This dissertation combines methods from engineering, operations research, and economics to analyze how emerging residential energy technologies can be effectively used to reduce both energy costs and carbon emissions. Our most important finding is that air-source heat pumps can be used to reduce both energy costs and carbon emissions in four out of the five major climate regions studied, but that electric retail rate reform is needed to provide customers with appropriate incentives. In cold climates, it may be advantageous to use heat pumps in tandem with fossil fuel-powered furnaces; in warmer regions, furnaces can be cost-effectively abandoned altogether. We do not find that distributed rooftop solar panels or distributed battery storage are effective tools for reducing the cost of energy services. Rather, in our simulations, customers adopt these technologies in response to poor price signaling by electric utilities. By reforming electric retail rates so that the prices paid by consumers better reflect the cost of energy services, utilities can promote the adoption of technologies that reduce both aggregate costs and carbon emissions.

<p>To reduce greenhouse gas emissions, shifting the energy sources used in buildings, transportation, industry, etc., from fossil fuels to clean electricity is a trend. The increasing electricity demand stresses the existing electric grids. Buildings consume 73% of all U.S. electricity and are responsible for 30% of U.S. greenhouse gas emissions.  Residential and commercial buildings' space heating/cooling system consumes considerable electricity. Integrating thermal energy storage (TES) in building heating/cooling systems can mitigate the challenge of electric grids. Applying TES to existing air-source heat pump (ASHP) systems is the most studied for residential buildings. However, the high-quality thermal energy requirement for charging the TES tank results in low thermal performance of the ASHP system. Moreover, the failure of ASHP in cold climates requires a supplemental electric heater that significantly reduces the system efficiency and may lead to a higher annual peak for the grids.</p> <p>This study proposes integrating TES with ground-source heat pump (GSHP) systems as a more effective solution for building decarbonization due to the high efficiency of renewable-energy-based GSHPs year-round. This study focuses on proving the effectiveness of TES-integrated GSHPs for building decarbonization.  A dual-source heat pump (DSHP) with a hybrid TES and ground heat exchanger (GHE) named dual-purpose underground thermal battery (DPUTB) is investigated. The study uses modeling and experiments to verify the system's energy efficiency, decarbonization potential, and demand response capability. The modeling process involves developing various models, from component-level to system-level, and investigating advanced control strategies. A first-of-this-kind dynamic model of the DPUTB is developed to enable high-resolution system simulation for the GSHP system. The simulation is conducted using Modelica with rule-based control (RBC). A model predictive control (MPC) is also developed based on dynamic building envelope and heating, ventilation, and air conditioning (HVAC) system models. A cutting-edge co-simulation testbed integrates Modelica physical models with a MATLAB MPC controller model for advanced control evaluation. A prototype system of the DPUTB+DSHP is tested in a flexible research platform (FRP) at Oak Ridge National Laboratory (ORNL), which allows for component and system-level testing and remote automation controls. </p> <p>The study highlights the importance of proper insulation in the performance of the DPUTB, which consists of a TES tank enclosed by an outer tank functioning as a GHE. With appropriate insulation, a full-size DPUTB can store 1-ton cooling (3.5 kW) for four hours after eight hours of charging. Simulation results suggest that decoupling the TES with the GHE could reduce energy consumption by 27%.  System-level simulations confirm that the DSHP+DPUTB system, with a customized RBC, outperforms the conventional ASHP. The proposed system can reduce the annual HVAC electricity cost by up to 50% while saving 45% on electricity consumption. In the Northern areas of the United States, the annual peak load of the HVAC system can be reduced by 60%.  However, this reduction is less in the Southern parts of the as the system's higher efficiency in winter dominates the overall decrease. The application of MPC can further reduce the cost and energy consumption of the system by 35% theoretically. However, the accuracy of model prediction affects its performance in practical applications, which can be mitigated by employing technologies such as machine learning and reinforcement learning. Further research is required to verify these technologies.</p> <p>The DSHP+DPUTB system, a type of TES-integrated GSHP, has been well-designed and demonstrated superior performance to conventional systems, with greater flexibility and thermal efficiency. As a result, this system can enable electrification in the space heating sector without requiring an escalation in the grid. Moreover, alternative controls can be utilized to exploit its decarbonization potential fully.</p>

In 2011 the mining industry purchased 14.5% of the electrical energy generated by Eskom. During 2011 in South Africa, dewatering pump systems on gold mines were the fourth largest electrical energy consumer on South African mines therefor making dewatering pumps ideal candidates to generate significant financial savings. These savings can be realised by controlling time-of-use (TOU) schedules. Previous studies concentrated on the impact of improving a pumping scheme of a single mineshaft. This dissertation will focus on the operations of a complete dewatering system consisting of multiple mineshafts. The case study will consist of a gold mine complex comprising of five different shafts - each with its own reticulation system – as well as the larger interconnected water reticulation system. Various pumping options were investigated, simulated and verified. The interaction between shafts was determined when load-shifting was scheduled for all the shafts taking each shaft’s particular infrastructure into account. The underground dewatering system was automated and optimised based on the simulation results. Mine safety protocols were adhered to while optimal pump operational schedules were introduced. / Thesis (MIng (Electrical and Electronic Engineering))--North-West University, Potchefstroom Campus, 2013.

In 2011 the mining industry purchased 14.5% of the electrical energy generated by Eskom. During 2011 in South Africa, dewatering pump systems on gold mines were the fourth largest electrical energy consumer on South African mines therefor making dewatering pumps ideal candidates to generate significant financial savings. These savings can be realised by controlling time-of-use (TOU) schedules. Previous studies concentrated on the impact of improving a pumping scheme of a single mineshaft. This dissertation will focus on the operations of a complete dewatering system consisting of multiple mineshafts. The case study will consist of a gold mine complex comprising of five different shafts - each with its own reticulation system – as well as the larger interconnected water reticulation system. Various pumping options were investigated, simulated and verified. The interaction between shafts was determined when load-shifting was scheduled for all the shafts taking each shaft’s particular infrastructure into account. The underground dewatering system was automated and optimised based on the simulation results. Mine safety protocols were adhered to while optimal pump operational schedules were introduced. / Thesis (MIng (Electrical and Electronic Engineering))--North-West University, Potchefstroom Campus, 2013.