No abstract

In this work, an optimization model was constructed to help address important design and operation questions for a novel system combining natural gas power plants with carbon capture and thermal storage. A control co-design (CCD) approach is taken where key plant sizing decisions (including storage capacities and energy transfer rates) and operational control (e.g., when to store and use thermal energy and operate the plant) are considered in an integrated manner using a simultaneous CCD strategy. The optimal design, as well as the operation of the system, are determined for an entire year (either all-at-once or through a moving prediction horizons strategy) in a large, sparse linear optimization problem. The results demonstrate both the need for optimal operation to enable a fair economic assessment of the proposed system as well as optimal sizing decisions due to sensitivity to a variety of scenarios, including different market conditions, site locations, and technology options.

The effective treatment of unconventional oil and gas (UOG) wastewater is a promising and potentially necessary strategy of wastewater management in the UOG industry. While tremendous efforts have been focused on the development of treatment technologies, logistical considerations such as wastewater transportation have been rarely studied in the literature. In this study, we applied spatial analysis tools based on geographic information systems to quantitatively investigate the effects of transportation distance and cost on centralized wastewater treatment (CWT) and deep-well injection (DWI) in Weld County of Colorado, a major UOG-producing state in the United States. CWT using membrane distillation technology powered by waste heat from natural gas compressor stations (NGCSs) was used as the model wastewater treatment approach in our analysis. By analyzing 7583 active UOG production wells, we demonstrate that the distance and cost of wastewater transportation for CWT are comparable to those for DWI in Weld County and that the comparison between CWT and DWI is dependent on the scale of analysis. We also correlated the waste heat availability with the potential UOG wastewater treatment demand at 35 NGCSs. Our analysis shows that the abundance of available waste heat does not always match wastewater treatment demand at NGCSs, requiring a diversion of wastewater that further increases the transportation distance and cost. Our work indicates the importance of logistical considerations in evaluating the viability of CWT for UOG wastewater management. The spatial analysis framework demonstrated in this study is a critical component complementary to the current efforts of treatment technology development, in order to better evaluate the viability and facilitate wide adoption of UOG wastewater treatment via a systems engineering approach.

The unique and beneficial characteristics of solid oxide fuel cell (SOFC) technology hold much promise for their eventual widespread adoption in numerous residential and commercial building applications. Nevertheless, cost and durability challenges remain that currently limit SOFC technology penetration in stationary energy applications. Under the U.S. DOE ARPA-E INTEGRATE program, the Colorado School of Mines and it partners are developing a novel hybrid stationary power system comprised of an intermediate temperature (600°C), solid oxide fuel cell stack integrated with a high efficiency stationary engine and novel balance-of-plant (BOP) equipment. In collaboration with Colorado State University, Kohler Power Systems, and Air-Squared, Inc., the project aims to demonstrate a system that can generate power (125 kW) from natural gas at high electric efficiency (>70%-LHV), and low cost (<900 $/kW). Project activities on the hybrid SOFC/IC engine system development and system requirements are discussed.

Flexible and dispatchable, high-efficiency power generation supplied with carbon-neutral renewable fuels is needed to help enable defossilization of the electric grid. Pressurized, hybrid SOFC systems fueled with hydrogen, biogas, or renewable natural gas can generate clean power at ultra-high efficiency. In this summary, we provide an update on the development progress of a full-scale, hybrid system that targets low cost (<1000 $/kW) and ultra-high efficiency (70%-LHV) distributed power generation for applications up to 1 MW. The system features pressurized, metal-supported SOFC technology from Ceres Power which is integrated with a modified diesel engine which converts the residual chemical exergy in the anode tail-gas from the SOFC to drive auxiliaries and produce net additional power. Updates on critical hardware advancements around pressurized multi-stack, 30 kW fuel cell modules, low-speed high efficiency rotating equipment, and ultra-high efficiency power electronics are provided. A techno-economic outlook for such power generation systems in various stationary applications.