Nicole Ryan
School of Natural Resources and Environment, University of Michigan
Nicole Ryan is a PhD student at the University of Michigan in the School of Natural Resources and Environment and in the Department of Mechanical Engineering. She is advised by Dr. Jeremiah Johnson and Dr. Steve Skerlos. Nicole is interested in researching methods of optimizing the use of current generation assets and advancing alternative energy resources in the electricity sector, with the goal of reducing emissions. The work she is presenting at ISSST/ISIE focuses on estimating the life cycle environmental impacts of energy storage for power system reserves.
Operating electricity grids safely and reliably requires generation and demand to match in real time. To correct mismatches, system operators deploy a suite of ancillary services, one of which is power system reserves, the... [ view full abstract ]
Operating electricity grids safely and reliably requires generation and demand to match in real time. To correct mismatches, system operators deploy a suite of ancillary services, one of which is power system reserves, the focus of this work. Reserves are becoming increasingly important as larger quantities of renewable generation, such as wind and solar power are integrated into the grid. Grid-connected distributed energy storage is widely seen as an attractive alternative to traditional generators for providing grid reserves. Energy storage is responsive, flexible, and has the potential to increase traditional generator operating efficiencies. To fully understand the environmental impacts of using this technology in this application, we coupled life cycle assessment data for battery materials, manufacturing, and end of life with a unit commitment and economic dispatch model to simulate power system operations, as well as a battery degradation model.
We found using lithium-ion batteries for reserves actually increases the life cycle and operating greenhouse gas (GHG), SOx and NOx emissions in nearly all cases examined when using an IEEE 9-bus test system under a variety of assumptions and system configurations. This contradicts common assertions that energy storage decreases average electricity emissions when combined with variable renewables. The only scenario with consistently reduced life cycle environmental impacts included significant renewable energy curtailment occurring without energy storage.
We determined generator commitment and dispatch by solving an optimal power flow problem for twelve grid configurations, with different percentages of wind, solar, coal, and natural gas, to determine the changes in generation from each resource attributable to the integration of energy storage. Upstream and end of life environmental impacts were calculated using Argonne National Lab’s BatPaC model and their Greenhouse gases, Regulation Emissions, Energy use in Transportation (GREET) fuel cycle model.
We found that the grid mix has the most substantial effect on life cycle environmental impacts, driving changes in generator operation and fuel consumption. In majority of cases, the environmental impacts from dispatch surpass the upstream and end of life environmental impacts of the lithium-ion batteries themselves. The dispatch changes impact combustion emissions, as well as, the upstream impacts from the differences in the natural gas or coal quantities consumed. Along with grid mix, fuel price, battery efficiency, and transmission congestion significantly impacted dispatch, in turn, having substantial impacts on the energy storage system's environmental impacts.
To improve the environmental impacts of energy storage for power system reserves policies need to focus on integration requirements and research should focus on reducing capacity degradation and improving overall round trip efficiency.
• Life cycle sustainability assessment , • Sustainable energy systems
