, numerous ESCOs, state energy offices, and others have contributed valuable information on energy-efficiency projects and ESCO industry activity. Review of US ESCO Industry Market Trends iv ABSTRACTThis article summarizes a comprehensive empirical analysis of U.S. energy service company (ESCO) industry trends and performance. We employ two parallel analytical approaches: a comprehensive survey of firms to estimate total industry size and a database of ~1500 ESCO projects, from which we report target markets and typical project characteristics, energy savings and customer economics. We estimate that industry investment for energy-efficiency related services reached US$2 billion in 2000 following a decade of strong growth. ESCO activity is concentrated in states with high economic activity and strong policy support. Typical projects save 150-200 MJ/m 2 /year and are cost-effective with median benefit/cost ratios of 1.6 and 2.1 for institutional and private sector projects. The median simple payback time is 7 years among institutional customers; 3 years is typical in the private sector. Reliance on DSM incentives has decreased since 1995. Preliminary evidence suggests that state enabling policies have boosted the industry in medium-sized states. ESCOs have proven resilient in the face of restructuring and will probably shift toward selling "energy solutions", with energy efficiency part of a package. We conclude that a private sector energy-efficiency services industry that targets large commercial and industrial customers is viable and selfsustaining with appropriate policy support -both financial and non-financial.

Direct, manipulative experiments can yield important insights into the role of biodiversity in ecosystem function, but they are intrinsically limited when it comes to aspects of this relationship that emerge over long temporal and large spatial scales. Natural experiments with model systems can be a powerful complement to direct, manipulative experiments, especially where the processes that regulate biodiversity have no more than modest direct impacts on ecosystem function. Mangrove ecosystems on continental land masses and isolated islands offer unusual potential as natural experiments for biodiversity and ecosystem function studies, largely because sites with similar physical environments can have clear contrasts in the diversity of the dominant autotrophs. These contrasts provide a starting point for exploring the role of species diversity of higher plants in modulating biogeochemical functions (e.g. production, nutrient cycling), ecological functions (e.g. habitat for organisms in different tropic levels), and anthropogenic functions (e.g. maintenance of fisheries, management of sediments), on a range of time scales.

The U.S. Energy Services Company (ESCO) industry is often cited as the most successful model for the private sector delivery of energy-efficiency services. This study documents actual performance of the ESCO industry in order to provide policymakers and investors with objective information and customers with a resource for benchmarking proposed projects relative to industry performance. We have assembled a database of nearly 1500 case studies of energyefficiency projects -the most comprehensive data set of the U.S. ESCO industry available. These projects include $2.55B of work completed by 51 ESCOs and span much of the history of this industry.We estimate that the ESCO industry completed $1.8-2.1B of projects in 2000. The industry has grown rapidly over the last decade with revenues increasing at a 24% annualized rate. We summarize and compare project characteristics and costs and analyze energy savings, including the relationship between predicted and actual savings. ESCOs typically invested about $2.30/ft 2 per project in various energy efficiency improvements, although there is large variation in project costs within and across market segments. We find that lighting-only projects report median electricity savings of 47% of targeted equipment consumption; the median for lighting-&-nonlighting projects is 23% of the total electric bill baseline. We examine project economics, including project net benefits, benefit/cost ratio and simple payback time. Median simple payback time is seven years for institutional sector projects and three years in the private sector. We estimate direct economic benefits of $1.62 billion for the 1080 projects in our database with both cost and savings data. The median benefit/cost ratio is 2.1 for 309 private sector projects and 1.6 for 771 institutional sector projects. We discuss the role of policies and programs adopted by state/federal legislatures and agencies that have played an important role in stimulating ESCO activity in various markets. Finally, we estimate the overall size and growth of the energy-efficiency services industry over the last ten years based on a survey of 63 ESCOs.iii Acknowledgements

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EXECUTIVE SUMMARYThis study investigates the effect of modeling assumptions about levelized costs and market penetration on the U.S. Department of Energy's Annual Energy Outlook (AEO) forecast for wind technologies.The AEO's annual report of energy supply, demand, and prices through 2020 is based on results from the Energy Information Administration (EIA) National Energy Modeling System (NEMS). NEMS predicts the market penetration of individual energy technologies based on a variety of inputs and assumed changes in these base values over time. The NEMS forecast of technology adoption and use is influenced most strongly by the model's assumptions about the levelized cost of energy for the various technologies. For each year, NEMS allocates a share of the energy market to least-cost technologies; this allocation affects forecasts for future years. NEMS uses cost multipliers and constraints to represent potential physical and economic limitations on growth in capacity; these limitations include depletion of resources, costs of rapid manufacturing expansion, and the stability or instability of the power grid when high levels of generation come from intermittent resources.In the AEO99 Reference Case version of NEMS, the electric generation supply mix remains fairly steady, and renewable energy technologies such as wind do not achieve significant market share during the forecast period. However, NEMS is also increasingly being used to analyze alternative scenarios (such as low-carbon futures) in which the role of renewables is likely to be enhanced. In these alternative scenarios, the way in which renewable energy technologies are modeled becomes critical.The structure of NEMS makes cost inputs of primary importance in determining the economic competitiveness of an energy technology. Aside from capital costs, other assumptions embedded in the cost-of-energy equation have generally been considered as secondary in importance. This report examines some of these other assumptions for wind power to determine which ones have the greatest impact on forecasts for this technology. Understanding the relative influence of these assumptions may help suggest areas where NEMS could be refined to increase the accuracy of its representation of the characteristics of renewable technologies.Wind power was chosen as a case study because it is found over a relatively wide geographic range and is the closest of the renewable technologies to being economically competitive. Because wind power is modeled similarly to some of the other renewable technologies, such as solar thermal and photovoltaics (PV), our f indings may be applicable to these areas of NEMS as well. Our sensitivity analysis focused on relaxing assumptions (not including capital cost) to make them less restrictive to wind development. In our initial explorations, we conducted a limited set of runs with more restrictive assumptions and found that those scenarios did not differ much from the Reference Case results. Therefore, we concluded that further restricting the assumption...

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