Our unique approach

Environmentally compatible, low cost hydropower

The SMH project contemplates the need for future energy demand to be met with holistic hydropower technologies that provide both energy and environmental benefits. SMH is not an individual technology or a specific facility design – it is a framework for developing new small hydropower projects.

Within the SMH paradigm, small hydropower development begins with the conceptualization of a facility as an integrated system of standardized modules. Both the facility and the modules operate with dedicated functionalities which together maintain the natural function of streams and watersheds, in a similar way that conventional hydropower systems operate. Modularity enables scalability in two ways – at a single site, by combining multiple modules of the same type, and across multiple sites, by using the same module in different locations. This scalability of standard module designs is hypothesized to lower design, manufacturing, development, and operational costs throughout the development lifecycle.

To achieve significant cost reductions, enhanced environmental performance, and greater acceptance, SMH research and development is guided by several core principles:

• standardization: seek to develop a framework of guidelines, rules, and specifications (i.e., standards) to maximize compatibility, acceptance, interoperability, quality, safety, and repeatability while minimizing environmental disturbance. In a hydropower context, standardization of design, review, regulation, manufacturing, operations, and maintenance, and other features is intended to reduce site specificity and project costs
• modularity: the physical or virtual organization of a hydropower facility into discrete functional units, known as modules. In SMH, the entire facility is envisioned as a modular structure, with generation, passage, and foundation modules assembled to deliver energy and environmental benefits at many different sites.
• environmental design: siting and developing hydropower facilities with an understanding that streams provide valuable environmental benefits that must be preserved. SMH development must embody an understanding of how coupled stream-hydropower systems can minimize disturbances to landscape features, water quantity, connectivity, geomorphology, water quality, and biota.
• stakeholder elicitation: diverse stakeholder groups participate in the design, development, review, acceptance, approval, and success of hydropower plants. Consequently, elicitation of stakeholder perspectives and experiences is a vital SMH project goal, and ongoing engagement with hydropower stakeholders has enabled improved understanding of the current small hydropower development landscape, alignment of SMH research activities with small hydropower community needs, and identification of challenges, risks, and opportunities for improvement in the design, assessment, optimization, and deployment of small hydropower.

Premise: Site classification seeks to assess and define commonalities among stream-reaches and existing water infrastructure to guide the need for and design of modular technologies. It builds upon the concept that module design should be informed by and maintain natural stream functionalities and existing water infrastructure operational requirements.

Approach: Site classification (as included in the SMH Explorer tool) used multivariate statistical techniques, specifically K Means Clustering, to group stream reaches into clusters defined by commonality among their physical and biological characteristics (Figure 1). Classification of over 300,000 National Hydrography Dataset (NHD) stream reaches was carried out for each module type: generation, water quality, foundation, sediment, fish passage, and recreation. The set of stream reaches was limited only to those with a mean annual flow between 50 and 25,000 cubic feet per second. Clustering variables included local in-stream attributes (ex: mean annual flow, gradient, species present, etc.), landscape features (ex: land use, soil type, impervious surfaces, agricultural practices, etc.), and other local or regional characteristics (ex: population density, existing dam presence, etc.).

Example Results:
Figure 2. A national map shows how site classification was used to define ten clusters that illustrate the variability in sediment characteristics across the country (Figure 2). Sediment clustering variables included % agricultural land in the watershed, stream flow, runoff, impervious surfaces, % sand in the watershed, % clay in the watershed, forested coverage, stream slope, mean water velocity, and erosion potential. These clusters can be used to inform the need and design requirements of different types of sediment transport modules.

Figure 3. A regional view of the predominant clusters for fish passage in the northeastern US reveals three distinct classes of stream reaches based on which migratory species are present and physical stream characteristics. This information should be valuable in reducing the number of different fish passage designs.

The results of SMH Site Classification research were integrated into the SMH Explorer tool. Associated data are available through two datasets: (1) Stream Network Attributes for SMH Explorer, and (2) Stream Network Clustering Attributes for SMH Explorer.

Extension to Non-Powered Dam Research

The idea of site classification was further extended to NPD research through the development of the Non-Powered Dam Custom Analysis and Taxonomy (NPDamCAT) framework. In contrast to the predefined clusters applied to streams in the SMH Explorer, the NPDamCAT describes a generalized approach to organizing information about NPDs. Stakeholders involved in hydropower development at NPDs are able to apply this approach to create classes and taxonomies of dams that respond to diverse objectives. Figure 4 illustrates the steps involved in the framework. The results of NPD classification research were integrated into the NPD Explorer tool and NPDamCAT tool. Associated data are available through the U.S. Non-Powered Dam Characteristics Inventory.

Premise: The Exemplary Design Envelope Specification (EDES) is a flexible, technology neutral framework for creating state-of-the-art modules and SMH facilities. It describes what functionalities must be accomplished by advanced technologies without stating how those functionalities should be accomplished. By focusing on functionality rather than specific design features, the EDES intends to invite competition and innovation within private industry to design within the envelope of acceptable technical, economic, and environmental outcomes.

Approach: An Exemplary Design Envelope Specification document has been created to guide module innovators through the technology neutral design framework. The framework offers design specifications for six modules: generation, fish passage, sediment passage, recreation passage, water passage, and foundation. Each specification defines the objectives, requirements, constraints, and performance measures modules must achieve, with supporting rationale developed from an extensive literature review of academic and industry documents. In addition, the specifications define important functional relationships that quantify the variability and dependencies between hydropower infrastructure systems and natural stream processes. Ongoing work is focused on refining specifications to align with Site Classification outputs and cluster results. In addition, we are engaging in collaborative research and development with small hydropower stakeholders to test and improve the module and facility specifications.

The figure below conceptually illustrates the hierarchical order of watersheds and power systems.  The organizing principle of EDES is to acknowledge this hierarchy and align module functionality with stream functionality at a site to achieve energy and non-energy objectives.

Example: An upstream fish passage module may be required to minimize the barrier to migratory fish movement posed by hydraulic infrastructure. The objective of a fish passage module is thus to allow the unimpeded and safe passage of fish across a facility. To achieve this objective, design requirements include the attraction of fish to the inlet, safe and timely passage of fish through the module, and allowance for safe exit of fish back into the river. As with all modules, an interface that allows modules to structurally integrate together is also a requirement. Constraints and measures of performance reflect quantifiable technical, economic, and environmental metrics as indicators of module success. They are technology agnostic and flexible to allow stakeholders, project developers, and technology innovators to move the dial and set specific metrics based on a species of interest with distinct biological limitations.

For more information on the SMH Exemplary Design Envelope Specification, please see ORNL’s technical report on the Publications page.

Extension to Non-Powered Dam Research

ORNL is in development of a NPD Retrofit Exemplary Design report that follows the framework set by the SMH EDES. That publication is forthcoming and is anticipated to be released in Spring 2022.

ORNL has ongoing research related to SMH facilities. Major research areas include the concept of Co-development and development of the water allocation tool enabling rapid small hydropower environmental design (waterSHED). Co-development is defined as “development of an energy project that creates or enhances a natural resource benefit as a result of, or in conjunction with, hydropower development”

In addition, ORNL is collaborating with two industry partners through Funding Opportunity DE-FOA_0001836. The goal of this FOA is to stimulate innovative designs for small, low-head hydropower facilities capable of lowering the capital costs and reducing the environmental impacts of development at new stream-reaches

• Upon completion, the hydropower industry will have scientifically-vetted SMH facility designs that can operate at significantly lower costs with smaller environmental footprints. Development of such modular facility designs will provide a critical benchmark for the technical, economic, and environmental feasibility of transformative new technologies and structures.

ORNL is collaborating with four industry partners through Funding Opportunity DE-FOA_0002080. The goal of this FOA is to develop new, innovative, transformative, modular hydropower technologies that balance performance, economics, and environmental sustainability. Proposed technologies must leverage advanced manufacturing techniques to lower the cost, increase performance, and/or facilitate rapid deployment of these technologies.

• Intended outcome is to develop a technology concept formulated with supporting information to demonstrate its feasibility (TRL 2). Through this award, the awardees will validate the concept through simulation and partial- or full-scale testing in a laboratory or relevant environment (TRL 4-7).

ORNL is also exploring (1) NPD site classification research, and (2) NPD retrofit exemplary design research.

As a part of the NPD site classification effort, the more than nearly 90,000 documented dams in the United States that do not generate electricity have been researched to assimilate characteristics and related data that could be relevant for hydropower development or other water infrastructure-related purposes. Since each dam is unique, with a wide range of characteristics including those related to its design, operation, environment, and socio-economic features an NPD Custom Analysis and Taxonomy (NPDamCAT) framework has been developed for better understanding and categorizing the diverse population of dams into smaller, more manageable groups which will facilitate easier evaluation of development opportunities and enable further research. The research resulted in the development of two online tools and an associated dataset:

• The NPD Explorer and NPDamCAT applications enable geo-visual analytics, subsetting, and classification of NPD data. NPD Explorer tool follows the example set by SMH Explorer. The NPDamCAT tool follows the NPDamCAT framework highlighted above and allows for custom analysis and taxonomy of NPDs.
• Both tools leverage the same dataset (U.S. Non-Powered Dam Characteristics Inventory).

As a part of the NPD Retrofit Exemplary Design research, ORNL is developing an NPD Retrofit Exemplary Design report that follows the framework set by the SMH Exemplary Design Envelope Specification. That publication is forthcoming and is anticipated to be released in Spring 2022.

Premise: The development of standardized modeling approaches and simulation techniques for SMH will pave the way for reliable, cost-effective methods for technology evaluation, optimization, and verification. A suite of modeling capabilities for evaluating, predicting, and optimizing the safety, performance, reliability, and cost of SMH facilities, individual SMH modules, and module combinations will enable rapid and comprehensive development of unproven yet high value technologies.

Approach: A Simulation and Modeling Capability report has been developed to identify use cases, capabilities, gaps, challenges and needs related to modeling and simulating SMH technologies. Current modeling capabilities have been identified in terms of the physical processes which occur in natural stream environments, the interactions and responses of SMH structures, and the salient socio-economic features that determine project feasibility. The current gaps and challenges associated with simulating critical SMH processes highlight opportunities to improve the state of hydropower modeling with a goal of increasing small hydropower development while maintaining the power and function of the natural stream. Ongoing work is focused on developing use cases to assess advanced modular designs and develop widely applicable modeling tools.

The diagram below reflects the structure of how simulation use cases, modeling capabilities, and gaps and challenges inform SMH Simulation and Modeling research.

Example: A generation module simulation use case is being formulated to “optimize composite turbine hydraulic efficiency and manufacturing cost trade-offs with respect to turbine blade material and design.” Modeling capabilities in computational fluid dynamics, finite element analysis, and fluid-structure interactions are being leveraged to resolve the hydraulic and structural processes relevant to the use case. Modeling results will be used to develop a design optimization tool for composite turbines.

The figure below illustrates some early-phase computational fluid dynamics modeling of a turbine blade under different operating conditions.

For more information on the SMH Simulation and Modeling Capability, please see ORNL’s technical report on the Publications page.