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This study investigated how subsurface and atmospheric leakage from geologic CO2 storage reservoirs could impact the deployment of Carbon Capture and Storage (CCS) in the global energy system. The Leakage Risk Monetization Model was used to estimate the costs of leakage for representative CO2 injection scenarios, and these costs were incorporated into the Global Change Assessment Model. Worst-case scenarios of CO2 leakage risk, which assume that all leakage pathway permeabilities are extremely high, were simulated. Even with this extreme assumption, the associated costs of monitoring, treatment, containment, and remediation resulted in minor shifts in the global energy system. For example, the reduction in CCS deployment in the electricity sector was 3% for the “high” leakage scenario, with replacement coming from fossil fuel and biomass without CCS, nuclear power, and renewable energy. In other words, the impact on CCS deployment under a realistic leakage scenario is likely to be negligible. We also quantified how the resulting shifts will impact atmospheric CO2 concentrations. Under a carbon tax that achieves an atmospheric CO2 concentration of 480ppm in 2100, technology shifts due to leakage costs would increase this concentration by less than 5ppm. It is important to emphasize that this increase does not result from leaked CO2 that reaches the land surface, which is minimal due to secondary trapping in geologic strata above the storage reservoir. The overall conclusion is that leakage risks and associated costs will likely not interfere with the effectiveness of policies for climate change mitigation.

© 2017, American Association for the Advancement of Science. All rights reserved. Estimates of climate change damage are central to the design of climate policies. Here, we develop a flexible architecture for computing damages that integrates climate science, econometric analyses, and process models. We use this approach to construct spatially explicit, probabilistic, and empirically derived estimates of economic damage in the United States from climate change. The combined value of market and nonmarket damage across analyzed sectors - agriculture, crime, coastal storms, energy, human mortality, and labor - increases quadratically in global mean temperature, costing roughly 1.2% of gross domestic product per +1°C on average. Importantly, risk is distributed unequally across locations, generating a large transfer of value northward and westward that increases economic inequality. By the late 21st century, the poorest third of counties are projected to experience damages between 2 and 20% of county income (90% chance) under business-as-usual emissions (Representative Concentration Pathway 8.5).

In this work, a control law for an unstable, non-minimum phase model of a hypersonic vehicle is developed. The control problem is difficult due to the locations of the plant poles and zeros. For an unstable system, feedback is required to stabilize the plant. However, one cannot make the loop gains arbitrarily large without driving one or more of the closed-loop poles into the right-half of the s-plane, since the system is nonminimum phase. Thus, there is a limited range of feedback gain that results in a stable system. The nonminimum phase behavior also places restrictions on the closed-loop bandwidth. For the hypersonic vehicle control problem, low frequency control is desired and a rule of thumb is that the closed-loop bandwidth must be less than one-half the right-half plane zero location. A right-half plane zero located in the region of the desired gain-crossover frequency makes it impossible to achieve the desired level of tracking performance. The achievable closed-loop bandwidth might be so small that adequate control of the system is not achieved. Direct cancellation of the right-half plane zero with an unstable pole in the controller is not an option. In this work, a modified dynamic inversion controller is developed for a linear, time-invariant model of a hypersonic vehicle. This modified dynamic inversion controller differs from the standard dynamic inversion approach in that it does not attempt to cancel the right-half plane zero with a pole, instead, it retains right-half plane zeros in the closed-loop transfer functions and uses an additional feedback loop to stabilize the zero dynamics

The 1Z expansion method is used to calculate the eigenvalues of the 2p3pP3 and 2p3dD1,3 states of the helium isoelectronic sequence. The results are compared to variational calculations for neutral helium. Wavelengths are predicted for a number of transitions originating in doubly excited states of the heliumlike ions up to Fe xxv. The results for neutral helium are compared to recent beam-foil experiments and alternative line identifications are made. The predicted wavelength for the 2p3dD3-2p2P3 transition is 3014, in close agreement with the line observed by Berry et al. at 3012 ± 2. © 1972 The American Physical Society.