Hydrogen is often proposed as the fuel of the future, but the transformation from the present fossil fuel economy to a hydrogen economy will need the solution of numerous complex scientific and technological issues, which will require several decades to be accomplished. Hydrogen is not an alternative fuel, but an energy carrier that has to be produced by using energy, starting from hydrogen-rich compounds. Production from gasoline or natural gas does not offer any advantage over the direct use of such fuels. Production from coal by gasification techniques with capture and sequestration of CO₂ could be an interim solution. Water splitting by artificial photosynthesis, photobiological methods based on algae, and high temperatures obtained by nuclear or concentrated solar power plants are promising approaches, but still far from practical applications. In the next decades, the development of the hydrogen economy will most likely rely on water electrolysis by using enormous amounts of electric power, which in its turn has to be generated. Producing electricity by burning fossil fuels, of course, cannot be a rational solution. Hydroelectric power can give but a very modest contribution. Therefore, it will be necessary to generate large amounts of electric power by nuclear energy of by renewable energies. A hydrogen economy based on nuclear electricity would imply the construction of thousands of fission reactors, thereby magnifying all the problems related to the use of nuclear energy (e.g., safe disposal of radioactive waste, nuclear proliferation, plant decommissioning, uranium shortage). In principle, wind, photovoltaic, and concentrated solar power have the potential to produce enormous amounts of electric power, but, except for wind, such technologies are too underdeveloped and expensive to tackle such a big task in a short period of time. A full development of a hydrogen economy needs also improvement in hydrogen storage, transportation and distribution. Hydrogen and electricity can be easily interconverted by electrolysis and fuel cells, and which of these two energy carriers will prevail, particularly in the crucial field of road vehicle powering, will depend on the solutions found for their peculiar drawbacks, namely storage for electricity and transportation and distribution for hydrogen. There is little doubt that power production by renewable energies, energy storage by hydrogen, and electric power transportation and distribution by smart electric grids will play an essential role in phasing out fossil fuels.

The hydrogen issue

In this paper we attempt to answer two questions: (1) Why should we be interested in the security of control systems? And (2) What are the new and fundamentally different requirements and problems for the security of control systems? We also propose a new mathematical framework to analyze attacks against control systems. Within this framework we formulate specific research problems to (1) detect attacks, and (2) survive attacks.

/pdf/research-challenges-for-the-security-of-control-systems-3gr941gj7o.pdf

Research challenges for the security of control systems

Energy Storage Technology and Cost Characterization Report

INTRODUCTION Cascading failures in power grids are inherently network processes, in which an initially small perturbation leads to a sequence of failures that spread through the connections between system components. An unresolved problem in preventing major blackouts has been to distinguish disturbances that cause large cascades from seemingly identical ones that have only mild effects. Modeling and analyzing such processes are challenging when the system is large and its operating condition varies widely across different years, seasons, and power demand levels. RATIONALE Multicondition analysis of cascade vulnerability is needed to answer several key questions: Under what conditions would an initial disturbance remain localized rather than cascade through the network? Which network components are most vulnerable to failures across various conditions? What is the role of the network structure in determining component vulnerability and cascade sizes? To address these questions and differentiate cascading-causing disturbances, we formulated an electrical-circuit network representation of the U.S.–South Canada power grid—a large-scale network with more than 100,000 transmission lines—for a wide range of operating conditions. We simulated cascades in this system by means of a dynamical model that accounts for transmission line failures due to overloads and the resulting power flow reconfigurations. RESULTS To quantify cascade vulnerability, we estimated the probability that each transmission line fails in a cascade. Aggregating the results from multiple conditions into a single network representation, we created a systemwide vulnerability map, which exhibits relatively homogeneous geographical distribution of power outages but highly heterogeneous distribution of the underlying overload failures. Topological analysis of the network representation revealed that the transmission lines vulnerable to overload failures tend to occupy the network’s core, characterized by links between highly connected nodes. We found that only a small fraction of the transmission lines in the network (well below 1% on average) are vulnerable under a given condition. When measured in terms of node-to-node distance and geographical distance, individual cascades often propagate far from the triggering failures, but the set of lines vulnerable to these cascades tend to be limited to the region in which the cascades are triggered. Moreover, large cascades are disproportionately more likely to be triggered by initial failures close to the vulnerable set. CONCLUSION Our results imply that the same disturbance in a given power grid can lead to disparate outcomes under different conditions—ranging from no damage to a large-scale cascade. The association between large cascades and the triggering failures’ proximity to the vulnerable set indicates that the topological and geographical properties of the vulnerable set is a major factor determining whether the failures spread widely. Because the vulnerable set is small, failures would often repeat on the same lines in the absence of interventions. Although the power grid represents a complex system in which changes can have unanticipated effects, our analysis suggests failure-based allocation of resources as a strategy in upgrading the system for improved resilience against large cascades.

Small vulnerable sets determine large network cascades in power grids

The work presented here is based on a review of 55 DFID-financed RNFE and livelihood diversification projects, programmes and research comprising rural household survey and other field-related research projects representing a broad range of methodologies borrowed from economics, sociology and social anthropology.

/pdf/the-rural-non-farm-economy-livelihoods-and-their-33s1c58a2y.pdf

The rural non-farm economy, livelihoods and their diversification: issues and options

Surveys the history of the Department of Energy, describing its structure, current functions, and influence on United States society.

The Department of Energy

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