PRIMRE Guidelines and Best Practices
The Portal and Repository for Information on Marine Renewable Energy (PRIMRE) is a central access point to data and information on engineering and technologies, resource characterization, device performance, and environmental effects of marine renewable energy (MRE , also known as marine and hydrokinetic energy or MHK). These guidelines and best practices apply to PRIMRE and the platforms that reside within PRIMRE (e.g., knowledge hubs, databases, GIS tools, and code repositories). The purpose of this document is to define and communicate the functionality, structure, ontology, and topology of PRIMRE to enable platform integration, data sharing, future expansion, and system integrity. Adhering to these guidelines is critical for platforms to seamlessly integrate within the PRIMRE universe, to ensure consistency in terms of data organization and accuracy, and to achieve the greatest benefit of information sharing between platforms. In addition to defining the metadata, terminology and data standards, this document provides an overview of PRIMRE, and platforms that currently reside within PRIMRE .
By clearly articulating the framework of PRIMRE, and providing development guidelines and best practices, current and future databases or platforms can be easily integrated into PRIMRE, and data can be seamlessly transferred to and from PRIMRE. This consistency allows PRIMRE to maximize information sharing capabilities while minimizing development issues and integration errors. By providing standards for metadata, units, variable naming, and file formats, data can be shared between platforms, thus improving the exchange of information. MRE data sites that adopt PRIMRE’s standardized terminology and metadata classification, as outlined in Appendices A and B below, can link their content to the content of other sites adopting the same schema to import content directly in their search results without duplication of effort, or to have their content appear in the centralized PRIMRE data search, or both. For example in the PRIMRE Knowledge Hubs: Tethys, Tethys Engineering, and MHK Data Repository (MHKDR), metadata are made available using these standards, so that users searching for data or information on PRIMRE are able to see results from all three sites simultaneously. These guidelines and best practices should be followed to ensure seamless integration with PRIMRE and other platforms integrated with PRIMRE.
The target audience for this guidelines and best practices document is members of the MRE community that intend to integrate their platforms with PRIMRE, as well as those who wish to understand the content and utility of PRIMRE to their work and gain the ability to download or contribute data in expected and consistent formats. The MRE community includes the MRE industry, regulators, academia, national laboratories, regulators, non-governmental research organizations, supply chain companies, and other stakeholders.
PRIMRE (https://primre.org) is a central access point to data and information on engineering and technologies, resource characterization, device performance, and environmental effects of MRE. It is designed to facilitate access to existing PRIMRE Knowledge Hubs, databases, and code repositories. PRIMRE also includes terminology related to MRE, such as information on upcoming events and workshops. The framework developed in PRIMRE ensures consistency among the knowledge hubs in terms of data organization and accuracy and enables the sharing of information between these platforms. PRIMRE also enables practitioners who collect engineering, resource characterization, and environmental effects information on MRE projects to store, organize, and access information that will support the commercial development of the MRE industry. The knowledge hubs currently housed on PRIMRE are described in Table 1.
Table 1. PRIMRE Knowledge Hubs
|PRIMRE Knowledge Hubs||Location||Purpose|
|MHK Data Repository||https://mhkdr.openei.org/||MHK Data Repository for US DOE funded data|
|Tethys||https://tethys.pnnl.gov/||Knowledge base and collaborative engagement platform on the environmental effects of MRE|
|Tethys Engineering||https://tethys-engineering.pnnl.gov/||Knowledge base on the technical and engineering aspects of MRE|
|MRE Software||https://primre.org/Software||A collection of MRE relevant software, including the Code Hub and Code Catalog.|
|MHK Instrumentation Database||https://openei.org/wiki/MHK_ISDB||Knowledge base on MHK instrumentation and sensor|
|PRIMRE Technology Database||https://primre.org/Databases/Technology_Database||A semantic database of MRE technologies, projects, and companies|
PRIMRE Standardized Content
Achieving standardization of metadata tags, categories, and terminology used to describe MRE information is a key goal for PRIMRE. Standardization will enable users to find the data they seek, wherever it is located within PRIMRE and associated repositories and knowledge bases – the PRIMRE universe. These standards describe metadata needed for each site to expose information to search engines, such as Google, and to ensure that the appropriate content is displayed in relevant searches. This practice is commonly referred to as Search Engine Optimization (SEO) and increases the likelihood of successful searches (i.e., discoverability); thus, driving MRE community members to PRIMRE and the resources they need. The adoption of these standards will also facilitate connections between disparate sites via the federation of metadata (i.e., sharing catalogs of data between sites) that will improve cross-site search capabilities. Adoption of the PRIMRE metadata standards allows any online organization in the MRE community to join with the PRIMRE universe by displaying their information within centralized PRIMRE search results or by incorporating the information from other sites into their own.
The PRIMRE Knowledge Hubs will display federated content in the global search on each website. When a user enters a search term, results from federated websites may appear alongside content for the current site, or results may appear in a separate tab with direct links to the origin. This method allows individual websites to maintain their own identity, with views that exclusively search content within their own site, while the global search unifies the PRIMRE Knowledge Hubs.
Most websites categorize content using custom metadata schemas, often comprised of common elements such as tags or keywords. These schemas vary from site to site, preserving the unique scope of each database. However, maintaining consistency across several main categories will create an opportunity to map across knowledge hubs. The PRIMRE team has worked to synchronize the classification of standard data and information package terms, as well as basic MRE technology terms, as the highest level of categorization on the knowledge hubs. The resulting metadata schema is intended to be comprehensive, yet not too specific, using established terminology based on the best available literature, building upon proven schemas (e.g., DCAT and Project Open Data). It is recommended that other databases in the MRE field, whether new or existing, follow the PRIMRE metadata schema, as detailed in Appendix B.
Individual knowledge hubs should continue to have their own information categorization and classification schemas, especially to describe the unique properties of their content. By incorporating the PRIMRE metadata schema into their classification, these knowledge hubs can more easily synchronize with PRIMRE and any other sites adopting the same classification, now and in the future. By creating consistency among metadata fields, knowledge hubs can more easily integrate with other sites in the PRIMRE community, and their content can be more easily organized to make it discoverable and familiar to users.
The PRIMRE metadata classification is a living schema managed by the PRIMRE community and available online at https://primre.org. As technologies are innovated or as new information becomes available, the schema will be reviewed and updated as necessary.
Integrating with Other Sites
Sites wishing to integrate with others in the PRIMRE community may publish their metadata using the PRIMRE Metadata Schema (Appendix B) and make those metadata available as a web-accessible JSON file, which is a lightweight data-exchange format that is easy to read, parse, and generate. These files can be read and processed by other knowledge hubs employing the PRIMRE Metadata Schema via a process known as data federation, creating a distributed network of datasets without redundancy.
Many sites in the MRE space have developed different ways of interpreting or handling key metadata elements. This section aims to clarify several of these elements as they pertain to the PRIMRE Metadata Schema.
The collection and storage of dates are critical metadata for MRE knowledge hubs, many of which have adopted their own definitions for key dates, including received, revised, accepted, originated, available, published, project start, project end, and more. Different sites may collect different subsets of these dates, or different dates entirely, as necessary to categorize their information. Complicating matters, different sites often have different concepts of what one or more of these dates actually mean, creating inconsistency. To avoid confusion, each knowledge hub should be clear about the definition of their metadata terms and the type of data being reported.
In order to simplify the PRIMRE Metadata Schema and consolidate to only the bare minimum needed to share information across sites, the PRIMRE Metadata Schema only requires two dates: the origination date, used to determine how new the data or information are; and the modified date, used to determine how new the metadata record for the data or information are. Origination date is an abstract concept meant to capture the critical creation date for all types of information, whether actually created, collected, instrumented, or published (as may be the case in a paper or journal article). Modified date is the most recent date the metadata record for this information was changed or updated and is intended to notify other sites sharing this information that they have been updated and should be included in a response to any request to pull in the latest information.
The PRIMRE Metadata Schema has been designed to encapsulate all types of information, from data to code to publications, from a variety of knowledge hubs. Each of these may have a different concept of a publisher. For some sites, a publisher might be the organization responsible for releasing the information to the public or the originating organization, for others it might be a more traditional publisher such as a scientific journal, magazine, or report.
For this reason, “publisher” has been omitted from the PRIMRE Metadata Schema, which only requires one or more authors and a source organization.
Sites adopting the PRIMRE Metadata Schema are encouraged to use the definition of publisher most appropriate for their site. For example, classic document types like journal articles and books are encouraged to use the established publisher, while sites containing grey literature, data, code, or any media lacking a formal publisher are encouraged to use the originating organization (i.e., report by Sandia National Laboratories).
PRIMRE Terminology, detailed in Appendix A, is adopted from IEC TS 62600-1:2011, Marine energy - Wave, tidal and other water current converters - Part 1: Terminology. IEC terms defined by TC114 are available on the IEC Glossary. For more information about international standards for marine energy conversion systems, refer to the IEC TC 114 website.
Standard metric units in MKS (meters-kilograms-seconds system) are recommended, as defined in Table 2. All higher order units should be combinations of these base units.
Table 2. SI unit guidelines
Adherence to International Standards and Guidelines
PRIMRE sites should adhere to the IEC TC 114 specifications and the International Energy Agency’s Ocean Energy Systems (IEA OES) guidelines and practices.
The specifications produced by IEC TC 114 address:
- management plans for technology and project development;
- performance measurements of marine energy converters;
- resource assessments;
- design and safety including reliability and survivability;
- deployment, commissioning, operation, maintenance, retrieval and decommissioning;
- electrical interface, including array integration and / or grid integration;
- testing laboratory, manufacturing and factory acceptance;
- additional measurement methodologies and processes.
For information on international collaboration, refer to the OES website: https://www.ocean-energy-systems.org/. Tasks are undertaken under OES by nations on a voluntary basis, as listed on the OES website (https://www.ocean-energy-systems.org/oes-projects/). Tasks of particular relevance to PRIMRE include: “Wave Energy Converters Modelling Verification and Validation” and “Assessment of Environmental Effects and Monitoring Efforts for Ocean Wave, Tidal, and Current Energy Systems” among others.
PRIMRE is a multi-laboratory project carried out by a team of researchers from Sandia National Laboratories (Sandia), Pacific Northwest National Laboratory (PNNL), and the National Renewable Energy Laboratory (NREL), supported through funding by the US Department of Energy (DOE) Water Power Technologies Office (WPTO). The PRIMRE guidelines and best practices document was developed by the PRIMRE multi-laboratory team.
Appendix A. PRIMRE Terminology
PRIMRE Terminology is adopted from IEC TS 62600-1:2011, Marine energy - Wave, tidal and other water current converters - Part 1: Terminology. IEC terms defined by TC114 are available on the IEC Glossary. For more information about international standards for marine energy conversion systems, refer to the IEC TC 114 website.
|Annual energy production (marine energy converter)||AEP||Estimate of total energy production of a marine energy converter system during a one-year period obtained by applying its power performance assessment to a prospective marine energy resource characterization and assuming 100 % availability, IEC 62600-1, ed. 1.0 (2011)|
|Archimedes screw||A helical surface surrounding a ventral cylindrical shaft. Energy is generated as water flow moves up the spiral and rotates the device.|
|Attenuator device||Energy converter which is aligned parallel to the predominant direction of wave incidence, IEC 62600-1, ed. 1.0 (2011)
NOTE: “Attenuator” in PRIMRE Metadata Schema
|Axial flow turbine||Kinetic energy conversion device in which the fluid moves in a direction parallel to the axis of rotation, IEC 62600-1, ed. 1.0 (2011)|
|Capture area (tidal)||Equal to the power captured by the hydrodynamically functional part of a TEC divided by power per square meter of the incident tidal stream, IEC 62600-1, ed. 1.0 (2011)|
|Capture length (wave), Capture width||Equal to the power captured by the hydrodynamically functional part of a WEC divided by power per meter of the incident wave field, IEC 62600-1, ed. 1.0 (2011)|
|Closed-cycle OTEC||OTEC system that pumps the warm sea water through a heat exchanger to warm the working fluid.|
|Cross-flow turbine||Kinetic energy conversion device in which the fluid moves in a direction perpendicular to the axis of rotation, IEC 62600-1, ed. 1.0 (2011)|
|Current energy converter||CEC||Devices that capture current energy from tidal channels, ocean currents, or rivers.
NOTE: “Current” in PRIMRE Metadata Schema
|Department of Energy||DOE||https://www.energy.gov/|
|Degree of freedom||DOF||Independent displacements and/or rotations that specify the orientation of a body or system, IEC 62600-1, ed. 1.0 (2011)|
|Doppler current profiler||DCP, ADCP||Acoustic device which measures current speed and direction in multiple layers throughout the water column, IEC 62600-1, ed. 1.0 (2011)|
|Free surface||Interface between the air and a body of water, IEC 62600-1, ed. 1.0 (2011)|
|Horizontal axis tidal turbine||Kinetic energy conversion device whose rotor axis is substantially parallel to the fluid flow, IEC 62600-1, ed. 1.0 (2011)|
|Hub height||Distance from the centroid of the TEC projected capture area to the sea floor, IEC 62600-200, ed. 1.0 (2013)|
|Hybrid OTEC||A hydrid OTEC system combines features of both the closed-cycle and open-cycle system|
|International Electrotechnical Commission||IEC||https://www.iec.ch/|
|Marine energy converter||MEC||Device which captures marine renewable energy and converts it into another form|
|Marine current||Persistent flow of seawater produced by natural physical processes, including the gravitational pull of celestial bodies, IEC 62600-1, ed. 1.0 (2011)|
|Mean water level||MWL, SWL||Surface level of a body of water with motions such as wind waves and/or changes due to the tides averaged out, IEC 62600-1, ed. 1.0 (2011)|
|Marine and hydrokinetics||MHK||Includes: Ocean Wave, Current, OTEC, and Salinity Gradient power. NOTE: used interchangeably with MRE|
|Marine and Hydrokinetic Data Repository||MHKDR||Hosts all data collected using funds from the MHK Program in the WPTO of the U.S. DOE, https://mhkdr.openei.org/|
|MHK Instrumentation Database||MHK ISDB||A semantic database of MRE technologies, projects, and companies, https://openei.org/wiki/MHK_ISDB|
|Marine renewable energy||MRE||Includes: Ocean Wave, Current, OTEC, and Salinity Gradient power. NOTE: used interchangeably with MHK|
|National Renewable Energy Laboratory||NREL||https://www.nrel.gov/|
|Ocean current||Large scale and persistent flow of seawater produced by mechanisms other than the gravitational forces of celestial bodies, IEC 62600-1, ed. 1.0 (2011)|
|Ocean thermal energy conversion||OTEC||Ocean thermal energy conversion technology converts solar energy stored in the layers of the tropical and subtropical oceans.|
|Open-cycle OTEC||OTEC system that pumps warm sea water into a low pressure chamber where it vaporizes, expands through a turbine, and condenses on the cold side.|
|Oscillating hydrofoil||CEC devices that do not have rotating blades, but instead have one or more hydrofoils that translate perpendicular to the flow direction by lift or drag.|
|Oscillating water column device||OWC||Energy converter with an enclosed air volume excited by waves causing reciprocating air to flow through a turbine, IEC 62600-1, ed. 1.0 (2011)|
|Oscillating wave surge converter||OWSC, OSWEC||Device which responds to the predominantly horizontal fluid motions in shallow and intermediate depth water, IEC 62600-1, ed. 1.0 (2011)|
|Overtopping device||Energy converter with a reservoir filled by wave overtopping, which typically discharges through a low head turbine, IEC 62600-1, ed. 1.0 (2011)
NOTE: "Overtopping" in PRIMRE Metadata Schema
|Pacific Northwest National Laboratory||PNNL||https://www.pnnl.gov/|
|Pressure differential device||A WEC Pressure differential device located below the waves and use the pressure difference between the crest and troughs of waves.
NOTE: “Pressure Differential” in PRIMRE Metadata Schema
|Pressure retarded osmosis||PRO||Salinity gradient technologies using pressure retarded osmosis (PRO) convert the osmotic pressure of saline solutions to hydraulic pressure, which is then used to drive a turbine and generate electricity.|
|Point absorber device||PA||WEC that is small relative to the wave length and typically absorbs wave energy independent of the direction of wave incidence, IEC 62600-1, ed. 1.0 (2011). NOTE: “Point Absorber” in PRIMRE Metadata Schema|
|Power curve, Power surface||Graphical description of the power capture as a continuous function of relevant met-ocean parameters, IEC 62600-1, ed. 1.0 (2011)|
|Power Matrix||Tabular description of power capture as a function of relevant met-ocean parameters, IEC 62600-1, ed. 1.0 (2011)|
|Portal and Repository for Information on Marine Renewable Energy||PRIMRE||https://primre.org|
|PRIMRE Technology Database||https://primre.org/Databases/Technology_Database|
|Power take-off||PTO||Mechanism that converts the motion of the prime mover into a useful form of energy such as electricity, IEC 62600-1, ed. 1.0 (2011)|
|Prime mover||Physical component that acts as the interface between the marine resource and the energy converter from which energy is captured, IEC 62600-1, ed. 1.0 (2011)|
|Resource assessment (marine energy)||Collection and processing of met-ocean data required for determining the performance of a marine energy converter or farm, IEC 62600-1, ed. 1.0 (2011)|
|Resource characterization||Parameterization of met-ocean data to enable determination of the performance of a marine energy converter or farm, IEC 62600-1, ed. 1.0 (2011)|
|Reverse electodialysis||RED||Salinity gradient technologies using reverse electrodialysis (RED) generate electricity from the controlled mixing of two water bodies with different salinities.
NOTE: “Electrodialysis” in PRIMRE Metadata Schema
|Salinity gradient||Salinity gradient technologies generate electricity from the chemical pressure differential created by differences in ionic concentration between freshwater and saltwater.|
|Sandia National Laboratories||Sandia||http://www.sandia.gov/|
|Scatter diagram||Tabular representation of the frequency of occurrence for given met-ocean conditions at a specific site, IEC 62600-1, ed. 1.0 (2011)|
|Tidal energy converter||TEC||Device which captures energy from tidal currents and converts it into another form, IEC 62600-1, ed. 1.0 (2011)|
|Telesto||Information on instrumentation and test facilities, https://openei.org/wiki/PRIMRE/Telesto|
|Tethys Engineering||Knowledge base on the technical and engineering aspects of MRE, https://tethys-engineering.pnnl.gov|
|Tethys||Knowledge base and collaborative engagement platform on the environmental effects of MRE and wind energy, https://tethys.pnnl.gov|
|Tethys Engineering||Knowledge base on the technical and engineering aspects of MRE, https://tethys-engineering.pnnl.gov|
|Tidal Kite||A tidal kite is comprised of a hydrodynamic wing, with a turbine attached, tethered by a cable to a fixed point that leverages flow to lift the wing.|
|Turbine||Rotating device that converts kinetic energy of flowing fluid to mechanical energy, IEC 62600-1, ed. 1.0 (2011)|
|Wave energy||Total kinetic and potential energy associated with the propagation of surface waves, integrated from the sea floor to the surface, IEC 62600-1, ed. 1.0 (2011)|
|Wave energy converter||WEC||Device which captures energy from surface waves and converts it into another form, IEC 62600-1, ed. 1.0 (2011)
NOTE: “Wave” in PRIMRE Metadata Schema
|Water Power Technologies Office||WPTO||https://www.energy.gov/eere/water/water-power-technologies-office|
Appendix B. PRIMRE Metadata Schema
The table below details the metadata schema used by sites within the PRIMRE community to support interoperability with each other and to register their assets in the centralized PRIMRE search. Only publicly-available metadata should be provided to PRIMRE.
|URI||The primary, unique identifier that represents the content on your site. Also a permanent, resolvable web address leading directly to the content.
|type||Overarching category to describe the content (e.g., Dataset, Document). Type should be provided as an array of Strings. These categories are controlled and managed by PRIMRE.
For more detail, you may also specify one or more subtypes:
|landingPage||Optional URL providing access to the human-friendly hub or landing page for the content that users can be directed to for all resources tied to the content. This URL should exist on the database being connected to PRIMRE. This field is not intended for an agency’s homepage (e.g. www.energy.gov). Any content behind a paywall or other accessibility barrier is required to have a publicly accessible landing page.
|sourceURL||URL providing access to the original source, if the source differs from the entry on the database.
|title||Human-readable name of the asset. (e.g. title of a conference paper). Should be in plain English and include sufficient detail to describe the contents of the asset. Avoid the use of internal language or acronyms not commonly understood.
|description||Human-readable description (or abstract) with sufficient detail to describe the contents of the asset in a way that enables users of the asset to quickly understand the contents and nuances of the asset.
No character limit.
|author||Name of the individual(s) who created or contributed to the content. Authors should be provided as an array of Strings.
|organization||The non-person entity or entities responsible for the creation of the content. This is often not the entity funding the creation of the content. Organizations should be provided as an array of Strings.
|originationDate||The date the content was originally created, derived, or collected. Dates should be provided in year, month, day. Time is not necessary.
All dates and times should be in UTC timezone.
|spatial||The range of spatial applicability of the content. At least one spatial extent is required. Extents can be a point or a bounding box. Points are specified by a coordinate pair (“coordinates”) and bounding boxes are specific using two points, the Northeast corner and the Southwest corner. See examples below:
spatial->boundingBox->[NE coords, SW coords]
Example (bounding box):
|technologyType||A list of marine renewable energy technology types. Values should be provided as an array of Strings. These categories are controlled and managed by PRIMRE.
For more detail, you may also specify one or more subtypes:
|tags||A curated list of terms and/or keywords used to describe the content. Content can be associated with multiple values. Consistency of tags between databases will aid in the discoverability of content. Tags should be provided as an array of Strings.
|signatureProject||A list of marine renewable energy projects funded by DOE's Water Power Technologies Office that are being highlighted to make project outputs more discoverable. Values should be provided as an array of Strings. These categories are controlled and managed by PRIMRE.
|modifiedDate||Most recent date and time on which the content or any of the metadata were changed, updated, or modified. Meant to inform which content should be pulled.
All dates and times should be in the UTC timezone.
Useful information on calculating the Levelized Cost of Energy (LCOE) and MHK Cost Breakdown Structure is available on the MHKDR and include:
- MHK LCOE Reporting Guidance (Updated October 8, 2015)
- MHK System Cost Breakdown Structure (CBS) (Updated October 2019)
- LCOE Reference Resource
- LCOE Reporting Guidance Presentation with Example Case This presentation is supplementary to the above LCOE Reporting Guidance.
Additional LCOE Guidance resources:
- Legacy MHK LCOE Reporting Guidance (September 9,2014 - October 7, 2015)
- National Renewable Energy Laboratory Risk Register - A repository for current risk information that could influence project success based on the findings in the MHK Risk Management Framework Report.
- LCOE Reference Resource - Updated January 27, 2016 MHK LCOE Reference Resource updated on January 27, 2016. Previous versions (October 8, 2015 - January 27, 2016) can be accessed here and (2013 - October 7, 2015) can be accessed here
- MHK SAM LCOE Calculator - System Advisor Model (SAM) with MHK LCOE Caculator (November 16, 2018) . Instructions can be found here