Testing Update

Ever since registering more than a year ago for the Wave Energy Prize, our teams have eagerly anticipated the opportunity to test their 1/20^th-scale WEC prototypes in the Navy’s Maneuvering and Seakeeping (MASK) Basin, at Carderock, Md. In a building with a footprint of more than five acres, what developer wouldn’t be giddy with excitement to test a new technology in the nation’s premier wave-making facility containing more than 12 million gallons of fresh water?

The beginning of August marked the beginning of the final round testing, and some of our Finalist Teams have already completed their 1/20^th scale model tests in the MASK Basin. Others are still awaiting their turn. M3 Wave was first in the tank, followed by Waveswing America, Harvest Wave Energy (Team FLAPPER), AquaHarmonics, CalWave Power Technologies, Oscilla Power and Sea Potential. RTI Wave Power is testing its prototype this week, and SEWEC is onsite building its device.

“Watching our Finalist Teams’ WEC concepts come to life at the MASK Basin has been a thrill,” said Alison LaBonte, Marine and Hydrokinetic Technology Program Manager in DOE’s Water Power Technologies Office. “We’re looking forward to the Judges’ analyses of the nine weeks of testing and learning how many and which technologies surpassed our goal of doubling the energy capture efficiency of wave energy converters.”

How does the Wave Energy Prize calculate ACE?

The goal of the Wave Energy Prize is to stimulate the development of innovative wave energy converters (WECs) that have the prospect for becoming commercially competitive with other forms of electricity generation.  Specifically, the Prize seeks to double the state-of-the-art performance of WECs. As mentioned in a previous blog, when comparing the economic attractiveness of power generating technologies, levelized cost of energy (LCOE) is a common metric frequently used in the power generation sector.  LCOE is the ultimate expression of the ratio between effort (cost) to benefit (energy generated).

Unfortunately, LCOE cannot be used in the Wave Energy Prize because the data needed to determine LCOE are either not available or are very unreliable at low Technology Readiness Levels (TRLs), and the Wave Energy Prize is fundamentally expecting to be operating with WEC technologies that are at low TRLs.

With support from Sandia National Laboratories and the National Renewable Energy Laboratory, the Prize team derived a new metric to determine effectiveness of low TRL concepts that is a modification of existing WEC metrics. Importantly, this metric allows for robust analysis of innovative WEC devices using novel methods and materials.  ACE is a benefit to cost ratio, and is a proxy for LCOE, appropriate for comparing low TRL WEC designs.

The two components that comprise the ratio ACE are described in full in the Wave Energy Prize Rules. In summary they are:

• Average Climate Capture Width (ACCW) = a measure of the effectiveness of a WEC at absorbing power from the incident wave energy field.
• Characteristic Capital Expenditure (CCE) = a measure of the capital expenditure in commercial production of the load bearing device structure.

Analyses of the current state of the art reveals that existing WEC concepts achieve an ACE value of 1.5 m/$M (meters per million dollars). For WEC technologies that emerge from the Wave Energy Prize to be on a development trajectory to become commercially competitive, our analysis shows that in the Prize, WECs must achieve a minimum threshold value for ACE of 3 m/$M. Below is a detailed description of how to calculate ACE.

Average Climate Capture Width

The average climate capture width (ACCW)—the numerator of ACE—represents an expected yearly average capture width for a WEC operating in typical West Coast wave climates. ACCW is calculated from a set of WEC capture widths for a select set of irregular wave conditions that are either measured in sub-scale physical model testing or calculated from numerical simulations.  The full scale capture widths are weighted by the yearly occurrence of the specified test wave conditions at select locations and summed to yield the ACCW.  This means that a device that performs very well in one sea state but poorly in other sea states may have a relatively low ACCW when compared with the maximum capture width.  Alternatively, a device that has modest performance over a wide range of sea states and wave directions may have a higher ACCW.

Calculating ACCW

ACCW is calculated in two steps, first by calculating the average annual capture width (AACW) for each wave climate of interest through weighted absorbed power measurements in the sea states of each wave climate, and then by averaging the AACW values to give ACCW.  For more details on these calculations, see Appendix I of the Wave Energy Prize Rules.  Below is a description of the approach for determining which tests to perform to determine ACCW, followed by a simple illustration of calculating AACW and ACCW.

Both tank testing and numerical simulations must cover enough sea states to represent a realistic wave climate. Simulations should be performed in enough irregular sea states that the power in every bin of the resource matrix, or joint probability distribution (JPD), at the wave climate can be approximated. For tank testing, testing at every sea state bin at the wave climate would be over burdensome, but enough sea states should be tested to represent the characteristics of that climate.

In both cases, the sea states that are tested should be weighted so that average annual power absorbed for a particular wave climate can be estimated. (This scaling is represented by Ξ in Appendix I of the Wave Energy Prize Rules.)  The resulting dataset will be a power ma­trix of device power absorbed for significant wave heights and energy periods that cover the range of sea states experienced at the wave climate of interest.  Multiplying the power matrix by the JPD and summing the values of the matrix yields the average device power absorbed for a particular wave climate. The average power absorbed is then used to determine the average annual capture width.

For example, for a particular wave climate, if the average power absorbed by a WEC is 90 kW and the average annual wave resource is 30 kW/m, the WEC would have an AACW of 3m.

P _{average absorbed} = 90 kW

P _resource = 30 kW/m

AACW = ( P _{average absorbed (kW)} / P _{resource (kW/m)} ) = 3 m

Per Appendix I of the Wave Energy Prize Rules, ACCW will then be given simply by averaging the AACW for all wave climates of interest.

Characteristic Capital Expenditure

Prior analysis performed at NREL shows that the largest contributor to wave energy LCOE is the structural cost of a WEC, and in the Prize, the Characteristic Capital Expenditure (CCE) is used to estimate the structural cost of a device (CCE and RST were discussed in a previous blog post, and are discussed in more detail here). The device structure accounts for the mass of any and all load bearing structures that are critical to the power conversion path. This includes:

1. Any structure that interacts with the wave environment
2. Any supporting structures used to resist forces in the power conversion chain in the load path/force flow path
3. Any significant load-bearing foundation components

This implies that for a heaving buoy, for example, not only must the structure of the buoy be used to calculate CCE, but the structure of the gravity base itself must also be used. For offshore devices that require substantial structures, such as jack up barges, those structures must be included as well.

Once the structure is defined the CCE of a device is calculated using the following equation:

CCE = RST * A_surf * ρ * MMC

where:

• RST = representative structural thickness [m]
• A_surf = total structural surface area [m²]
• ρ = material density [kg/m³]
• MMC = manufactured material cost [US$/kg]

If more than one structural material is used in a device, the individual CCEs for each material are summed to give a total CCE.  Below are details on calculating each of the variables above for a single material in a device.

Representative Structural Thickness

The representative structural thickness (RST) mentioned in the above equation is a scalar that is used to determine the total structural mass when multiplied by the surface area of the material. The RST can be visualized as a single uniform thickness obtained by “melting down” all of the structural components of a material, and then “casting” the shape of the WEC with a constant wall thickness, the RST. This means that all stiffeners and support structures are “lumped” together. A simple representation of the RST is shown below with a flat plate. The original structure includes a grid of stiffeners with a thin hull. That same quantity of material is then represented by a solid plate with the thickness given by the RST.

Manufactured Material Cost

The last critical variable to calculate CCE is the manufactured material cost (MMC). This value represents the total cost to manufacture the material used in a device at full production scale. Therefore, the MMC includes the raw material cost, any fabrication, forming, and assembly.

In practice, the value of MMC will fluctuate due to material suppliers, complexity of device, number of devices, along with many other market factors. For example, the raw cost of structural steel may be approximately 1 $US/kg but by the time any forming, cutting, or welding is made the MMC may be closer to 3 $US/kg at full production. For a device already built, one can back out the MMC by dividing the total cost to build the device using a particular material by the mass of that material used.

Summary and Example Calculation of RST, CCE, and ACE

Once all the above variables have been defined, one can calculate the RST, CCE, and ACE values for any wave device. Below is an example calculation using cost and performance estimates from the DOE MHK Reference Model #5 which is made of steel and is assumed to operate offshore of Humboldt Bay, Calif.  The absorbed power for Reference Model #5 was simulated at each sea state using the numerical code WEC-Sim developed by the National Renewable Energy Laboratory and Sandia National Labs:

Using this method one can estimate and compare the economic viability of different devices at an early stage. However, one must be careful when employing this method for devices that have different percentage breakdowns with regards to structure, power take-off, mooring, etc. In these situations, and when comparing devices, a more reliable method would be to include all capital costs in the CCE. If all the initial capital costs were included, the CCE would increase from $2.4M to $4.97M, yielding an ACE of 0.84 m/$M.

 

9 Finalists Move Forward in the Wave Energy Prize

The Wave Energy Prize announced today that the nine finalist teams identified on March 1 will all proceed through Technology Gate 3 to test their 1/20^th scale wave energy converter prototypes at the Navy’s Maneuvering and Seakeeping Basin beginning next month. Many thanks to our Wave Energy Prize alternates who continued work on their technologies since March, and we wish the best of luck to the Finalist Teams as they put the finishing touches on their prototypes before shipping them to Carderock!

Wave Energy Prize Program Update: A Look Back at Our First Year, a Look Ahead at Achieving Our Goals

By Alison LaBonte, Ph.D.

Program Manager, Marine and Hydrokinetic Technologies, Wind and Water Technologies Office, U.S. Department of Energy

In 2012, the U.S. Department of Energy (DOE) realized that revolutionary advancements in wave energy were needed for it to play a significant role in our clean energy portfolio, making wave energy a great candidate for a public prize competition. The Wave Energy Prize is not your average research and development program: compressed timelines spark rapid innovation, resulting in revolutionary technology development.

Before we opened registration for the Wave Energy Prize, our team set an aggressive goal to double the state-of-the-art energy captured per unit structural cost of wave energy converters (WECs). With this goal came a number of program objectives, which are to:

• mobilize new and existing talent,
• conduct a rigorous comparison between device types,
• advance the understanding of pathways to achieve long-term levelized cost of energy goals, and
• attract investors and create a strong foundation for future funding opportunities

So far, we’re achieving these ambitious objectives. A year ago, 92 teams registered for the Prize, three times more than we expected. Of these, 66 turned in technical submissions, which were evaluated by our panel of expert judges to identify 20 Qualified Teams. Most teams that registered were not previously known to DOE. Seventeen of the 20 Qualified Teams’ completed the initial small scale testing phase, and only two of the nine teams selected for the final phase of testing have received any funding from DOE in the past.

In April, I updated the MHK community gathered at Waterpower Week in Washington, D.C., on the progress of the Prize during a panel discussion on innovation. So far, most of the teams have met the aggressive timelines for the Prize, which puts DOE in a great position to achieve the remaining objectives. To meet the requirements for Technology Gate 2, the Qualified Teams built 1/50^th-scale model devices, tested them at university facilities around the country, and conducted significant numerical modeling studies in just four months.

The nine Finalist and two Alternate Teams have put forward diverse WEC designs, which include two submerged areal absorbers; four point absorbers; two attenuators; and three terminators. And in these designs, we’re already seeing technical innovations in the areas of geometry, materials, power conversion and controls. Some of these include:

• adaptive sea state-to-sea state control,
• wave-to-wave control,
• power absorption in multiple degrees of freedom,
• optimized float shapes and dimensions for energy absorption for broad bandwidth of wave frequencies,
• survival strategies such as submerging beneath the surface for extreme storms,
• use of structures and materials that are cost effective to manufacture, and
• flexible membranes that react to the wave pressure over a broad area.

Waterpower Week attendees saw some of these innovations firsthand when they met the Finalists and Alternate Teams during the Wave Energy Prize Showcase in which the 1/50^th-scale models were on display.

Industry stakeholders are taking notice, and the public’s awareness of wave energy is increasing because of the teams’ efforts in the Prize. In just over a year, more than 100 news stories have featured the Prize, including in outlets like Popular Science, The Weather Channel and National Geographic. The Prize’s website has hosted more than 23,000 visitors, and its social media channels have logged more than a half million impressions. This increased awareness of the potential contribution of wave energy to the nation’s renewable energy mix will exist long after the Prize ends, and will likely set the stage for future private-sector investments and government funding opportunities.

It’s an exciting time to be in the wave energy community. The teams are putting the finishing touches on their 1/20^th-scale prototypes, which will be rigorously tested at the U.S. Navy’s MASK Basin from August through early October. Follow our teams’ progress at waveenergyprize.org, and save the date for November 16, when winner(s), if any, will be announced!

Wave Energy Prize Finalist Teams and Alternates Showcased at Waterpower Week

Wave Energy Prize Finalist and Alternate Teams recently had a unique opportunity to showcase their technologies and network with industry, academic, and government stakeholders during Waterpower Week 2016 in Washington, D.C.

The week’s events kicked off during the National Hydropower Association Annual Conference’s opening plenary session on Monday, April 25 when José Zayas, Director of the U.S. Department of Energy’s Wind and Water Power Technologies Office, highlighted the work of the teams to the more than 700 conference attendees.

On Monday and Tuesday, the teams had their 1/50^th-scale WEC models on display, meeting with Zayas, Cristin Dorgelo, Chief of Staff of the White House Office of Science and Technology, and other event attendees during the conference’s coffee breaks. On Tuesday afternoon, teams switched gears and took part in a Wave Energy Prize Team Summit, a key part of Waterpower Week, where they were able to meet each other and share ideas; learn about the requirements of upcoming Technology Gates 3 and 4; and participate in on-camera interviews discussing their thoughts on the role of government in innovation, their teams’ successes so far, and the challenges they are overcoming in the upcoming final phase of the Prize. The teams then traveled to the MASK Basin at Carderock, Md., on Wednesday morning to better understand the logistical and technical requirements related to 1/20^th-scale testing, and to tour the world-class facility where they will test their prototype devices beginning in August.

Thanks to all those who joined us for Waterpower Week and the Team Summit, as well as all those who helped make the event a success!

From the Wave Energy Prize website: A question about ‘overtopping’

A university student from Texas writes:

“I read the ‘types of devices proposed by these teams include point absorbers, terminators, attenuators, oscillating water columns, and oscillating wave surge converters’ from your website. I am just reviewing some papers about WECs and found that there is another type of WEC which is called overtopping. My question is whether the overtopping type is less efficient so none of the top teams use it.”

(“WEC” means “Wave Energy Converter” or sometimes “Wave Energy Conversion.” It is common to say “WEC device” as well.)

To answer, the Wave Energy Prize provides an avenue to allow teams to develop innovative technologies that have the prospect for achieving a long-term impact of lowering the cost of electricity to make wave energy competitive with other means of generating power.  If someone came forward with a design for an “overtopping device” that shows promise achieving our overall program goal, as outlined in our Technology Performance Level (TPL)* assessment, then it may well have progressed in the competition.

To learn more about TPL, refer to “Details on the Technical Submission” written by Jochem Weber from National Renewable Energy Laboratory (NREL).

U.S. Department of Energy’s Wave Energy Prize Announces Finalist Teams

The U.S. Department of Energy (DOE) announced Tuesday that nine teams have been named finalists in the Wave Energy Prize, a 20-month design-build-test competition, and will proceed to the next phase of the competition.

The nine finalists and two alternates, identified from the 17 remaining official qualified teams, will continue their quest to double the energy captured from ocean waves and win a prize purse totaling more than $2 million. Each of the finalists and alternates will now receive seed funding from DOE to develop 1/20th scale models of their wave energy converter (WEC). These models will be tested at the nation’s most advanced wave-making facility, the Naval Surface Warfare Center’s Maneuvering and Seakeeping (MASK) Basin at Carderock, Md., beginning in the summer of 2016.

Official finalist teams are:

• AquaHarmonics (Portland, Ore.)
• CalWave (Berkeley, Calif.)
• M3 Wave (Salem, Ore.)
• Oscilla Power (Seattle, Wash.)
• RTI Wave Power (York, Maine)
• Sea Potential (Bristol, R.I.)
• SEWEC (Redwood City, Calif.)
• Wavefront Power (Team FLAPPER) (Research Triangle Park, N.C.)
• Waveswing America (Sacramento, Calif.)

Alternate teams are:

• McNatt Ocean Energy (Greensboro, Md.)
• Wave Energy Conversion Corporation of America (WECCA) (North Bethesda, Md.)

“The qualified teams’ efforts resulted in some very promising technologies for the judges to evaluate,” said Wes Scharmen, principal investigator at Ricardo, Inc. and chief judge of the Wave Energy Prize. “Based on our preliminary evaluation, the data indicates that many of the teams identified as finalists have the potential to achieve the ACE threshold, and thus the potential to exceed DOE’s program goal. We’re looking forward to further verifying their designs performance at 1/20th scale in the MASK Basin at Carderock this summer.”

ACE—a benefit-to-cost ratio—was selected by the Wave Energy Prize as a metric appropriate for comparing low Technology Readiness Level WEC concepts when there is not enough data to calculate the levelized cost of energy —itself a cost-to-benefit ratio—from a device. ACE is determined by dividing, in essence, the wave energy extraction efficiency of a WEC by its structural cost. Finalists were determined based on their potential to achieve the doubling of the current state-of-the-art ACE value of 1.5 meters per million dollars (m/$M) to 3 m/$M during 1/20th scale tank testing at the MASK Basin, making them eligible to win the grand prize.

A panel of expert judges evaluated each qualified team based on their revised technical submissions, numerical modeling results, Model Design and Construction Plans, and the results of small-scale tank testing of their 1/50th scale models, and determined aggregate scores to identify the finalist pool.

The Wave Energy Prize is encouraging the development of game-changing WECs that will reduce the cost of wave energy, making it more competitive with traditional energy solutions.

Congratulations to the finalist teams, and thanks to all who have participated in theWave Energy Prize to date!

From Qualified Teams to Finalists: The Assessment at Technology Gate 2

The purpose of the Wave Energy Prize’s Technology Gate 2 (TG2) is to evaluate the likelihood of each Qualified Team’s success in achieving the ACE threshold (the doubling of the state-of-the-art ACE from 1.5 m/$M to 3 m/$M) if they were to test a larger, 1/20^th scale model of their device in the MASK Basin. Those that present a high likelihood of achieving the ACE threshold will, through a rigorous judging process during TG2, be deemed Finalists.

As specified in the Wave Energy Prize Rules, TG2 will evaluate Qualified Teams using several metrics, as detailed below:

1. As a first step in the evaluation process, judges will consider each Qualified Team’s Model Design and Construction Plan to determine if the team exhibits a reasonable understanding of the effort, tasks, timeline and materials that will be needed to design and build a 1/20^th scale model. The assessment criteria for the Model Design and Construction Plans can be found in the table below:
   

   Criterion	Narrative Document	Timing Plan	Bill of Materials
   To score a “Pass” Assessment	The document illustrates a concise and thought out plan describing how the Team will successfully design and construct a 1/20th scale model in the allotted timeframe	A detailed Gantt chart or similar timeline graphic shows the tasks that the Team plans to complete in the allotted timeframe	The provided BoM template document is filled out with a logical breakdown of systems, subsystems, assemblies, and components along with actual or predicated quantity, mass, cost, supplier data for each item
   To score a “Fail” Assessment	No document provided or a document that shows a significant lack of understanding of the phases, tasks, and/or steps needed to design and build a scale model	No document provided or the provided document shows a significant lack of understanding the tasks and timeline needed to complete the build of a scale model.	No document provided, document provided is not in the approved template form or the provided document shows a significant lack of understanding the materials to build and test a scale model

   Only teams that provide credible plans will be eligible to continue in the Prize.

2. If the judging panel determines that a Qualified Team’s Model Design and Construction Plan is credible, i.e. if it is given a “pass,” it will then use the following information to evaluate the likelihood of the proposed wave energy converter (WEC) concept in satisfying the required threshold value for ACE during the 1/20^th scale testing:
   • The capture width of the physical 1/50^th scale model from the 1/50^th scale testing, scaled up to full scale.
   • Assessment by the judges of the correlations between numerical model predictions and measurements for capture widths and device motions.  Predictions are at full scale for 1/50 wave conditions; experimental measurements from 1/50 test campaign are scaled up to full scale.
   • Revised Technical Submission and its re-evaluation using the Technology Performance Level rubric used in TG1.
   • Predictions of ACE (in m/$M) that can be expected in the MASK Basin testing.

   Criterion	Capture Width of the Physical 1/50th Scale Model from 1/50th Scale Testing, Scaled up to Full Scale	Correlation of Numerical Modeling Results to 1/50th Scale Waves	Re-Evaluation of Technical Submission using TPL	Predictions of ACE Expected in MASK Basin
   Value range	1 to 9 grouped in low, medium, high	1 to 9 grouped in low, medium, high	1 to 9 grouped in low, medium, high	1 to 9 grouped in low, medium, high
   Weighting for combined score	15%	25%	30%	30%

   The judges will score each of the above four criteria on a scale of 1 to 9. Then, they will calculate an overall combined score by computing a weighted average of the four individual scores.

   Qualified Teams will then be ranked from the highest overall combined score down to the lowest; up to 10 will be named Finalist Teams and up to two Alternate Teams will be identified.

   If the judges and/or Small-Scale Test Facilities are unable to test, measure and analyze the 1/50th scale WEC device in order to adequately determine absorbed power, the device will be eliminated from the Wave Energy Prize.

For more information on the assessment of the construction plan, evaluation of the four criteria, and the weighting of each as part of the overall combined score, please see the Wave Energy Prize Rules.

Year in Review and 2016 Preview: Wave Energy Prize Program Update

It has been a busy year at the Wave Energy Prize! On April 27, DOE Office of Energy Efficiency and Renewable Energy Assistant Secretary Dr. Dave Danielson announced the opening of the prize, and an impressive 92 teams registered. Sixty-six of these teams submitted technical submissions for Technology Gate 1, which were reviewed by our judges over the summer. On August 14, we announced the 20 official Qualified Teams.

As 2015 draws to a close, the Wave Energy Prize is approaching Technology Gate 2, a key milestone for the program and for the Qualified Teams. Seven qualified teams have now completed small-scale testing, including Atlas Ocean Systems, Super Watt Wave Catcher Barge Team, Sea Potential, SEWEC, Team FLAPPER, IOwec and RTI Wave Power. Ten teams are scheduled to complete small-scale testing January 4 through 29, 2016: M3 Wave, Mocean Energy, Oscilla Power, Principle Power, AquaHarmonics, WECCA, CalWave, Float Inc. – BergerABAM, Advanced Ocean Energy @ VA Tech and WaveSwing America. The remaining three Qualified Teams, Atlantic Wave Power Partnership, Enorasy Labs and OceanEnergy USA, announced their withdrawal from the competition in November.

Additionally, Qualified Teams will submit the Model Design and Construction Plans for their 1/20^th scale models by January 29. This plan, along with the results of small-scale testing, numerical modeling and revisions to their technical submissions, will be evaluated by the Wave Energy Prize judges at Technology Gate 2 to determine which teams will advance as official Finalist Teams. The Wave Energy Prize anticipates announcing the Finalist Teams and alternates at the beginning of March!

We have a lot to look forward to in 2016, including 1/20^th scale model testing for our finalists at the Naval Surface Warfare Center’s Maneuvering and Seakeeping Basin at Carderock, Md., beginning this summer, and ultimately the announcement of winner(s) who have successfully demonstrated achievement of the Wave Energy Prize’s goal in November!

We wish the wave energy community a happy holiday season, and we’re looking forward to keeping you updated throughout 2016!

Wave Energy Prize, team featured on ‘Weather Channel’ morning show

HAPPY FRIDAY! The ‪‎Wave Energy Prize‬ was featured earlier today on The Weather Channel’s “AMHQ” program. The segment featured M3 Wave, one of our Qualified Teams, and highlighted the potential of clean, renewable wave energy for the United States.

There’s even a shot of the U.S. Navy’s Maneuvering And Sea Keeping (MASK) basin, the world’s largest wave test facility at Carderock Division of the Naval Surface Warfare Center, where our top Teams will test their Wave Energy Converter (WEC) designs.

SEE THE VIDEO: http://www.weather.com/tv/shows/amhq/video/harnessing-wave-energy-for-power

* The Wave Energy Prize is a public prize challenge sponsored by the U.S. Department of Energy. LEARN MORE: http://waveenergyprize.org/