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1. Simultaneous Demand Response Program and Conservation Voltage Reduction for Optimal Operation of Distribution Systems

   https://doi.org/10.1109/ias44978.2020.9334720  

   Khalili, Tohid; Jafari, Amirreza; Kalajahi, Seyed Mohammad; Mohammadi-Ivatloo, Behnam; Bidram, Ali (October 2020, 2020 IEEE Industry Applications Society Annual Meeting)

   null (Ed.)

   Due to the dependency of electric loads on the voltage, the load consumption can be controlled by controlling the voltage level. Optimal voltage regulation can benefit the distribution system by reducing the costs of purchasing electric power in the conservation voltage reduction (CVR) mode and increasing the sold energy income in the optimal voltage increase mode. Moreover, implementing demand response programs (DRP) is an effective way to decrease the costs and increase the profit of utilities and customers. This paper investigates the impact of incentive-based DRP and CVR on the operation of the distribution system under different objective functions. The cost of electricity consumption, the profit obtained by the electricity market, and system reliability are the three objective functions. Respect to the considered objective functions, eight scenarios are studied, and their results are compared. Finally, the obtained results validate the method and confirm the positive effect of simultaneous DRP and CVR. 

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2. Is closing the agricultural yield gap a “risky” endeavor?

   Gatti, N; Cecil, M; Baylis, K; Estes, L; Blekking, J; Heckelei, T; Vergopolan, N; Evans, T (May 2023, Agricultural systems)

   CONTEXT Sub-Saharan Africa (SSA) has the climatic and biophysical potential to grow the crops it needs to meet rapidly growing food demand; however, agricultural productivity remains low. While potential maize yields in Zambia are 9 t per hectare (t/ha), the average farmer produces only 1–2. OBJECTIVE We evaluate the contribution of responses to weather risk to that gap by decomposing the yield gap in maize in Zambia. While we know that improved seed and fertilizer can expand yield and profit, they may also increase the variance of yield under different weather outcomes, reducing their adoption. METHODS We use a novel approach combining crop modeling and statistical analysis of survey data to obtain the yield gap components in Zambia driven by input cost and input risk. We use a crop model to simulate district-level marginal effects of fertilizer and seed maturity choice on the mean and variance of expected yield and profit under all-weather outcomes for each district for the past 30 years. We compare input levels that maximize expected yield to those that maximize expected profit and maximize the expected mean-variance trade-off assuming risk-aversion. To determine how much farmers' input choices are made to reduce risk, we then quantify differences in the expected riskiness of inputs by district. RESULTS AND CONCLUSIONS We find approximately one-quarter of the yield gap can be explained by risk-reducing behavior, albeit with a substantial geographic variation. Given this finding, under present conditions, we expect that the average maximum yield that farmers can obtain without increasing risk is 6.75 t/ha compared to a potential profit-maximizing level of 8.84 t/ha. SIGNIFICANCE The risk-related yield gap is only expected to increase with weather extremes driven by climate change. Promoting “one-size-fits all” solutions to closing the yield gap could underestimate the effect of risk mitigation on agricultural production while increasing farmers' risk exposure. 

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3. Analysis of individual-level data from 2018–2020 Ebola outbreak in Democratic Republic of the Congo

   https://doi.org/10.1038/s41598-022-09564-4  

   Vossler, Harley; Akilimali, Pierre; Pan, Yuhan; KhudaBukhsh, Wasiur R.; Kenah, Eben; Rempała, Grzegorz A. (December 2022, Scientific Reports)

   Abstract The 2018–2020 Ebola virus disease epidemic in Democratic Republic of the Congo (DRC) resulted in 3481 cases (probable and confirmed) and 2299 deaths. In this paper, we use a novel statistical method to analyze the individual-level incidence and hospitalization data on DRC Ebola victims. Our analysis suggests that an increase in the rate of quarantine and isolation that has shortened the infectiousness period by approximately one day during the epidemic’s third and final wave was likely responsible for the eventual containment of the outbreak. The analysis further reveals that the total effective population size or the average number of individuals at risk for the disease exposure in three epidemic waves over the period of 24 months was around 16,000–a much smaller number than previously estimated and likely an evidence of at least partial protection of the population at risk through ring vaccination and contact tracing as well as adherence to strict quarantine and isolation policies. 

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4. Space-time dynamics of electricity markets incentivize technology decentralization

   https://doi.org/10.1016/j.compchemeng.2019.05.005  

   Shao, Yue; Zavala, Victor (January 2019, Computers chemical engineering)

   We study economic incentives provided by space-time dynamics of day-ahead and real-time electricity markets. Specifically, we seek to analyze to what extent such dynamics promote decentralization of technologies for generation, consumption, and storage (which is essential to obtain a more flexible power grid). Incentives for decentralization are also of relevance given recent interest in the deployment of small-scale modular technologies (e.g., modular ammonia and biogas production systems). Our analysis is based on an asset placement problem that seeks to find optimal locations for generators and loads in the network that minimize profit risk. We show that an unconstrained version of this problem can be cast as an eigenvalue problem. Under this representation, optimal network allocations are eigenvectors of the space-time price covariance matrix while the eigenvalues are the associated profit variances. We also construct a more sophisticated placement formulation that captures different risk metrics and constraints on types of technologies to systematically analyze trade-offs in expected profit and risk. Our analysis reveals that space-time market dynamics provide significant incentives for decentralization and strategic asset placement but that full mitigation of risk is only possible through simultaneous investment in generation and loads (which can be achieved using batteries or microgrids). 

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5. Sediment Exchange Between the Created Saltmarshes of Living Shorelines and Adjacent Submersed Aquatic Vegetation in the Chesapeake Bay

   https://doi.org/10.3389/fmars.2021.727080  

   Vona, Iacopo; Palinkas, Cindy M.; Nardin, William (October 2021, Frontiers in Marine Science)

   Rising sea levels and the increased frequency of extreme events put coastal communities at serious risk. In response, shoreline armoring for stabilization has been widespread. However, this solution does not take the ecological aspects of the coasts into account. The “living shoreline” technique includes coastal ecology by incorporating natural habitat features, such as saltmarshes, into shoreline stabilization. However, the impacts of living shorelines on adjacent benthic communities, such as submersed aquatic vegetation (SAV), are not yet clear. In particular, while both marshes and SAV trap the sediment necessary for their resilience to environmental change, the synergies between the communities are not well-understood. To help quantify the ecological and protective (shoreline stabilization) aspects of living shorelines, we presented modeling results using the Delft3D-SWAN system on sediment transport between the created saltmarshes of the living shorelines and adjacent SAV in a subestuary of Chesapeake Bay. We used a double numerical approach to primarily validate deposition measurements made in the field and to further quantify the sediment balance between the two vegetation communities using an idealized model. This model used the same numerical domain with different wave heights, periods, and basin slopes and includes the presence of rip-rap, which is often used together with marsh plantings in living shorelines, to look at the influences of artificial structures on the sediment exchange between the plant communities. The results of this study indicated lower shear stress, lower erosion rates, and higher deposition rates within the SAV bed compared with the scenario with the marsh only, which helped stabilize bottom sediments by making the sediment balance positive in case of moderate wave climate (deposition within the two vegetations higher than the sediment loss). The presence of rip-rap resulted in a positive sediment balance, especially in the case of extreme events, where sediment balance was magnified. Overall, this study concluded that SAV helps stabilize bed level and shoreline, and rip-rap works better with extreme conditions, demonstrating how the right combination of natural and built solutions can work well in terms of ecology and coastal protection. 

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