Retrofitting of Non-Powered Dams for Hydropower Using 3D Concrete Printing

The Opportunity:
The United States has more than 80,000 non-powered dams (NPDs)—dams that do not produce electricity—providing a variety of services ranging from water supply to inland navigation. If the United States could harvest the energy produced through these existing non-powered dams, our conventional hydropower fleet could be increased nearly 12 GW, or around 15% of current renewable capacity. The U.S. has already invested hundreds of millions of dollars in civil work and environmental impact studies for its 80,000 NPDs. According to the Department of Energy, the development of some NPD’s for energy purposes is achievable with lower installed cost, lower levelized cost-of-energy, fewer barriers to development, less technological and business risk, and in a shorter time frame than development requiring new dam construction [Hadjerioua 2012].

These non-powered dams have been serving their primary purpose of holding back massive amounts of water for decades. However, in many cases, water is discharged daily through the primary outlets with massive amounts of force creating a potential to produce clean renewable energy. Great interest in retrofitting NPDs exists, and some upward trends is evident. From 2014 to 2017, 39 NPDs with 636 MW of cumulative capacity received an original license to add a hydropower project, a significant increase from the 19 NPDs with 252 MW of cumulative capacity licensed in the prior eight years. However, mass production of these systems is only obtainable “using a cluster approach, where dams with similar head, flow, purpose, type, and location are retrofitted for hydroelectric generation using a standard plant design [Witt 2017].

RCAM's Proposed Solution:
RCAM Technologies proposes to use new large-scale 3D printing technologies with low cost concrete in a process called 3D Concrete Printing (3DCP) to manufacture low cost retrofits for a wider variety NPDs than is presently possible using conventional manufacturing technologies. RCAM envisions 3DCP structures can be digitally designed and printed on-site downstream of the dam. 3DCP can be used to print custom designed concrete parts, structures and buildings, in-situ, using locally sourced materials and the existing concrete supply chain that exists in nearly every region of the country. The structures will be designed to accommodate modular hydropower turbine equipment such as Voith’s StreamDivers or other modular turbine/generators. 3DCP is a digital manufacturing technology that eliminates formwork enabling custom designs to be quickly manufactured to that meet the unique requirements of America’s many NPDs.

3DCP can be combined with digital design methods including 3D scanning, optimization, and computer aided design (CAD). We envision the first step of the process would be to obtain 3D images and scans of the existing structure using a state-of-the-art technology such as 3D drone mapping. 3D drone mapping uses drones to take detailed photographs of the site that are mapped using a technique called photogrammetry which makes precise and accurate measurements from the photographs collected in the field. An accurate 3D CAD model can then be created of the site to identify where to locate and how to customize components of the 3D concrete printed infrastructure. Key parameters collected necessary for 3DCP design will include the dimensions of the primary outlet, the slope of the dam wall, the topography of the ground around and near the primary outlet, and the dimensions of the existing downstream spillway.

The next step in RCAM’s NPD retrofit process is the 3D concrete printing. 3DCP is a digital manufacturing technique, which opens up a new possibility in how structures are designed. A vast number of companies and research organizations internationally have entered into the 3DCP field in the last several years creating extremely quick advancements in the technology. A number of new large-scale printers are already available. For RCAM’s concept, we selected a radial-arm 3D printer developed by Apis-Cor in California. The printer is relatively light weight at just under 2 tons (less than a standard American pickup truck) allowing it to be transported and positioned with light-duty industrial equipment.

An important benefit of 3DCP compared to conventional concrete construction is the ability to create organic and complex shapes that are not practical with conventional concrete construction. This design flexibility provides architects with the tools to create designs that are both functional and aesthetically pleasing. Such aesthetically pleasing designs will increase public acceptance when retrofitting a dam and help inspire a new hydropower workforce and advocacy groups.

Hadjerioua, B., (2012). An Assessment of Energy Potential at Non-powered Dams in the United States, Wind and Water Power Program, U.S. DOE.

Witt, A. (2017). United States trends in non-powered dam electrification, U.S. DOE.