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Energy cost and energy return on investment (EROI) for stakeholder-developed pathways to resilient, sustainable cities
Citation:
Balogh, S., A. Lugo, T. Munoz-Erickson, D. Iwaniec, AND T. McPhearson. Energy cost and energy return on investment (EROI) for stakeholder-developed pathways to resilient, sustainable cities. Energy and Society in Transition, 2nd International Conference on Energy Research and Social Science, Tempe, AZ, May 28 - 31, 2019.
Impact/Purpose:
Creating cities that are sustainable, meaning that they operate within the limits of nature, and resilient, meaning they can resist or bounce back from disturbances, requires investments in infrastructure, people, and in conserving or restoring nature. Since the money and resources to pay for these investments are limited, for example by a municipal budget, cities tend to choose projects that produce the greatest level of benefits for the lowest price-tag, this is referred to as a cost-benefit analysis. Another way to compare the trade-offs of these investments is by accounting for the energy and materials required to complete them, for example the diesel needed to operate dredges to clear a shipping channel, or the concrete needed to build a sea wall. For islands like Puerto Rico, these energy and material flows are especially important because most everything used in the economy must be imported there. Therefore changing the way the city looks, runs, and provides protection against disaster would have important impacts on the energy and material imports and the wastes produced. This presentation describes a way of estimating the energy and material costs of sustainability and resiliency projects and how they can be compared in a non-monetary way.
Description:
A series of workshops were held in San Juan, Puerto Rico with the goal to develop plausible and desirable futures for the city and for the island. The final workshop, led by scientists from the UREx Sustainability Research Network, took place in February 2019. Intervention pathways to achieve those futures are being developed and refined through computer models based on participant input. An accounting of the energy costs and net energy analysis (NEA) of the proposed interventions can inform decisions about the investments in human, built, and natural capital needed to increase the social and ecological resilience to extreme events, such as flooding, heat waves, hurricanes, and sea level rise. This is especially important for island cities and territories, like Puerto Rico, that are completely dependent on energy imports. NEA can provide complementary information to economic analyses and land use change modeling, which otherwise may neglect important impacts on material and energy flows and therefore exclude information that is valuable in assessing projects more holistically. A methodology was developed to analyze the energy investments needed to achieve resilient futures and quantify the impact of interventions on energy and material flows. We provide example calculations and quantify trade-offs and synergies between potential interventions. Our methods were applied to two important components of the San Juan social-ecological system: agriculture and electricity production and delivery. First, we quantified the energy cost of desired futures using energy data, e.g. direct and indirect investments from life-cycle analysis (LCA) or energy literature, or financial data by multiplying estimated costs by an energy-to-dollar conversion factor. Next, when possible, we calculated energy return on investment (EROI) for energy production systems (food or fuel) or energy saved on investment (ESOI) for those capital investments or tactics designed to avoid rebuilding or replacing infrastructure damaged by extreme events.