Micro hydropower in the North Carolina Piedmont: A feasibility study on integrating existing low-head dams into the regional grid
The integration of hydropower facilities on existing low-head, non-Federal dams and their subsequent tie to regional electricity grids may serve as a useful de-centralized component of renewable domestic energy integration. We focus specifically on functionally obsolete dams - those that are no longer used for hydropower. This research assesses opportunities to leverage some of these structures as domestic energy resources, and thus an alternative to their being liabilities to society with an eventual fate of abandonment or removal. We conducted a regional feasibility study for installing hydropower infrastructure on existing low-head dams contained within four North Carolina Piedmont river basins. Existing dam sites were evaluated to determine the financial viability of the capital investments required to up-fit these facilities for hydropower generation using a run-of-river approach. We also identified the most prominent engineering, economic, and political factors influencing the decision to improve existing, non-powered dams. Preliminary analysis indicates that many of these dams are not economically feasible for hydropower production based on a broad spectrum of barriers ranging from structural conditions to permitting and licensing issues. However, some dams may have viability depending on physical site conditions, increased availability of pre-manufactured generation systems, or improved financial incentives stemming from the State's Renewable Energy and Energy Efficiency Portfolio Standard (REPS). Over 1,000 existing dam sites with available gross hydraulic head ranging from 15 feet to 35 feet were catalogued using a combination of ArcGIS data obtained through publicly available dam inventories, consultation with dam owners and low-head hydropower specialists, and personal site visits/surveys. Potential power capacity for 49 of these existing low-head dams generally ranged from 1 kW to 168 kW, thus qualifying them as "micro" hydropower sites capable of electrical grid integration. Realistic potential for hydropower generation, greenhouse gas reductions, and financial viability was further refined for test dam sites over a 30-year life cycle using RETScreen software. A sensitivity analysis and a risk analysis using Monte-Carlo simulation were then performed to determine the site-specific relationships between design parameters and key financial indicators. The potential for retrofitting existing low-head, non-Federal dams within the North Carolina Piedmont region has been mostly ignored since the early 1980s. Interest levels by electrical utilities and the general public are steadily increasing across the state (and the nation) for the incorporation of sustainable domestic energy sources. This research will provide qualitative and quantitative data specific to micro hydropower potential that will allow stakeholders from both the power sector and the environmental conservation community to make more informed decisions on whether an existing low-head dam should be retrofitted for regional power generation - or whether removal of the structure is a more realistic long-term solution.
