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Credit: Josh Humbert

Electricity Generation

Wave and Tidal

Wave- and tidal-energy systems harness natural oceanic flows—among the most powerful and constant dynamics on earth—to generate electricity. A variety of companies, utilities, universities, and governments are working to realize the promise of consistent and predictable ocean energy, which currently accounts for a fraction of global electricity generation.

While the ocean’s perpetual power makes wave and tidal energy possible, it also creates obstacles. Operating in harsh and complex marine environments is a challenge—from designing systems to building installations to maintaining them over time. It is more expensive than producing electricity on solid ground.

Despite decades of work, marine technologies are still in early development and lag well behind solar and wind. Tidal energy is more established than wave, with more projects in operation today. Across the world, a variety of wave-energy technologies are being tested and honed, in pursuit of the ideal design for converting waves’ kinetic energy into electricity.

Wave and tidal energy is currently the most expensive of all renewables. Still, the opportunity of marine-based energy is massive. Proponents believe wave power could provide 25 percent of U.S. electricity, for example. Realizing it will require substantial investment and expanded research.

References

Yoshio Masuda…oscillating water column: Falcão, A.F.O. “Developments in Oscillating Water Column Wave Energy Converters and Air Turbines.” In Renewable Energies Offshore, edited by Guedes Soares. London: Taylor & Francis Group, 2015.

west coasts…wave activity: Lewis, A., S. Estefen, J. Huckerby, W. Musial, T. Pontes, and J. Torres-Martinez. “Ocean Energy.” In IPCC Special Report on Renewable Energy Sources and Climate Change Mitigation. Cambridge University Press, 2011.

[challenges of] operating in salt water: Lewis et al, “Ocean Energy.”

[potential supply] of U.S. electricity: Levitan, Dave. “Why Wave Power Has Lagged Far Behind as Energy Source.” Yale Environment 360. April 28, 2014.

[potential supply] in Australia: Parkinson, Giles. “New Generation Wave Energy: Could It Provide One Third of Australia’s Electricity?” The Guardian. November 30, 2015.

[potential supply] In Scotland: Levitan, “Wave Power.”

view all book references

Technical Summary

Wave and Tidal

Project Drawdown defines wave and tidal as: wave energy converters and tidal systems for electricity generation. This solution replaces conventional electricity-generating technologies such as coal, oil, and natural gas power plants.

This assessment focuses on three types of marine renewables: wave energy converters, tidal stream, and tidal barrage, together called wave and tidal. Wave energy converters are devices which convert the kinetic motion of ocean waves into electricity. Tidal stream energy can be tapped by using devices which act as underwater wind turbines, converting the flow of tidal currents into electricity. Tidal plants are large, utility-scale systems which direct the flow of tides through turbines to generate electricity, akin to hydropower electricity generation.

Of the many types of renewable energy, wave and tidal energy is arguably the most predictable. While the resource is spread out globally, there are only a few locations where wave and tidal energy can be harnessed commercially. The technologies used to convert marine energy to electricity are quite different. Tidal plants, which are more akin to large hydro plants, have replacement timeframes on the order of 40 years or more. On the other hand, wave energy converters only last a couple of decades. The capacity factor of these technologies also differs: tidal plants typically have a smaller capacity factor in the range of 22-28 percent, compared to 25-40 percent for wave energy converters and tidal stream. Similarly, the installation costs are quite different, with tidal plants having the lowest at US$5,500-6,000 per kilowatt.

Methodology

This analysis models wave energy converters and tidal systems for electricity generation.

Total Addressable Market [1]

The total addressable market for wave and tidal is based on projected global electricity generation in terawatt-hours from 2020-2050, with current adoption [2] being almost negligible: 0.95 terawatt-hours, representing only 0.004 percent of global electricity (IRENA, 2016).

Adoption Scenarios [3]

Impacts of increased adoption of wave and tidal from 2020-2050 were generated based on three growth scenarios, which were assessed in comparison to a Reference Scenario where the solution’s market share was fixed at the current levels. Future adoption of the Plausible and Drawdown Scenarios reflects an adoption pathway derived from recent long-term projection estimates from the Energy Technology Perspectives 2°C Scenario (IEA, 2016) and the Energy [R]evolution Scenario from Greenpeace (2015).

  • Plausible Scenario: This scenario follows a high-growth trajectory, capturing 2.86 percent of the market share in 2050 (1,486 terawatt-hours).
  • Drawdown Scenario: This scenario is aligned with the Greenpeace Advanced Energy [R]evolution Scenario [4] trajectory until 2050, reaching a 3.36 percent share of the global electricity generation market.
  • Optimum Scenario: This scenario is also aligned with the Greenpeace Advanced Energy [R]evolution Scenario trajectory until 2050, reaching a 3.51 percent share of the global electricity generation market.

Financial Model

The financial inputs used in the model assume an average installation cost of US$8,040 per kilowatt, [5] with a learning rate of 15.5 percent applied. That reduces the cost to US$2,039 per kilowatt in 2030 and to US$1,359 in 2050. This cost is evaluated in comparison to a weighted average of US$1,923 per kilowatt for the conventional technologies (i.e. coal, natural gas, and oil power plants) the solution is replacing. An average capacity factor of 30 percent is used for the solution, compared to 55 percent for conventional technologies. Variable operation and maintenance costs of US$0.115 per kilowatt-hour, and of US$72.5 per kilowatt for fixed operating costs, are considered for this solution, compared to US$0.005 per kilowatt-hour and US$33.0 per kilowatt, respectively, for the conventional technologies.

Integration [6]

Through the process of integrating wave and tidal with other solutions, the total addressable market for electricity generation technologies was adjusted to account for reduced demand resulting from the growth of more energy-efficient technologies, [7] as well as increased electrification from other solutions like electric vehicles and high-speed rail. Grid emissions factors were calculated based on the annual mix of different electricity generating technologies over time. Emissions factors for each technology were determined through a meta-analysis of multiple sources, accounting for direct and indirect emissions.

Results

The results for the Plausible Scenario show that the net first costs compared to the Reference Scenario would be US$411.84 billion from 2020-50, and over US$1 trillion in additional costs over the same period. Increasing the use of wave and tidal energy from the current figures to 2.86 percent of world electricity generation by 2050 would require an estimated US$981.88 billion in cumulative first costs. Under the Plausible Scenario, the adoption of wave and tidal could reduce 9.2 gigatons of carbon dioxide-equivalent greenhouse gas emissions from 2020-2050, compared to a Reference Scenario where the solution is not adopted.

Both the Drawdown and Optimum Scenarios are more ambitious in the growth of wave and tidal, with impacts on greenhouse gas emission reductions over 2020-2050 of 14.7 and 13.61 gigatons of carbon dioxide-equivalent, respectively.

Discussion

Given the relative immaturity of the wave and tidal industry, it is difficult to predict how it will develop over the next three decades. The uncertainty increases considering the small percentage of wave and tidal systems currently in the global electricity mix and the range of technologies under testing. Once operational, the low carbon footprint of wave and tidal systems makes them increasingly more attractive. Nevertheless, there are many technical, financial, and policy-related challenges which need to be overcome before these systems can be deployed at a large scale in the world. The fact that there are only a couple of utility-scale tidal barrage stations indicates that the deployment may need a big push from governments. Conversely, wave energy’s relative immaturity, coupled with the much shorter timescale on which it operates, is more akin to the early wind energy industry. Once engineers and scientists settle on a design, the market will congeal, prompting true competition and further adoption. The current situation with a smattering of wave and tidal technology designs means that widespread development and installation is still in a very early stage.


[1] For more about the Total Addressable Market for the Energy Sector, click the Sector Summary: Energy link below.

[2] Current adoption is defined as the amount of functional demand supplied by the solution in the base year of study. This study uses 2014 as the base year due to the availability of global adoption data for all Project Drawdown solutions evaluated.

[3] To learn more about Project Drawdown’s three growth scenarios, click the Scenarios link below. For information on Energy Sector-specific scenarios, click the Sector Summary: Energy link.

[4] It represents an ambitious pathway towards a fully decarbonized energy system in 2050 with significant additional efforts compared to the Energy [R]evolution Scenario. The Advanced Energy [R]evolution Scenario needs strong efforts to transform the energy systems of all world regions towards a 100 percent renewable energy supply.

[5] All monetary values are presented in US2014$.

[6] For more on Project Drawdown’s Energy Sector integration model, click the Sector Summary: Energy link below.

[7] For example: LED lighting, heat pumps.

Full models and technical reports coming in late 2017.

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