Office of Fossil Energy

Climate change is expected to increase both the frequency and intensity of major tropical cyclones, raising the risk from extreme ocean waves. Reliable estimation of these waves is essential for maritime-structure design, yet assessments that rely solely on historical records cannot capture the ongoing non-stationary changes already under way. We introduce a physics-based Gulf of Mexico–wide framework that couples ∼20,000 synthetic tropical cyclone events with a third-generation spectral wave model explicitly resolving present (1980–2010) and future (2070–2100, SSP5-8.5) climates using five CMIP6 GCMs. This synthetic approach overcomes the dual limitations of short observational records and coarse GCM resolution. Results show that the 100-year significant-wave height derived from present synthetic events already exceeds API values based on historical data by ∼2 m, and that this design metric is projected to increase by up to 30 % by the late century in the northern Gulf. Such changes imply that structures designed today under stationary assumptions will face a higher probability of encountering their design wave during service. These findings underscore the need for robust present-day design databases and the integration of non-stationary wave climate projections into future design frameworks to safeguard maritime assets and ensure long-term resilience. • Synthetic tropical cyclones are used to estimate extreme wave conditions. • Increases up to 30 % by the end of the 21st century was found for the Gulf of Mexico. • Non-stationary wave climate approaches can better account for changing extreme waves. • API wave estimates may not capture potential future wave climate shifts.

The localized corrosion behavior of Type 304L stainless steel (UNS S30400), Alloy 625 (UNS N06625), and three experimental NiCoCrMo multiprincipal element alloys (MPEA), exposed to methanol/lithium chloride solutions with different water contents, is examined in this paper. Cyclic potentiodynamic polarization tests indicated that water increased the pitting and repassivation potentials and the critical temperature at which localized corrosion occurred in chloride solutions. The effect of water on repassivation potential in methanol-chloride solution depended on the chloride concentration and alloy content. At lower chloride concentration and higher alloy content, water had a greater inhibiting effect on repassivation potential, suggesting a competitive reaction between chloride and water on the metal surface in the pit. The localized corrosion resistance of the MPEAs followed the same trend as that of commercial stainless steels and Ni-base alloys in terms of the effect of alloying elements. The implications of these results on the mechanisms of localized corrosion are discussed.

ABSTRACT Corrosion by alkali metals and their compounds poses a significant challenge to the long-term material stability and service life for both metal alloys and ceramics at high operating temperatures. Chemical reactivity between alkali metals and materials underlie numerous industry challenges ranging from fireside corrosion in biomass-fired boilers to reaction with silica-based refractory ceramics in glass furnaces. The problem is particularly significant in magnetohydrodynamic (MHD) generators, where potassium or cesium compounds are introduced to improve the electrical conductivity of the working fluid. Thus, resistance to attack by alkali metal vapor is an important consideration in the selection and fabrication of ceramic electrodes and insulators for MHD generators. We evaluated several refractory ceramics to assess phase stability and known reactions with potassium and its compounds at high temperatures (T > 1,200 °C). Refractory ceramics were tested for potassium vapor corrosion using a modified ASTM standard test method with in situ monitoring of gas composition. Unlike other materials, the magnesia (MgO) and ceria (CeO2) samples did not exhibit corrosion, and no phase or mass changes were observed. This indicates that CeO2 and MgO could exhibit long lifetimes as plasma facing components in MHD generators. Ultimately, this development provides valuable data in evaluating critical materials performance issues that can attest to the viability of high temperature direct fired MHD generator applications.

Several factors have led to the decline of electricity generation from coal over the past decade, and projections forecast high rates of growth for wind and solar technologies in coming years. This analysis uses hourly generation data from large coal-fired power stations to determine how operations have been modified in recent years and describes the implications of these changes for plant equipment and unit reliability. The data shows increasing variability in intraday generation output that affects nearly all of the units in the sample, but the magnitude of increase varies widely among plants. Outage patterns were examined as was the relationship between renewable energy growth in a region and the changes in coal plant operations. Aggregate direct and indirect costs associated with running coal plants as load-following units have not yet been quantified in large-scale studies on a sector-wide basis, largely due to differences in how specific equipment responds to output fluctuations. Due to findings from the hourly generation data analysis and the high degree of potential impact on coal plant equipment, the study suggests the development of a new modeling tool that will represent the costs of running coal-fired power plants at lower capacity factors.

Ash agglomeration issues that arise due to the sticking of slag-wetted, colliding particles have been creating operational difficulties and monetary losses for the fluidized bed combustion (FBC) industry. Difficulties have been experienced in the detection of slag-liquid at the low operating temperatures in fluidized bed combustors (FBCs) and predicting the agglomeration behavior of fuel. This study aims to study the effect of heterogeneity in ash composition on the detection of slag-liquid in FBCs. It quantifies the slag-liquid amounts at the particle-level, under oxidizing environments, by dividing the bulk fuel into density classes. FactSage™ thermodynamic simulations of each of the particle classes, along with experimental validation of the trends with thermo-mechanical analysis (TMA) and high temperature X-ray diffraction (HT-XRD) were performed. The results obtained can be used to estimate the stickiness of particles in the development of ash agglomeration models based on particle collisions. The study of these particle classes shows that particle classes with specific minerals can form low temperature eutectics and lead to onset of slag-liquid formation at temperatures below those predicted by bulk analysis alone. Comparison of the differences in slag-liquid formation tendencies under reducing and oxidizing environments is also presented.

This paper will briefly review the history and current state of Carbon Capture and Storage (CCS) research and development and describe the technical barriers to carbon capture. it will argue forcefully for a new approach to R&D, which leverages both simulation and physical systems at the laboratory and pilot scales to more rapidly move the best technoogies forward, prune less advantageous approaches, and simultaneously develop materials and processes.