Waves of Change in Sustainable Energy Use -

Ocean Waves as a Source of Utility-Scale Electricity Production for Coastal Communities[footnoteRef:1] [1: This work bridges policy and technology for the UN Ocean Conference 2020 ‘Scaling up ocean action based on science and innovation for the implementation of Goal 14’. ]

Elira Karaja[footnoteRef:2] Michael Raftery[footnoteRef:3] [2: Served as Lead Economist, Strategy and Institutional Partnerships launching GPOWET Private Public Partnership introducing SurfWEC technology to the United Nations and Representative Missions. ] [3: Vice-President, Chief Technology Officer, SurfWEC LLC ]

Columbia University/ AGORÀ Martin&Ottaway / SurfWEC /

ek2825@columbia.edu mraftery@surfwec.com

Working Paper Prepared for the UN Ocean Conference 2020

- Do not cite without permission-

ABSTRACT

The United Nations - Sustainable Development Goals (SDG) Agenda 2030 address some of the most pressing global challenges for humanity. With the launch of the decade of action for the SDGs the United Nations General Assembly called for support on the implementation of the 17 SDGs, including SDG 14: “Conserve and sustainably use the ocean, seas, and marine resources for sustainable development". This work aims at bridging the science-engineering-policy nexus on the use of the oceans for renewable energy, more specifically, the use of wave energy conversion (WEC) systems as part of the marine renewable power nexus. Our work advocates use of the marine hydro-kinetic (MHK) resources including wind-generated surface waves, and aims to inform policy makers and practitioners, in the field of renewable and sustainable use of Earth’s oceans. WEC systems can be made to be commercially viable by use of “offshore artificial beaches” in the ocean environment. The SurfWEC system design is a commercially-viable wave energy capture (WEC) technology capable of utility-level electricity generation from ocean waves based on the hydrodynamics and physics of converting incident wavelength to wave height. We argue, that once established, those applications will promote social, environmental, and economic benefits as new skilled jobs will be created on islands and in developing coastal communities, further advancing the implementation of the 2030 SDG Agenda.

INTRODUCTION TO WAVE ENERGY

The United Nations – 17 SDGs, are a blueprint to achieve a better and more sustainable future for all, address some of the most pressing global challenges for humanity, such as mitigating poverty, inequality, climate change, environmental degradation, and enabling global peace and justice. With the launch of the decade of action (2020 – 2030) for the SDGs, the United Nations General Assembly called for support on the implementation of the 17 SDGs, including SDG 14 which states: “Conserve and sustainably use the ocean, seas, and marine resources for sustainable development".

Human wellbeing and livelihoods are dependent upon Earth’s elements, and oceans play a crucial role is access to elemental resources, hence innovative science and engineering practices are required to address the challenges and opportunities unique to the oceans.

This work aims to bridge the science-engineering-policy nexus on the use of the oceans for sustainable energy use, more specifically, the use of WEC systems as part of the marine renewable power nexus. A global awareness is required to justify development of utility-scale WEC projects co-located with solar, wind, geostrophic current, and tidal power systems for coastal and island communities. As documented in literature and found in on-going projects, solar and wind renewable power systems are now mature, commercially-viable sustainable technologies which are economically competitive with existing fossil fuel and nuclear options. Our work advocates for use of the marine hydro-kinetic (MHK) resources including wind-generated surface waves, geostrophic currents, and tidal currents or tidal barrages as greenhouse gas-free (GHG-free) power sources. The MHK resources provide us a way to produce utility scale amounts of electric power without emissions of carbon dioxide, sulfur dioxides, or nitrogen oxides during the electric power generation process. The wind-generated surface waves possess the highest magnitude of available power of these resources by more than an order of magnitude relative to the other resources.

As our previous research shows (Raftery 2019), it is time for WEC systems to be part of the sustainable energy toolbox at a utility level.

This work is to inform policy makers and practitioners, in the field of renewable and sustainable use of Earth’s oceans, WEC systems can be made to be commercially-viable by use of “offshore artificial beaches” in the ocean environment. The only reason WEC systems have not been commercially viable to date is the average orbital velocities of water particles in naturally-occurring waves in offshore locations is too low to power commercially-viable systems. For offshore WEC systems to be commercially-viable, the water particles acting on the power takeoff (PTO) components must be accelerated to velocities which impart sufficient kinetic energy into the PTO components to produce commercially-viable amounts of useful power or stored energy, such as, electricity, or electric potential and pressurized fluids respectively. For this paper, “offshore” is defined as any WEC project one kilometer (1km) or greater from shore, where 99.9% of the resource resides. The length of all the coastlines on Earth is approximately 360,000 kilometers and the surface area of Earth’s global oceans is approximately 365 million square kilometers, which equates to 99.9% of the resource being “offshore”.

We recognize the long-running success of shore-based WEC projects such as the “Limpet” in the Orkney Islands off Northern Scotland (commissioned in 2000), and the Mutriku Wave Energy Plant in the Basque Country of Spain (commissioned in 2011), but these type of projects do not scale to provide a significant amount of power to mitigate global warming, other WEC projects run through offshore sea-trials have not demonstrated performance levels required for utility-scale commercial viability and multiple units have sank during testing since 1995 (Wavegen - OSPREY, Finivera - AquaBuOY, Trident - DECM, and Wello-Oy – Penguin). The sinking issues can be mitigated with a “Boston Whaler” approach to the naval architecture in the design process.

The reasons our policy suggestion is to mandate WEC projects are planned and located in “offshore” locations include: Most wave energy (wave height) and wave power (combined wave height and wavelength) from Earth’s oceans is attenuated due to waves interacting with the seafloor long before arriving within 1km of shore, many shore locations are used by numerous other stakeholders such as beach-goers, fishermen, tourists, surfers, etc., performance of WEC systems within 1km of shore is at the mercy of large tidal ranges in a large portion of Earth’s coastlines, WEC systems moored to the seafloor within 1km of shore are subjected to “hydraulic sandblasting” in most global locations, nearshore/shallow-moored/shore-based WEC systems have no physical way to avoid extreme wave loads during storm events without being removed from their moorings or shore location. The vast majority of the resource is offshore, extreme wave loads can be avoided in deep-water/offshore locations by using variable-depth platforms/systems, scour at moorings and on hulls and components is minimal in deep-water locations, tidal ranges are minimal and have little to no effect on WEC performance in offshore locations, mooring depths can be optimized to enable storm-load avoidance/variable-depth features based on historic extreme storm event wave data.

Under SDG Goal 14, on the conservation and sustainable use of the ocean, seas and marine resources for sustainable development, the SurfWEC technology, designed to enable multiple existing WEC designs to perform at commercially-viable levels, aligns with targets 14.3, 14.7 and 14.A as follows:

14.3 Minimize and address the impacts of ocean acidification, including through enhanced scientific cooperation at all levels by replacing existing fossil fuel powered systems, which emit carbon dioxide into the atmosphere, which in turn is converted to carbonic acid in the ocean, with ocean wave powered systems which do not produce carbon dioxide during the process of generating electricity.

14.7 By 2030, increase the economic benefits to Small Island developing States and least developed countries from the sustainable use of marine resources by enabling the build-out of combined WEC training, manufacturing, operations, and maintenance facilities on the islands or in the coastal nations using the WEC systems.

14.A Increase scientific knowledge, develop research capacity and transfer marine technology, taking into account the Intergovernmental Oceanographic Commission Criteria and Guidelines on the Transfer of Marine Technology, in order to improve ocean health and to enhance the contribution of marine biodiversity to the development of developing countries, in particular small island developing States and least developed countries.

We argue that It is time for Wave Energy Conversion (WEC) to be part of the sustainable energy toolbox at a utility level. We focus specifically on economic benefits for Small Islands Developing States and developing coastal nations.

SUSTAINABLE DEVELOPMENT AND RENEWABLE ENERGY

Access to useful forms of energy is the central driver of human development and access to energy is central to major challenges and opportunities we face today at a global level. Human progress is directly related to the way we harness, store, and use energy. In human terms, access to useful forms of energy is power. Increased energy efficiency and the increased use of sustainable energy sources is recognized as crucial to creating more sustainable resilient and inclusive communities.

Working towards this goal is especially important as it interlinks with other Sustainable Development Goals. Focusing on universal access to energy, through use of sustainable energy sources, will create new economic and employment opportunities, will mitigate energy poverty in developing nations, and is crucial to creating more sustainable and inclusive communities resilient to environmental issues such as a rapidly changing climate.

A World Bank Report published in 2019, tracking SDG 7, states that access to sustainable energy sources, and technologies which improve efficiency during energy use is a daunting challenge. Evidence cited in the report indicates that one-third of access-deficit countries face more than one disruption in electricity supply per week and that basic electricity was unaffordable for 40 percent of households in about half of these countries. Alongside the need for strong political commitment and adequate policy and energy infrastructure planning, the report stresses the fact that we are still lagging behind on the goals of use of sustainable energy use solutions.

The most recent United Nations Report on the World Economic Situation and Prospects (2020) urges action, as climate disruption poses a serious and increasing threat to short and long-term economic prospects of many nations. The report further indicates changing the energy supply mix, transitioning from fossil fuels to renewable power sources, using sustainable, flowing-energy sources such as solar, wind, and water power as the primary ways to break the link between greenhouse gas emissions and economic activity. Rightfully, it is argued that emission levels will require not only a combination of technology changes to enhance energy efficiency but also political prioritization and public support driven by behavioral changes.  Our proposed WEC technology integration with existing WEC technologies and other renewable systems, interlinks the above need and sub-targets of SDG 14, and helps to minimize the impacts of ocean acidification and benefits Small Islands Developing States and developing coastal communities.

As van Hemmen (van Hemmen,2020) argues, innovative solutions are often ignored in the marketplace, most often because the innovation disrupts too many entrenched commercial concepts.

This delay in the adoption of new technologies has been described as “jumping the chasm”, and finding the proper springboard to jump the chasm is a central issue in new technology adoption.

Technically and mathematically, worldwide sustainable energy is a real possibility, but, on a societal level, sustainable energy production has not jumped the chasm. It will require a very significant change in thinking, attitudes, efforts, and financial commitments to accomplish energy sustainability.

Human energy demand is expected to grow at a rapid rate in the coming decades, due to global population growth and improvements in living conditions, and emerging and developing economies face significant barriers compared to developed economies, i.e. political economy constraints related to the role of government, regulations and markets.

Considering the control of stored energy, a form of financial power, the switch to sustainable energy is a very significant opportunity to increase the world’s standard of living. Energy that can be harnessed and stored from many sources, becomes social power.

This work stresses that renewable energy solutions should be context focused and account for communities’ available resources, cultural environment, challenges and opportunities the communities need to address. Uncertainty of outcomes is detrimental to energy market reform. We argue that successful implementation of sustainable energy solutions can have the greatest positive impact for SIDS communities in the near-term while leading to other socially desirable outcomes. As argued by Karaja (Fidrmuc, Karaja, 2013), reforms might occur in waves of power infrastructure transformation from country to country driven by informational spillovers, as learning from neighbor countries experience reduces outcome uncertainty. We also advocate for a model of competition between different sustainable-energy-use approaches based on technology and innovation performance in capital expenses, power production (i.e. electricity), and maintenance expenses.

Focusing on SDG 14, the goal of sustainable use of the ocean, seas and marine resources for sustainable development, wave energy conversion (WEC) technologies must be developed which are capable of utilizing the full power in ocean waves by controlling the steepness and water particle velocities in the waves to allow the next generations of humans to transition many island states and coastal communities to GHG-free power infrastructures. Enabling commercially-viable WEC systems, for SIDS and developing coastal nations, addresses the issues of carbon emissions into the Earth’s atmosphere; therefore, ocean acidification (target 14.3) and health and biodiversity of reef-like environments (target 14.A), while over time, reducing cost per kilowatt-hour of electricity for industrial, commercial, residential and transportation customers, increasing the economic benefits for SIDS and developing coastal countries (14.7).

WAVE ENERGY CONVERSION: SurfWEC TECNOLOGY

In the following section we discuss SurfWEC, the Surf-making Wave Energy Converter technology.

Wave energy conversion research and development has been documented since the first patent filed in Paris, France in 1799 by Pierre-Simon Girard. A Martin & Ottaway research project, in collaboration with industry partners; Cashman Equipment, Bosch-Rexroth, Airline Hydraulics, Lankhorst Ropes, Deeptek, Delmar, ISCO, ABB, and others, has identified at least 28 wave energy conversion efforts where substantial expenditures have been made and numerous sea trials performed to harness the power in ocean waves and convert the wave power to a useful form of power such as electricity or stored energy such as the electric potential in batteries.

For wave energy conversion, as all power-generation systems, commercial-viability depends on the cost to produce and install the system, maintenance costs, and on the ability to earn back the cost to produce and maintain the system by selling sufficient amounts of power or stored energy to provide a return on investment.

Wave energy conversion has not had a successful track record of producing enough useful power or energy (i.e., in the form of electricity or pressurized fluids) to pay back the return on investment at a utility/grid-rate scale. This is fundamentally due to the slow motion of WEC devices in sea or swell wave conditions (Raftery 2018). There have been numerous efforts that have produced electricity, they are achieving some levels of engineering successes, but the ability to be commercially viable is not likely for these systems, due to a fundamental barrier in the physics that exists for conventional/legacy ocean wave energy conversion systems. These systems may be able to reliably harness small amounts of energy, but they cannot be economically scaled to utility-level power production due to the average velocity of the prime mover/power takeoff component.

The SurfWEC system design is a commercially-viable wave energy capture (WEC) technology capable of utility-level electrical power generation from ocean waves based on the hydrodynamics and physics of converting incident wavelength to wave height; thereby, increasing wave steepness and the corresponding water particle velocities in the waves. Once the kinetic energy in the steep waves is harnessed, that energy can be used to generate electricity for transfer by cable to an on-shore distribution hub for national grids or other land-based or ocean-based energy-intensive applications. Historic wave buoy data, from hundreds of locations globally, indicate, WEC systems capable of converting wavelength to wave height, will have approximately twice the power generation potential per unit area of sea surface on an annual basis than existing wind power units based on the higher availability of the wave power resource. Offshore (1km to 1000+ km offshore) WEC systems integrated with the SurfWEC technology present no negative effects for the tourism industry or oceans flora and fauna, and will have the capability to produce emission-free electricity to power applications used to desalinate seawater and produce industrial-scale amounts of hydrogen gas, offering SIDS and other coastal communities’ entry to the marketplace as a commercial-scale hydrogen gas supplier, as on-going in the Orkney Islands.

Further, water-stressed islands can benefit from a new source of potable water for human consumption and agricultural, industrial, and tourism use. Land-based and ocean-based transport systems can be electrified or hydrogen powered.

We argue, that once established, those applications will create social, environmental, and economic benefits as new skilled jobs will be created on islands and in developing coastal communities. Sustainable revenue streams will be generated on SIDS and in developing coastal communities that offer the potential for the societal challenge envisioned in the 2030 Agenda to be met.

SurfWEC systems can also be joined-up with wind power, solar power, current power, tidal power, and battery and other storage systems, desalination, and electrolysis systems (using desalinated/deionized water in electrolysis devices) to meet the electric power load demands of a modern power grid.

It is critical to note the desalination/electrolysis system is likely to be an essential sub-system to future grid operations as value-added loads for times when renewable power supply exceeds the grid demand as these systems do not have the capacity limitations of fixed capacity battery-backup systems.

Further, when deployment of SurfWEC-integrated WEC systems is realized, it will transform the energy supply of small island states (SIDS) and the coastal communities to include:

· A system capable of reducing the cost per kilowatt-hour, in ten to fifteen years, in nations with the highest existing electricity rates on the order of 50 percent or more;

· A system capable of stabilizing grid power (SurfWEC units are designed to remain fully-operational in hurricanes, typhoons, cyclones, and tsunamis with 1 megawatt-hour of on-demand energy storage each) to reduce outages on small island states and at coastal communities struck by storms or tsunamis;

· A system capable of providing on-demand, zero-emissions renewable power source for multiple applications including the desalinization of seawater and the production of industrial-scale amounts of hydrogen gas

· A system integrated with smart-technologies capable of generating climate data with sensors calibrated to monitor the ocean and air/atmosphere, and transmitting the data to scientists who will use quality assurance practices before making the data publicly-available

SurfWEC TECHNOLOGY AND OPERATING PRINCIPLES

Ocean wave energy conversion involves the simple relationship between mass and velocity. The term “marine hydro-kinetic” is often used to describe these systems and abbreviated “MHK” systems.

The more water mass a WEC displaces per second, and the higher the velocity of the water particles in the flow field, the more power that is input to the power takeoff (PTO) components, energy storage systems, and energy conversion subsystems.

The use of a variable-depth platform to create surf conditions offshore was researched in the model basin at Stevens Institute of Technology from 2010 through 2011 with a grant from the Office of Naval Research (ONR). The platform had a foam core that made the platform buoyant and it was moored and pulled under the surface by 4 – 1200lb capacity cable pullers.

The variable-depth platform was located near the free surface (still water line) of the wave tank. Waves were run over the platform with the platform at various depths and the top deck of the platform level relative to the still water line. A Particle Image Velocimetry (PIV) system was used in 2010 to record the acceleration and resulting velocities of neutrally-buoyant “seed” particles which were put in the wave tank over the platform before each wave run. When the platform was fixed at depth of less than four times the incoming (incident) wave height, the maximum particle velocities, recorded over the platform, reached speeds of up to four times the maximum orbital velocities, of the incident waves before the waves passed over the platform, based on Airy wave theory equations (Airy wave theory is valid to project maximum water particle velocities, in undisturbed wave motions, where waves are not impacting a platform or other object). These particle accelerations created by the platform “shearing” the flow field quantify the physics required for WEC systems to be commercially viable.

As Figure 1 shows, there is an increase in wave power density over the platform because the wave ‘lenses” over the platform.

Figure 1: The SurfWEC base creates a “lens-effect” in the presence of water waves which concentrates the wave power over the platform similar to the process when a magnifying glass concentrates light to a smaller area than before passing through the lens.

Therefore, if one were to install an artificial beach (SurfWEC base) in the ocean in an offshore location, the operator of the beach would be able to shoal or break (create surging waves) waves on their terms using remote mooring winch controls, which would enable the units to impart more kinetic energy to WEC devices over the platform than if they were not over the base. Since waves break at a water depth of roughly twice the wave height, and since the ocean has tides and variable size waves, the beach depth must be variable for optimal WEC power takeoff performance.

The first computer-aided design (CAD) iteration of a “SurfWEC” unit was developed in 2008 when the technology development was restricted to work at Stevens Institute of Technology under the “Seahorse Power LLC” name, with input from Airline Hydraulics, Bosch-Rexroth, Delmar Mooring Systems engineers and technicians and Alex Benham (Figure 2. SolidworksTM developer), Corey Linden (model fabrication), Matt Gordon (PIV test data processing) and Figure 2 was the “embodiment” of the technology until 2018.

Figure 2: Early SolidworksTM rendering of the “Surf-making Wave Energy Converter” (SurfWEC) (2006-2012, SolidworksTM , developer Alex Benham)

Since the technology was brought to Martin & Ottaway in 2018 by Michael Raftery, the “Wave Energy Harnessing Device” US Patent 8093736/Seahorse Power device/SurfWEC device inventor, the SurfWEC point-absorber configuration, has become more cost effective than the earlier version due to higher energy recovery potential (increased power takeoff from 5-degrees of freedom to the maximum available 6-degrees of freedom), higher nameplate capacity (integrated existing 2019 offshore wind generators operated using hydraulic motors replacing the turbine-blade-gearbox of wind systems), more energy storage capacity (added Tesla Power Towers to increase energy storage capacity to 1MWh), and a platform design modification to enable harnessing of waves from any direction using vertical centroid axisymmetric geometry and four PTO winches with geometry optimized for annual average Mid-Atlantic Bight wave conditions (Figure 3).

Figure 3: 2019 SolidworksTM 3D-CAD Embodiment of the SurfWEC system optimized for the wave conditions off the East Coast of the United States over the Outer Continental Shelf (OCS) (Solidworks developer, Karolina Kolodziej).

SurfWEC consists of two prime components; one component tethered to the base and accelerated by wave loads (float, point-absorber, “the bobber”) and one moored component (the variable-depth barge or “the base”) also accelerated by waves in the other direction as the float, which occurs naturally due to the elongated/highly-elliptical waves propagating over the base.

The SurfWEC system works by raising or lowering the base below the water surface until the passing waves achieve optimal height and surfing wave shape. The bobber is moved by these surfing waves and the wave energy is converted to electricity using a regenerative braking system inside the base and power takeoff system in the base.

The SurfWEC system causes the bobber/float to move back and forth 10 to 30 meters per wave in average conditions (5 to 10 second period waves) where the bobbers in other existing WEC systems only move 1 to 3 meters per wave in identical offshore wave conditions.

Unlike the surfer near shore, where the surf ride is a one-way trip, this system sets up an oscillating motion between the bobber/float and base as the waves pass on their way towards shore. When the bobber/float has surfed as far as the wave can push it, the power takeoff (PTO) winch lines connected to the bobber are quickly rewound and pay out again as the bobber passes over the base heading towards the next incoming wave.

The biggest problem in WEC industry is that ocean waves are not easy to harness efficiently and safely. SurfWEC converts offshore seas and swell to surf waves in mild to moderate waves to address the efficiency issues and lowers itself near the seafloor to avoid damage from waves in storms to address the safety issues.

Once mild to moderate waves are converted to surf, the energy is concentrated over the base and the bobber can be moved forward and backward much farther per wave than in swell or seas. When storm waves begin impacting the bobber, the base automatically lowers itself near the seafloor, which gives the bobber/float more line to move and eliminates almost all of the wave energy impacting the base. The bobber can be flooded and lowered beneath the surface in less than 10 minutes to continue harnessing wave energy in extreme storms and raised back to the surface in less than 2 hours using bilge pumps after the storm passes.

SurfWEC is a practical and scalable technology as the components needed to produce and deploy the system are readily available. The materials, technologies, transportation, maintenance systems, and skilled labor force already exist. Multiple units, in ‘wave farms’, can meet the needs of a wide range of applications. In addition, when co-located with wind farms, the SurfWEC levelized cost of energy

(LCOE) is reduced by using shared transmission infrastructure, further amplifying the SurfWEC

design’s cost competitiveness. Unlike other WEC systems, SurfWEC units are designed to remain productive in severe storm conditions to reduce outages. In the most severe storm conditions, the SurfWEC platform can be retracted (submerged) on-site autonomously and remain fully operational.

Last but not least, the founding company holds the license to a patent that enables the production of energy for 80% of the time by utilizing a wave shoaling feature, projected to enable it to economically outperform existing utility-level wind and solar systems, which are productive for 50% and 30% of the time respectively.

IMPACT FOR SMALL ISLAND DEVELOPING STATES

Small Island Developing States (SIDS) are recognized as a distinct group of developing countries facing specific social, economic and environmental vulnerabilities. SIDS were recognized as a special case both for their environment and development at the United Nations Conference on Environment and Development (UNCED), also known as the Earth Summit, held in Rio de Janeiro, Brazil 3–14 June 1992. SIDS are spread over three geographical regions; including, the Caribbean region, the Pacific region, and the Atlantic - Indian Ocean - Mediterranean and South China Sea (AIMS) region. The Office of the High Representative for the Least Developed Countries, Landlocked Developing Countries and Small Island Developing States (UN-OHRLLS) has defined SIDS fossil-based energy dependence as a major source of economic vulnerability. This leads to an increased need for commercially-feasible options of energy supply, such as wind, solar, geothermal, biomass, and conventional hydro and ocean energy.

Climate change presents a unique challenge to Small Island Developing States (SIDS). It is argued that the difficulties that all countries face in effectively coping with climate change impacts are exacerbated in SIDS because of their small geographical area, isolation and exposure. UN-OHRLLS Office lead the voice of the international community calling for support for ‘research, development and utilization of renewable sources of energy and related technologies and improve the efficiency of existing technologies and end-use equipment based on conventional energy sources’

The 2030 Agenda for Sustainable development builds on the above considerations and stressing the importance of ensuring synergies with the SAMOA Pathway, a key request being the establishment of SIDS Partnership Framework – formally established in 2015.

On October 2, 2019 the island nation Barbados officially introduced its “Roadmap to 2030” energy sustainability plan which aims at a massive transformation to sustainable energy on the Island.

Figure 4 shows some of the features that makes Barbados a prime candidate for adoption of the SurfWEC technology and “renewable triad” approach to upgrading the power infrastructure.

Figure 4: A conceptual layout of a sustainable, expandable power triad producing an average of approximately 350 MW of electricity, including 150MW from SurfWEC units, about 1/3 to 1/2 of what is needed to currently power all of Barbados depending on seasonal/tourist variations

ECONOMIC IMPACT EXAMPLE OF SURFWEC-INTEGRATED WAVE ENERGY CONVERSION PROJECT FOR TWO SMALL ISLAND DEVELOPING STATES – TONGA AND JAMAICA

During wave tank testing at Stevens Institute of Technology (2004 -2011), it was determined the critical capability required to make wave energy conversion systems commercially-viable is the ability for the units to convert wavelength to wave height and generate a “two-body harmonic motion” in the process. The power conversion of the system depends on the oscillation range of the prime mover (red float in Fig 5.)

Figure 5. Typical oscillation distance (distance from the vertical center of the base in this photo) of a float in conditions where the wavelength has been converted to wave height (US Patent 8093736 “Shoaling Feature”). The red float is a 0.2 meter – high toroid that is 0.76 meter in diameter. The platform is 1.2 meters x 1.2 meters square and set a at 0.4-meter water depth level to the still water line. The spectral waves in this photo have a significant wave height of 0.1-meter and energy period of 2.25 seconds.

A video of this wave run is available at:

https://martinottaway.com/mraftery/approaches-to-replacing-fossil-fuels-with-ocean-wave-power/

From hundreds of wave-runs, it was determined the float would oscillate over the platform a significant portion of the wavelength.

The average tether payout distance per wave, in Figure 5, was calculated to be 24% of the wavelength based on the relative geometries of the float and platform size and the platform depth.

This range of motion corresponded to waves which were 50% of the height of the float. The range of motion, as a percentage of the wavelength, was determined to be directly proportional to the incident wave height approaching a magnitude of 33% of the wavelength with wave heights equal to or greater than the height of the float.

Dimensionless analysis, based on Froude scaling, is used to project performance of full-scale/prototype units at the locations of nine Small Island Developing States (SIDS) being approached for potential wave energy conversion project viability. Froude scaling is a well-proven engineering method for projecting full-scale performance from wave tank testing.

Ten countries which have been recommended for project analysis include; Antigua and Barbuda, Barbados, Fiji, Grenada, Jamaica, Maldives, Mauritius, Seychelles, Solomon Islands, and Tonga. A logical policy approach to consideration of wave energy conversion projects is to determine the project most likely to succeed based on the combination of factors including; wave climate, electricity rates, electricity demand (total project market), geotechnical/bathymetry (mooring and power cable requirements), historic extreme events (minimum storm-load avoidance depth), recreational, fishing, and historic area use conflicts/considerations, training/manufacturing/operations/maintenance/ capabilities of local population and infrastructure, and project scalability.

Preliminary work has been initiated to determine the commercial viability in Tonga based on the wave climate and electricity rates, of the nine countries the Global Partnership for Ocean Wave Energy Technology (GPOWET) was asked to assess, Tonga has one of the highest electricity rates on Earth as of January 2020:

https://www.worldatlas.com/articles/electricity-rates-around-the-world.html

At $0.47 US per kilowatt-hour, the GPOWET team considers Tonga as having one of the highest levels of “energy inequality”. Based on Froude scaling to full scale performance projections and an overall conversion efficiency of 25% based on performance of existing hydraulic regenerative braking systems, as used in the SurfWEC technology, real-time performance projections for Tongatapu, Tonga for 30 Jan 2020 are based on data from https://www.surf-forecast.com/regions/Tonga-Tongatapu and buoyweather.com :

Figure 6. Wave heights, in meters, projected for 30 Jan 2020 for Tongatapu, Tonga region from: https://www.surf-forecast.com/regions/Tonga-Tongatapu

A likely location for a 10-unit (60-megawatt (60MW) plate capacity project) would be off the western shore of Tongatapu (approximately 72,000 residents) in water depths of 50 to 100 meters south of the “Motels” recreational surfing location (gold star on the map). The projected wave heights in this region for 30 Jan 2020 are 0.8 meters and the wave periods are projected to be 8 seconds.

Figure 7. Numerical model of full-scale performance projections for a 10-unit wave energy conversion project off the western shore of Tongatapu, Tonga based on the shoaling feature of the SurfWEC technology which is capable of increasing the 0.8-meter-high incident waves to 1.55-meters-high before impacting the power takeoff float.

Based on the wave tank motion studies and 25% overall conversion efficiency, each unit would be outputting 1.16MW of electricity or 11.6MW output from a 10-unit project producing $5453 per hour in revenue at $0.47/kWh, approximately $47 million per year if this is the average wave condition (historical data is required to project a precise annual power output and corresponding revenue estimate). The projected annual operations and maintenance budget for the 10-unit project is $6 million (twice the US rate based on logistic expenses). This would leave $41 million to pay towards the estimated $200 million capital expenditure required for the project. The power production per year is expected to remain fairly constant with +/- 15 per cent variability and electricity rates are to be reduced over the life of the project. These projection numbers were based on the wave conditions during the time this paper was written. A data set of the daily wave climate has been processed for data from 15 February 2020 until 1 July 2020, and the average projected electricity for that time frame is approximately 2400 kilowatts or 2.4 megawatts which is more than twice the projected power production from the initial draft of this document in February 2020 or over $10,000 per hour at $0.47/kWh. The 2020 residential rate for Tonga is used as the starting point for the power purchase agreement as this is the rate the people of Tonga currently pay for electricity produced from fossil fuel resources. Once the capital expenses are paid off, and the main expenses are operations and maintenance, more units can be built by the people of Tonga to meet all power demands of the country and then distribute units to other islands in the region.

Figure 8. Electricity rates for 2023 – 2050 for a 60-megawatt, $200 million US, SurfWEC project for Tonga

If this near the average available wave power, then 10 units will provide and annual average electric power output of 10-megawatts which will be sufficient to cover the operation and maintenance expenses of the project with a power purchase agreement which reduces the cost of electricity for Tonga residents by 5% per year over the 20+ year project lifecycle until the electricity rate is established at an equitable rate relative to the national residential average in the United States of approximately $0.12/kWh. The data collected from February to July 2020 project to a total average 10 units project electricity output of 24-megawatts, more than twice the estimate from the short-term wave data set originally used during writing this document.

The highest levels of uncertainty are in the logistics and maintenance costs for the project. The performance projections have a high level of confidence as the hydrodynamics and other related physics involved in converting the power in ocean waves to on-demand electric power are well-understood. It is critical that long-term (annual, hourly) data is acquired to determine the available annual average wave power at any specific location as there is considerable amounts of variability based on exposure of the project to the open ocean. Daily wave climate data has now been collected and processed for Tonga from February to July 2020 with an updated projected average power output of 2400 kilowatts of electricity per individual unit.

Similar assessments are being performed for the other eight nations mentioned in this section.

At $0.45 US per kilowatt-hour, the GPOWET team considers Jamaica as having the second highest level of “energy inequality” of the countries we agreed to assess. The February to July 2020 wave climate data set projects average electricity production at 1500 kilowatts for a project in the north near Port Antonio and 2000 kilowatts for a project in the south near Kingston which increases projections from early estimates.

Figure 9. Wave heights, in meters, projected for 1 Feb 2020 for the Jamaica region of the Caribbean Sea

A likely location for a 250-unit (1,500-megawatt (1500MW) plate capacity project) would be off the southern shore of Jamaica in water depths of 50 to 100 meters south of Kingston (the gold star with the number “2” on the map). The projected wave heights in this region for 1 Feb 2020 are 1.0 meters and the wave periods are projected to be 6 seconds.

Figure 6. Numerical model of full-scale performance projections for a 250-unit wave energy conversion project off the southern shore of Jamaica based on the shoaling feature of the SurfWEC technology which is capable of increasing the 1.0-meter-high incident waves to 1.66-meters-high before impacting the power takeoff float.

Kingston has approximately 1,250,000 residents, so approximately the electrical load can be based on 250,000 homes at 1-kilowatt average use each for a 250 – megawatt load or the average output of approximately 250 SurfWEC units located offshore south of Kingston in 50-100 meters of water depth. This would be a much larger project than Tonga. The estimate for a 250-unit project off southern Jamaica is $3 billion which is less per unit ($2 per Watt of capacity vice $3.33 per Watt for Tonga) due to proximity to the United States which reduces logistic costs and uncertainty.

Figure 10. Electricity rates for 2023 – 2050 for a 1500-megawatt, $3 billion US, SurfWEC project for Jamaica

CONCLUSION

Addressing the 2030 Agenda for Sustainable Development, and the 17 Sustainable Development Goals (SDGs) with a specific focus on the sustainable use the ocean, seas and marine resources (SDG 14) involves focus on renewable power system development. Renewable power system development work bridges the policy-technology nexus by focusing on the ocean as the future locations of renewable power projects including Wave Energy Conversion technologies capable of performing at commercially-viable levels. Commercially-viable, zero-GHG-emissions technologies capable of utility-level electrical power generation from ocean waves will provide economic and social benefits for Small Island Developing States and other coastal communities.

-----

REFERENCES

1. Karaja, E, Fidrmuc, J & “Uncertainty, Informational Spillovers and Policy Reform: A gravity model approach” European Journal of Political Economy (2013)

2. Raftery, M.W. (2011) ‘Determining and Controlling Peak Energy Density Location During Water Wave Deformation’. Research Gate. DOI: 10.13140/

3. Raftery, M. W., & Jones, C. A. (2019). ‘The Use of Wave Focusing Technologies for Wave Energy Conversion Applications’ The Society of Naval Architects and Marine Engineers. Tacoma, Washington USA

4. Sandia. (2014) ‘Methodology for Design and Economic Analysis of Marine Energy Conversion (MEC) Technologies’ SAND2014-9040. Sandia National Laboratories, Water Power Technologies Department, Albuquerque, NM.

5. Small Island Developing States (2013) Office of the High Representative for the Least Developed Countries, Landlocked Developing Countries and Small Island Developing States (UN-OHRLLS)

6. Stakeholder Forum (2019 ‘The Global Partnership for Ocean Wave Energy Technology' (Concept Note, Stakeholder Forum for a Sustainable Future, New York, NY.

7. Tracking SDG7: The Energy Progress Report (2019) ©2019 International Bank for Reconstruction and Development / The World Bank

8. Van Hemmen, H. F., & Raftery, M. W. (2019). ‘An Update on Large Scale Wave Energy Conversion’ The Society of Naval Architects and Marine Engineers. Tacoma, Washington USA

9. Van Hemmen, H. F., & Raftery, M. W. (2018). ‘Is This the Right Time for Large Scale Wave Energy Conversion?’ The Society of Marine and Port Engineers, Joint Society Meeting, Newark, New Jersey USA

10. World Economic Situation and Prospects Report (2020); ©2020 United Nations, ISBN: 978-92-1-109181-6