Robyn Fry - Academia.edu (original) (raw)

Papers by Robyn Fry

Greenhouse Gas Measurement and Management, 2012

Seam gas released during coal mining is a substantial source of fugitive greenhouse gas emissions... more Seam gas released during coal mining is a substantial source of fugitive greenhouse gas emissions worldwide. Most of these emissions originate from underground mining; however, lack of robust global data means that the scale of emissions remains uncertain. Some coal-producing countries are attempting to improve the quality of emission estimates by using ventilation data to calculate emissions from individual mines. Legislation recently introduced in Australia now requires coal mine operators to estimate and report annual fugitive emissions. This article examines the methodology currently used at most Australian mines to meet these requirements. To assess the performance of this methodology, we compared the results of routine measurements of ventilation air flow rate and gas composition to those made with reference methods. The primary sources of uncertainty in the techniques are identified and their contributions to the uncertainty of the reported fugitive emission fluxes are estimated.

International Journal of Coal Preparation and Utilization, 2009

ABSTRACT The gas-induced swelling behavior of coal is important when considering CO2 sequestratio... more ABSTRACT The gas-induced swelling behavior of coal is important when considering CO2 sequestration into coal seams or enhanced coalbed methane applications, but coals may also swell in the presence of moisture, or shrink on drying. In this paper we examine the moisture-swelling properties of coals from Australia and elsewhere. Results on the moisture uptake and corresponding swelling measurements are presented for 15 coals of various ranks (sub-bituminous and bituminous) at 22°C and atmospheric pressure. Measurements were made by exposing sample blocks of coal (nominally 30 × 10 × 10 mm) to relative humidities ranging from 0% to 97%. A selection of coals was also fully saturated in water.Moisture uptake at 97% relative humidity (RH) ranged from about 2.5% to more than 16% db. Maximum linear strain associated with the moisture sorption (measured at 97% RH) varied from about 0.2% to 1.3%, with lower rank coals showing the most swelling. In all cases, swelling was greater in the direction perpendicular to the bedding plane. These results correspond to volumetric swelling of about 0.5% to around 5%. Although exhibiting significant expansion, all of the samples returned to their original dimensions upon drying.Volumetric moisture sorption and the amount of swelling induced were found to be strongly correlated by a single linear expression that held for all of the coals examined. It was further found that the volume of the water adsorbed was linearly related to the pore space within the coal, however, at 97% relative humidity, only about 60% of the available pore space is occupied by water. Exposure to liquid water allowed the pores to completely fill; although for the lowest rank coals, the volume of water absorbed appeared to be slightly more than the corresponding pore volume. Despite the additional water uptake, immersion in water did not produce further swelling beyond that induced at 97% relative humidity.

International Journal of Coal Geology, 2011

ABSTRACT Determining the feasibility of injecting CO2 into coal seams for enhanced coalbed methan... more ABSTRACT Determining the feasibility of injecting CO2 into coal seams for enhanced coalbed methane (ECBM) recovery as well as providing long-term carbon sequestration is an active area of research. It is now well known that coal swells in the presence of water and gases, which in turn may affect its in-seam permeability. If the swelling of the coal matrix by each component can be quantified, it may be possible to make better predictions about the suitability of particular seams for ECBM and carbon sequestration. Despite numerous studies where coal swelling has been measured in gases or water, there is relatively little information relating to how swelling of coals by gases is affected by water.In this paper we report on the gas-induced swelling behaviour of four moist Australian coals. Blocks of coal, nominally 30×9×9mm, were cut parallel and perpendicular to the bedding plane from larger lumps. Samples were moisture-equilibrated at 97% relative humidity before being exposed to CO2 or CH4 at pressures up to 16MPa and a temperature of 55°C. Swelling of each sample was measured directly using digital cameras to monitor the change in length of the block as a function of pressure.Results show that swelling was greater in CO2 than CH4, with lower rank coals swelling more than high rank material. The presence of moisture significantly reduced the amount of additional swelling by the gas compared to dry coals; however, the degree to which the swelling of the coals was affected by moisture depended on the rank of the coal. It was also found that, proportionally, CH4-induced swelling was more affected by the presence of moisture than CO2-induced swelling. Although moist coals swelled less in CO2 or CH4 than dry coals, if the swelling due to moisture is included, the total swelling is more than that induced by the corresponding gas in the dry coal.

International Journal of Coal Geology, 2012

Swelling of coal, especially in the presence of CO 2 , may reduce the permeability of coal seams ... more Swelling of coal, especially in the presence of CO 2 , may reduce the permeability of coal seams thus affecting the viability of enhanced coalbed methane production or CO 2 sequestration operations. In this paper we report laboratory measurements of swelling in four Australian bituminous and sub-bituminous coals in CO 2 , methane and various mixtures of the two gases. Measurements were made on unconstrained monolithic samples at 55°C and at pressures up to about 15 MPa. Volumetric swelling at 15 MPa ranged from about 1.9% to 5.5% in CO 2 and 1.0% to 2.5% in CH 4 depending on the rank of coal and the proportion of CO 2 in the gas mixture. Swelling measurements made at a constant pressure of 15 MPa but with varying gas composition showed that even CO 2 with a high affinity for coal could be completely displaced by helium, which does not adsorb, causing the coal sample to shrink to its original dimensions. Similarly, CH 4 was displaced by injecting CO 2 into the system which then caused the coal to swell to the same level as if it had been exposed to pure CO 2. The results of these experiments show that there is no enhanced swelling in mixed gases above that would be observed in the pure CO 2 at the same total pressure. As well, the swelling behaviour of coal in mixed gases was determined solely by the partial pressure of the sorbing gas so that weakly or non-sorbing gases are effective at displacing strongly adsorbed gases.

International Journal of Coal Geology, 2008

... Thumbnails - selected | Full-Size images. Article. Article - selected. Figures/Tables. Figure... more ... Thumbnails - selected | Full-Size images. Article. Article - selected. Figures/Tables. Figures/Tables - selected. References. References - selected. International Journal of Coal Geology Volume 74, Issue 1, 3 March 2008, Pages 41-52. ...

Environmental Monitoring and Assessment, 2009

Spontaneous combustion and low-temperature oxidation of waste coal and other carbonaceous materia... more Spontaneous combustion and low-temperature oxidation of waste coal and other carbonaceous material at open-cut coal mines are potentially significant sources of greenhouse gas emissions. However, the magnitude of these emissions is largely unknown. In this study, emissions from spontaneous combustion and low-temperature oxidation were estimated for six Australian open-cut coal mines with annual coal production ranging from 1.7 to more than 16 Mt. Greenhouse emissions from all other sources at these mines were also estimated and compared to those from spontaneous combustion and low-temperature oxidation. In all cases, fugitive emission of methane was the largest source of greenhouse gas; however, in some mines, spontaneous combustion accounted for almost a third of all emissions. For one mine, it was estimated that emissions from spontaneous combustion were around 250,000 t CO(2)-e per annum. The contribution from low-temperature oxidation was generally less than about 1% of the total for all six mines. Estimating areas of spoil affected by spontaneous combustion by ground-based surveys was prone to under-report the area. Airborne infrared imaging appears to be a more reliable method.

Energy & Fuels, 2010

ABSTRACT If CO2 can be sequestered in coal seams while simultaneously displacing coalbed methane ... more ABSTRACT If CO2 can be sequestered in coal seams while simultaneously displacing coalbed methane [enhanced coalbed methane (ECBM)], some of the sequestration costs can be recovered through the production of methane. One potential difficulty with ECBM is that CO2 is known to swell coal, which may reduce its permeability. Coals also swell in other gases, although not to the same extent. Here, we report on the swelling of sub-bituminous and bituminous coals in CO2, CH4, N2, CF4, ethane, and various noble gases. Helium and Ne induced negligible swelling; all other gases swelled the coals to varying degrees. The maximum swelling was proportional to the critical temperature of the gas, except for CF4, which is attributed to its greater size, preventing it from penetrating the coal as completely as the other gases. This indicates that swelling of these coals by all of these gases has a similar basic mechanism; CO2 is only different in the extent to which it swells coal. All coals swelled more in the direction perpendicular to the bedding plane than parallel to it, with the ratio of the swelling in each direction independent of pressure or gas type. Gas sorption and swelling in coal were found to be related according to a simple quadratic polynomial expression. The same relationship held for all of the coals and all gases investigated here. This means that swelling can be accurately predicted from the condensed volume of the gas adsorbed, regardless of the type of coal or gas.

Greenhouse Gas Measurement and Management, 2012

Seam gas released during coal mining is a substantial source of fugitive greenhouse gas emissions... more Seam gas released during coal mining is a substantial source of fugitive greenhouse gas emissions worldwide. Most of these emissions originate from underground mining; however, lack of robust global data means that the scale of emissions remains uncertain. Some coal-producing countries are attempting to improve the quality of emission estimates by using ventilation data to calculate emissions from individual mines. Legislation recently introduced in Australia now requires coal mine operators to estimate and report annual fugitive emissions. This article examines the methodology currently used at most Australian mines to meet these requirements. To assess the performance of this methodology, we compared the results of routine measurements of ventilation air flow rate and gas composition to those made with reference methods. The primary sources of uncertainty in the techniques are identified and their contributions to the uncertainty of the reported fugitive emission fluxes are estimated.

International Journal of Coal Preparation and Utilization, 2009

ABSTRACT The gas-induced swelling behavior of coal is important when considering CO2 sequestratio... more ABSTRACT The gas-induced swelling behavior of coal is important when considering CO2 sequestration into coal seams or enhanced coalbed methane applications, but coals may also swell in the presence of moisture, or shrink on drying. In this paper we examine the moisture-swelling properties of coals from Australia and elsewhere. Results on the moisture uptake and corresponding swelling measurements are presented for 15 coals of various ranks (sub-bituminous and bituminous) at 22°C and atmospheric pressure. Measurements were made by exposing sample blocks of coal (nominally 30 × 10 × 10 mm) to relative humidities ranging from 0% to 97%. A selection of coals was also fully saturated in water.Moisture uptake at 97% relative humidity (RH) ranged from about 2.5% to more than 16% db. Maximum linear strain associated with the moisture sorption (measured at 97% RH) varied from about 0.2% to 1.3%, with lower rank coals showing the most swelling. In all cases, swelling was greater in the direction perpendicular to the bedding plane. These results correspond to volumetric swelling of about 0.5% to around 5%. Although exhibiting significant expansion, all of the samples returned to their original dimensions upon drying.Volumetric moisture sorption and the amount of swelling induced were found to be strongly correlated by a single linear expression that held for all of the coals examined. It was further found that the volume of the water adsorbed was linearly related to the pore space within the coal, however, at 97% relative humidity, only about 60% of the available pore space is occupied by water. Exposure to liquid water allowed the pores to completely fill; although for the lowest rank coals, the volume of water absorbed appeared to be slightly more than the corresponding pore volume. Despite the additional water uptake, immersion in water did not produce further swelling beyond that induced at 97% relative humidity.

International Journal of Coal Geology, 2011

ABSTRACT Determining the feasibility of injecting CO2 into coal seams for enhanced coalbed methan... more ABSTRACT Determining the feasibility of injecting CO2 into coal seams for enhanced coalbed methane (ECBM) recovery as well as providing long-term carbon sequestration is an active area of research. It is now well known that coal swells in the presence of water and gases, which in turn may affect its in-seam permeability. If the swelling of the coal matrix by each component can be quantified, it may be possible to make better predictions about the suitability of particular seams for ECBM and carbon sequestration. Despite numerous studies where coal swelling has been measured in gases or water, there is relatively little information relating to how swelling of coals by gases is affected by water.In this paper we report on the gas-induced swelling behaviour of four moist Australian coals. Blocks of coal, nominally 30×9×9mm, were cut parallel and perpendicular to the bedding plane from larger lumps. Samples were moisture-equilibrated at 97% relative humidity before being exposed to CO2 or CH4 at pressures up to 16MPa and a temperature of 55°C. Swelling of each sample was measured directly using digital cameras to monitor the change in length of the block as a function of pressure.Results show that swelling was greater in CO2 than CH4, with lower rank coals swelling more than high rank material. The presence of moisture significantly reduced the amount of additional swelling by the gas compared to dry coals; however, the degree to which the swelling of the coals was affected by moisture depended on the rank of the coal. It was also found that, proportionally, CH4-induced swelling was more affected by the presence of moisture than CO2-induced swelling. Although moist coals swelled less in CO2 or CH4 than dry coals, if the swelling due to moisture is included, the total swelling is more than that induced by the corresponding gas in the dry coal.

International Journal of Coal Geology, 2012

Swelling of coal, especially in the presence of CO 2 , may reduce the permeability of coal seams ... more Swelling of coal, especially in the presence of CO 2 , may reduce the permeability of coal seams thus affecting the viability of enhanced coalbed methane production or CO 2 sequestration operations. In this paper we report laboratory measurements of swelling in four Australian bituminous and sub-bituminous coals in CO 2 , methane and various mixtures of the two gases. Measurements were made on unconstrained monolithic samples at 55°C and at pressures up to about 15 MPa. Volumetric swelling at 15 MPa ranged from about 1.9% to 5.5% in CO 2 and 1.0% to 2.5% in CH 4 depending on the rank of coal and the proportion of CO 2 in the gas mixture. Swelling measurements made at a constant pressure of 15 MPa but with varying gas composition showed that even CO 2 with a high affinity for coal could be completely displaced by helium, which does not adsorb, causing the coal sample to shrink to its original dimensions. Similarly, CH 4 was displaced by injecting CO 2 into the system which then caused the coal to swell to the same level as if it had been exposed to pure CO 2. The results of these experiments show that there is no enhanced swelling in mixed gases above that would be observed in the pure CO 2 at the same total pressure. As well, the swelling behaviour of coal in mixed gases was determined solely by the partial pressure of the sorbing gas so that weakly or non-sorbing gases are effective at displacing strongly adsorbed gases.

International Journal of Coal Geology, 2008

... Thumbnails - selected | Full-Size images. Article. Article - selected. Figures/Tables. Figure... more ... Thumbnails - selected | Full-Size images. Article. Article - selected. Figures/Tables. Figures/Tables - selected. References. References - selected. International Journal of Coal Geology Volume 74, Issue 1, 3 March 2008, Pages 41-52. ...

Environmental Monitoring and Assessment, 2009

Spontaneous combustion and low-temperature oxidation of waste coal and other carbonaceous materia... more Spontaneous combustion and low-temperature oxidation of waste coal and other carbonaceous material at open-cut coal mines are potentially significant sources of greenhouse gas emissions. However, the magnitude of these emissions is largely unknown. In this study, emissions from spontaneous combustion and low-temperature oxidation were estimated for six Australian open-cut coal mines with annual coal production ranging from 1.7 to more than 16 Mt. Greenhouse emissions from all other sources at these mines were also estimated and compared to those from spontaneous combustion and low-temperature oxidation. In all cases, fugitive emission of methane was the largest source of greenhouse gas; however, in some mines, spontaneous combustion accounted for almost a third of all emissions. For one mine, it was estimated that emissions from spontaneous combustion were around 250,000 t CO(2)-e per annum. The contribution from low-temperature oxidation was generally less than about 1% of the total for all six mines. Estimating areas of spoil affected by spontaneous combustion by ground-based surveys was prone to under-report the area. Airborne infrared imaging appears to be a more reliable method.

Energy & Fuels, 2010

ABSTRACT If CO2 can be sequestered in coal seams while simultaneously displacing coalbed methane ... more ABSTRACT If CO2 can be sequestered in coal seams while simultaneously displacing coalbed methane [enhanced coalbed methane (ECBM)], some of the sequestration costs can be recovered through the production of methane. One potential difficulty with ECBM is that CO2 is known to swell coal, which may reduce its permeability. Coals also swell in other gases, although not to the same extent. Here, we report on the swelling of sub-bituminous and bituminous coals in CO2, CH4, N2, CF4, ethane, and various noble gases. Helium and Ne induced negligible swelling; all other gases swelled the coals to varying degrees. The maximum swelling was proportional to the critical temperature of the gas, except for CF4, which is attributed to its greater size, preventing it from penetrating the coal as completely as the other gases. This indicates that swelling of these coals by all of these gases has a similar basic mechanism; CO2 is only different in the extent to which it swells coal. All coals swelled more in the direction perpendicular to the bedding plane than parallel to it, with the ratio of the swelling in each direction independent of pressure or gas type. Gas sorption and swelling in coal were found to be related according to a simple quadratic polynomial expression. The same relationship held for all of the coals and all gases investigated here. This means that swelling can be accurately predicted from the condensed volume of the gas adsorbed, regardless of the type of coal or gas.