Australian Coal-fired Power Station Research Articles

Air Pollution Issues in Australia.

This researcher examined air quality in Australia and, compared to other countries, found that there were considerable gaps in Australian’s actions and legislation towards air pollution. Firstly Australia has a Neoliberal Federal Government who are committed to continuing with fossil fuel development. As well as a preference for coal, gas is regarded as being a big contender in the Australian economy. The Federal Government is now keen to undertake CSG mining to extract gas which produces methane which is approximately 30 times more dangerous to the climate in greenhouse gas emissions than carbon dioxide. Further concerns have arisen in regard to lack of fuel standards which mean that car owners can use whatever types of petrol they wish. Diesel is also another option. Both these fuel sources are creating toxic, uncontrolled pollution. Another worrying consideration is the 40 year old Australian coal-fired power stations. The author was affronted at the terrible toxins being emitted from the Liddell coal-fired power station, well above the international standards, and there only being dated control in place, unlike the reduction of emissions in other countries. The research project the author undertook on: “Supporting the Upper Hunter valley community in the transition from coal power to renewable energy with the closure of the Liddell power station in 2022,” showed that individual and family health results were concerning as there was confusion about whether respondents considered their health was impacted. Interestingly focus groups highlighted that many people did understand that once the power station closed their health would definitely improve. NSW and Australia need policy development and action in air quality. The evidence of bad pollution – no fuel standards; dated controls on emissions for 40 year old coal-fired power stations; and probable continued greenhouse gas emissions increasing through continued coal use and gas mining – show that Australia is at the crossroads in regard to air quality and climate change. Zali Steggall, an Independent Member of Parliament, is proposing a Climate Change Bill by November 2020. Her supporters are arguing for a conscience vote. If enacted, the Bill would address the issue of climate change in a scientific and systematic way and, in so doing, tackle the multi-faceted problem of Australia’s poor air quality.

Health benefits of reducing Australian coal-fired power stations emissions

Health benefits of reducing Australian coal-fired power stations emissions

A site trial demonstration of CO2 capture from real flue gas by novel carbon fibre composite monolith adsorbents

A carbon fibre composite solid sorbent CO2 capture prototype unit was developed and site trialled at a coal-fired power station using actual flue gas. Over 200 test cycles of adsorption and sorbent regeneration were performed to evaluate the performance of the adsorbents. Under the study conditions, the CO2 adsorption efficiency of the carbon fibre composite adsorbents was found to be consistently over 98% with or without flue gas pre-treatment. The adsorption performance of the solid sorbents was maintained even after more than 200 tests and it was demonstrated for the first time that the carbon fibre composite solid sorbents were very stable under real flue gas conditions without any noticeable impact of SO2 and NOx on their CO2 adsorption performance. CO2 desorption efficiency of the adsorbent material using combined heat and vacuum swing was found to be between 90 and 95%. Besides, the adsorbents exhibited consistently very high removal performance of SO2 and NOx from flue gas and can very well eliminate the need for conventional chemical based caustic scrubber pre-treatment systems, which is generally required for solvent based capture processes. The carbon composite adsorption systems also have potential to be a pre-treatment or pre-cleaning technology, particularly for Australian coal-fired power stations which lack flue gas de-sulphurisation and de-nitrification facilities.

Pilot‐scale evaluation of concentrated piperazine for CO2 capture at an Australian coal‐fired power station: duration experiments

AbstractDuration operation was completed as the final stage of evaluating concentrated piperazine as a CO2 capture solvent at the Tarong pilot plant. For the duration tests, a single operating set‐point was maintained for an extended period of time. The purpose of the duration tests was to monitor the formation of degradation products and the robustness of the solvent. Two duration tests were conducted that differed only in the regeneration temperature used (125 or 155 °C). Four hundred twenty‐five hours of operation were achieved on the solvent with a regeneration temperature of 125 °C. This was followed by a further 421 h of operation with a regeneration temperature of 155 °C, giving a total operating time on the solvent of 1700 h by the end of the project. For the duration experiments, roughly 500 tonnes of flue gas was treated, and approximately 70 tonnes of CO2 captured. The heat stable salt (HSS) measured in highest concentration was formate, with the rate of formation increasing with regeneration temperature. The effect of pre‐treatment could be seen with sulfate concentration in the solvent increasing sharply when caustic supply to the pre‐treatment column was interrupted. Despite the formation of degradation products in the solvent regeneration energy requirements were not notably effected. For operation up to 1700 h on a real coal flue gas, no loss of plant performance was observed. © 2015 Society of Chemical Industry and John Wiley & Sons, Ltd

Pilot-scale evaluation of concentrated piperazine for CO2 capture at an Australian coal-fired power station: Nitrosamine measurements

Concentrated piperazine is a promising new solvent under consideration for post combustion capture (PCC) of CO2. As it is a secondary amine, one of the concerns when applying this solvent to flue gases is the potential formation of nitrosamines. Secondary amines will form stable nitrosamines, which are generally considered to be carcinogens. The Tarong CO2 capture pilot plant was recently used to evaluate the concentrated piperazine process on a real coal flue gas. During duration operation completed at the plant, solvent samples were regularly collected and analysed for their nitrosamine content. Mononitrosopiperazine (MNPZ) concentration in the solvent was noted to increase with operating time, reaching a steady state level of approximately 7.5mmol/kg when operating with a regeneration temperature in the stripping column of 125°C. The concentration of MNPZ in the solvent was noted to decrease sharply to 2.5mmol/kg when the regeneration temperature was increased to 155°C. The results provided here suggest that the concentration of MNPZ formed in the solvent can be controlled through the choice of plant operating conditions.

Bioremediation for coal-fired power stations using macroalgae

Macroalgae are a productive resource that can be cultured in metal-contaminated waste water for bioremediation but there have been no demonstrations of this biotechnology integrated with industry. Coal-fired power production is a water-limited industry that requires novel approaches to waste water treatment and recycling. In this study, a freshwater macroalga (genus Oedogonium) was cultivated in contaminated ash water amended with flue gas (containing 20% CO2) at an Australian coal-fired power station. The continuous process of macroalgal growth and intracellular metal sequestration reduced the concentrations of all metals in the treated ash water. Predictive modelling shows that the power station could feasibly achieve zero discharge of most regulated metals (Al, As, Cd, Cr, Cu, Ni, and Zn) in waste water by using the ash water dam for bioremediation with algal cultivation ponds rather than storage of ash water. Slow pyrolysis of the cultivated algae immobilised the accumulated metals in a recalcitrant C-rich biochar. While the algal biochar had higher total metal concentrations than the algae feedstock, the biochar had very low concentrations of leachable metals and therefore has potential for use as an ameliorant for low-fertility soils. This study demonstrates a bioremediation technology at a large scale for a water-limited industry that could be implemented at new or existing power stations, or during the decommissioning of older power stations.

The sequential application of macroalgal biosorbents for the bioremediation of a complex industrial effluent.

Fe-treated biochar and raw biochar produced from macroalgae are effective biosorbents of metalloids and metals, respectively. However, the treatment of complex effluents that contain both metalloid and metal contaminants presents a challenging scenario. We test a multiple-biosorbent approach to bioremediation using Fe-biochar and biochar to remediate both metalloids and metals from the effluent from a coal-fired power station. First, a model was derived from published data for this effluent to predict the biosorption of 21 elements by Fe-biochar and biochar. The modelled outputs were then used to design biosorption experiments using Fe-biochar and biochar, both simultaneously and in sequence, to treat effluent containing multiple contaminants in excess of water quality criteria. The waste water was produced during ash disposal at an Australian coal-fired power station. The application of Fe-biochar and biochar, either simultaneously or sequentially, resulted in a more comprehensive remediation of metalloids and metals compared to either biosorbent used individually. The most effective treatment was the sequential use of Fe-biochar to remove metalloids from the waste water, followed by biochar to remove metals. Al, Cd, Cr, Cu, Mn, Ni, Pb, Zn were reduced to the lowest concentration following the sequential application of the two biosorbents, and their final concentrations were predicted by the model. Overall, 17 of the 21 elements measured were remediated to, or below, the concentrations that were predicted by the model. Both metalloids and metals can be remediated from complex effluent using biosorbents with different characteristics but derived from a single feedstock. Furthermore, the extent of remediation can be predicted for similar effluents using additive models.

Further Investigation into the Formation Mechanism of Ash Cenospheres from an Australian Coal-Fired Power Station

This study continues the investigation into the ash cenosphere formation mechanism using a series of narrow size-fractioned ash cenosphere samples separated from the fly ash of an Australian coal-fired power station. The gas products locked inside various ash cenosphere size fractions are dominantly CO2 and some N2. With increasing ash cenosphere particle size from 63–75 μm to 150–250 μm, the average gas pressure decreases from 0.227 atm (at normal temperature and pressure, NTP) to 0.172 atm while the amount of CO2 and N2 locked in ash cenospheres increases significantly. The SiO2/Al2O3 ratio decreases with increasing ash cenosphere size, accompanied with an increase in the sum of TiO2 and Fe2O3 contents. Thermomechanical analysis further shows that ash cenospheres of different size fractions cannot achieve full melting at 1600 °C, suggesting that the formation of these ash cenospheres requires higher temperatures. Further analysis based on ash chemistry of individual cenospheres suggests that the optimum...

Dynamic Modeling and Validation of Post-combustion CO2 Capture Plants in Australian Coal-fired Power Stations

Flexible operation of post-combustion CO2 capture (PCC) plants can improve efficiency through coordinating the balance between consumer demands for electricity and CO2 emission reductions. This strategy however, will impose process disturbances while the PCC plant is ramped up, ramped down or turned off. This paper presents the preliminary development of a dynamic model for PCC in a brown coal-fired power plant using the process simulation software Aspen Plus Dynamics. Validation of the dynamic model will be against both steady state and dynamic data from the pilot plant. By gaining this understanding of the dynamic behavior, the technical and financial performance of PCC can be optimised.

Post-combustion capture of CO2 from coal-fired power plants in China and Australia: An experience based cost comparison

Abstract A techno-economic comparative assessment is made for an amine based post-combustion capture (PCC) process applied to representative coal-fired power plants in Australia and China. The assessment is based on an in-depth analysis of the cost of generation. The process and cost models for integrated power and capture plants have been obtained using ASPEN Rate-Sep, Steam-Pro, Steam-Master and PEACE software packages for process modelling and cost estimation. The equipment costs as well as the fuel costs have been based on the national experiences and circumstances. Important differences between PCC in China and Australia have been identified: - the limited environmental controls in existing Australian coal fired power stations requiring a retrofit to include extensive flue gas pre-treatment, - the low fuel cost in Australia as power plants are closely located to coal mines - the low capital costs in China as a result of lower local manufacturing costs. The results indicate that PCC in China can benefit significantly from more energy efficient processes, whereas for the Australian circumstances the focus should be on reduction of capital costs.

Impact of liquid absorption process development on the costs of post-combustion capture in Australian coal-fired power stations

Australian power generators produce approximately 170 TWh per annum of electricity using black and brown coals that accounts for 170 Mtonne of CO 2 emissions per annum or over 40% of anthropogenic CO 2 emissions in Australia. This paper describes the results of a techno-economic evaluation of liquid absorption based post-combustion capture (PCC) processes for both existing and new pulverised coal-fired power stations in Australia. The overall process designs incorporate both the case with continuous capture and the case with the flexibility to switch a CO 2 capture plant on or off depending upon the demand and market price for electricity, and addresses the impact of the presently limited emission controls on the process cost. The techno-economic evaluation includes both air and water cooled power and CO 2 capture plants, resulting in cost of power generation for the situations without and with PCC. Whilst existing power plants in Australia are all water cooled sub-critical designs, the new power plants are deemed to range from supercritical single reheat to ultra-supercritical double reheat designs, with a preference for air-cooling. The process evaluation also includes a detailed sensitivity analysis of the thermodynamic properties of liquid absorbent for CO 2 on the overall costs. The results show that for a meaningful decrease in the efficiency and cost penalties associated with the post combustion CO 2 capture, a novel liquid sorbent will need to have heat of absorption/desorption, sensible heat and heat of vaporisation around 50% less in comparison with 30% (w/w) aqueous MEA solvent. It also shows that the impact of the capital costs of PCC processes is quite large on the added cost of generation. The results can be used to prioritise PCC research in an Australian context.

Post-combustion capture R&D and pilot plant operation in Australia

Abstract Post-combustion capture of CO2 is a key technology for the reduction of greenhouse gas emissions from Australian coal fired power stations. It is an emerging technology, which still faces significant challenges in scaling up to full commercial scale suitable for power station applications. To increase adoption by the power industry significant cost reductions in capital and operating cost must be realised. CSIRO has developed an integrated post-combustion capture R&D and pilot plant program aimed at bringing down the barriers for commercial deployment. This paper provides an overview of the program and its status.

Semi-quantitative characterisation of ambient ultrafine aerosols resulting from emissions of coal fired power stations

Emissions from coal fired power stations are known to be a significant anthropogenic source of fine atmospheric particles, both through direct primary emissions and secondary formation of sulfate and nitrate from emissions of gaseous precursors. However, there is relatively little information available in the literature regarding the contribution emissions make to the ambient aerosol, particularly in the ultrafine size range. In this study, the contribution of emissions to particles smaller than 0.3 μm in the ambient aerosol was examined at a sampling site 7 km from two large Australian coal fired power stations equipped with fabric filters. A novel approach was employed using conditional sampling based on sulfur dioxide (SO 2) as an indicator species, and a relatively new sampler, the TSI Nanometer Aerosol Sampler. Samples were collected on transmission electron microscope (TEM) grids and examined using a combination of TEM imaging and energy dispersive X-ray (EDX) analysis for qualitative chemical analysis. The ultrafine aerosol in low SO 2 conditions was dominated by diesel soot from vehicle emissions, while significant quantities of particles, which were unstable under the electron beam, were observed in the high SO 2 samples. The behaviour of these particles was consistent with literature accounts of sulfate and nitrate species, believed to have been derived from precursor emissions from the power stations. A significant carbon peak was noted in the residues from the evaporated particles, suggesting that some secondary organic aerosol formation may also have been catalysed by these acid seed particles. No primary particulate material was observed in the minus 0.3 μm fraction. The results of this study indicate the contribution of species more commonly associated with gas to particle conversion may be more significant than expected, even close to source.

Speciation of chromium in Australian fly ash

The concentrations of chromium (III) and (VI) in fly ash from nine Australian coal fired power stations were determined. Cr(VI) was completely leached by extraction with 0.01 M NaOH solution and the concentration was determined by inductively coupled plasma atomic emission spectrometry (ICP-AES). This was confirmed by determining Cr(III) and Cr(VI) in the extracts of fly ash that had been spiked with chromium salts. These analytical measurements were done using a combination of ion-exchange chromatography and ICP-AES. The elutant was 0.05 M HNO 3 containing 0.5%-CH 3OH. When the column was operated at a flow rate of 1.2 ml min −1 and samples were injected by use of a sample loop with a volume of 100 μl, Cr(III) and Cr(VI) in sample solution was exclusively separated within approximately 10 min. The detection limits (3 σ) were 5 ng for Cr(III) (0.050 mg l −1) and 9 ng for Cr(VI) (0.090 mg l −1), respectively. A relative standard deviation of 1.9% ( n = 6) was obtained for the determination by IC–ICP–AES of 0.25 mg l −1 Cr(III) and Cr(VI).