- Email: [email protected]
00339 Fluid circulation and heat extraction from engineered geothermal reservoirs
07
However. the development of a commercial market with fewer regulations tends to level out prices. Consumers on the household market purchase small quantities and do not have the same possibility as district heating companies to take advantage of the oversupply opportunity and thus face a faster price development. In addition, the weaker market position of the consumers also tends to give homogeneous prices between regions for the residential sccror.
00/00334
Research
on the process
of biomass
formed coke
Zhou, S. et ul. ,%‘cirun Zhuanhna. 1999, 22, (2). 62-65. (In Chinese) Biomass is used as a caking additive in the hriquetting of coal. After they are dried and mixed. hiomass. anthracite and bituminous coal are hriquetted at the normal temperature. Research was conducted into the effects of the biomass and bituminous coal content, hriquetting force and coal class on the compressive strength of briquette and formed coke. The experimental results demonstrate that all of the four factors have significant effects on the compressive strength of briquette. However, only the bituminous coal content and hriquetting force have a marked effect on the strength of formed coke. The preferred process conditions include, 18% biomass. a I :2 ratio of anthracite to fat and a hriquetting force of 460 kN. The yield of volatile matter from a hriquette is X3% and in comparison to the yield of tar. which is 49’Y. This difference is due to large molecules in the volatile matter reacting again and evolving solid in the pore.
00/00335 Bangladesh
Simulation
of rural household
fuel consumption
in
Alam. M. S. cf rrl. Ener&y. 1999, 24, (8).743-752. Presented in this paper is a quantitative dynamic simulation model as a system study for rural household-biomass fuel consumption in LDCs such as Bangladesh. ‘The rural areas of Bangladesh serve for model validation. The parameters. constants and initial values in the model represent present conditions. The performance of the system has been evaluated by incorporating alternativ,e policies. and the model has been simulated to project the statu\ of the system over an extended period of time. Several variables have hern selected to assess system response as well as the impacts of policies. An assessment of household-biomass fuel consumption impact on environmental degradation is made for deforestation.
00/00336
Solar thermochemical
conversion
of biomass
Lede. J. Sol&/c E,rerp. 1999, 65. (1). 3-13. The standard routes of biomass thermochemical conversion are discussed in this well referenced review. In addition, the possibility of using concentrated solar energy to provide the necessary heat for the processes is also evaluated. Gasification. fast and slow pyrolysis are described in more detail. The above mentioned processes can he conducted with the intention of preparing of a vast range of possible products that can he used as energy carriers and/or as a source of chemical commodities. The gasification procedures are intended for the preparation of gas mixtures (CO. HZ) for chemical synthesis, heat. or electricity generation. The fast pyrolysis formerly carried out for gas production (CO, Hz, and light hydrocarbons) is now mainly analysed with the objective to produce liquids (hio-oils). Slow pyrolysis is in use for a long period of time for the preparation of solids (charcoal). The nature and quality of the products depend primarily on the experimental conditions of the process, including, heating rates, temperature and residence times. The possibility of a solar power being incorporated in to the gasification and pyrolysis processes is then discussed. The technical and scientific advantages, as well as the problems, are underlined. indicating the necessity to design novel types of specific reactors. From a fundamental point of view the benefit\ are also underlined of using a concentrated radiation as a laboratory tool for examining the very fast primary steps of biomass thermal decomposition. as well as the probable existence of intermediate short life time species that are still not understood.
00100337 quantitative
Steam-assisted biomass fractionation. Part Ill: a evaluation of the ‘clean fractionation’ concept
Ihrahim. M. and Glasser. W. G. Riore~ource Technolop. 1999, 70, (2) 181-192. Accounting for mas\ fractions and chemical components during the fractionation of red oak (QIICI.~~I.T rtthra) wood chips into fihres and polymer products representing biomass constituents was approached arithmetically. The fractionation involved sequential treatments by steam explosion, water washing and lignin-extraction with either aqueous alkali, aqueous acetic acid or aqueous ethanol. Cleanness of the fractionation was asae\sed in term\ of the release of constitutive component mass from a solid\ fraction during each processing step. Fractionation behaviour was studied in relation to different steam treatment severities. The results indicate that best fractionation conditions for hemicelluloses are reached at low treatment severities, where up to 72% of this component may he collected in the water extract. The best ligninitannin yields are achieved at high treatment severities where 82% may theoretically he harvested in the alkali-soluble fraction. Best results require the elimination of all fihre losses during steam explosion. a condition not reached in the present study. The fractionation performance in either organic solvent mixture, 80% acetic acid or 705/r ethanol resulted in 20% less delignification. Lignin is progressively contaminated with associated furfural as severity increases.
Alternative
Energy Sources (geothermal
energy)
00100338 Utilization of damaged sorghum and rice grains for ethanol production by simultaneous saccharification and fermentation Suresh, K. ef ni. Biormmrce Techmlogy. 1990. 68, (3), X)1-X14. The simultaneous saccharification and fermentation (SSF) of damaged grains of sorghum and rice was carried out using Avpergillu.~ rr&r (NCIM 1248) and Succirarom,rce~ cer&siae VSJI. More ethanol was produced from the damaged sorghum (2.90% v/v) than damaged rice (2.09? v/v,) under optimal fermentation conditions. This study revcal\ that damaged grain\ can he utilized efficiently hy an SSF process for the production of ethanol.
Geothermal
00100339 engineered
Energy
Fluid circulation and heat extraction geothermal reservoirs
from
Brown, D. et al. Geothermics, 28. (415). 5~53-572. A large amount of fluid circulation and heat extraction (i.e., thermal power production) research and testing has heen conducted on engineered geothermal reservoirs in the past IS years. In confined rc\ervoir\. which best represent the original Hot Dry Rock concept, the flow dirtrihution at any given time is primarily determined hy three parameters. Firstly. the nature of the interconnected network of pressure-stimulated joints and open fractures within the flow-accessible reservoir region. Secondly, the mean pressure in the reservoir, and thirdly, the cumulative amount of fluid circulation and therefore reservoir coolmg-that has occurred. For an initial reservoir rock temperature distribution and mean fluid outlet temperature. the rate of heat extraction (i.e. thermal power) is at first i~nl! a function of the production flow rate. since the production temperature can he expected to remain essentially constant for some time (months, or even years). However, as reservoir circulation proceed?, the production temperature will eventually start to decline. as determined hy the mean effective joint spacing and the total flow-accessihlc (i.e. heat-transfer) volume of the reservoir. The rate of heat extraction. w*hich depend\ on the production flow rate. can also vary with time as a result of continuing changes in the flow distribution arising from reservoir cooling. The thermal power of engineered reservoirs can most readily be increased hy increasing the production flow rate, as long as this does not lcad to premature cooldown, the development of short-circuit flow paths. or excessive water losses. In general, an increase in flow rate can he accomplished hy increasing the injection pressure within limits. This strategy increases the driving pressure drop across the reservoir and the mean reservoir pressure, which in turn reduces the reservoir flow impedance by increasing the amount of joint dilation. However, the usefulness of this strategy is limited to reservoir operating pressures below the fracture extension pressure. and may lead to excessive water losses, particularly in less-confined reservoir\. Under such conditions, a downhole production-well pump may he employed to increase productivity by recovering more of the injected fluid at lower mean reservoir operating pressures.
00/00340 creation
HDRIHWR
reservoirs:
concepts,
understanding
and
Baria, R. et al. Geothernucs, 28, (4/S), 533-552. Hot Dry Rock (HDR) technology was created from an idea to help fulfil future energy needs as the availability of cheap fossil and other known fuels slowly reduces. The HDR concept itself is very simple hut the development of the associated technology has taken significantly longer than anticipated. Anyone with experience of natural materials such as rocks knows that there are always imponderahles that have not been really understood and indeed cannot at present be dealt with in a fully satisfactory manner. Furthcrmorc. geology always has a habit of presenting us with new problems. The results of the 1997 circulation test at Soultz-soua-Foret\ (France) indicate that the type of concept and an appropriate set of hackground site conditions to advance the technology may have been made available. The concept of an HDR reservoir has evolved from that of a single penny-shaped fracture borrowed from the oil industry to the present grahen or HWR (Hot Wet Rock) concept. International co-operation has been a key issue so far, and the expensive nature of this research demands that co-operation of this type continues to break new ground in the future. The necessary supporting technology has also evolved and the time appears to be ripe for taking advantage of this new and exciting development. It is worth remembering that there is still no commercial HDR plant in existence to provide real data on building, operating and maintenance costs for planning a new unit. This should not he regarded as an insuperable problem. If such were the case then we would not have any aircraft, steel, shipping. telecommunication or nuclear industries. It is believed that HDR technology will he a necessity in the near future and the important question now’is how, quickly it can he put into practice when the need does arise.
00/00341 geothermal
Hydraulics reservoirs
and well testing
of engineered
Murphy, H. et al. Georhermic.r, 2X. (415). 4Y I-506. In most engineered reservoirs the water to extract the geothermal energy must be supplied, in other words, forced into the reservoir. rather than merely extracted as is common for conventional geothermal reservoirs. One operational hydraulic parameter of great interest i\ the impedance. which
Fuel and Energy Abstracts
January 2000
35
However. the development of a commercial market with fewer regulations tends to level out prices. Consumers on the household market purchase small quantities and do not have the same possibility as district heating companies to take advantage of the oversupply opportunity and thus face a faster price development. In addition, the weaker market position of the consumers also tends to give homogeneous prices between regions for the residential sccror.
00/00334
Research
on the process
of biomass
formed coke
Zhou, S. et ul. ,%‘cirun Zhuanhna. 1999, 22, (2). 62-65. (In Chinese) Biomass is used as a caking additive in the hriquetting of coal. After they are dried and mixed. hiomass. anthracite and bituminous coal are hriquetted at the normal temperature. Research was conducted into the effects of the biomass and bituminous coal content, hriquetting force and coal class on the compressive strength of briquette and formed coke. The experimental results demonstrate that all of the four factors have significant effects on the compressive strength of briquette. However, only the bituminous coal content and hriquetting force have a marked effect on the strength of formed coke. The preferred process conditions include, 18% biomass. a I :2 ratio of anthracite to fat and a hriquetting force of 460 kN. The yield of volatile matter from a hriquette is X3% and in comparison to the yield of tar. which is 49’Y. This difference is due to large molecules in the volatile matter reacting again and evolving solid in the pore.
00/00335 Bangladesh
Simulation
of rural household
fuel consumption
in
Alam. M. S. cf rrl. Ener&y. 1999, 24, (8).743-752. Presented in this paper is a quantitative dynamic simulation model as a system study for rural household-biomass fuel consumption in LDCs such as Bangladesh. ‘The rural areas of Bangladesh serve for model validation. The parameters. constants and initial values in the model represent present conditions. The performance of the system has been evaluated by incorporating alternativ,e policies. and the model has been simulated to project the statu\ of the system over an extended period of time. Several variables have hern selected to assess system response as well as the impacts of policies. An assessment of household-biomass fuel consumption impact on environmental degradation is made for deforestation.
00/00336
Solar thermochemical
conversion
of biomass
Lede. J. Sol&/c E,rerp. 1999, 65. (1). 3-13. The standard routes of biomass thermochemical conversion are discussed in this well referenced review. In addition, the possibility of using concentrated solar energy to provide the necessary heat for the processes is also evaluated. Gasification. fast and slow pyrolysis are described in more detail. The above mentioned processes can he conducted with the intention of preparing of a vast range of possible products that can he used as energy carriers and/or as a source of chemical commodities. The gasification procedures are intended for the preparation of gas mixtures (CO. HZ) for chemical synthesis, heat. or electricity generation. The fast pyrolysis formerly carried out for gas production (CO, Hz, and light hydrocarbons) is now mainly analysed with the objective to produce liquids (hio-oils). Slow pyrolysis is in use for a long period of time for the preparation of solids (charcoal). The nature and quality of the products depend primarily on the experimental conditions of the process, including, heating rates, temperature and residence times. The possibility of a solar power being incorporated in to the gasification and pyrolysis processes is then discussed. The technical and scientific advantages, as well as the problems, are underlined. indicating the necessity to design novel types of specific reactors. From a fundamental point of view the benefit\ are also underlined of using a concentrated radiation as a laboratory tool for examining the very fast primary steps of biomass thermal decomposition. as well as the probable existence of intermediate short life time species that are still not understood.
00100337 quantitative
Steam-assisted biomass fractionation. Part Ill: a evaluation of the ‘clean fractionation’ concept
Ihrahim. M. and Glasser. W. G. Riore~ource Technolop. 1999, 70, (2) 181-192. Accounting for mas\ fractions and chemical components during the fractionation of red oak (QIICI.~~I.T rtthra) wood chips into fihres and polymer products representing biomass constituents was approached arithmetically. The fractionation involved sequential treatments by steam explosion, water washing and lignin-extraction with either aqueous alkali, aqueous acetic acid or aqueous ethanol. Cleanness of the fractionation was asae\sed in term\ of the release of constitutive component mass from a solid\ fraction during each processing step. Fractionation behaviour was studied in relation to different steam treatment severities. The results indicate that best fractionation conditions for hemicelluloses are reached at low treatment severities, where up to 72% of this component may he collected in the water extract. The best ligninitannin yields are achieved at high treatment severities where 82% may theoretically he harvested in the alkali-soluble fraction. Best results require the elimination of all fihre losses during steam explosion. a condition not reached in the present study. The fractionation performance in either organic solvent mixture, 80% acetic acid or 705/r ethanol resulted in 20% less delignification. Lignin is progressively contaminated with associated furfural as severity increases.
Alternative
Energy Sources (geothermal
energy)
00100338 Utilization of damaged sorghum and rice grains for ethanol production by simultaneous saccharification and fermentation Suresh, K. ef ni. Biormmrce Techmlogy. 1990. 68, (3), X)1-X14. The simultaneous saccharification and fermentation (SSF) of damaged grains of sorghum and rice was carried out using Avpergillu.~ rr&r (NCIM 1248) and Succirarom,rce~ cer&siae VSJI. More ethanol was produced from the damaged sorghum (2.90% v/v) than damaged rice (2.09? v/v,) under optimal fermentation conditions. This study revcal\ that damaged grain\ can he utilized efficiently hy an SSF process for the production of ethanol.
Geothermal
00100339 engineered
Energy
Fluid circulation and heat extraction geothermal reservoirs
from
Brown, D. et al. Geothermics, 28. (415). 5~53-572. A large amount of fluid circulation and heat extraction (i.e., thermal power production) research and testing has heen conducted on engineered geothermal reservoirs in the past IS years. In confined rc\ervoir\. which best represent the original Hot Dry Rock concept, the flow dirtrihution at any given time is primarily determined hy three parameters. Firstly. the nature of the interconnected network of pressure-stimulated joints and open fractures within the flow-accessible reservoir region. Secondly, the mean pressure in the reservoir, and thirdly, the cumulative amount of fluid circulation and therefore reservoir coolmg-that has occurred. For an initial reservoir rock temperature distribution and mean fluid outlet temperature. the rate of heat extraction (i.e. thermal power) is at first i~nl! a function of the production flow rate. since the production temperature can he expected to remain essentially constant for some time (months, or even years). However, as reservoir circulation proceed?, the production temperature will eventually start to decline. as determined hy the mean effective joint spacing and the total flow-accessihlc (i.e. heat-transfer) volume of the reservoir. The rate of heat extraction. w*hich depend\ on the production flow rate. can also vary with time as a result of continuing changes in the flow distribution arising from reservoir cooling. The thermal power of engineered reservoirs can most readily be increased hy increasing the production flow rate, as long as this does not lcad to premature cooldown, the development of short-circuit flow paths. or excessive water losses. In general, an increase in flow rate can he accomplished hy increasing the injection pressure within limits. This strategy increases the driving pressure drop across the reservoir and the mean reservoir pressure, which in turn reduces the reservoir flow impedance by increasing the amount of joint dilation. However, the usefulness of this strategy is limited to reservoir operating pressures below the fracture extension pressure. and may lead to excessive water losses, particularly in less-confined reservoir\. Under such conditions, a downhole production-well pump may he employed to increase productivity by recovering more of the injected fluid at lower mean reservoir operating pressures.
00/00340 creation
HDRIHWR
reservoirs:
concepts,
understanding
and
Baria, R. et al. Geothernucs, 28, (4/S), 533-552. Hot Dry Rock (HDR) technology was created from an idea to help fulfil future energy needs as the availability of cheap fossil and other known fuels slowly reduces. The HDR concept itself is very simple hut the development of the associated technology has taken significantly longer than anticipated. Anyone with experience of natural materials such as rocks knows that there are always imponderahles that have not been really understood and indeed cannot at present be dealt with in a fully satisfactory manner. Furthcrmorc. geology always has a habit of presenting us with new problems. The results of the 1997 circulation test at Soultz-soua-Foret\ (France) indicate that the type of concept and an appropriate set of hackground site conditions to advance the technology may have been made available. The concept of an HDR reservoir has evolved from that of a single penny-shaped fracture borrowed from the oil industry to the present grahen or HWR (Hot Wet Rock) concept. International co-operation has been a key issue so far, and the expensive nature of this research demands that co-operation of this type continues to break new ground in the future. The necessary supporting technology has also evolved and the time appears to be ripe for taking advantage of this new and exciting development. It is worth remembering that there is still no commercial HDR plant in existence to provide real data on building, operating and maintenance costs for planning a new unit. This should not he regarded as an insuperable problem. If such were the case then we would not have any aircraft, steel, shipping. telecommunication or nuclear industries. It is believed that HDR technology will he a necessity in the near future and the important question now’is how, quickly it can he put into practice when the need does arise.
00/00341 geothermal
Hydraulics reservoirs
and well testing
of engineered
Murphy, H. et al. Georhermic.r, 2X. (415). 4Y I-506. In most engineered reservoirs the water to extract the geothermal energy must be supplied, in other words, forced into the reservoir. rather than merely extracted as is common for conventional geothermal reservoirs. One operational hydraulic parameter of great interest i\ the impedance. which
Fuel and Energy Abstracts
January 2000
35