December 1997This is an informal report intended primarily for internal or limited external distribution.
AbstractRemote Alaskan communities pay economic and environmental penalties for electricity, because they must import diesel as their primary fuel for electric power production, paying heavy transportation costs and potentially causing environmental damage with empty drums, leakage, and spills. For these reasons, remote villages offer a viable niche market where sustainable energy systems based on renewable resources and advanced energy storage technologies can compete favorably on purely economic grounds, while providing environmental benefits. These villages can also serve as a robust proving ground for systematic analysis, study, improvement, and optimization of sustainable energy systems with advanced technologies.This paper presents an analytical optimization of a remote power system for a hypothetical Alaskan village. The analysis considers the potential of generating renewable energy (e.g., wind and solar), along with the possibility of using energy storage to take full advantage of the intermittent renewable sources available to these villages. Storage in the form of either compressed hydrogen or zinc pellets can then provide electricity from hydrogen or zinc-air fuel cells when renewable sources are unavailable.The analytical results show a great potential to reduce fossil fuel consumption and costs by using renewable energy combined with advanced energy storage devices. The best solution for our hypothetical village appears to be a hybrid energy system, which can reduce consumption of diesel fuel by over 50% with annualized cost savings by over 30% by adding wind turbines to the existing diesel generators. When energy storage devices are added, diesel fuel consumption and costs can be reduced substantially more. With optimized energy storage, use of the diesel gensets can be reduced to almost zero, with the existing equipment only maintained for added reliability. However about one quarter of the original diesel consumption is still used for heating purposes. (We use the term 'diesel' to encompass the fuel, often called 'heating or fuel oil', of similar or identical properties.)
Several large scale laser applications require diode pumps for high efficiency and average power, but are sensitive to diode performance-cost tradeoffs. This paper describes approaches for addressing these issues, using the example of inertial fusion energy drivers. OCIS codes: (140.0140) Lasers and laser optics, (140.3480) Lasers, diode-pumped (140.2010) Diode laser arrays
IntroductionThere is currently great interest in extremely large laser systems for applications such as inertial fusion energy (IFE) and scientific exploration. These applications require excellent beam quality and optical pulse durations of a few nanoseconds, for which laser designs utilizing optically pumped gain media are typically employed.[e.g.; 1-4] When such systems must operate at high repetition rates (above 10 Hz) or with high efficiency (>10%), semiconductor laser diodes are used to pump the gain media because of their high brightness, high wallplug efficiency, and narrow emission spectrum.The diode pumps can contribute a significant fraction of the overall cost of these large systems. For this reason, several approaches have been proposed to mitigate the impact of diode costs. These include design choices at the system level, such as simplifying the requirements for pump coupling to the gain medium [1] and using gain media with longer energy storage lifetimes.[3-5] These approaches also include component level design modifications, including increasing the power per diode chip,[1, 6] simplifying the package design, [7] and operation at cryogenic temperatures.[8] This paper discusses the performance tradeoffs of such approaches, methodologies for quantitatively assessing their impact on system costs, and the conclusions resulting from these analyses.
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