Carbon capture and storage (CCS) is broadly recognised as having the potential to play a key role in meeting climate change targets, delivering low carbon heat and power, decarbonising industry and, more recently, its ability to facilitate the net removal of CO2 from the atmosphere. However, despite this broad consensus and its technical maturity, CCS has not yet been deployed on a scale commensurate with the ambitions articulated a decade ago. Thus, in this paper we review the current state-of-the-art of CO2 capture, transport, utilisation and storage from a multi-scale perspective, moving from the global to molecular scales. In light of the COP21 commitments to limit warming to less than 2 °C, we extend the remit of this study to include the key negative emissions technologies (NETs) of bioenergy with CCS (BECCS), and direct air capture (DAC). Cognisant of the non-technical barriers to deploying CCS, we reflect on recent experience from the UK's CCS commercialisation programme and consider the commercial and political barriers to the large-scale deployment of CCS. In all areas, we focus on identifying and clearly articulating the key research challenges that could usefully be addressed in the coming decade.

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Carbon capture and storage (CCS): the way forward

A copy of Guangbo jiemu bao [Broadcast Program Report] was being passed from hand to hand among a group of young people eager to be the first to read the article introducing the program "What Is Revolutionary Love?" It said: "… Young friends, you are certainly very concerned about this problem'. So, we would like you to meet the young women workers Meng Xiaoyu and Meng Yamei and the older cadre Miss Feng. They are the three leading characters in the short story ‘The Place of Love.’ Through the description of the love lives of these three, the story induces us to think deeply about two questions that merit further examination.

This is How the Discussion Started

Recent developments in the direct-current geoelectrical imaging method

• Stability of steady frictional sliding, inertia and the quasi-static limit • work on ps 4; see course web site

The Mechanics Of Earthquakes And Faulting

A solution is presented for the change in water level in a well of finite diameter after a known volume of water is suddenly injected or withdrawn. A set of type curves computed from this solution permits a determination of the transmissibility of the aquifer.

Response of a finite-diameter well to an instantaneous charge of water. Paper No. H-21

Picoseismic data set of the 12 Grimsel HS and HF ISC hydraulic stimulation experiments

. Two borehole ground penetrating radar (GPR) surveys were conducted during saline tracer injection experiments in fully-saturated crystalline rock at the Grimsel Test Site in Switzerland. The saline tracer is characterized by an increased electrical conductivity in comparison to formation water. It was injected under steady state flow conditions into the rock mass that features sub-mm fracture apertures. The GPR surveys were designed as time-lapse reflection GPR from separate boreholes and a time-lapse transmission survey between the two boreholes. The local increase in conductivity, introduced by the injected tracer, was captured by GPR in terms of reflectivity increase for the reflection surveys, and attenuation increase for the transmission survey. Data processing and difference imaging was used to extract the tracer signal in the reflection surveys, despite the presence of multiple static reflectors that could shadow the tracer reflection. The transmission survey was analyzed by a difference attenuation inversion scheme, targeting conductivity changes in the tomography plane. By combining the time-lapse difference reflection images, it was possible to reconstruct and visualize the tracer propagation in 3D. This was achieved by calculating the potential radially-symmetric tracer reflection locations in each survey and determining their intersections, to delineate the possible tracer locations. Localization ambiguity imposed by the lack of a third borehole for a full triangulation was reduced by including the attenuation tomography results into the analysis. The resulting tracer flow reconstruction was found to be in good agreement with data from conductivity sensors in multiple observation locations in the experiment volume and gave a realistic visualization of the hydrological processes during the tracer experiments. Our methodology proved to be successful for characterizing flow paths related with geothermal reservoirs in crystalline rocks, but it can be transferred in a straightforward manner to other applications, such as radioactive repository monitoring or civil engineering projects.

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4D Tracer Flow Reconstruction in Fractured Rock throughBorehole GPR Monitoring

3-D Time-lapse Electrical Resistivity Monitoring of Injected CO 2 in a Shallow Aquifer

We are using 3D time-lapse borehole electrical resistivity tomography (ERT) to investigate the hydrological properties of a producing aquifer in north-eastern Switzerland. During the frequent flooding of an adjacent river, relatively high-resistivity river water infiltrates the gravel aquifer. As a consequence, the electrical characteristics of the infiltrating water can be used as a natural tracer to delineate preferential flow paths through the 7 m thick aquifer. For this research we have installed eighteen monitoring boreholes that completely penetrate the underlying aquifer. Each borehole has been instrumented with 10 electrodes that span the thickness of the aquifer. A multichannel resistivity system, programmed to cycle through various four-point electrode configurations of the 180 electrodes in a rolling sequence, allows the collection of approximately 15,500 apparent resistivity measurements every seven hours on a continuous basis. Three-dimensional static ERT inversions at periods of stable hydrological conditions were carried out to investigate the resolving capability of our acquisition scheme, to define the main lithological structures within the aquifer, to study the superposed time-varying effects (e.g. water table height fluctuations, changes in salinity and temperature) on the measurements, and to provide a base model for future time-lapse inversion studies.

Joseph Doetsch

Papers

Picoseismic data set of the 12 Grimsel HS and HF ISC hydraulic stimulation experiments

4D Tracer Flow Reconstruction in Fractured Rock throughBorehole GPR Monitoring

3-D Time-lapse Electrical Resistivity Monitoring of Injected CO 2 in a Shallow Aquifer

A Multi-borehole 3-D ERT Monitoring System for Aquifer Characterization Using River Flood Events as a Natural Tracer

Hydrogeophysical investigations of three-dimensional lithology and river-groundwater interactions in restored and unrestored river corridors