A 174-page study done with the backing of the federal Oak Ridge National Laboratory (ORNL) and the Electric Power Research Institute (EPRI) has used a number of factors, including available land and nearby water supplies, to identify a number of possible power plant sites around the U.S.
The report, released recently by EPRI, covers an internal National Electric Generation Siting Study, which is an ongoing multiphase study addressing several key questions related to national electrical energy supply. This effort has led to the development of a tool, OR-SAGE (Oak Ridge Siting Analysis for power Generation Expansion), to support siting evaluations.
“We think the greatest value from this report and from future use of ORNL’s model will be in support of long-term strategic planning at the national level, as it relates to national energy security, environmental protection, and prudent use of natural resources, particularly water,” said Francisco de la Chesnaye, EPRI’s Energy and Environment Analysis program manager. “It will also provide critical input to regional generating capacity needs as a function of population growth and electricity demand and reliability.”
The initial phase of the study examined nuclear power generation, the report noted. These early nuclear phase results were shared with staff from EPRI, which formed the genesis and support for an expansion of the work to several other power generation forms, including advanced coal with carbon capture and storage (CCS), solar, and compressed air energy storage (CAES). Wind generation was not included in this scope of work for EPRI.
“The OR-SAGE tool is essentially a dynamic visualization database,” the report noted. “The results shown in this report represent a single static set of results using a specific set of input parameters. In this case, the [Geographic Information Systems] input parameters were optimized to support an economic study conducted by EPRI. A single set of individual results should not be construed as an ultimate energy solution, since US energy policy is very complex. However, the strength of the OR-SAGE tool is that numerous alternative scenarios can be quickly generated to provide additional insight into electrical generation or other GIS-based applications.”
The screening process divides the contiguous United States into one-hectare squares (cells), applying successive power generation-appropriate site selection and evaluation criteria (SSEC) to each cell. There are just under 700 million cells representing the contiguous U.S. If a cell meets the requirements of each criterion, the cell is deemed a candidate area for siting a specific power generation form relative to a reference plant for that power type. Some SSEC parameters preclude siting a power plant because of an environmental, regulatory, or land-use constraint. Other SSEC assist in identifying less favorable areas, such as proximity to hazardous operations. All of the selected SSEC tend to recommend against sites.
Critical assumptions supporting this work include: the supply of cooling water to thermoelectric power generation; a methodology to provide an adequate siting footprint for typical power plant applications; a methodology to estimate thermoelectric plant capacity while accounting for available cooling water; and a methodology to account for future siting limitations as population increases and demands on freshwater sources change.
Stream flow is the primary thermoelectric plant cooling source evaluated in the study. All cooling was assumed to be provided by a closed-cycle cooling (CCC) system requiring makeup water to account for evaporation and blowdown. Limited evaluations of shoreline cooling and the use of municipal processed water (gray) cooling were performed.
Evaluation leads to 515 GW(e) of power sites
These calculations, based on a single set of input parameters, show that sufficient stream flow cooling is available to support the placement of 515 GW(e) in large reactor plants. State-by-state results are affected by the unbiased nature of the initial plant placement in any given water basin, the use of single plant sites, and the arbitrary limit of 20 miles between placement of hypothetical units. However, the OR-SAGE plant capacity estimate indicates that states in a significant portion of the country can support siting at least 10 GW(e) in large reactor facilities with no siting challenges.
Likewise, calculations independent of the large reactor results show that sufficient stream flow cooling is available to support placement of at least 201 GW(e) in small reactor plants. The small reactor capacity estimate is a minimum value based on the constraints of the plant generation capacity estimate algorithm.
The OR-SAGE plant capacity estimate projects a gross capacity of 216 GW(e) for new advanced (clean) coal generation. Assuming a parasitic load for scrubbing and carbon capture, this represents a net capacity of approximately 158 GW(e). The states with the strongest projection for advanced coal plant installations and capacity are Montana, Illinois, Missouri, Arkansas, Texas, Louisiana, Tennessee, Alabama and Georgia.
Concentrated solar power (CSP) can power a water-cooled thermoelectric generation plant or a dry-cooled generation plant. The OR-SAGE plant capacity estimate projects a total capacity of 18 GW(e) in water-cooled CSP generation. The states with the strongest projection for plant installations and capacity (more than 15 sites each) are California, Idaho, Montana and Wyoming. States with good capacity (6 to 15 sites each) are Oregon, Nevada, Utah, Arizona, Colorado, New Mexico, Nebraska and Texas.
Dry-cooled CSP generation does not require placement near a cooling water source, and the tracking of available water by the OR-SAGE plant capacity estimate algorithm is not required. A simple comparison of the available dry-cooled CSP land to the water-cooled CSP land indicates that there would be at least 60 GW(e) of dry-cooled CSP capacity.
Coal a little easier to place than nukes
Taking coal plant sites as an example, the report said that siting of advanced coal plants is not held to the same regulatory rigor as nuclear power plant siting. However, the nuclear plant siting SSEC were considered to be a reasonable starting point to establish the advanced coal SSEC. Nuclear plants must consider seismic restrictions and earthquake faults as a public safety issue. Seismic and earthquake fault restrictions for advanced coal plants become an investment protection issue.
Therefore, it is assumed that there are no seismic or earthquake fault issues for advanced coal plant siting, beyond local building codes. Likewise, proximity to hazardous facilities (nuclear plant SSEC) is not considered applicable to advanced coal plant placement as a public safety precaution; rather, proximity to hazardous facilities would be expected to be governed by local zoning restrictions.
Population density of greater than 500 people per square mile begins to be an urban setting, so new advanced coal plants in these areas are excluded based on anticipated available space and zoning restrictions. However, there is no need to include a buffer for public safety. Engineering judgment indicated that other nuclear SSEC such as wetlands and open water, protected lands, slope, landslide hazards, and floodplains should continue to be excluded for new advanced coal plant candidate area siting.
The placement algorithm projects the placement of 288 advanced coal plants for a gross capacity of 216 GW(e). Assuming a parasitic load for scrubbing and carbon capture, this represents a net capacity of approximately 158.4 GW(e). The states with the strongest projection for advanced coal plant installations and capacity (10 or more sites each) are Montana, Illinois, Missouri, Arkansas, Texas, Louisiana, Tennessee, Alabama and Georgia. The placement algorithm estimated about 99 GW(e) of gross capacity directly over saline geological formations and 117 GW(e) of gross capacity within 150 miles of a saline geological formation for carbon storage.