More Like this

1. Urban agriculture’s bounty: contributions to Phoenix’s sustainability goals

   https://doi.org/10.1088/1748-9326/ab428f  

   Uludere Aragon, Nazli ; Stuhlmacher, Michelle ; Smith, Jordan P. ; Clinton, Nicholas ; Georgescu, Matei ( September 2019 , Environmental Research Letters)

   With over half of the world’s population living in cities, there is mounting evidence indicating that investments in urban sustainability can deliver high returns on socioeconomic and environmental fronts. Current scholarship on urban agriculture (UA) reports a wide range of benefits which have been shown to vary with the scale and type of benefit examined. Notably, most city-scale studies do not align benefits of UA with locally meaningful goals. We fill this gap by conducting a city-scale analysis for Phoenix, the fifth largest city in the USA by population, and evaluate these benefits based on their ability to contribute to select desired outcomes specified in Phoenix’s 2050 Sustainability Goals: the elimination of food deserts, provision of green open space, and energy and CO₂emissions savings from buildings. We consider three types of surfaces for UA deployment—undeveloped vacant lots, flat rooftops, and building façades—and find that the existing building stock provides 71% of available UA space in the study area. The estimated total food supply from UA is 183 000 tons per year, providing local produce in all existing food deserts of Phoenix, and meeting 90% of current annual consumption of fresh produce based on national per capita consumption patterns. UA would also add green open space and reduce by 60% the number of block groups underserved by public parks. Rooftop deployment of UA could reduce energy use in buildings and has the potential to displace more than 50 000 tons of CO₂per year. Our work highlights the importance of combining a data-driven framework with local information to address place-based sustainability goals and can be used as a template for city-scale evaluations of UA in alternate settings.

    

   more » « less
2. Socially-differentiated urban metabolism methodology informs equity in coupled carbon-air pollution mitigation strategies: insights from three Indian cities

   https://doi.org/10.1088/1748-9326/ac881e  

   Nagpure, Ajay Singh ; Tong, Kangkang ; Ramaswami, Anu ( September 2022 , Environmental Research Letters)

   A differentiated urban metabolism methodology is developed to quantify inequality and inform social equity in urban infrastructure strategies aimed at mitigating local in-boundary PM2.5 and co-beneficially reducing transboundary greenhouse gas (GHG) emissions. The method differentiates community-wide local PM2.5 and transboundary GHG emission contributions by households of different income strata, alongside commercial and industrial activities. Applied in three Indian cities (Delhi, Coimbatore, and Rajkot) through development of new data sets, method yields key insights that across all three cities, top-20% highest-income households dominated motorized transportation, electricity, and construction activities, while poorest-20% homes dominated biomass and kerosene use, resulting in the top-20% households contributing more than three times GHGs as the bottom-20% homes. Further, after including commercial and industrial users, top-20% households contributed as much or more in-boundary PM2.5 emissions thanallcommercial ORallindustrial emitters (e.g. Delhi’s top-20% homes contributed 21% of in-boundary PM2.5 similar to industries at 21%. These results enabled co-benefit analysis of various infrastructure transition strategies on the horizon, finding only three could yield both significant GHG and PM2.5 reductions (>2%-each): (a) Modest 10% efficiency improvements among top-20% households, industry and commercial sectors, requiring a focus on wealthiest homes; (b) Phasing out all biomass and kerosene use within cities (impacting poorest); (c) Replacing gas and diesel vehicles with renewable electric vehicles. The differentiated PM2.5 and GHG emissions data-informed social equity in the design of the three co-beneficial infrastructure transitions by: (a)-prioritizing free/subsidized clean cooking fuels to poorest homes; (b)-increasing electricity block rates and behavioral nudging for wealthiest homes; and, (c)-prioritizing electrification of mass transit and promoting electric two-wheelers ahead of providing subsidies for electric cars, where the free-rider phenomenon can occur, which benefits wealthiest homes. The methodology is broadly translatable to cities worldwide, while the policy insights are relevant to rapidly urbanizing Asia and Africa to advance clean, low-carbon urban infrastructure transitions.

    

   more » « less
3. Prediction of odor complaints at a large composite reservoir in a highly urbanized area: A machine learning approach

   https://doi.org/10.1002/wer.1191  

   Mulrow, John ; Kshetry, Nina ; Brose, Dominic A. ; Kumar, Kuldip ; Jain, Darshan ; Shah, Mohil ; Kunetz, Thomas E. ; Varshney, Lav R. ( August 2019 , Water Environment Research)

   Odorous compound emissions and odor complaints from the public are rising concerns for agricultural, industrial, and water resource recovery facilities (WRRFs) near urban areas. Many facilities are deploying sensors that measure malodorous compounds and other factors related to odor creation and dispersion. Focusing on the Metropolitan Water Reclamation District of Greater Chicago's (MWRDGCs) Thornton Composite Reservoir (7.9 billion gallon capacity), we used meteorological, operational, and H2S sensor data to train a 3‐day advance‐warning predictor of local odor complaints, so as to implement targeted odor prevention measures. Using a machine learning approach, we bypassed difficulties in modeling both physical dispersion and human perception of odors. Utilizing random forest algorithms with varied settings and input attributes, we find that a small network of H2S sensors, meteorological data, and operational data are able to predict odor complaints three days in advance with greater than 60% accuracy and less than 25% false‐positive rates, exceeding MWRDGC’s standards required for full‐scale deployment.

   A random forest algorithm trained on H₂S, weather, and operations data successfully predicted odor complaints surrounding a large composite reservoir.

   Thirty‐two data attribute combinations were tested. It was found that H₂S sensor data alone are insufficient for predicting odor complaints.

   The best predictor was a Random Forest Classifier trained on weather, operational, and H₂S readings from the reservoir corner locations.

   This study demonstrates odor complaint prediction capability utilizing a limited set of data sources and open‐source machine learning techniques.

   Given a small network of H₂S sensors and organized data management, WRRFs and similar facilities can conduct advance‐warning odor complaint prediction.

    

   more » « less
4. Near-term potential of organic waste management infrastructure for soil carbon sequestration in rangelands

   https://doi.org/10.1088/2634-4505/ac970f  

   Hall, A. L. ; Potts, M. D. ; Silver, W. L. ( November 2022 , Environmental Research: Infrastructure and Sustainability)

   Contemporary food and agricultural systems degrade soils, pollute natural resources, and contribute to greenhouse gas emissions. The waste output from these systems, however, can be repurposed as an agricultural input, reducing emissions associated with organics disposal while actively sequestering atmospheric carbon in soils—thus transitioning the sector from a carbon source to a carbon sink. This research estimates the near-term technical and economic potential of utilizing composted organic feedstocks as a soil amendment to mitigate climate change and improve long-term soil quality, in line with California’s organics diversion policies, by connecting food scraps and organics residuals in California’s municipal solid waste to existing infrastructure and working lands in the state. The multi-objective spatial optimization results indicate considerable carbon sequestration benefits in the range of −1.9 ± 0.5 MMT CO₂eq annually, by applying compost to 6 million hectares of California rangelands at a price of approximately $200 per ton, presenting a cost-effective climate change mitigation strategy within proposed federal sequestration credits. Expanding composting capacity is predicted to increase the total amount of carbon sequestered while reducing the cost per ton and per hectare treated. This model aids decision makers in considering the technical, economic, and institutional potential of actively managing the State’s organic materials in municipal waste streams for climate change mitigation.

    

   more » « less
5. Was it worthwhile? Where have the benefits of rooftop solar photovoltaic generation exceeded the cost?

   https://doi.org/10.1088/1748-9326/aa815e  

   Vaishnav, Parth ; Horner, Nathaniel ; Azevedo, Inês L. ( September 2017 , Environmental Research Letters)

   We estimate the lifetime magnitude and distribution of the private and public benefits and costs of currently installed distributed solar PV systems in the United States. Using data for recently-installed systems, we estimate the balance of benefits and costs associated with installing a non-utility solar PV system today. We also study the geographical distribution of the various subsidies that are made available to owners of rooftop solar PV systems, and compare it to distributions of population and income. We find that, after accounting for federal subsidies and local rebates and assuming a discount rate of 7%, the private benefits of new installations will exceed private costs only in seven of the 19 states for which we have data and only if customers can sell excess power to the electric grid at the retail price. These states are characterized by abundant sunshine (California, Texas and Nevada) or by high electricity prices (New York). Public benefits from reduced air pollution and climate change impact exceed the costs of the various subsidies offered system owners for less than 10% of the systems installed, even assuming a 2% discount rate. Subsidies flowed disproportionately to counties with higher median incomes in 2006. In 2014, the distribution of subsidies was closer to that of population income, but subsidies still flowed disproportionately to the better-off. The total, upfront, subsidy per kilowatt of installed capacity has fallen from $5200 in 2006 to $1400 in 2014, but the absolute magnitude of subsidy has soared as installed capacity has grown explosively. We see considerable differences in the balance of costs and benefits even within states, indicating that local factors such as system price and solar resource are important, and that policies (e.g. net metering) could be made more efficient by taking local conditions into account.

    

   more » « less