humidity processes in the dryer chamber using solar energy for heating the air. The steady-state model determining the distribution of temperature and humidity in the dryer depends on climatic (solar radiation, temperature and humidity of external air and wind velocity) and working conditions (mass flow rate of air and material for wing).

02/00993 Boiling flow in a horizontal fracture Wang, C.T. and Horne, R.N. Geothermics, 2000, 29, 759-772.

The modelling of a geothermal reservoir requires an in-depth under- standing of the heat transfer process that causes the fluid flowing within a fracture to boil as heat is transferred to the fluid from the

surrounding rock. One of the key parameters that describes this process is the boiling heat transfer coefficient. In this work, experiments were performed and a model based on the experiments was developed in order to quantify the heat transfer coefficient. In the process, it was also determined that flow in fractures may be described using linear relative permeability functions.

02lOO994 Chemical and isotopic compositions of water and dissolved sulfate from shallow wells on Vulcan0 Island, Aeolian Archipelago, Italy Cortecci, G. er rrl. Georhermics, 2001, 30, (I), 69-9 I. Twenty-two cold and thermal waters from shallow wells sampled in June 1995 in the Vulcan0 Porto area, Vulcan0 Island, were analysed from major and minor chemical constituents, oxygen and hydrogen isotopes and tritium contents, and sulfur isotopes in the dissolved sulfate. The sulfur isotopic composition of the dissolved sulfate ranges between +0.6 and +6.5”h (mean +3.7 *1.7X)), and is interpreted as deriving mainly from fumarolic SO2 undergoing oxidation in deep and shallow aquifers, with possible minor contributions from oxidation of H$. Dissolution of secondary anhydrite may have been a minor source ot the isotopically heavy aqueous sulfate in the cold groundwaters. The chemical and isotopic features of the waters support previous interpretative hydrologic models of Vulcano Porto, which comprise a number of aquifers fed basically by two major end-members, i.e. meteoric water and crater-type fumarolic inputs, the latter in the form of absorbed emissions or condensate. These data, along with the sulfur isotopes of aqueous sulfate, exclude involvement of seawater in the recharge of the groundwater system of the island.

02/00995 Evidence for thermal mining in low temperature geothermal areas in Iceland Tdmasson, J. and Arason, P. Georhermics. 2000, 29, (6). 723-735. This study deals with thermal mining in several geothermal systems in Iceland. A number of 2500- to 3000-m deep drillholes have been drilled into low temperature geothermal areas in the country. The conductive gradient outside active geothermal areas has also been mapped, and shows a systematic variation from lower than SO”C/km in the outer parts of the Tertiary basalts to over lOO”C/km on the borders of the volcanic zones (rift zones). The difference between formation temperatures inside geothermal systems and the surrounding con- ductive gradient can be computed as a function of depth. This difference is termed A T in this paper. The L T-curves show that the upper parts of the geothermal systems are heated and the lower parts are cooled compared to the undisturbed conductive gradient. In many cases the cooling of the lower part is greater than the heating in the upper part, so that a net thermal minmg has occurred. This thermal mining is calculated for several ,geothermal systems, and the systems are compared. The net thermal mming in the top 3000 m appears to be much greater in formations of Pleistocene and Pliocene age. It gradually decreases to zero for formations older than 6 million years. However, the net thermal mining is critically dependent on the maximum depth of water convection in these systems, which is unknown.

02lOO996 Optimizing the position of the tube casing slotted section for geothermal wells with a downhole heat exchanger Carotenuto, A. er crl. Geothrrmics, 2001, 30, (I). l33- 157. The use of downhole heat exchangers (DHE) in the exploitation of geothermal resources is characterized by an absence of mass with- drawal from the aquifer. Although this peculiarity reduces installation costs it also imposes limits on the heat flow withdrawable (generally less than 100 kW), and, therefore, on the use of DHEs in small applications such as greenhouse, small buildings or thermal baths. For this reason DHEs are mainly used in superficial geothermal aquifers (up to 30 m depth), usually with liquid-phase water at temperatures greater than 60°C. A study has been made of the influence of the position of the casing slotted section within an aquifer on the heat withdrawal rates using DHEs. This study numerically simulates an aquifer using the finite-element method to determine the heat flow that can be withdrawn by the DHE when the slotted section position is varied within a geothermal aquifer. The simulations carried out also enable us to determine the influence of the main characteristics of the aquifer and the extraction plant on the design of the tube casing slotted section. On the basis of the numerical results obtained, a particular configuration of slotted section is proposed where this is subdivided into different sections, one placed in the lower part of the aquifer and the other in the upper part. The results obtained have shown that this configuration optimizes the heat flow drawn hy the DHE from the geothermal aquifer.

02/00997 Potential for surface gas flux measurements in exploration and surface evaluation of geothermal resources Klusman, R.W. (11 rrl. Georhermic.s, 2000. 29. (6) 637 6?0

Fuel and Energy Abstracts March 2002 121