greenhouse gas emissions
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A Bayesian inversion technique to determine the location and strength of trace gas emissions from a point source in open air is presented. It was tested using atmospheric measurements of nitrous oxide (N2O) and carbon dioxide (CO2) released at known rates from a source located within an array of eight evenly spaced sampling points on a 20 m radius circle. The analysis requires knowledge of concentration enhancement downwind of the source and the normalized, three-dimensional distribution (shape) of concentration in the dispersion plume. The influence of varying background concentrations of ~1% for N2O and ~10% for CO2 was removed by subtracting upwind concentrations from those downwind of the source to yield only concentration enhancements. Continuous measurements of turbulent wind and temperature statistics were used to model the dispersion plume. The analysis localized the source to within 0.8 m of the true position and the emission rates were determined to better than 3% accuracy. This technique will be useful in assurance monitoring for geological storage of CO2 and for applications requiring knowledge of the location and rate of fugitive emissions.
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Eddy Covariance (EC) is considered a key atmospheric technique for quantifying CO2 leakage. However the complex and localised heterogeneity of a CO2 leak above the background environmental signal violates several of the critical assumptions made when implementing the EC technique, including: - That horizontal gradients in CO2 concentration are zero. - That horizontal and vertical gradients in the covariance of CO2 and orthogonal wind directions are zero. The ability of EC measurements of CO2 flux at the surface to provide information on the location and strength of CO2 leakage from below ground stores was tested during a 144 kg/day release event (27 March - 13 June 2012) at the Ginninderra controlled release facility. We show that the direction of the leak can be ascertained with some confidence although this depends on leak strength and distance from leak. Elevated CO2 levels are seen in the direction of the leakage area, however quantifying the emissions is confounded by the potential bias within each measurement through breaching of the assumptions underpinning the EC technique. The CO2 flux due to advection of the horizontal CO2 concentration gradients, thought to be the largest component of the error with the violation of the EC technique's assumptions, has been estimated using the modelling software Windtrax. The magnitude of the CO2 flux due to advection is then compared with the measured CO2 flux measured using the EC technique, to provide an initial assessment of the suitability of the EC technique to quantifying leakage source rates. Presented at the 2013 CO2CRC Research Symposium
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Hot Rocks in Australia - National Outlook Hill, A.J.1, Goldstein, B.A1 and Budd, A.R.2 goldstein.barry@saugov.sa.gov.au hill.tonyj@saugov.sa.gov.au Petroleum & Geothermal Group, PIRSA Level 6, 101 Grenfell St.Adelaide SA 50001 Anthony.Budd@ga.gov.au Onshore Energy & Minerals Division, Geoscience Australia, GPO Box 378 Canberra ACT 26012 Abstract: Evidence of climate change and knowledge of enormous hot rock resources are factors stimulating growth in geothermal energy research, including exploration, proof-of-concept appraisals, and development of demonstration pilot plant projects in Australia. In the six years since the grant of the first Geothermal Exploration Licence (GEL) in Australia, 16 companies have joined the hunt for renewable and emissions-free geothermal energy resources in 120 licence application areas covering ~ 67,000 km2 in Australia. The associated work programs correspond to an investment of $570 million, and that tally excludes deployment projects assumed in the Energy Supply Association of Australia's scenario for 6.8% (~ 5.5 GWe) of Australia's base-load power coming from geothermal resources by 2030. Australia's geothermal resources fall into two categories: hydrothermal (from relatively hot groundwater) and the hot fractured rock i.e. Enhanced Geothermal Systems (EGS). Large-scale base-load electricity generation in Australia is expected to come predominantly from Enhanced Geothermal systems. Geologic factors that determine the extent of EGS plays can be generalised as: - source rock availability, in the form of radiogenic, high heat-flow basement rocks (mostly granites); - low thermal-conductivity insulating rocks overlying the source rocks, to provide thermal traps; - the presence of permeable fabrics within insulating and basement rocks, that can be enhanced to create heat-exchange reservoirs; and - a practical depth-range, limited by drilling and completion technologies (defining a base) and necessary heat exchange efficiency (defining a top). A national EGS resource assessment and a road-map for the commercialisation of Australia's EGSs are expected to be published in 2008. The poster will provide a synopsis of investment frameworks and geothermal energy projects underway and planned in Australia.
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CO2CRC Project 1 - Site Specific Studies for Geological Storage of carbon Dioxide Part 1: Southeast Queensland CO2 Storage Sites - Basin Desk-top, Geological Interpretation and Reservoir Simulation of Regional Model
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In July 2010 Geoscience Australia and CSIRO Marine & Atmospheric Research jointly commissioned a new atmospheric composition monitoring station (' Arcturus') in central Queensland. The facility is designed as a proto-type remotely operated `baseline monitoring station' such as could be deployed in areas that are likely targets for commercial scale carbon capture and geological storage (CCS). It is envisaged that such a station could act as a high quality reference point for later in-fill, site based, atmospheric monitoring associated with geological storage of CO2. The station uses two wavelength scanned cavity ringdown instruments to measure concentrations of carbon dioxide (CO2), methane (CH4), water vapour and the isotopic signature (?13C) of CO2. Meteorological parameters such as wind speed and wind direction are also measured. In combination with CSIRO's TAPM (The Air Pollution Model), data will be used to understand the local variations in CO2 and CH4 and the contributions of natural and anthropogenic sources in the area to this variability. The site is located in a region that supports cropping, grazing, cattle feedlotting, coal mining and gas production activities, which may be associated with fluxes of CO2 and CH4. We present in this paper some of the challenges found during the installation and operation of the station in a remote, sub-tropical environment and how these were resolved. We will also present the first results from the site coupled with preliminary modelling of the relative contribution of large point source anthropogenic emissions and their contribution to the background.
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Monitoring is an important aspect in verifying the integrity of the geological storage of greenhouse gases. Geoscience Australia is working with CSIRO, the CO2CRC, the Australian National University, the University of Adelaide and the University of Wollongong to develop and evaluate new techniques to detect and quantify greenhouse gas emissions.
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Hydrothermal and hot fractured rock (HFR) resources are prevalent in Australia. This, and evidence of risks posed by climate change are factors stimulating growth in geothermal energy exploration, proof-of-concept and demonstration power generation projects in Australia. In the six years since the grant of the first Geothermal Exploration Licence (GEL) in Australia in 2001, 16 companies have joined the hunt for renewable and emissions-free geothermal energy resources in 122 licence application areas covering ~ 68,000 km2. The associated work programs correspond to an investment of $570 million, a tally which excludes up-scaling and deployment projects assumed in the Energy Supply Association of Australia's scenario for 6.8% (~ 5.5 GWe) of Australia's base-load power coming from geothermal resources by 2030. Most investment is focused on HFR for enhanced geothermal systems (EGS) to fuel binary power plants. At least two companies are also focused on hydrothermal resources, also to fuel binary power plants. A national EGS resource assessment and a road-map for the commercialisation of Australian EGS are expected to be published in 2008. Geoscience Australia's preliminary work suggests Australia's hot rock energy between 150oC and 5 km is roughly 1.2 billion PJ (roughly 20,000 years of Australia's primary energy use in 2005), without taking account of the renewable characteristics of hot rock EGS plays. The presentation will provide up-to-date accounts of: 1. Exploration, proof-of-concept and demonstration projects on the path to commercializing hot rock resources in Australia; 2. Government designed investment frameworks that aim to attract and facilitate progress to commercializing hot rock resources in Australia; 3. Methods adopted by regulators to meet community expectations that only safe operations (including EGS projects) will be approved by regulators; and 4. Proposed methods for the portfolio management of EGS projects vying for funding within companies, and competing for research and demonstration grants from governments.
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Having techniques available for the accurate quantification of potential CO2 surface leaks from geological storage sites is critical for regulators, public assurance and for underpinning carbon pricing mechanisms. Currently, there are few options available that enable accurate CO2 quantification of potential leaks at the soil-atmosphere interface. Integrated soil flux measurements can be used to quantify CO2 emission rates from the soil and atmospheric techniques such as eddy covariance or Lagrangian stochastic modelling have been used with some success to quantify CO2 emissions into the atmosphere from simulated surface leaks. The error for all of these techniques for determining the emission rate is not less than 10%. A new technique to quantify CO2 emissions was trialled at the CO2CRC Ginninderra controlled release site in Canberra. The technique, termed atmospheric tomography, used an array of sampling sites and a Bayesian inversion technique to simultaneously solve for the location and magnitude of a simulated CO2 leak. The technique requires knowledge of concentration enhancement downwind of the source and the normalized, three-dimensional distribution (shape) of concentration in the dispersion plume. Continuous measurements of turbulent wind and temperature statistics were used to model the dispersion plume.
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Quantification of leakage into the atmosphere from geologically stored CO2 is achievable by means of atmospheric monitoring techniques if the position of the leak can be located and the perturbation above the background concentration is sufficiently large for discrimination. Geoscience Australia and the CO2CRC have recently constructed a site in northern Canberra for the controlled release of greenhouse gases. This facility enables the simulation of leak events and provides an opportunity to investigate techniques for the detection and quantification of emissions of CO2 (and other greenhouse gases) into the atmosphere under controlled conditions. The facility is modelled on the ZERT controlled release facility in Montana. The first phase of the installation is complete and has supported an above ground, point source, release experiment (e.g. simulating leakage from a compromised well). Phase 2 involves the installation of a shallow underground horizontal well for line source CO2 release experiments and this will be installed during the first half of 2011. A release experiment was conducted at the site to explore the application of a technique, termed atmospheric tomography, to simultaneously determine the location and emission rate of a leak when both are unknown. The technique was applied to the release of two gas species, N2O and CO2, with continuous sampling of atmospheric trace gas concentrations from 8 locations 20m distant from a central release point and measurement of atmospheric turbulence and dispersive conditions. The release rate was 1.10 ± 0.02 g min-1 for N2O and 58.5 ± 0.4 g min-1 for CO2 (equivalent to 30.7 ± 0.2 tonnes CO2 yr-1). Localisation using both release species occurred within 0.5 m (2% error) of the known location. Determination of emission rate was possible to within 7% for CO2 and 5% for N2O.
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There is increasing recognition that minimising methane emissions from the oil and gas sector is a key step in reducing global greenhouse gas emissions in the near term. Atmospheric monitoring techniques are likely to play an important future role in measuring the extent of existing emissions and verifying emission reductions. They can be very suitable for monitoring gas fields as they are continuous and integrate emissions from a number of potential point and diffuse sources that may vary in time. Geoscience Australia and CSIRO Marine & Atmospheric Research have collected three years of continuous methane and carbon dioxide measurements at their atmospheric composition monitoring station ('Arcturus') in the Bowen Basin, Australia. Methane signals in the Bowen Basin are likely to be influenced by cattle production, landfill, coal production, and conventional and coal seam gas (CSG) production. Australian CSG is typically 'dry' and is characterised by a mixed thermogenic-biogenic methane source with an absence of C3-C6+ alkanes. The range of '13C isotopic signatures of the CSG is similar to methane from landfill gas and cattle emissions. The absence of standard in-situ tracers for CSG fugitive emissions suggests that having a comprehensive baseline will be critical for successful measurement of fugitive emissions using atmospheric techniques. In this paper we report on the sensitivity of atmospheric techniques for the detection of fugitive emissions from a simulated new CSG field against a three year baseline signal. Simulation of emissions was performed for a 1-year period using the coupled prognostic meteorological and air pollution model TAPM at different fugitive emission rates (i.e. estimates of <1% to up to 10% of production lost) and distances (i.e. 10 - 50 km) from the station. Emissions from the simulated CSG field are based on well density, production volumes, and field size typical of CSG fields in Australia. The distributions of the perturbed and baseline signals were evaluated and statistically compared to test for the presence of fugitive methane emissions. In addition, a time series model of the methane baseline was developed in order to generate alternative realizations of the baseline signal. These were used to provide measures of both the likelihood of detecting fugitive emissions at various emission levels and of the false alarm rate. Results of the statistical analysis and an indicative minimum fugitive methane emission rate that can be detected using a single monitoring station are presented. Poster presented at the American Geophysical Union meeting, December 2013, San Francisco