Stability Analysis of Nonlinear Attitude Determination and Control Systems

This report describes the modelling and performance of an attitude determination and control system (ADCS) for a small satellite in lunar orbit. The focus is on stability analyses of each of the components in the system, and of the system as a whole. In connection to this, the separation principle for nonlinear systems is investigated. Central background information is presented, covering necessary rigid body dynamics and stability properties. Three different controller types are analysed and compared herein, namely a model-dependent linearizing controller, a robust controller and a standard PD-controller. An observer is chosen based on earlier work, but some detail modifications are made to its structure. A state-space model of the satellite and environment is derived and implemented in Matlab, along with the observer and controllers. The observer and all three controllers are shown to be stable with Lyapunov analysis. The total ADCS including the observer is shown to have a cascaded structure, on which theory of nonlinear separation principles is used to establish stability properties of the total system. Finally, the ADCS is put to simulation tests imitating real-life scenarios and the performance of the different controllers are compared. The PD-controller shows the best performance, both in speed of convergence and robustness to model errors. While not completely satisfactory, the results give a basis on which to perform further work

Marine monitoring for offshore geological carbon storage—a review of strategies, technologies and trends

publishedVersio

ACT4storage - Acoustic and Chemical Technologies for environmental GCS monitoring. D4 - Recommended guidelines report

Carbon capture and storage (CCS) is a promising tool for accelerating decarbonization and reaching international climate goals. The process involves capturing CO2 from energy-intensive industries such as waste-to-energy plants, fertilizer production, and fossil fuel combustion, and injecting it into suitable geological formations for safe and permanent storage instead of releasing it into the atmosphere. A dedicated monitoring plan is required to verify that the CO2 is safely stored over time and to detect and quantify leakage if it should occur. For offshore carbon storage, the primary monitoring is based on seismic methods and in-well monitoring, complemented by marine monitoring targeting the seabed and the water column above the storage reservoir. This report is intended to provide support for parties involved in the design of a marine monitoring program for offshore CCS sites. ...publishedVersio

Acoustic characterization of an artificial CO2 seep using split-beam echo sounders

Geological carbon storage (GCS) has emerged as a promising method for reducing greenhouse gas emissions and achieving international climate goals. Currently, sub-seafloor GCS sites sequester about 1.8 MtCO2/yr. Additional sites are under development and by 2050, there is potential for storage of ≈ 100 Mt CO2/yr. For the expansion of sub-seafloor GCS to be successful, cost-efficient and effective leak monitoring systems must be available. The ACT4storage project is tasked with development of leak monitoring through the selection and use of available technologies. A part of the monitoring suite is the use of active acoustics to detect and quantify free CO2 bubbles and droplets. An artificial seep device was created to simulate leaks of CO2 bubbles. Leak simulations were quantified by two broadband split-beam echosounders (50-90 kHz and 250-450 kHz). The split-beam echosounders offer high sensitivity, broadband transmission and were calibrated to quantify flux from a leakage site. The split-beam echosounders show promise as cost-efficient and effective methods for the detection and quantification of free CO2.publishedVersio

The correlation between pO2 and pCO2 as a chemical marker for detection of offshore CO2 leakage

A controlled CO2 release experiment was carried out in order to mimic unintended leakage of geologically stored CO2, and to study methods for detecting these leak events. The experiment was carried out at 60 m depth in the Oslo Fjord over the course of one month. During the simulated leak events, the water chemistry was monitored by sensors mounted on stationary templates located 10 and 22 m horizontally from the source, as well as sensors mounted on an Autonomous Underwater Vehicle (AUV). During baseline conditions (no CO2 release), we observe a strong biogenic correlation between O2 and CO2. This correlation is lacking during CO2 releases, indicating that the CO2-O2 correlation can be used as a marker for CO2 leakage. The same deviations were not initially detected by the CO2 sensor mounted on the AUV due to the longer response time of membrane-based CO2 sensors. However, by applying response time correction in the post-processing of the AUV CO2 data, the generated CO2 plume was detected. Moreover, the plume was clearly detected by the AUV using the faster responding pH sensors, where the correlation with O2 again could be used to confirm the anomaly.publishedVersio

Acoustic characterization of an artificial CO2 seep using split-beam echo sounders

Geological carbon storage (GCS) has emerged as a promising method for reducing greenhouse gas emissions and achieving international climate goals. Currently, sub-seafloor GCS sites sequester about 1.8 MtCO2/yr. Additional sites are under development and by 2050, there is potential for storage of ≈ 100 Mt CO2/yr. For the expansion of sub-seafloor GCS to be successful, cost-efficient and effective leak monitoring systems must be available. The ACT4storage project is tasked with development of leak monitoring through the selection and use of available technologies. A part of the monitoring suite is the use of active acoustics to detect and quantify free CO2 bubbles and droplets. An artificial seep device was created to simulate leaks of CO2 bubbles. Leak simulations were quantified by two broadband split-beam echosounders (50-90 kHz and 250-450 kHz). The split-beam echosounders offer high sensitivity, broadband transmission and were calibrated to quantify flux from a leakage site. The split-beam echosounders show promise as cost-efficient and effective methods for the detection and quantification of free CO2.publishedVersio

Marine monitoring for offshore geological carbon storage—a review of strategies, technologies and trends

publishedVersio

D4 - Recommended guidelines report

Carbon capture and storage (CCS) is a promising tool for accelerating decarbonization and reaching international climate goals. The process involves capturing CO2 from energy-intensive industries such as waste-to-energy plants, fertilizer production, and fossil fuel combustion, and injecting it into suitable geological formations for safe and permanent storage instead of releasing it into the atmosphere. A dedicated monitoring plan is required to verify that the CO2 is safely stored over time and to detect and quantify leakage if it should occur. For offshore carbon storage, the primary monitoring is based on seismic methods and in-well monitoring, complemented by marine monitoring targeting the seabed and the water column above the storage reservoir. This report is intended to provide support for parties involved in the design of a marine monitoring program for offshore CCS sites. ..

Acoustic characterization of an artificial CO2 seep using split-beam echo sounders

Geological carbon storage (GCS) has emerged as a promising method for reducing greenhouse gas emissions and achieving international climate goals. Currently, sub-seafloor GCS sites sequester about 1.8 MtCO2/yr. Additional sites are under development and by 2050, there is potential for storage of ≈ 100 Mt CO2/yr. For the expansion of sub-seafloor GCS to be successful, cost-efficient and effective leak monitoring systems must be available. The ACT4storage project is tasked with development of leak monitoring through the selection and use of available technologies. A part of the monitoring suite is the use of active acoustics to detect and quantify free CO2 bubbles and droplets. An artificial seep device was created to simulate leaks of CO2 bubbles. Leak simulations were quantified by two broadband split-beam echosounders (50-90 kHz and 250-450 kHz). The split-beam echosounders offer high sensitivity, broadband transmission and were calibrated to quantify flux from a leakage site. The split-beam echosounders show promise as cost-efficient and effective methods for the detection and quantification of free CO2