Carbon capture and sequestration (CCS) is designed to reduce atmospheric emissions of greenhouse gases (GHGs). The CCS process captures carbon dioxide (CO2) generated at large-scale industrial sources (power plants, refineries, gasification facilities, etc.) and transports it to an injection site to be permanently stored in the subsurface. With extensive research linking GHG concentrations in the atmosphere to observed changes in global temperature patterns, CCS technology could play an important role in policy efforts to limit the global average temperature rise. Even with the wealth of experience already in place within the oil and gas industry, the obstacles to advancing CCS to the forefront of GHG mitigation technologies remain significant. Large-scale CO2 injection projects remain primarily in the realm of commercial CO2-EOR (enhanced oil recovery) projects. The key challenges to enabling CCS include cost-effective capture and transport of industrial CO2, clear access to pore space for CO2 storage in geologic formations, proven methodologies for demonstrating storage integrity, and dissemination of best practices. SPE members can play a significant role in addressing these challenges. Cost-Effective Capture of Power Sector and Industrial CO2 A major technical challenge facing capture at electric generating facilities is that the CO2 concentration in large-volume flue streams is quite low. Current removal technologies include techniques that apply amines, chilled ammonia, membranes, and ionic liquids to strip the CO2 from the flue stream. However, these technologies were developed to handle smaller-scale operations and higher-CO2-purity streams. When applied to large electric generating plants, process efficiency is reduced, and the energy penalty associated with the capture process drives up costs, increasing the levelized cost of electricity by 50% or more, depending on local factors. Also, to accommodate the substantial volumes of the CO2 and flue gas at full-scale industrial sources, the removal technologies require significant scale up and footprint for deployment. While early movers are developing large-scale capture demonstrations such as SaskPower’s Boundary Dam Project, Southern Company’s Kemper Energy Facility (Fig. 1), and NRG’s Petro Nova Facility, we are still very early on the “learning curve.” Support for more development of next-generation capture technologies and large demonstrations is required to push us down the cost curve. This involves reducing the cost of materials and construction, parasitic costs related to energy for operations, compression, and operation and maintenance costs.
We developed two new methods for analyzing the fractal characteristics of adsorbents. In the first method, the fractal dimension of the adsorbent is determined based on the Hurst index (H) calculated for the random process of development of the Langmuir isotherm. In the second method, the Langmuir isotherm is calculated from measurements of the random field of the adsorbed molecules. Then the fractal dimension is determined. using the proposed methods, we calculated the fractal dimensions of samples of xerogel at low-temperature nitrogen adsorption, lunar regolith sample at a low temperature of krypton and n-heptanes, and water vapour adsorption at ambient temperature.
The fracture and release mechanism of radioactive aerosols of HLW glass and HLW canisters are studied experimentally by laboratory scale and full scale drop tests. The experimental conditions model the conditions of accidental drops in a deep salt repository. The laboratory scale drop tests have a scaling factor of 1:10. Accelerated probes of simulated HLW glass impact on a ground plate and the size distributions of broken fines and released aerosols are measured by sieving and scanning electron microscopy (SEM) of aerosol samples. The impact velocity is determined as the dominating impact parameter. Further parameters tested, such as waste glass composition, cooling time (residual thermal stresses), probe temperature at impact, and ground characteristics, show no measurable influence. Source terms of released respirable aerosols are evaluated for two reference cases, borehole drop (impact velocity v = 80 m/s) and reloading hall drop (v = 14 m/s), the values being 0.1 % and to 2.10-4 % respectively of the glass probe mass. The full scale drop tests are performed with European Standard HLW canisters. The canisters keep their integrity in all tests up to drop heights of 14 m. On opening the canisters, the broken fines are analyzed by sieving. The results are in good agreement with the small scale tests and confirm their acceptability for use in a safety analysis.
It could be shown that it is possible to determine the weight fractions of crystalline substances dispersed in a glass matrix. The error is about 10% of the actual content for weight fractions between 4 and 10 wt%. It is about 20 % for weight fractions between 1 and 4 wt% and up to 100 % for weight-fractions less than 1 wt%. Stable phases like ruthenium, were in fact determined with the expected weight fractions. Chemical reactions which may occur during sintering can be followed quantitatively. This method appears to be well suited for determining the recrystallization behaviour of nuclear waste glasses. We learned during the conference that a similar procedure is applied by the CEA to characterize French HLW-glasses /8/.
