# Hydropower

2021 ATB data for hydropower include data for two broad resource categories: non-powered dams (NPD) and new stream developments (NSD). Cost projections are derived independently for the two resource categories. The data for NPD are based on updated calculations in (Oladosu, G. et al., 2021), whereas those for NSD are retained from the 2020 ATB, which are based on projections developed for the Hydropower Vision study (DOE, 2016).

The NPD and NSD data combine calculations of costs based on a baseline and potential future cost reductions using a mix of bottom-up modeling, technological learning and other assumptions, input from a technical team of Oak Ridge National Laboratory (ORNL) researchers, and the experience of expert hydropower consultants. The three scenarios for technology innovation are:

• Conservative Technology Innovation Scenario (Conservative Scenario): no change for in CAPEX, OPEX and capacity factor for NPD  and NSD; consistent across 2021 ATB
• Moderate Technology Innovation Scenario (Moderate Scenario): near-term innovations for NPD using new materials for tunnel lining and penstock, and replacement of large bulb turbines with matrix-type turbines; incremental technology learning for NSD, consistent with the Reference case in the Hydropower Vision study (DOE, 2016) to reduce capital expenditures (CAPEX)
• Advanced Technology Innovation Scenario (Advanced Scenario): gains expected from potential new technologies, such as modularity (in both civil structures and power train design), advanced manufacturing techniques, and materials, consistent with the Advanced Technology case in the Hydropower Vision study (DOE, 2016); both CAPEX and operation and maintenance (O&M) cost reductions implemented.

## Resource Categorization

Hydropower resources can be categorized into broad groups depending on analytical needs and technology characteristics. The following hydropower categories are included in the 2021ATB:

• Powering Non-Powered Dams (NPD): These are existing dams that do not currently have hydropower. Previous studies have estimated up to 12 GW of technical potential of U.S. NPD based on an average monthly flow rate over a 30-year period and a design flow rate exceedance level of 30% at more than 54,000 dams in the contiguous United States. However, recent development activity suggests the economic potential of NPD may be lower based on current technologies. (Technical potential encompasses technologically feasible sites; economic potential includes only those where economic benefits exceed economic costs to society; market potential includes those where financial benefits exceed financial costs.) Most of this potential (5 GW, or 90% of resource capacity) is associated with fewer than 700 dams.
• New Stream Development (NSD): These are greenfield hydropower developments along previously undeveloped waterways (DOE, 2016). The resource potential is estimated to total 53.2 GW/301 TWh at nearly 230,000 individual sites (Kao et al., 2014) after accounting for locations that are statutorily excluded from hydropower development, such as national parks, wild and scenic rivers, and wilderness areas. In general, NSD potential represents smaller-capacity facilities with lower head than most of the historical data. These characteristics lead to higher CAPEX estimates than past projects, as many of the larger, higher-head sites in the United States have been previously developed. New hydropower facilities are assumed to apply run-of-river operation strategies. Run-of-river operation means the flow rate into a reservoir is equal to the flow rate out of the facility. These facilities do not have dispatch capability.
• Upgrades of Existing Facilities (NSD): These are existing hydropower infrastructure investments that have the potential to continue providing electricity in the future through upgrades (DOE, 2016). At individual facilities, investments can be made to improve the efficiency of existing generating units through overhauls, generator rewinds, or turbine replacements. In particular, as plants reach the license renewal period, upgrades to existing facilities to increase capacity or energy output are typically considered. The bulk of upgrade potential is from large, multimegawatt facilities, with a total of total of 6.9 GW/24 TWh (at about 1,800 facilities) based on a series of case studies or owner-specific assessments (DOE, 2016).

## Representative Technology

In the 2021 ATB, CAPEX are provided for eight representative NPD plants. The NPD sites are grouped into lock and lake design categories, each with four cost  groups (Low Cost, Medium Cost, High Cost and Very High Cost). CAPEX estimates for NPD sites are based on a set of 19 reference sites selected to capture variations in the U.S. resource base and are  analyzed in some detail to understand the drivers of costs at these sites (Oladosu, G. et al., 2021). The detailed cost analysis is extended to an additional set of 100 sites for which the required data are readily available. The NPD reference plants shown below are plants near the middle range of costs within each design and cost categories previously highlighted. There are plans to extend these estimates to about 3,100 NPD sites with initial estimated potentials of  >= 100 kW in a previous ORNL NPD Resource Assessment (Hadjerioua et al., 2012).

The 2021 ATB retains NSD data for four representative plants from the 2020 ATB. These are based on binning approximately 8,000 potential NSD sites by head and capacity estimates from the ORNL resource assessment (Kao et al., 2014). Analysis of these bins is used to estimate future hydropower deployment. The table below shows resource and technology characteristics for the hydropower categories included in the 2021 ATB; details are provided in the ATB data spreadsheet. The reference plants for NSD are developed using the average characteristics (weighted by capacity) of the resource groups within each set of ranges. For example, NSD 1 is constructed from the capacity-weighted average values of NSD sites with 3–30 feet of head and 0.5–10.0 MW of capacity. The weighted-average values are used as input to the cost formulas (O'Connor et al., 2015a) to calculate site CAPEX and O&M costs for NSD sites.

The 2021 ATB does not include cost estimates for hydropower upgrade potential. This is currently modeled in the ReEDS model as becoming available at the relicensing date or plant age of 50 years or both.

Design Values of Representative Hydropower Plants

## Scenario Descriptions

In general, differences among the technology innovation scenarios in the ATB reflect different levels of adoption of innovations. Reductions in technology costs, particularly in the Advanced Scenario, reflect opportunities outlined in the Hydropower Vision study (DOE, 2016), which includes road map actions to lower technology costs. The tables below provide an overview of potential hydropower innovations. A recent analysis of NPD sites also identified potential near-term opportunity for reducing the cost of NPD hydropower under the Moderate Scenario(Oladosu, G. et al., 2021).

Summary of Technology Innovation: Moderate Scenario (2030)

Summary of Technology Innovation: Advanced Scenario (2030)

## Methodology

This section describes the methodology to develop assumptions for CAPEX, O&M, and capacity factor. For standardized assumptions, see labor costregional cost variationmaterials cost indexscale of industrypolicies and regulations, and inflation.

### Capital Expenditures (CAPEX)

Definition: Hydropower capital costs are defined according to the breakdown structure described by O'Conner et al. (O'Connor et al., 2015a). The broad components of CAPEX include initial capital costs (site preparation, water conveyance system, powerhouse, electromechanical system, electrical infrastructure, among others) and development costs.

Recent Trends: Data from the literature and other sources are reviewed as shown in the historical and literature review charts below. An attempt is made to identify potential CAPEX reduction for resources of similar characteristics over time (e.g., estimated cost to develop the same site in 2019, 2030, and 2040 based on different technology, installation, and other technical aspects). Because the sample size is limited, all literature projections are analyzed together without distinguishing types of technologies. Note that the costs for the three 2021 ATB hydropower scenarios are for the lowest cost category (i.e. NPD 1). However, the number of such sites have dwindled as the most productive sites are built first.

For CAPEX, estimates represent actual and proposed projects from 1981 to 2014. Year represents the commercial online date for a past or future plant.

IEA-ETSAP: International Energy Agency (IEA)-Energy Technology Systems Analysis Program (ETSAP); IRENA: International Renewable Energy Agency

Base Year: CAPEX estimates for NPD sites are based on a detailed analysis of 19 reference sites using simulations with the bottom-up smHIDEA model. The results of the simulations are extended to an additional set of more than 100 sites where the required data are readily available. The bottom-up simulations include estimates for the broad components of capital costs as outlined previously (Oladosu, G. et al., 2021). Estimates for NSD plants are based on statistical analysis of historical plant data from 1980 to 2015 as a function of key design parameters, plant capacity, and hydraulic head (O'Connor et al., 2015b) as given in the following equation:

NSD CAPEX = (9,605,710 × P0.977 × H-0.126) + (610,000 × P0.7)

where P is capacity in megawatts, and H is head in feet. Actual and proposed NPD and NSD CAPEX from 1981 to 2014 (O'Connor et al., 2015b) are shown in box-and-whiskers format for comparison to the ATB current CAPEX estimates and future projections.

Base year estimates of CAPEX for NPD sites in the 2021 ATB range from $2,400/kW to$14,500/kW. These estimates reflect the variation in resource potentials and site features considered in the NPD reference cost analysis as outlined in the above table. In general, the higher-cost sites reflect lower-head and smaller-flow that may also require significant civil works and transmission connections. These sites have fewer analogues in the historical data because the most productive NPD sites have already been built. Base Year estimates of CAPEX for NSD, based on the above equation, range from $5,500/kW to$7,900/kW. The estimates reflect potential sites with 3 feet of head to more than 60 feet of head and from 1 MW to more than 30 MW of capacity. The higher-cost ATB sites generally reflect small-capacity, low-head sites that are not comparable to the historical data sample's generally larger-capacity and higher-head facilities. These characteristics lead to higher ATB Base Year CAPEX estimates than past data suggest. For example, the NSD projects that became commercially operational in this period are dominated by a few high-head projects in the mountains of the Pacific Northwest and Alaska.

Future Years: Projections for NPD sites are based on Baseline and Near-term innovation cost estimates in (Oladosu, G. et al., 2021), and other assumptions, including technological learning, for the specific years in the 2021 ATB. Projections for NSD are based on the Hydropower Vision study (DOE, 2016) using technological learning assumptions, analysis of process and/or technology improvements to estimate future costs. The three scenarios for hydropower in the 2021 ATB are as follows:

• Conservative Scenario: NPD and NSD CAPEX are unchanged from the Base Year
• Moderate Scenario:
• NPD CAPEX for 2026 to 2035 are based on cost reductions for the Reference sites in (Oladosu, G. et al., 2021) relative to 2019 Baseline. CAPEX for 2040 are assumed to be 4% lower than in 2030.
• NSD CAPEX is reduced 5% in 2035 and 8.6% in 2050. These estimates are not imposed in the 2021 ATB. There is an ongoing effort to update the cost estimates to support future ATB scenarios. This is consistent with the Reference case in the 2016 Hydropower Vision study.
• NPD CAPEX for 2026 to 2030 and 2031 to 2040 are, respectively, 5% and 10% lower than the Moderate Scenario for 2030.
• All NSD CAPEX reduced 30% in 2035 and 35.3% in 2050. This is consistent with the Advanced Technology case in the 2016 Hydropower Vision study:

Use the following table to view the components of CAPEX.

### Operation and Maintenance (O&M) Costs

Definition: Operation and maintenance (O&M) costs represent average annual fixed expenditures (and depend on rated capacity) required to operate and maintain a hydropower plant over its lifetime, including items noted in the table below.

Base Year: The core metric chart shows the Base Year estimate and future year projections for fixed O&M (FOM) costs for each technology innovation scenario. The estimate for a given year represents annual average FOM costs expected over the technical lifetime of a new plant that reaches commercial operation in that year.

A statistical analysis of long-term plant operation costs from Federal Energy Regulatory Commission Form-1 results in a relationship between annual, FOM costs, and plant capacity. Values are updated to 2019\$.

Lesser of Annual O&M = (227,000 × P0.547) or (2.5% of CAPEX)

This equation was used for estimating O&M costs for both NPD and NSD plant groups.

Future Years: Projections developed for the Hydropower Vision study (DOE, 2016) using technological learning assumptions and bottom-up analysis of process and/or technology improvements provide a range of future cost outcomes. Three different FOM projections are developed for scenario modeling as bounding levels:

• Conservative Scenario: FOM costs unchanged from the Base Year to 2050; consistent with all ATB technologies
• Moderate Scenario: FOM cost for NPD are based on the same scenario assumptions as those used for CAPEX described above, relative to the base year. FOM costs for NSD plants are unchanged from 2019 to 2050, which is consistent with the Reference case in Hydropower Vision study.
• Advanced Scenario: FOM cost for NPD are based on the same scenario assumptions as those used for CAPEX described above, relative to the base year. FOM costs for NSD plants reduced by 50% in 2035 and 54% in 2050, which is consistent with the Advanced Technology case in the Hydropower Vision study.

Use the following table to view the components of O&M.

### Capacity Factor

Definition: The capacity factor represents the expected annual average energy production divided by the annual energy production, assuming the plant operates at rated capacity for every hour of the year. Capacity factor is intended to represent a long-term average over the lifetime of the plant; it does not represent interannual variation in energy production. Future year estimates represent the estimated annual average capacity factor over the technical lifetime of a new plant installed in a given year. The capacity factor is influenced by site hydrology, design factors (e.g., exceedance level), and operation characteristics (e.g., dispatch or run-of-river).

Recent Trends: Actual energy production from about 200 run-of-river plants operating in the United States from 2003 to 2012 (EIA, 2016) is shown in the historical chart below. This sample includes some very old plants that might have lower availability and efficiency. It also includes plants that have been relicensed and may no longer be optimally designed for the current operating regime (e.g., a peaking unit now operating as run-of-river). This contributes to the broad range, particularly on the low end. Interannual variation of hydropower plant output for run-of-river plants might be significant because of hydrological changes such as drought. This impact might be exacerbated by climate change over the long term.

For capacity factor, historical data represent energy production from about 200 run-of-river plants operating in the United States from 2003 through 2012 where year represents calendar year. Projection data represent expected annual average capacity factor for plants with the commercial online date specified by year.

Base Year: Base Year capacity factors for NPD are based on the simulation results used to estimate CAPEX as discussed previously. Base Year capacity factors for NSD are assumed to be near the 80th percentile of the historical range, with a small range.

Future Years: The capacity factor remains largely unchanged from the Base Year through 2050, except for cases where technology changes lead to slight differences in capacity, plant efficiency, or flow/head range of operation.

## References

The following references are specific to this page; for all references in this ATB, see References.

Oladosu, G., George, L., and Wells, J. “2020 Cost Analysis of Hydropower Options at Non-Powered Dams.” Oak Ridge, TN: Oak Ridge National Laboratory, 2021.

DOE. “Hydropower Vision: A New Chapter for America’s Renewable Electricity Source.” Washington, D.C.: U.S. Department of Energy, 2016. https://www.energy.gov/sites/prod/files/2018/02/f49/Hydropower-Vision-021518.pdf.

Kao, Shih-Chieh, Ryan A. McManamay, Kevin M. Stewart, Nicole M. Samu, Boualem Hadjerioua, Scott T. DeNeale, Dilruba Yeasmin, M. Fayzul K. Pasha, Abdoul A. Oubeidillah, and Brennan T. Smith. “New Stream-Reach Development: A Comprehensive Assessment of Hydropower Energy Potential in the United States.” Oak Ridge, TN: Oak Ridge National Laboratory, April 2014. https://doi.org/10.2172/1130425.

O’Connor, Patrick W., Qin Fen (Katherine) Zhang, Scott T. DeNeale, Dol Raj Chalise, and Emma E. Centurion. “Hydropower Baseline Cost Modeling.” Oak Ridge, TN: Oak Ridge National Laboratory, 2015a. https://doi.org/10.2172/1185882.

Hadjerioua, Boualem, Yaxing Wei, and Shih-Chieh Kao. “An Assessment of Energy Potential at Non-Powered Dams in the United States.” Oak Ridge, TN: Oak Ridge National Laboratory, April 2012. https://doi.org/10.2172/1039957.

O’Connor, Patrick W., Scott T. DeNeale, Dol Raj Chalise, Emma Centurion, and Abigail Maloof. “Hydropower Baseline Cost Modeling, Version 2.” Oak Ridge, TN: Oak Ridge National Laboratory, 2015b. https://doi.org/10.2172/1244193.

EIA. “Capital Cost Estimates for Utility Scale Electricity Generating Plants.” Washington, D.C.: U.S. Energy Information Administration, 2016. https://www.eia.gov/analysis/studies/powerplants/capitalcost/pdf/capcost_assumption.pdf.