The benefits of converting non-powered dams to hydropower dams are:
● Lower installation costs
● Lower levelized cost-of-energy (LCOE)
● Fewer barriers to development
● Less risk within a shorter time frame.
According to the U.S. Department of Energy, of the 80,000 dams registered in the U.S., only 3% produce power. The Energy Potential at Non-Powered Dams in the United States report claims that 54,391 non-powered dams have the potential to be converted and generate electricity as hydropower dams. This can possibly add 12 GW (12,000 megawatts or MW) of renewable and reliable energy and help local communities across America move towards sustainability. In this article, we will discuss the pros and cons of such a transition, things to consider before converting a non-powered dam, and the ways to do it.
The Benefits of Converting Non-Powered Dams Explained
Upgrading a non-powered dam in most cases is a more cost-effective solution compared to building a new hydroelectric facility. Firstly, it is less time-intensive. As the dam owners maximize the existing infrastructure, they often need fewer permits, less equipment, and experience lower construction costs. Secondly, when we talk about the environmental concerns, there are fewer barriers to the existing development. Finally, refurbishing existing non-powered dams supports local communities by adding jobs that could not be outsourced otherwise. For example, the comprehensive study done by Navigant Consulting Inc. revealed that expanding hydropower potential could create 1.4 million quality jobs.
Small Distributed Hydropower
Fortunately, new technologies such as small distributed hydropower make the hydropower more accessible for sites with a generating capacity up to 10 MW. The existing small hydropower locations make up about 75% of the current US hydropower fleet in terms of the number of plants. Moreover, we firmly believe that this number will grow. In order to support the small hydropower industry, the federal government has recently introduced new laws that simplify the permitting requirements for small hydropower facilities and approve additional funding. As a result, we expect the economic feasibility of developing new small hydropower projects to slowly improve over time. If the trend continues, more and more communities will get access to small distributed power in the US.
If we talk about the installation requirements, most small hydropower schemes fit into two main categories: run-of-river systems and integrated into existing water infrastructure, including dams.
Considerations When Converting Non-Powered Dams into a Hydropower Source
- Water Availability
To analyze the future energy potential of the non-powered dam, start by looking at water availability and physical relief data. For this purpose determine the regional water availability by looking at the precipitation (P) and runoff (Q) ratio, also known as Q/P ratio. After you finish your analysis, you will find that the locations with higher latitude and colder climates generally have higher hydropower potential. Unfortunately, high evaporation in warmer climates reduces available runoff making the water resources for hydropower less accessible. Additionally, the high precipitation in humid climates also challenges possible flood operations, making these areas less attractive for development.
Streamflow refers to the amount of water flowing in a river. Seasonal changes alter streamflow since precipitation contributes to higher streamflows. While stream gauge monitoring is the most effective way to measure available streamflow, many non-powered dams will not have records pre-dating the 2000’s. To estimate the monthly average streamflow, use the formula below:
Streamflow = Drainage Area * Runoff
Please refer to the National Inventory of Dams (NID) database or the National Hydrography Dataset (NHDPlus) for estimating the drainage area. NHDPlus, which geospatially models the flow of water across the United States, provides the cumulative drainage area at the endpoint of most streams. In most cases, the cumulative drainage area of a stream resembles the drainage area of the stream on which a non-powered dam is located.
- Hydraulic Head
This is the change in vertical height between hydro intake and discharge points. Measure the height difference between headwater and tailwater elevations to get the most accurate hydraulic head measurement if available.
- Power Generation and Capacity
Take the hydraulic head and monthly average streamflow measurements to calculate the potential generation capacity.
Methods for Converting Non-Powered Dams Into Hydropower Dams
There are hundreds of NPDs with potential capacities greater than 1 MW, which are mapped out below by the US Department of Energy. See the list below:
Downstream penstock (Mahoning Creek Hydroelectric Project)
Adjacent to dam (Meldahl Hydroelectric Facility, KY)
Downstream of dam (Montgomery Locks and Dam Hydroelectric Project)
Through dam (Robert Moses Niagara Hydroelectric Power Station in Lewiston, NY)
In gate (Lower St. Anthony Falls Hydroelectric Project)
In lock (proposed Heidelberg Hydroelectric Project, KY)
Non-Powered Dam (NPD) Locations in the US
There are hundreds of NPDs with potential capacities greater than 1 MW, which are mapped out below by the US Department of Energy.
Notably, the three hydrologic regions with the most hydropower potential are Ohio, Upper Mississippi, and Arkansas-White-Red. Given the amount of precipitation and low evaporation ratios, Eastern Ohio, Tennessee, and Pacific Northwest are the most favorable regions for hydropower generation. On the contrary, the Colorado River System and the Rio Grande regions have low Q/P ratio and heavily rely on storage in large reservoirs (like Hoover Dam). Due to limited water availability in these regions, there are fewer hydropower projects to be developed.
Considering that the energy potential at non-powered dams could increase the US hydropower capacity by up to 15% or to 90 GW total, converting non-powered dams is the important step to expanding renewable energy capabilities in the US. Sorensen Systems is here to support the efforts of municipalities switching to renewable energy production.
Hadjerioua, Boualem. An Assessment of Energy Potential at Non-Powered Dams in the United States. U.S. Department of Energy. https://www.energy.gov/sites/prod/files/2013/12/f5/npd_report_0.pdf