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151 Assessing the Trade-Offs for an Urban Green Economy MYRNA HALL, NING SUN, STEPHEN BALOGH, CATHERINE FOLEY, AND RUIQI LI Advocates of green fuels, green infrastructure, and green jobs propose implementation of various nature-based technologies to revitalize the economies of cities. Some, such as tree planting, provide ecosystem services such as reduction of urban air pollutants , temperatures, and storm water runoff. Others, such as solar energy capture technologies, are intended to reduce dependence on fossil fuel and home energy costs. Yet others, such as community gardens and urban agricultural production, are a means to enhance nutrition and reduce food costs in urban neighborhoods where access to fresh food is often limited. Some technologies (e.g., green roofs, naturally draining bio-retention basins, or porous paving) are very energy intensive to build and all require considerable maintenance. Furthermore, all compete for the limited space and funds available in the urban environment, and installation of one may preclude the benefits of others. Enthusiasm for these technologies is leading to their implementation in cities around the world without much, if any, evaluation of the tradeoffs of installing one over another, for example in terms of their economic efficiency, energy costs, energy return on investment, the number of jobs they would contribute to the “green economy,” or citizen receptivity, which is key to their long-term success. Such an analysis is critical as world energy supplies dwindle and global unemployment is on the rise. We propose a methodology for the assessment of trade-offs based on net energy gains and apply it to a neighborhood in Syracuse, New York. We find, for example, that the net energy gain of food production and solar thermal installations combined approximately equals that derived from planting trees. INTRODUCTION Around the world advocates of green fuels, green infrastructure (GI), and green jobs have proposed various nature-based technologies as means to revitalize the economies of cities (UNECE, 2011). In the United States the Sustainable Communities Partnership consisting of the Environmental Protection Agency (EPA), the Department of Housing and Urban Development (HUD), and the Department of Transportation has recently announced its second round of funding for its Greening America’s Capitals program with this goal in mind. 152| Hall et al. Along with “smart growth” and transportation planning the partnership is promoting green building and green infrastructure, including such elements as tree planting, vegetated storm water controls, and solar energy capture. The Partnership suggests that these innovations in design and structure of our communities will not only provide jobs but also save taxpayers energy and money (EPA, 2010). Science has shown that green infrastructure can positively impact the urban environment. The urban forest reduces the urban heat island effect (Heisler et al., 2007; Murphy et al., 2011) and can influence household summertime cooling demand or provide winter wind protection (Heisler, 1986, 1991). Recent work by Alfredo, Montalto, and Goldstein (2010) has shown the storm flow runoff reduction potential from green roofs, however many storm water management solutions (e.g., green roofs, rain gardens, naturally draining bioswales, or porous paving), are very energy intensive to build. Unfortunately such energy costs are generally not included in the focus of scientific papers that assess their effectiveness. All GI, including trees and gardens, requires considerable maintenance. Furthermore, all technologies compete for the limited space in the urban environment and may preclude other green technologies such as photovoltaic (PV) installations or solar thermal (hot water) systems that can reduce heating or cooling costs. They may also occupy precious space for urban food production, also recognized by many as an essential way to improve inner-city quality of life and health and contribute to overall urban sustainability. Finally, whether or not these technologies can be implemented in neighborhoods either in public or private spaces depends on citizen knowledge, attitudes toward nature in the city, and willingness to participate. Hence the constraints to successfully moving toward a “greener” city physically, ecologically, economically, and socially are many. Although science has quantified many of the ecological benefits of the urban forest, many of which are included in the US Forest Service collaborative I-Tree software (USDA, 2011), it is difficult to find studies that have quantified the effectiveness of other GI options, let alone analyzed (1) the ecological or economic benefits versus the dollar or energy costs of individual GI technologies, or (2) the trade-offs to be considered when deciding to invest in one over another. Most surprising, given the world energy crisis, is the lack...

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