ANALYSIS AND SIMULATION OF ENERGY USE AND COST AT A MUNICIPAL WASTEWATER TREATMENT PLANT

The cost of electricity, a major operating cost of municipal wastewater treatment plants, is related to influent flow rate, power price, and power load. With knowledge of inflow and price patterns, plant operators can manage processes to reduce electricity costs. Records of influent flow, power price, and load are evaluated for Blue Plains Advanced Wastewater Treatment Plant. Diurnal and seasonal trends are analyzed. Power usage is broken down among treatment processes. A simulation model of influent pumping, a large power user, is developed. It predicts pump discharge and power usage based on wet-well level. Individual pump characteristics are tested in the plant. The model accurately simulates plant inflow and power use for two pumping stations [R2 = 0.68, 0.93 (inflow), R2 =0.94, 0.91(power)]. Wet-well stage-storage relationship is estimated from data. Time-varying wet-well level is added to the model. A synthetic example demonstrates application in managing pumps to reduce electricity cost.

Essays on the Effects of Social Insurance for Disability

This dissertation examines how social insurance, family support and work capacity enhance individuals' economic well-being following significant health and income shocks. I first examine the extent to which the liquidity-enhancing effects of Worker's Compensation (WC) benefits outweigh the moral hazard costs. Analyzing administrative data from Oregon, I estimate a hazard model exploiting variation in the timing and size of a retroactive lump-sum WC payment to decompose the elasticity of claim duration with respect to benefits into the elasticity with respect to an increase in cash on hand, and a decrease in the opportunity cost of missing work. I find that the liquidity effect accounts for 60 to 65 percent of the increase in claim duration among lower-wage workers, but less than half of the increase for higher earners. Using the framework from Chetty (2008), I conclude that the insurance value of WC exceeds the distortionary cost, and increasing the benefit level could increase social welfare. Next, I investigate how government-provided disability insurance (DI) interacts with private transfers to disabled individuals from their grown children. Using the Health and Retirement Study, I estimate a fixed effects, difference in differences regression to compare transfers between DI recipients and two control groups: rejected applicants and a reweighted sample of disabled non-applicants. I find that DI reduces the probability of receiving a transfer by no more than 3 percentage points, or 10 percent. Additional analysis reveals that DI could increase the probability of receiving a transfer in cases where children had limited prior information about the disability, suggesting that DI could send a welfare-improving information signal. Finally, Zachary Morris and I examine how a functional assessment could complement medical evaluations in determining eligibility for disability benefits and in targeting return to work interventions. We analyze claimants' self-reported functional capacity in a survey of current DI beneficiaries to estimate the share of disability claimants able to do work-related activity. We estimate that 13 percent of current DI beneficiaries are capable of work-related activity. Furthermore, other characteristics of these higher-functioning beneficiaries are positively correlated with employment, making them an appropriate target for return to work interventions.