Nuclear-renewable hybrid energy systems appear 'feasible'
The Joint Institute for Strategic Energy Analysis (JISEA) and Idaho National Laboratory (INL) have issued a series of reports examining the feasibility of nuclear-renewable hybrid energy systems (N-R HESs). By comparing greenhouse gas-emitting plants with those which do not, and assessing the technical and economic viability of N-R HESs, JISEA and INL concluded N-R HESs could "reduce industrial emissions and support the power system".
However, the economic feasibility of these systems may depend on future natural gas prices, electricity market structures, and clean energy incentives. A series of new reports from the Joint Institute for Strategic Energy Analysis (JISEA) and Idaho National Laboratory (INL) examines various hybrid system configurations to provide a basis to identify opportunities for clean energy use and examine the most economically viable configurations.

Nuclear-renewable hybrid energy systems (N-R HESs) can enable low-carbon, on-demand electricity while providing reduced-emission thermal energy for industrial processes. N-R HES systems are managed by a single entity that link a nuclear reactor that generates heat, a thermal power cycle for heat-to-electricity conversion, at least one renewable energy source, and an industrial process that uses thermal and/or electrical energy.

N-R HESs are physically coupled facilities that include both nuclear and renewable energy sources and produce electricity and another product such as a fuel, thermal energy, hydrogen, and desalinated water. Energy and materials flows among energy production and delivery systems are dynamically integrated so that the production rate of each product can be varied.

In one report, Generation and Use of Thermal Energy in the US Industrial Sector and Opportunities to Reduce its Carbon Emissions, researchers from INL and the Energy Department’s National Renewable Energy Laboratory (NREL) identify key greenhouse gas (GHG) emission sources in the industrial sector and propose low-emitting alternatives using targeted, process-level analysis of industrial heat requirements.

The report examines emissions generated during process heat generation. The study focuses on the 14 industries with the largest emissions as reported under the Environmental Protection Agency’s Greenhouse Gas Reporting Program in 2014.

Approximately 960 plants from those industries represent less than one half of one percent of all manufacturing in the US, but they emit nearly 25% of all industrial sector emissions—5% of total US GHG emissions in 2014.

The report also identifies non-GHG-emitting thermal energy sources that could be used to generate heat without emissions. Those potential sources include small modular nuclear reactors, solar heat for industrial processes, and geothermal heat. The report identifies potential opportunities for each source, identifies implementation challenges, and proposes analyses to identify approaches to overcome the challenges.

In a second report, Status on the Component Models Developed in the Modelica Framework: High-Temperature Steam Electrolysis Plant & Gas Turbine Power Plant, INL details a modeling and simulation framework to assess the technical and economic viability of an N-R HES. INL, with support from Oak Ridge National Laboratory and Argonne National Laboratory, developed a dynamic, physics-based modeling capability of N-R HESs using the Modelica programming language.

The report presents details on newly developed high-temperature steam electrolysis (for hydrogen production) and gas turbine power plant subsystems. Simulations of several case studies show that the suggested control scheme could maintain satisfactory plant operations even under rapid variations in net load. The study finds that the N-R HESs modeled could provide operational flexibility to participate in energy management at the utility scale by dynamically optimizing the use of excess plant capacity.

In a third report, The Economic Potential of Three Nuclear-Renewable Hybrid Energy Systems Providing Thermal Energy to Industry, NREL researchers explore the economics of an N-R HES that sells a thermal product (steam or a high-temperature heat transfer fluid) to one or more industrial customers. Under each scenario examined, the economically optimal system configuration includes a nuclear reactor generating a thermal product such as steam or a heat transfer fluid—a configuration that can economically reduce GHG emissions from industry.

In addition, configurations that include a thermal power cycle can support resource adequacy for the electricity grid while maximizing production of the thermal energy product if the markets sufficiently incentivize that option.

Together, these three reports indicate nuclear renewable hybrid energy systems can reduce industrial emissions and support the power system.

The Joint Institute for Strategic Energy Analysis is operated by the Alliance for Sustainable Energy, LLC, on behalf of the US Department of Energy’s National Renewable Energy Laboratory, the University of Colorado-Boulder, the Colorado School of Mines, Colorado State University, Massachusetts Institute of Technology, and Stanford University.