In addition to the pressing need to transition electricity generation to more widespread use of renewables, attention needs to be given to how these low-carbon systems might be integrated with other net-zero interventions. While wind and solar power deservedly receive much attention, not only is geothermal energy an important low-carbon source of electricity, but there are creative ways of integrating geothermal systems with other net-zero approaches to create a virtuous cycle of clean power generation and carbon sequestration. A team of Brian Ellis at the University of Michigan, Jeffrey Bielicki at The Ohio State University, and Jeremiah Johnson at North Carolina State University will address these challenges by examining the potential to pump carbon dioxide underground—after being captured from industrial processes such as coal-fired power generation—in order to enhance renewable geothermal power systems. How might these carbon dioxide streams get pumped into the subsurface? They are sent underground using excess electricity generated by wind or solar installations. These researchers will examine various dimensions of such systems that might allow the use of carbon-rich fluids to boost renewable energy production while simultaneously being sequestered underground. First, this team will investigate basic geological characteristics related to how differences in rock pore size and mineralogy may influence how these carbon-rich fluids flow in underground reservoirs. Second, they will look to aggregate this information about basin-scale geological characteristics to shed light on the viability of using such carbon-rich fluids to enhance geothermal energy production across power systems that have rather different power production and geographical characteristics. The results have the potential to inform how such net-zero systems might be optimized to help make renewables like geothermal power even more attractive as a twenty first century energy source.

Funds from this grant support the continuation and completion of work by an interdisciplinary team led by Granger Morgan at Carnegie Mellon University (CMU). The team is attempting to quantify the challenges and opportunities associated with transitioning the U.S. high-voltage electricity transmission system from alternating current (HVAC) to direct current (HVDC).  A transition to direct current has several potential advantages that could aid in decarbonizing the energy system.  For instance, direct current is more efficient than alternating current at transmitting significant quantities of electricity over long distances. That is important for the future viability of renewable energy technologies like wind and solar, where electricity, to be maximally useful, needs to be generated in windy or sunny locales and then transmitted over long distances.  Second, high voltage DC power lines can be sited alongside AC lines and sometimes in areas where AC lines cannot, thereby providing another tool to help advance clean electricity technologies. Using a method called expert elicitation, which asks subject matter experts to assess the likelihood of a range of factors associated with the technology’s development, the CMU team will closely examine the development of the novel power electronics technologies that are crucial to make the switch from HVAC to HVDC. This project will place a particular focus on the development of novel transistors, switching devices, and other power electronics necessary to advance HVDC lines. The result will be the identification of a set of well-informed parameters that can inform models designed to assess the likely costs and performance of a future HVDC system in the US.

Carbon capture and storage (CCS) technology is an important tool in the fight against climate change. Carbon dioxide gas is captured following fossil fuel production or other industrial processes, then compressed and pumped underground under extremely high temperatures and pressures, and stored in depleted oil and gas wells or, in some cases, in underground salt caverns or saline aquifers. A key concern with CCUS technology is the ability to verify that the carbon dioxide remains in place and stored underground. If the carbon dioxide leaks from the disposal wellbores, this not only impairs the effectiveness of the sequestration process, but it can contaminate other underground water regions nearby. These wellbores are harsh environments to monitor, under intensely high pressures and chemically corrosive. Such environments are not friendly to the delicate conditions that most sensors need to operate effectively.  This grant will fund work by researchers Debbie Senesky at Stanford University and Pingfeng Wang at the University of Illinois at Urbana-Champaign to develop and deploy a novel, durable sensor system capable of operating in the harsh conditions of a CCS wellbore and thus able to monitor whether the sequestered carbon dioxide is staying put or seeping out. The project has the potential to significantly advance understanding of the effectiveness of CCS sequestration, and thus to help inform the future development of these technologies in the fight against greenhouse gas emissions. The project will train at least two graduate students and is expected to result in a number of academic publications and the development of new sensor technologies.