IEAGHG Summer School Environmental Impacts of Geological Storage of CO 2. Jen Roberts, University of Strathclyde

Transcription

1 IEAGHG Summer School 2015 Environmental Impacts of Geological Storage of CO 2 Jen Roberts, University of Strathclyde

2 Overview of environmental impacts How science is addressing environmental concerns Examples of environmental impacts - Release from storage formation - Groundwater impacts - Ecosystem impacts Current challenges Presentation Outline - Value of Information - Communication Introduction CO 2 bubbles at seabed, Panarea (Sicily)

3 What is environmental impact? (for the geological storage part of the CCS chain) [Working definition] Potential effect(s) to the environment caused by the activities relating to the geological storage of CO 2, or by the unintended release of CO 2 and/or brine from the storage formation. Environment The setting or conditions (biophysical & social) in which an activity is carried out. Source: G. Johnson S. Africa - CO 2 bubbles in a stream Introduction

4 Protecting the Environment Built into the project - so begins in the planning phase Site characterization Risk assessment Criteria for site selection Permitting Project engineering and management - Pressure / stress effects. - Potential leakage (CO 2 /brine) Introduction

5 CO 2 storage: where/ when might Site development Baseline Operation CO 2 injection there be impacts? Operation & Post closure Pressure dissipation Fluid migration in the storage formation Monitoring? Fluid migration from the storage formation? Remediation

6 Environmental concerns CO 2 storage Local Global Bio-physical & social impacts Pre-operation: Operation & closure: Unintended leak: Disturbance (construction/baseline) Induced seismicity Pressure perturbation (heave/brine displ) Disturbance (operation/monitoring) Alteration of groundwater chemistry Ecosystem impacts (onshore or marine) (incl. acidification of soils, and H&S) Acceptability of CCS Climate change mitigation

7 Environmental concerns CO 2 storage Pre-operation: Operation & closure: Unintended leak: Local Disturbance (construction/baseline) Induced seismicity Pressure perturbation Disturbance (operation/monitoring) Alteration of groundwater chemistry Ecosystem impacts (onshore or marine) (incl. acidification of soils, and H&S) For a range of env. & geol. settings, need to establish: Risk of event occurring? Risk of adverse impact? Nature of impact? Magnitude of impact? MM of impact? etc.

8 Science addressing questions Little experience of full-scale CCS, and none that have leaked, so we have to look to: Analogues - Natural analogues - Industrial analogues Controlled Releases/Injections - Deep pilot injection projects - Shallow controlled releases onshore & marine Simulations: - Laboratory experiments - Numerical modeling Research Q s Photo of NGL labs (or other) Core lab experiment (NGL)

9 Potential environmental impacts - CO 2 injection & storage Carbon Capture Project 1. Env. disturbance during development Terrestrial (land), or marine environment Little different to other industrial analogues, and risks/impacts can be managed as such. 2. Induced seismicity: micro-seismic / felt-seismic. Fault reactivation / induced fracturing. Potential impacts: opening leak pathways, damage to infrastructure, disrupting human activities. Small number of low magnitude events usual (clever monitoring design to detect). Low prob. of high mag events.

10 Potential environmental impacts - 3. Pressure changes Ground displacement Potential issues of subsidence, and ground/infrastructure stability. A number of examples e.g. In Salah. Brine displacement Potentially perturb groundwater systems Impact freshwater aquifers? 4. CO 2 leak during injection From surface/subsurface infrastructure (e.g. compressors or e.g. via well bore) Few e.g s from industrial analogues. Impacts CO 2 injection & storage InSAR measured surface deformations at In Salah (Algeria). White et al (2014) PNAS

11 Potential environmental impacts Unintentional leaks Most likely to leak via fault or well bore or bypass seal e.g. hydrodynamic flow of CO 2 sat brine? Can leak as a gas or dissolved Solitary or clustered seeps Attenuation /loss - how much? e.g. QICS 15% made it to seabed. CO 2 bubbling through water. S. Africa (G. Johnson) Dispersion in (near) surface Spread/flow in soil? Topographic effect? Rate of CO 2 leakage? Variation in rate of leakage? Due to dynamics of leak from reservoir or in near surface e.g. geyser CRC-2 style well / var. head of (CO2CRC) water table depth (seasonal) /other process.

12 Potential environmental impacts Unintentional leaks 1. Alteration of groundwater chemistry: a)migrating CO 2 and any capture impurities (dissolves into water) - ph decrease (buffered in seawater - QICS) - Mobilisation of heavy metals (by mineral dissolution and by detachment from grain surfaces). b) Displaced brine (and its constituents, CO 2 or not) High in TDS, low in oxygen. may import species not usually in the aquifer e.g. organics. Knowledge Gaps: injection impurities, residual gases (CH 4, H 2 S, capture compounds), impact of brine injection (e.g. field exp s).

13 Potential environmental impacts Unintentional leaks 2. Ecosystem health - terrestrial For ecosystems, the CO 2 in soil has more effect than in atm. Critical threshold of 10-15% CO 2 soil gas at 20 cm depth (roots) Reduced productivity in affected plants (field trials) Observe changes in ecosys. due to different biogeochemistry. Change in species above this threshold (diff. tolerances) Nr seep, find acid-tolerant anaerobic microorganisms (analogues). Observe enhanced biomass and diversity at some analogues. These effects are localised, sometimes patchy. Knowledge Gaps: response of soil microbes, effect of gas impurities.

14 Potential environmental impacts Unintentional leaks 2. Ecosystem health marine These systems are naturally variable in space and time baseline impl. 2 impact zones: (i) Below seabed pore water (ii) Above seabed - mobile CO 2 plumes Local acidification of seawater acidosis affect on ecosys? able to cope with short term exposure (dep on life stage etc) ability to cope is affected by nutrient availability. reduced tolerance to other env. stressors etc. Few field experiments QICS

15 Potential environmental impacts Unintentional leaks 2. Ecosystem health marine How big are the plumes? Flux mixing in water by currents Mixing by buoyancy of bubbles Thermal effects?.? Key issues: Impact of displaced brine?

16 Environmental concerns - Post injection: unintentional leaks 3. Human & animal health and safety CO 2 accumulation to high concentrations - Acidification of soils & enhanced weathering - Human and animal health & safety Rapid release?

17 Remaining challenges Variety of impacts in different geo & ecosystems Which impact will occur? Value of information - Scaling up from laboratory to basin - How analogous? - Subsurface conditions; time scales; mass flux. Communication of risks and impacts to stakeholders (inc. public) Appropriate monitoring design Identify positive impacts? Remediating impacts? Leaky well remediation?! S. Africa (G. Johnson) Impacts

18 An environmental impact can be defined as: potential effect(s) to the environment caused by the activities relating to CO 2 geological storage. Conclusions Environmental impacts may occur along the storage activity chain. Environmental protection is built into projects, starting with site selection. Conclusions Field tests, analogues, lab experiments, and modeling give information useful for understanding and predicting env. impacts. A great deal of research on environmental impacts has been done in the past 10 years or so, but there remain some questions to be answered. Environmental impacts are a major stakeholder concern and must be effectively communicated.

19 IEAGHG Summer School 2015 Jen Roberts, University of