• Energy Research

AbstractA field facility has been developed to allow controlled studies of near surface CO2 transport and detection technologies. The key component of the facility is a shallow, slotted horizontal well divided into six zones. The scale and fluxes were designed to address large scale CO2 storage projects and desired retention rates for those projects. A wide variety of detection techniques were deployed by collaborators from 6 national labs, 2 universities, EPRI, and the USGS. Additionally, modeling of CO2 transport and concentrations in the saturated soil and in the vadose zone was conducted. An overview of these results will be presented.

Abstract This paper demonstrates a deep neural network approach for predicting carbon dioxide (CO2) plume migration from an injection well in heterogeneous formations with high computational efficiency. With the data generation and training procedures proposed in this paper, we show that the deep neural network model can generate predictions of CO2 plume migration that are as accurate as traditional numerical simulation, given input variables of a permeability field, an injection duration, injection rate, and injection location. The neural network model can deal with permeability fields that have high degrees of heterogeneity. Unlike previous studies which did not consider the effect of buoyancy, here we also show that the neural network model can learn the consequences of the interplay of gravity, viscous, and capillary forces, which is critically important for predicting CO2 plume migration. The neural network model has an excellent ability to generalize within the training data ranges and to a limited extent, the ability to extrapolate beyond the training data ranges. To improve the prediction accuracy when the neural network model needs to extrapolate to situations or parameters not contained in the training set, we propose a transfer learning (fine-tuning) procedure that can quickly teach the trained neural network model new information without going through massive data collection and retraining. With the approaches described in this paper, we have demonstrated many of the building blocks required for developing a general-purpose neural network for predicting CO2 plume migration away from an injection well.

AbstractA significant amount of theoretical, numerical and observational work has been published focused on various aspects of capillary trapping in CO2 storage since the IPCC Special Report on Carbon Dioxide Capture and Storage (2005). This research has placed capillary trapping in a central role in nearly every aspect of the geologic storage of CO2. Capillary, or residual, trapping – where CO2 is rendered immobile in the pore space as disconnected ganglia, surrounded by brine in a storage aquifer – is controlled by fluid and interfacial physics at the size scale of rock pores. These processes have been observed at the pore scale in situ using X-ray microtomography at reservoir conditions. A large database of conventional centimetre core scale observations for flow modelling are now available for a range of rock types and reservoir conditions. These along with the pore scale observations confirm that trapped saturations will be at least 10% and more typically 30% of the pore volume of the rock, stable against subsequent displacement by brine and characteristic of water-wet systems. Capillary trapping is pervasive over the extent of a migrating CO2 plume and both theoretical and numerical investigations have demonstrated the first order impacts of capillary trapping on plume migration, immobilisation and CO2 storage security. Engineering strategies to maximise capillary trapping have been proposed that make use of injection schemes that maximise sweep or enhance imbibition. National assessments of CO2 storage capacity now incorporate modelling of residual trapping where it can account for up to 95% of the storage resource. Field scale observations of capillary trapping have confirmed the formation and stability of residually trapped CO2 at masses up to 10,000tons and over time scales of years. Significant outstanding uncertainties include the impact of heterogeneity on capillary immobilisation and capillary trapping in mixed-wet systems. Overall capillary trapping is well constrained by laboratory and field scale observations, effectively modelled in theoretical and numerical models and significantly enhances storage integrity, both increasing storage capacity and limiting the rate and extent of plume migration.

AbstractThe CO2 reduction potential of battery and fuel cell electric vehicles (BEV/FCEV) is linked to the success of the energy transition. Both vehicle types can facilitate the integration of intermittent renewables. H2 generation and storage infrastructure to support FCEVs is a promising opportunity for synergy between the transportation and building sectors in renewables integration, through grid storage and Power2Gas (i.e. blending H2 into the natural gas supply). However, as FCEVs also require more than twice as much electric energy per distance traveled than BEVs, an integrated analysis is necessary to evaluate which electric vehicle (EV) offers the lowest cost for reducing CO2 emissions.We use an integrated analysis to determine the overall cost and CO2 emissions when BEVs or FCEVs are deployed in two communities in southern Germany. Based on a comprehensive scenario for future cost and technology developments for 2025 and 2035, the cost-optimal mix of energy generation and storage technologies is determined to meet all energy demands (heating, electricity and transportation) in the communities.This integrated analysis finds, that the higher energy consumption of FCEVs could not be compensated by system benefits like Power2Gas and grid storage. The result is consistent with a similar analysis of a community in California. The simulation results reveal, that while the two vehicle types enable similar CO2 emission reductions, these can be realized at lower costs with BEVs than with FCEVs. The most striking observation was, that in the event seasonal H2 grid storage becomes necessary, FCEVs would in fact be less favorable than BEVs, which require less energy per km traveled and therefore leave more energy available for stationary applications.

Batteries for stationary applications can prove to be crucial for enabling high penetration of solar energy, but production and use of batteries comes with an energetic cost.

AbstractThrough the use of analytical solutions derived from a simplified geologic model, this paper investigates the magnitude of pressure transients in permeable zones overlying CO2 storage reservoirs associated with brine migration through the sealing cap rock. A wide range of geologic settings and injection parameters is evaluated from which a generalized correlation is constructed to relate the hydrologic properties of the storage reservoir and seal to the magnitude of expected pressure buildups associated with brine migration across the seal. This correlation, referred to as the detection factor (DF), provides insight into the feasibility and interpretation of pressure changes measured in zones overlying CO2 storage reservoirs as a means of monitoring and leakage detection.

Worker safety in a mature carbon capture and storage industry in the United States based upon analog industry experience Preston D. Jordan a,∗ , Sally M. Benson b a b Earth Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, United States Department of Energy Resources Engineering, Stanford University, Stanford, CA 94305, United States abstract Insight into worker safety in a mature carbon capture and storage (CCS) industry in the United States (US) can be gained by analogy to a variety of existing industries. Worker safety in capture facility construction will be below median, as is typical for construction. Worker safety in capture operation will be above median based on the oil refining, fossil fuel electric power generation, and industrial gas processing analogs. Pipeline construction and operation worker injury rates will be below median based on analogy with oil and gas pipeline construction and operation; however construction will have the unfortunately typical high fatality rate. Storage field worker safety will be mixed with below median injury rates but high fatality rates based on the oil and gas production analog. Still, safety in the oil and gas production analog is better than in the heavy and civil engineering construction industry and much better than in some other common industries, such as marine and truck transportation. CCS worker safety will be greater than the analogs due to the lack of flammable fluid handling, extremely high or low temperatures, product transportation by truck, and relatively less drilling effort, more geophysics effort, and more onshore work. Many of these differences also suggest CCS will be safer for the public than the analogs. 1. Introduction Storage of carbon dioxide (CO 2 ) in permeable rocks in the sub- surface is one option for reducing greenhouse gas emissions in the future. As currently envisioned, CO 2 from large, stationary emis- sion sources, such as power plants and cement factories, would be separated (captured) from the flue gas,purified and compressed to a liquid state. The CO 2 liquid would be transported by pipeline to a suitable storage field where it would be injected into the subsurface for storage in a supercritical state. Likely suitable storage fields are oil and gas reservoirs and permeable rocks filled with brine (saline aquifers) beneath relatively impermeable cap rocks meeting var- ious criteria, such as pressure and temperature. Fig. 1 shows the portions of the coterminous United States (US) underlain by saline aquifers assessed as meeting these criteria as well as the location of all hydrocarbon wells as of 2008. Taken as a whole, the industry described above is typi- cally termed the carbon capture and storage (CCS) industry (Intergovernmental Panel on Climate Change [IPCC], 2005). The safety of such an industry is an area of active study. For instance Ha- Duong and Loisel (2011) projected hundreds of additional fatalities ∗ Corresponding author. Tel.: +1 510 486 6774; fax: +1 510 486 5686. E-mail address: pdjordan@lbl.gov (P.D. Jordan). Worldwide resulting from such an industry through 2050. Most of the fatalities were due to mining and rail transportation of addi- tional coal to power capture plants. However it is by no means assured that coal will be the energy source for such plants. For instance the planned post-combustion capture unit on the coal- fired Petra Nova power plant in Texas will be operated on natural gas. In addition, there is considerable uncertainty in projecting how much energy will be needed for capture as the technology develops. More broadly, numerous studies have identified uncertainties bearing on the environmental and/or public impact of CCS (Wildaya et al., 2011; Koornneef et al., 2012). In general worker safety had not been a particular focus of study, nor what can be learned from exist- ing worker safety data in closely related industries. Such research is motivated by conclusions drawn by the IPCC (2005) indicating that “the local health, safety and environment risks of geological stor- age would be comparable to risks of current activities such as natural gas storage, EOR, and deep underground disposal of acid gas.” It could help bound the uncertainty regarding this key group, and perhaps also provide some perspective on impacts on the public and envi- ronment. This paper pursues such study to develop a perspective on worker safety in a mature CCS industry in the US, using data from current industrial analogs. In particular, this study considers (1) all nonfatal cases of on-the-job injury and/or illness, (2) cases with days away from work due to on-the-job injury and illness, and