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This paper uses simple electricity market models to demonstrate the workings of, and problems with, Ontario's zonal price/two-schedule electricity market design. The roles played by zonal prices, Shadow LMP prices, and out-of-market congestion payments are explained. This market design is compared and contrasted to the much better-known single-schedule designs with LMP pricing used in neighboring U.S. markets. The ways in which congestion payments can, and have been, gamed is highlighted and shown to be special cases of counter-trading "inc-dec games". The bizarre outcomes for interjurisdictional trading arising from Ontario's use of congestion pricing on its interties combined with uniform pricing on the internal grid are demonstrated. Some gaming problems identified in other markets are reviewed compared to Ontario's situation. Finally, the paper recaps the system operator's efforts to remedy the various problems with the market while preparing a fundamental redesign. [ABSTRACT FROM AUTHOR]

• Lake processes are generally as sensitive to changes in wind speed as they are to changes in surface air temperature. • Changing climate resulted in a general increase in lake water temperature and the corresponding decrease in lake ice thickness and ice cover duration. • While lake water temperature is projected to increases at all depths, the shallow epilimnion layer is more sensitive to the changing climate than the deeper hypolimnion layer. • Projected climate resulted in seasonal changes in the biogeochemical cycling including projected change in the magnitude and timing of chlorophyll-a concentration over the depth of the lake. Regional climate plays an important role on in-lake physical and biogeochemical processes and determines the state of water quality and ecology of the lakes. This paper presents the result of a one-dimensional numerical modelling of lake ice cover, water temperature, as well as nutrient and phytoplankton dynamics in Lake 239 (Rawson Lake) located in the Experimental Lakes Area (ELA), Ontario, Canada. Using observed meteorological and inflow/outflow data, the Multi-year Lake simulation model (MyLake) was setup to replicate measured lake water temperature, ice-cover, dissolved organic carbon, particulate and dissolved phosphorus, and chlorophyll-a concentrations over the entire depth of the lake. The sensitivity of the lake to changes in climatic drivers, specifically to changes in surface air temperature and wind speed, was examined by incrementally changing the model input forcing for temperature and wind speed and mapping the resulting changes in the simulated outputs. The results show that lake processes are generally as sensitive to changes in wind speed as they are to changes in air temperature. Simulated changes in lake variables corresponding to projected changes in Global Climate Models (GCMs) under RCP4.5 and RCP8.5 emission scenarios reveal a general increase in lake water temperature and the corresponding decrease in lake ice thickness and ice cover duration under the changing climate. While lake water temperature increases at all depths, the shallow epilimnion layer is more sensitive to the changing climate than the deeper hypolimnion layer, reaching mean annual change value of +3.7 °C for RCP 8.5 and the 2090s as compared to the 1990s baseline period. While the simulated change in lake ice thickness reaches −20 cm by 2090s for the RCP 8.5 scenario, the corresponding change in ice-cover duration reaches -47 days. These changes are shown to result in seasonal changes in the biogeochemical cycling over the depth of the lake with projected increases in chlorophyll-a concentration during ice covered season of December to May reaching up to +0.15 mg/m3 for RCP 8.5 and the 2090s followed by a decrease during open water season of June to November reaching −0.15 mg/m3 compared to the 1990s baseline period. [ABSTRACT FROM AUTHOR]

This paper studies the challenges of designing and operating adiabatic compressed air energy storage (A-CAES) systems, identifies core causes for the reported discrepancies between round-trip efficiencies from current literature models versus experiments, and presents a near-adiabatic CAES (NA-CAES) system design that addresses these issues. The core causes are overly simplified heat management modeling, neglect of heat losses in the thermal energy reservoir, single-cycle modeling, replacing a diabatic CAES combustor with a TES without other major design changes, using a mirrored compression-expansion design, and/or efficiency definition limitations. To demonstrate an approach to designing an NA-CAES system that addresses the core causes of modeling vs. experiment efficiency discrepancies, a case study is presented for Ontario, Canada. This full system view approach yielded NA-CAES systems with maximum round-trip efficiencies of 60.5, 61.1, and 61.5% for a constant reservoir volume throttled system, a constant reservoir volume variable pressure system, and a constant pressure reservoir system, respectively. A sensitivity analysis was conducted to identify primary with a strong influence on efficiency (such as reservoir pressure limits and the expanders' pressure ratio), and secondary parameters that more strongly affect TES size (including TES charging and discharging mass flow rates, inlet temperatures to the expanders, and TES tank temperatures). Multi-objective hierarchical optimization was employed to improve efficiency while reducing TES capacity. In brief, the results reveal that through design configuration selection it should still be possible to achieve in practice high NA-CAES efficiencies in excess of 60%. • Core causes of efficiency disparities between models and experiments are identified. • A case study is presented to address the core causes of efficiency discrepancies. • Primary and secondary parameters affecting efficiency and TES size are determined. • A-CAES efficiency is enhanced through optimization techniques, considering TES capacity. • Possibility of achieving efficiencies above 60% through design selection is affirmed. [ABSTRACT FROM AUTHOR]